### FACT SHEET FO R NPDES PERMIT WA-002958-1 KING COUNTY SOUTH WAST EWATER TREATMENT PLANT September 30, 2009

PURPOSE of this Fact Sheet

This fact sheet explains and documents the d ecisions Ecology made in drafting the proposed National Pollutant Discharge Elimination Sy stem (NPDES) permit fo r King County’s South Wastewater Treatment Plant (South WWTP).

This fact sheet complies with Section 173-220- 060 of the Washington Administrative Code (WAC), which requires Ecology to prepare a draft permit and accompanying fact sheet for public evaluation before issuing an NPDES permit.

Ecology makes the draft permit and fact sheet available for public review and comment at least thirty (30) days before issuing the final permit. Copies of the fact sheet and draft permit for King County’s South WWTP NPDES permit WA-002958-1, were available for public review and comment from July 31, 2009, until September 18, 2009. For more details on preparing and filing comments about these documents, please see Appendix A—Public Involvement Information

. King County (County) reviewed the draft permit a nd fact sheet for factual accuracy. Ecology corrected any errors or omissions regarding th e facility’s location, hi story, discharges, or receiving water.

After the public comment period closed, Ecolog y included all comments received and provided responses to them. Ecology included the summary and responses to comments in this fact sheet

as Appendix J—Response to Comments , and published it when issuing the final NPDES permit. Ecology will not revise the rest of the fa ct sheet, but the full document will become part of the legal history contained in the facility’s permit file.

Mark Henley, P.E., municipal pe rmit manager, prepared the permit and this fact sheet.Fact Sheet for NPDES Permit WA-002958-1 Page 2 of 101 King County South Wastewater Treatment Plant

TABLE OF CONTENTS

I. EXECUTIVE SUMMARY .................................................................................................5 Dilution Factors .............................................................................................................. .....5 Effluent Limits ............................................................................................................... ......5 Sediment Monitoring ........................................................................................................... 6 Source Tracking ............................................................................................................... ....6 Priority Pollutant Testing .................................................................................................... .7 Receiving Water Characterization................................................................. 7 Nitrogen Reduction Study....................................................................................................7 INTRODUCTION.................................................................................... 8

II. BACKGROUND INFORMATION ....................................................................................9 Table 1. General Facility Information ...................................................................9 Figure 1. Vicinity Map - King County South WWTP ..........................................9 Figure 2. Aerial Photograph - King County South WWTP ................................10 A. Facility Description ................................................................................................10 History............................................................................................................10 Collection System Status .......................................................................................11 Table 2. Agencies Tributary to South WWTP ....................................................11 Figure 3. Average Monthly Flow and Total Monthly Rainfall ...........................12 Figure 4. Average Monthly Influent B OD and TSS Mass Loadings ..................13 Table 3. Current and Projected (2009-2014) In fluent Flow and Loadings .........13 Treatment Processes ...............................................................................................14 Figure 5. South WWTP – Simplified Process Flow Schematic ..........................14 Table 4. South WWTP Staffing ..........................................................................17 Discharge Outfalls .................................................................................................17 Residual Solids.......................................................................................................19 Reuse - Secondary Treated Effluent ......................................................................19 B. Permit Status ..........................................................................................................19 Table 5. Previous Permit’s Effluent Limits .........................................................20 C. Summary of Compliance W ith Previous Permit Issued on September 30, 2004 ..20 Table 6. Compliance With Efflue nt Permit Limits .............................................21 D. Wastewater Effluent, Whole Effluent Toxicity, and Sediment Characterizations ....................................................................................................21 Table 7. Wastewater Effluent Characterization ..................................................22 Whole Effluent Toxicity Testing ...........................................................................22 Table 8. Detected Chemicals Above or Approaching SQS Criteria ...................24 Figure 6. Sediment Sampling Locations from 1994-2001 .................................24 E. SEPA Compliance .................................................................................................25

III. PROPOSED PERMIT LIMITS .........................................................................................25 A. Design Criteria .......................................................................................................25 Table 9. Design Standards fo r King County South WWTP........................ 26 B. Technology-Based Effluent Limits ........................................................................26 Table 10. Technology-Based Limits. ..................................................................26Fact Sheet for NPDES Permit WA-002958-1 Page 3 of 101 King County South Wastewater Treatment Plant

C. Surface Water Quality-Based Effluent Limits .......................................................27 Numerical Criteria for the Protection of Aquatic Life and Recreation ..................27 Numerical Criteria for the Pr otection of Hu man Health ........................................27 Narrative Criteria ...................................................................................................27 Antidegradation ......................................................................................................28 Mixing Zones.................................................................................. 29 D. Designated Uses and Surface Water Quality Criteria ............................................33 Table 11. Aquatic Life Uses and Associated Criteria .........................................34 Table 12. Recreational Uses ................................................................................34 Table 13. Aquatic Life Uses & Associated Criteria ............................................35 Table 14. Recreational Uses and Associated Criteria .........................................35 E. Evaluation of Surface Water Quality-Bas ed Effluent Limits for Numeric Criteria ...................................................................................................................35 Puget Sound Outfall No. 001 .................................................................................35 Chronic Mixing Zone (Outfall 001) .......................................................................36 Acute Mixing Zone (Outfall 001) ..........................................................................36 Dilution Factors .....................................................................................................36 Table 15. Comparison of Dilution Ratios ...........................................................36 Table 16. Dilution Ratio for Outfall No. 001 ......................................................37 Table 17. Dilution Ratio - Green River Outfall No. 002 .....................................41 F. Whole Effluent Toxicity ........................................................................................42 G. Human Health ........................................................................................................43 H. Sediment Quality ...................................................................................................44 I. Ground Water Quality Limits ................................................................................45 J. Comparison of Effluent Limits W ith the Previous Permit Issued on September 30, 2004 ...............................................................................................45 Table 18. Comparison of Effluent Limits ...........................................................45

IV. MONITORING REQUIREMENTS ..................................................................................46 A. Lab Accreditation ...................................................................................................46

V. OTHER PERMIT CONDITIONS .....................................................................................47 A. Reporting and Record Keeping ..............................................................................47 B. Prevention of Facility Overloading ........................................................................47 C. Operation and Maintenance (O&M) ......................................................................47 D. Pretreatment ...........................................................................................................47 Duty to Enforce Discharge Prohibitions ................................................................47 E. Solid Waste Control ...............................................................................................48 F. Spill Plan ................................................................................................................48 G. Outfall Evaluation ..................................................................................................48 H. General Conditions ................................................................................................49

VI. PERMIT ISSUANCE PROCEDURES .............................................................................49 A. Permit Modifications .............................................................................................49 B. Proposed Permit Issuance ......................................................................................49

VII. REFERENCES FOR TEXT AND APPENDICES............................................................50Fact Sheet for NPDES Permit WA-002958-1 Page 4 of 101 King County South Wastewater Treatment Plant

APPENDIX A

— PUBLIC INVOLVEMENT INFORMATION ...................................................51

APPENDIX B

— GLOSSARY .......................................................................................................52

APPENDIX C

— SOUTH WWTP APPLICATION PR IORITY POLLUTANT DATA SUMMARY ....................................................................................................................... 56

APPENDIX D

— SOUTH WWTP DISCHARGE MONITORING REPORT SUMMARY TABLES ........................................................................................................................ ....60

APPENDIX E

— SOUTH WWTP DISCHARGE MONI TORING REPORT GRAPHS ..............63

APPENDIX F

— OUTFALL DIAGRAMS ....................................................................................69

APPENDIX G

— WHOLE EFFLUENT TOXICITY (WET) TESTING RESULTS .....................73

APPENDIX H

— TECHNICAL CALCULATIONS ......................................................................74 Table H-1: South WWTP – Water Quality Crit eria for Detected Pollutants ...............75 Table H-2: South WWTP – Ammonia Ca lculation Spreadsheet .................................76 Table H-3: South WWTP – Reasonable Potential to Exceed the Water Quality Standards ....................................................................................................77 Table H-4: South WWTP – Chlorine Limit to Meet Water Quality Limit ..................78 Table H-5: South WWTP – Reasonable Potential to Exceed Human Health Criteria .......................................................................................................79 Table H-6: South WWTP – Ambient Monitoring Data Summary ...............................81 Table H-7: South WWTP – Dilution Assessment for Temperature .............................82 Table H-8: South WWTP – Dilution Assessment for Fecal Coliform Bacteria ..........83 Table H-9: South WWTP – Assessment for Impacts to Dissolved Oxygen ................84 Table H-10: South WWTP – Assessment for pH ...........................................................85

APPENDIX I

— INDUSTRIAL DISCHARGERS TO COUNTY’S SOUTH WWTP ..................86

APPENDIX J

— RESPONSE TO COMMENTS ............................................................................87Fact Sheet for NPDES Permit WA-002958-1 Page 5 of 101 King County South Wastewater Treatment Plant



### I. EXECUTIVE SUMMARY

Washington State rules require that the owner of a municipal wastewater treatment plant (WWTP) obtain a National Pollutant Discharge Elimination System (N PDES) permit prior to discharging wastewater to State waters. Statutes, rules, and guidance are used to establish the discharge limitation for pollutants and other pe rmit requirements. Most NPDES permits are effective for five years and ma y be administratively extended.

King County’s Wastewater Treat ment Division owns and ope rates the South WWTP. King County applied for the renewal of their NPDE S permit for the South WWTP on March 30, 2009. Ecology prepared a draft permit and accompanying fact sheet and made it available for public comment on July 31, 2009.

The information below describes major changes from the previous permit (October 1, 2004 to September 30, 2009) to the proposed, renewed permit (November 1, 2009 to September 30, 2014).

Dilution Factors

Ecology provided a thorough review of the County’s data, dilution factors, and modeling in June 2009. Ecology verified that the County used conservative assumptions and provided rigorous modeling to obtain dilution factor s. The dilution ratios pred icted from the current modeling effort are substantially different (lower) from t hose predicted in the previous analysis, and are described in the table below. Ecology revised the dilution factors because the County 1) used new and improved computer models, 2) collected additional density profil e data; and 3) updated plant flow rates. Ecology cons iders the dilution factors in th e proposed permit more up-to-date and representative than the factors in the previous permit. Note that all of the dilution factors decreased (more restrictive) from the previous permit.
Comparison of Dilution Ratio

Outfall Chronic Mixing Zone Radius (feet) a Zone of Acute Criteria Exceedance (feet) a Proposed Chronic Dilution

Ratio Current Chronic Dilution

Ratio Proposed Acute Dilution

Ratio Current Acute Dilution

Ratio

South WWTP 825 82.5 225:1 429:1 186:1 233:1

a – as measured horizontally from each port

Effluent Limits

The following table compares the effluent limits from the previous permit to this final permit. The effluent limits for the South Wastewater Tr eatment Plant are unchanged from the previous permit because:

1. Washington State’s rule requiri ng secondary treatment limits for municipal WWTPs has not changed.Fact Sheet for NPDES Permit WA-002958-1 Page 6 of 101 King County South Wastewater Treatment Plant

2. South WWTP did not violate any of its effl uent parameters in the last 5 years.

3. The reasonable potential analysis did not indi cate that any priority pollutant or toxic pollutant in the South WWTP’s discharge had a reasonable potential to violate the water quality standards.

4. The whole effluent toxicity (WET) testing on fish indicated that the South WWTP’s discharge is unlikely to cause fish toxicity problems in Puget Sound.

For more specific information, please refer to the a dditional fact sheet inform ation that follows.
Comparison of Effluent Limits (South WWTP – Outfall 001)

Parameter Basis of Limit Previous Effluent Limits: Outfall # 001 Proposed Effluent Limits: Outfall # 001 Average Monthly Average Weekly Average Monthly Average Weekly Biochemical Oxygen Demand (5-day) Technology 30 mg/L, 36,000 lbs/day, 85% removal of influent BOD 45 mg/L, 54,000 lbs/day 30 mg/L, 36,000 lbs/day, 85% removal of influent BOD 45 mg/L, 54,000 lbs/day

Total Suspended Solids Technology 30 mg/L, 36,000 lbs/day, 85% removal of influent BOD 45 mg/L, 54,000 lbs/day 30 mg/L, 36,000 lbs/day, 85% removal of influent BOD 45 mg/L, 54,000 lbs/day

Fecal Coliform Bacteria Technology 200/1 00 mL 400/100 mL 200/100 mL 400/100 mL pH Technology Daily Minimum is equal to or greater than 6.0 and the daily maximum is less than or equal to 9.0 Daily Minimum is equal to or greater than 6.0 and the daily maximum is less than or equal to 9.0
Parameter Basis of Limit Previous Effluent Limits: Outfall # 001 Proposed Effluent Limits: Outfall # 001 Average Monthly Maximum Daily Average Monthly Maximum Daily
Total Residual Chlorine Guidance/TechnologyBased 0.5 mg/L 0.75 mg/L 0.5 mg/L 0.75 mg/L

Sediment Monitoring

The proposed permit requires King County to test mo re extensively for sediment toxicity in the vicinity of the South WWTP outfall than the previous permit. The proposed permit includes bioassays to be performed, if the chemical concentrations are near or above the numeric chemical criteria in the Sediment Management Standards.

Source Tracking

In order to more fully characterize industrial discharges into the County’s conveyance system and ultimately to South WWTP, the County must conduct pollutant analysis for metals, cyanide, phenols, volatile compounds, acid compounds, and base/neutral compounds of at least one industry in each of the metal- finishing/electroplating, centra lized waste treatment, plastic products, coil coating, and f ood processing categories.Fact Sheet for NPDES Permit WA-002958-1 Page 7 of 101 King County South Wastewater Treatment Plant
Priority Pollutant Testing

The previous permit included priority pollutant sampling once per year for the South WWTP effluent. This permit includes priority pollutant sampling twice per year.

Receiving Water Characterization

In the vicinity of the South WWTP outfall, the Pe rmittee must provide data via ambient monitoring stations or collect receiving wate r information via field sampling necessary to determine if the effluent has a reasonable poten tial to cause a violation of the water quality standards.

Nitrogen Reduction Study

Ecology has two studies underway to inform on the impacts of nutrient-laden discharges to Puget Sound. Ecology expects to complete the Sout h Sound Dissolved Oxygen Study along with the Puget Sound Hydrodynamic Modeling by December 2010.

Upon completion of both the South Puget Sound Dissolved Oxygen Study and Hydrodynamic Modeling, Ecology will determine whether the di scharge from King County’s South WWTP is significantly and quantifiably impacting dissolv ed oxygen levels in South Puget Sound. If Ecology concludes that there is a significant and quantifiable a dverse impact from the South WWTP discharge on dissolved oxygen in Sout h Puget Sound, then Ecology will require King County to submit a Nitrogen Reduction Study to evalua te feasible alternativ es to reduce nitrogen contributions from the South WWTP discharge.Fact Sheet for NPDES Permit WA-002958-1 Page 8 of 101 King County South Wastewater Treatment Plant

INTRODUCTION The Federal Clean Water Act (FCWA, 1972, a nd later amendments in 1977, 1981, and 1987) established water quality goals for the navigable (surface) waters of the United States. One mechanism for achieving the goals of the Clean Water Act is the National Pollutant Discharge Elimination System (NPDES), administered by the federal Environmental Protection Agency (EPA). The EPA authorized the State of Wash ington to manage the NPDES permit program in our state. Our state legislature accepted th e delegation and assigned the power and duty for conducting NPDES permitting and enforcement to Ecology. The legislature defined Ecology's authority and obligations for the wastewater discharge permit program in 90.48 RCW (Revised Code of Washington).

The following regulations apply to municipal NPDES permits:

• Procedures Ecology follows for issuing NPDES permits (Chapter 173-220 WAC)

• Technical criteria for discharges from municipal wast ewater treatment fa cilities (Chapter 173-221 WAC)

• Water quality criteria for surface waters (Chapter 173-201A WAC) and for ground waters (Chapter 173-200 WAC)

• Sediment management standa rds (Chapter 173-204 WAC)

• Submission of Plans and Reports for Construc tion of Wastewater Facilities (Chapter 173-240 WAC)

These rules require any treatment facility operato r to obtain an NPDES permit before discharging wastewater to state waters. They also help de fine the basis for limits on each discharge and for requirements imposed by the permit.

Under the NPDES permit program and in response to a complete and acce pted permit application, Ecology must prepare a draft permit and accompanyi ng fact sheet, and make them available for public review before final issuan ce. Ecology must also publish an announcement (public notice) telling people where they can read the draft pe rmit, and where to send their comments, during a period of thirty days (WAC 173-220-050). (See Appendix A—Public Involvement Information for more detail about the public notice and comment procedures). After th e public comment period ends, Ecology may make changes to the draf t NPDES permit. Ecology will summarize the responses to comments and any chan ges to the permit in Appendix J.Fact Sheet for NPDES Permit WA-002958-1 Page 9 of 101 King County South Wastewater Treatment Plant



### II. BACKGROUND INFORMATION

Table 1. General Facility Information

Applicant: King County Department of Natural Resources and Parks Wastewater Treatment Division 201 S. Jackson Street, MS KSC-NR-0500 Seattle, WA 98104-3855 Facility Name and Address: King County South Wastewater Treatment Plant 1200 Monster Road SW Renton, WA 98057 Type of Treatment: Secondary Treatment, Activated Sludge Discharge Location: Puget Sound North Diffuser South Diffuser Latitude: 47 ° 36' 10" N 47 ° 35' 59" N Longitude: 122 ° 25' 44.4" W 122 ° 25' 44.5" W Emergency/Maintenance (Green River) Latitude: 47 ° 28' 03" N Longitude: 122 ° 14' 39" W

Figure 1. Vicinity Map - King County South Wastewater Treatment PlantFact Sheet for NPDES Permit WA-002958-1 Page 10 of 101 King County South Wastewater Treatment Plant

Figure 2. Aerial Photograph - King Co unty South Wastewater Treatment Plant

A. Facility Description

History In 1958, voters in Seattle and King County create d Metro, an agency charged with creating a regional wastewater conveyance and treatmen t system. The South Wastewater Treatment Plant (South WWTP) located in Renton is often referred to by County staff as the South Treatment Plant (STP). Metro completed cons truction of the plant in 1965. The original plant had the capacity to treat 24 million gallons per day (MGD) of wastewater to secondary treatment levels using an activated sludge bi ological process. The third, and latest, expansion of the plant began in 1991 and was considered complete in 2000-2001. This last upgrade brings the plant desi gn capacity to 144 MGD maximum month flow (MMF). In 2003, the County replaced the 90-ton railcar ch lorine system with an interim sodium hypochlorite (12.5% NaOCl solution) disinfection facility. The City of Renton required the County to remove gaseous chlorine from th e South WWTP site. The County is currently constructing a permanent sodium hypochlorite di sinfection facility and plans completion in 2010. In 2005, the solids dewatering facility was expanded by replac ing eight belt filter presses (50-gpm each) with th ree high-solids centrifuges (350-gpm capacity each). The South Wastewater Treatment Plant is design ated as an EPA major facility due to the magnitude of its daily discharge volume.Fact Sheet for NPDES Permit WA-002958-1 Page 11 of 101 King County South Wastewater Treatment Plant
Collection System Status

The South Wastewater Treatment Plant serves an area of 152 square miles. King County owns and operates the major sewer interceptors and pump stations that carry the wastewater to the treatment plant. The component agencies (tabulated below) individually own, operate, and maintain the pipelines and other conveyance faci lities that carry wastew ater to the County’s interceptors. Wastewater is c onveyed to the treatment plant via three intercepto rs, the Tukwila Interceptor, the South Interceptor, and the Eastsi de Interceptor and by the 26 pump stations in the system. The County monitors and controls the collection system using a SCADA (Supervisory Control and Data Acquisition) system located at the South Wastewater Treatment Plant.

The South Wastewater Treatment Plant serves 25 jurisdictions and utility districts as noted in the County’s 2009 NPDES permit applic ation and as listed below.
Table 2. Agencies Tributary to South WWTP Agencies Cities Sewer/Utility Districts Other Algona Cedar River Water And Sewer District Muckleshoot Indian Tribe Auburn Coal Creek Utility District Shorewood Apartments Bellevue Lakehaven Utility District Black Diamond Northeast Sammamish Sewer And Water District Issaquah Northshore Utility District Kent Sammamish Plateau Water And Sewer District Kirkland Seattle Public Utilities Mercer Island Skyway Water And Sewer District Pacific Soos Creek Water And Sewer District Redmond Valley View Sewer District Renton Tukwila



### CSO Status All component agencies that provide flow to th e South Wastewater Treatm ent Plant are separated sanitary systems with the exception of a small portion (approximately 4%) of the Seattle system that is a combined system. The South Wastew ater Treatment Plant will continue to treat a portion of the flow from the He nderson CSO and Martin Luther King (MLK) diversion structure combined systems during the term of this permit. During heavy rain events, King County’s West Point Treatment Plant treats some of the flow . The MLK/Henderson/Norf olk project provides a tunnel for the storage and primary sedimentati on of flows from Henders on, Martin Luther King, and Norfolk CSOs. During small rain events, th e tunnel stores CSO flows for transfer to the South Wastewater Treatment Plant for secondary tr eatment. During the largest storms and when the tunnel fills, any flows that exceed the capac ity of the tunnel storage will be treated and disinfected and discharged th rough the existing Norfolk CSO (which is included in King County’s West Point Treatment Plant Permit).


### Flow Blending During the previous permit cycle, Ecology au thorized King County’s South Wastewater Treatment Plant to utilize flow blending to ma nage peak flow events. The South WWTP had twelve blending events between October 2004 and February 2009. In all of the twelve blendingFact Sheet for NPDES Permit WA-002958-1 Page 12 of 101 King County South Wastewater Treatment Plant
events, the County initiated blending only after solids started to wash out of the secondary process or when secondary flows were notab ly above 190-200 MGD. According to King County staff, blending proved successful at reduci ng the washout of secondary solids from the secondary clarifiers. There is no formally-adopted policy for flow blending in federal or state regulations at the writ ing of this permit. This permit does not authorize the use of flow blending, but rather relies on the bypass provisi on in Special Condition S5 of the permit to address any bypassing of treatment units.



### Inflow and Infiltration The King County Council has approved the Regiona l Infiltration/Inflow (I/I) Control Program as part of its Regional Wastewater Services Plan (RWSP). It is the first comprehensive investigation of I/I in the local agency servi ce areas and is based on a cooperative partnership between King County and the 34 local agencies serving the Seattle Metropolitan area.



### Flow and Waste Load King County submitted, with the application for permit renewal and as required by the previous permit, a Flow and Waste Load Asse ssment. The graphs below show the hydraulic and organic loading to the South Wastewater Treatment Plant from October 2004 through December 2008 as based on data submitted in the DMRs.

Figure 3. Average Monthly Flow and Total Monthly Rainfall Per Figure 3, the highest average monthly fl ow for the time period October 2004 – December 2008 was 133 MGD in January 2006. It was the resu lt of the second wettest January on record (11.65-inches) which followed a very wet second half of December 2005. The 133 MGD monthly flow is the highest monthly flow ever recorded at South WWTP. In fact, the 30-day running average reached 138 MGD (on January 22, 2006). This 30-day running average is only 6-mgd short of South WWTP’s ma ximum monthly flow capacity of 144-mgd. South WWTP met all of its effluent limits in January 2006 in spite of the heavy rainfall. South Plant Flow and Rain 2004 - 2008

40 60 80 100 120 140 160 180 200 220 240Jan-04Jan-05Jan-06Jan-07Jan-08Jan-09Flow, MGD

0 4 8 12 16 20 24 28 32 36 40Rainfall, inches (month total) Flow, month avg Flow, max-day Rain, month totalFact Sheet for NPDES Permit WA-002958-1 Page 13 of 101 King County South Wastewater Treatment Plant

Figure 4. Average Monthly Influent BOD and TSS Mass Loadings
The maximum-month average TSS load during the last five years was 208,000 TSS lbs/day, which occurred in December 2004 and January 2005. The maximum month average TSS load of 208,000 lbs/day is 88% of the design maxi mum month loading. The maximum month BOD loading of 214,000 lbs/day oc curred in January 2009, when the treatment plant received a large amount of deicer waste.


### Capacity Analysis Table 3 summarizes South WWTP’s design capacity and its current and projected flow and loadings through 2014. The County projected that all of the flows and loads between 2009 and 2014 will be below South WWTP’s current design cap acity assuming an average growth rate of 1.5% to 1.8% per annum. Brightwater Wastewater Treatment Plant is schedul ed to start operations in 2011, which will reduce South WWTP’s annual flow and loads by about 8%, and its wet weather flow and loads by 15%. Thus, the largest flows and loads over the next five years are projected to occur in 2010 and 2011 (i.e., just before the Brig htwater Plant starts op eration in 2011).

Table 3. Current and Projected (2009-2014 ) Influent Flow and Loadings

Parameter Design Capacity 2004-09 Max Projected 2010-11 Projected 2014 Flow Average Wet Weather, MGD 115 102 105 93 Flow Max Month, MGD 144 133 138 121 BOD Max Month Load, lbs/day 251,000 214,000 221,500 188,000 TSS Max Month Load, lbs/day 235,000 208,000 215,100 182,000 South WWTP Influent Loads Monthly Avg. BOD and TSS

75,000 100,000 125,000 150,000 175,000 200,000 225,000

Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09Influent Loads, lbs/day TSS

BODFact Sheet for NPDES Permit WA-002958-1 Page 14 of 101 King County South Wastewater Treatment Plant

Treatment Processes

Figure 5. South Wastewater Treatment Plant – Simplified Process Flow SchematicFact Sheet for NPDES Permit WA-002958-1 Page 15 of 101 King County South Wastewater Treatment Plant



### Headworks The raw sewage can flow through eight bar sc reens to remove rags and plastics. The screenings are conveyed down a trough to th e grinder pumps. The ground screenings are cleaned and dewatered in prepara tion for disposal at a landfill. The raw (influent) pumps lift the wastewater 40 feet to a division cha nnel providing for gravity flow through the remaining treatment processes. The wastewater flows through the aerated grit channels to allow for grit to settle out. The grit is pumpe d to the cyclones, discharged to the classifiers, and then into dumpsters.


### Primary Treatment The division channel splits flow between a north set of 4 primar y clarifiers and south set of 8 primary clarifiers. The north clarifiers use re turn flights and tipping troughs to capture and remove scum and grease. The south clarifie rs use surface water spray to move scum and grease to a helical screw located at the upstream end of the tank; the return flights stay submerged on the south primaries. The primary clarifier effluent overf lows via launders with submerged orifices. The launders saw-tooth weirs allow it to handle higher flows. Primary effluent flows by gravity to the aeration tanks . Primary sludge is continuously pumped from the bottom of the clarifiers to the dissolved ai r floatation tanks (DAFTs) for further treatment.


### Secondary Treatment Secondary treatment is accomplished using an ac tivated sludge process. There are 4 aeration basins with fine bubble diffusers used for air distribution. The first part of each aeration basin is anaerobic when operati ng in the selector mode. Operators adjust the dissolved oxygen and sludge age to achieve a settable slud ge. The aeration basin effluent flows from the aeration basins to the mixed liquor channel before distribution to the secondary clarifiers. There are 6 secondary clarifie r pods each with 4 clarifiers for a total of 24 secondary clarifiers. Each pod has an effluent contro l center (ECC) where flow and turbidity are monitored. Pumps return the solids that settle out in the secondary cl arifiers back to the aeration basins as return activ ated sludge (RAS) or pump them to solids handling as waste activated sludge (WAS).



### Disinfection and Effluent Beginning in June 2003, the facility converted to sodium hypochlorite for disinfection in order to eliminate handling of chlorine gas. Hypochlorite is added at several locations along the chlorine contact channels. The chlorinated effluent flows through the chlorine contact channel to the forebay tank located before the effluent pumps. The effluent pumps discharge the treated wastewater from the fo rebay to the plant’s Puget Sound outfall located 12 miles away off a point of land north of Alki . The outfall terminates 10,000 feet off shore and is 625 feet deep (refer to Appendix F). A dditionally, the effluent can flow by gravity to the outfall during low flow conditions.



### Water Reclamation This facility produces Class A water for reuse fr om a small portion of the plant’s flow. Plant operators use the chlorinated effluent water, refe rred to as C3 water, internally throughout the process in addition to feeding the water reclamation process. The Class A water treatmentFact Sheet for NPDES Permit WA-002958-1 Page 16 of 101 King County South Wastewater Treatment Plant
process includes the required tr eatment steps of coagulation and filtration. The coagulant, currently a polyaluminum chlorhydrate product (P AC), is added to C3 water and mixed via an inline static mixer. The water th en flows through Parkson DynaSand ® continuously back flushing sand filters. The filtered effluent is disinfected with hypochlorite through a series of three contact tanks.

The plant designers set up the control logic for the reuse facility so that high turbidity (>3 NTU) or low total residual chlorine detected in the water will automatically valve the off-specification water back to the treatment plant headworks. Only water meeting the Class A specifications flows into the 500,000-gallon reuse water storage tank. In addition to supplying the off-site customers by pipeline, the facility allows customers to load reuse water in truck mounted storage tanks for off-site use. Ecology permits water distribution from the reclamation facilities under a se parate Reclaimed Water Permit.


### Solids Handling Solids from the primary clarifiers, WAS from the secondary clarifiers, and scum are pumped to the DAFTs. The DAFTs (4 older tanks, 2 ne w larger tanks) thicken the sludge. Inside these tanks, a mixture of sludge, polymer, and air fo rm a thick layer of sludge that floats to the surface. A scraper arm controls the thickness of the floating sludge blanket and moves solids out of the DAFT to the Thickened Sludge Blen ding Tank. The water layer below the sludge blanket in the DAFT is pumped to the aeration tanks. The thin sludge layer that forms on the bottom of the DAFT is pumped to grit cyclones for degritting and sent back to the DAFTS for reprocessing.

The contents of the thickened sludge blendi ng tank are pumped on leve l control to 1 of 4 anaerobic digesters. Operators collect daily process control samp les of the digester sludge. The digested sludge is transferred to the 5 th digester that serves as th e blended sludge storage tank. Polymer is added as a coagulant to the sludge as it is pumped from th e blended sludge storage tanks to the centrifuges. Th e centrifuges produce a biosolids product that is about 20-25% solids. The biosolids are hauled to beneficial reuse sites in Eastern Washington (agriculture applications), and Western Washington (fores t applications and commercial composting).



### Odor Control
Odor control consists of a c ouple different air scrubbing system s. Chemical scrubbers use caustic and hypochlorite solutions to control odors from the secondary treatment area, the primary treatment area, the sludge thickeners , and the dewatering ar ea. Carbon scrubbers control odors in the sludge thickening and dewatering areas. In addition, the facility maintains a biofilter to control odors on th e influent interceptor collection system.


### Emergency Backup Power The facility’s two independent power feeders to the plant prov ide redundancy. In addition, an emergency generator powers essential services, for example, lighting, alarms, security, etc., although it is not sufficient to power the influent pumps or other plant processes. An 8-Mega Watt (MW) cogeneration facility is also located on-site. It consists of two 3.5-MW gas turbine generators and a 1-MW st eam turbine generator. The c ogeneration facility is fueled by pipeline natural gas or scrubbed dige ster gas produced at the South WWTP.Fact Sheet for NPDES Permit WA-002958-1 Page 17 of 101 King County South Wastewater Treatment Plant



### Industrial and Commercial Users Ecology delegated King County the authority to run a Pretreatment Program. The South Wastewater Treatment Plant’s application for permit renewal lists a total of 65 industrial user discharges received by the treatment plan t. There are 27 Signi ficant Industrial Users (SIUs) and 38 Categorical Industrial Users (CIU s). Please refer to Appendix I for a list of the industrial users.


### Staffing Currently, the South WWTP employs 142 full- time employees (FTEs). The 142 FTEs provide service to not on ly the South WWTP and its off-site pump stations, but also to the treatment facilities for the C ity of Carnation, Vashon Island, and Buelah Cove and Park. The plant is staffed 24 hours per day with 12- hour shifts. Operators monitor and control critical plant operations from a central cont rol room using a distri buted control system (DCS). A supervisory control and data acqui sition (SCADA) system is used to monitor off-site pump stati ons and facilities.

Table 4. South WWTP Staffing

Work Group Est. FTEs Responsibilities Shift Crew (4 shifts, 6 FTE per shift) 24 Operations

Day Operations Crew 14 Assist with pl ant operations, training, special projects, and backfill for shift crews. Process Control Crew 11 Permit compliance issues, sampling, lab analysis, reporting, data handling, pr ocess setpoints, etc. Pump-run crew 11 Operation of off-site pump stations and treatment systems.
Maintenance Staff 36 Electricians and Instrument Technicians and Mechanics. Other 37 Administration, Purchasing & Inventory, Building and Grounds Maintenance, Engineering & As-Builts, Technical Publications, etc.



### Future Construction Plans The facility is currently converting a temporar y sodium hypochlorite system to a permanent system. The County is not plan ning any other major projects at the plant during the upcoming permit cycle.

Discharge Outfalls


### Puget Sound Outfall 001 Secondary treated and disinfected effluent is discharged from the facility via a 12-mile long 8-foot diameter transfer line. The outfall consists of two pipelines, each extending over 10,000 feet northwest into Elliot Bay from Duwamish Head. For nearshore protection, the initial portion is supporte d by legs and the remainder of the outfall rests along the seafloor in a shallow trench. An outfall junc tion structure is located at the end of the effluent transferFact Sheet for NPDES Permit WA-002958-1 Page 18 of 101 King County South Wastewater Treatment Plant
system (ETS) force main just west of Luna Park in West Seattle. The structure contains a 64-inch diameter manifold connecting the 96-inch ETS to the two 64-inch outfall lines. The diffuser sections are on the final 500-ft of each leg. Each diffuser has 168-sweep radius diffuser ports, each 14 inches long and 4 inches in diameter. (This a total of 336 diffuser ports with a total diffuser opening of 336 * 0.087 ft 2 /port = 29.32 ft 2 .) The diffusers are staggered side-to-side every 3 feet. Each diffuser port is ma de of a copper-nickel alloy to inhibit bio-fouling. The diffu sers are about 625 feet deep. The County inspected the marine outfall in 2004-2005. The extensive inspection concluded that all external components of the outfalls and associated structures appeared in good condition with no evidence of damage. Howeve r, the inspection report noted that many spans of the pipeline were unsupported, particul arly in the steep sl oping areas. Also, the report noted that sediments have buried signi ficant portions of both pipelines since its installation. King County submitted video f ootage of the inspection along with the inspection report. Appendix F diagrams show the location of the marine outfall and the emergency outfall described in the next section.


### Green River Outfall (Maintenance & Emergency Purposes Only)
The Green River outfall was the South WWTP’ s sole discharge point prior to the construction of the marine outfall in 1987. Th e County increased the firm capacity (total capacity with one pump out of service) of the e ffluent transfer system (ETS), which carries flow to the marine outfall, to 325 MGD with the pumping system upgrade in 1999. With all pumps running, the predicted capacity is 340-360 MGD (depending on the tide). The proposed permit authorizes the treatment plan t to discharge to the Green River during emergencies and for maintenance purposes only.

An emergency discharge is an unplanned and unavoidable discharge which is necessary to prevent sewage overflows or damage to the pl ant. Emergency discha rges may occur during a severe, heavy rain event when the flow exceed s the capacity of the ETS, or in the extreme event that the ETS loses significant capacity due to multiple equipment failures or power failure.

Maintenance discharges are perf ormed periodically to ensure that the outfall will function normally during an emergency event. During a maintenance discharge, the County uses a sufficient flow rate of disinf ected and dechlorinated effluent to flush sediment from the diffuser ports. The proposed permit specifically authorizes discharges to the Green River for maintenance purposes.

The diffuser is a 12-foot by 12-foot structure that is 44 feet long extending into the river. There are 8 discharge ports located on the downs tream side of the diffuser. The top of each port is at the elevation of the river bottom.

During the last permit cycle, no maintenance act ivities were performed on the Green River Outfall and therefore, no effluent wa s discharged to the Green River.Fact Sheet for NPDES Permit WA-002958-1 Page 19 of 101 King County South Wastewater Treatment Plant

Residual Solids

The treatment facilities remove solids duri ng the treatment of the wastewater at the headworks (grit and screenings), and at the prim ary and secondary clarifiers, in addition to incidental solids (rags, scum, and other debris ) removed as part of the routine maintenance of the equipment. Grit, rags, scum, and scre enings are drained and disposed of as solid waste at a landfill. Primary and waste seconda ry sludge are co-thickened in the Dissolved Air Floatation Tanks. The thickened sludge is fed to the anaerobic, mesophilic digesters, which are maintained at 35-38 °C. The County blends and stores dige sted sludge in a tank followed by dewatering with centrifuges to produ ce biosolids. The biosolids are applied to forest and agriculture lands under a permit from the King County Health Department.
The County periodically analyzes the bioso lids for various chemical contaminants. Regulatory and compliance issues regarding bi osolids are managed by the Department of Ecology’s Biosolids Program.

Reuse - Secondary Treated Effluent
A separate state Reclaimed Water Permit covers the existing water reclamation facility, the distribution of the Class A wate r it produces, and any future sec ondary effluent that is not returned to the ETS (effluent transfer syst em). The proposed NPDES permit regulates all direct discharges of treated s econdary effluent that ultimatel y return the treated secondary effluent back to the ETS for discharge via the Puget Sound outfall.
The proposed NPDES permit (Conditions S16) aut horizes the County to distribute effluent from the ETS to Boeing for a specifically-identif ied use and allows it to distribute effluent for similar uses provided it receives written a pproval from both Ecology and the Department of Health. Following use the effluent discharges back to the ETS. Departmental approval is required for each application of direct reuse to ensure that such use does not cause a violation of the state water quality standards. The intent of the NPDES permit is to allow the Permittee flexibility to provide noncontac t reuse water to customers with sufficient safeguards to ensure that the water quality standards are not violated.
At the time of the writing of the permit, King County had one customer using treated secondary effluent in this manner. The Boei ng Company uses secondary treated effluent in a closed-loop chiller system primarily during the summer mo nths at the Boeing Training Center located in Renton, Wash ington. King County is permitt ed to enlist other customers located along the ETS corridor for noncontact use of the seconda ry treated effluent with return to the ETS for discharg e at the Puget Sound Outfall.

B. Permit Status
Ecology issued the previous permit for this facility on September 30, 2004. The previous permit placed effluent limits on 5-day Biochemical Oxygen Demand (BOD 5 ), Total Suspended Solids (TSS), pH, Fecal Colifor m Bacteria, and Total Residual Chlorine.
King County submitted an application for permit renewal on March 31, 2009. Ecology accepted it as complete on April 14, 2009.Fact Sheet for NPDES Permit WA-002958-1 Page 20 of 101 King County South Wastewater Treatment Plant
The effluent limits in the previous permit are as follows.

Table 5. Previous Permit’s Effluent Limits

EFFLUENT LIMITS a : OUTFALL # 1 Paramete r A vera g e Monthl y Avera g e Weekl y Biochemical Oxygen Demand b (BOD 5 ) 30 mg/L, 36,000 lb/day 85% minimum removal 45 mg/L, 54,000 lb/day

Total Suspended Solids b 30 mg/L, 36,000 lb/day 85% minimum removal 45 mg/L, 54,000 lb/day

Fecal Coliform Bacteria 200/100 mL 400/100 mL pH c Daily minimum is equal to or greater than 6.0 and the daily maximum is less than or equal to 9.0.
Paramete r A vera g e Monthl y Maximum Dail y d Total Residual Chlorine 0.5 mg/L, 600 lb/day 0.75 mg/L
Footnotes:

a The average monthly and weekly effluent limits are based on the arithmetic mean of the samples

taken with the exception of fecal colifor m, which is based on the geometric mean.

b The average monthly effluent concentration for BOD 5 shall not exceed 30 mg/L or 15 percent of the

respective monthly average influent concent rations, whichever is more stringent. The average monthly effluent concentration for TSS shall not exceed 30 mg/L or 15 percent of the

respective monthly average influent concentrations, whichever is more stringent.

c Indicates the range of permitted values. When pH is continuously monitored, excursions between

5.0 and 6.0, or 9.0 and 10.0 shall not be consider ed violations provided no single excursion exceeds 60 minutes in length and total excursions do not exceed 7 hours and 30 minutes per month. Any excursions below 5.0 and above 10.0 are violati ons. The instantaneous maximum and minimum pH shall be reported monthly.

d The maximum daily effluent concentration determined from a continuous measurement is calculated

as the average of the pollutant conc entrations measured over the day.

C. Summary of Compliance With Previous Permit Issued on September 30, 2004
Ecology staff last conducted a sampling compliance inspection on April 14-15, 2008. A compliance inspection report was issued on Ma y 21, 2008. The inspectors found the facility to be operating in accordance with th e permit and found no violations.
King County has complied with the effluent limits throughout the duration of the permit issued on September 30, 2004. Ecology assesse d compliance based on its review of the facility’s discharge monitoring reports (DMR s) and on inspections conducted by Ecology.
The County submits two discharge monitoring reports (DMRs) each month, one for the treatment plant discharge and one for the reclai med water discharge during months in which off-site use occurs. The following table summar izes the effluent DMR data (discharge No. 001) submitted from September 2004 to December 2008. Ecology permits the reclaimed water system under Reclaimed Water Permit ST- 7445 and its compliance record is described in the associated fact sheet. Appendix D pr ovides a complete summary of monthly DMR data submitted by the Permittee from September 2004 to April 2009.Fact Sheet for NPDES Permit WA-002958-1 Page 21 of 101 King County South Wastewater Treatment Plant
Table 6. Compliance With Effluent Permit Limits September 2004 – December 2008

Parameters Average Max Min Permit Limits
BOD 5 – lbs/d, Monthly Avg. 10,397 19,843 4,293 ≤ 36,000 BOD 5 – lbs/d, Max. Weekly Avg. 13,114 29,360 4,800 ≤ 54,000 BOD 5 – mg/L, Monthly Avg. 16 25 9 ≤ 30 BOD 5 – mg/L, Max. Weekly Avg. 19 30 10 ≤ 45 TSS – lbs/d, Monthly Avg. TSS 11,360 32,357 4,388 ≤ 36,000 TSS – lbs/d, Max. Weekly Avg. 15,157 50,971 4,999 ≤ 54,000 TSS – mg/L, Monthly Avg. 17 30 8 ≤ 30 TSS – mg/L, Max. Weekly Avg. 21 41 9 ≤ 45 Fecal Coliforms, no./100 mL, Monthly 74 170 17 ≤ 200
pH - Daily Low 6.7 7.4 6.0 ≥ 6.0 pH - Daily High 7.4 9.8 a 6.8 ≤ 9.0 Cl2 Residual – mg/L, Monthly Avg. 0.04 0.29 0.00 ≤ 0.5 Cl2 Residual – mg/L, Max. Daily 0.09 0.75 0.00 ≤ 0.75 Cl2 Residual – lb/d, Monthly Avg. 20 231 0 ≤ 600 BOD Removal - %, Monthly Avg. 93 96 86 ≥ 85 TSS Removal - %, Monthly Avg. 93 97 85 ≥ 85 Flow - mgd, Monthly Avg. 76 133 45 b NA Source: NPDES Permit Application.

a The County reports that the pH value of 9.8 is an artifact of hypochlorite dosing the final effluent

sample line. The County believes that the maximum pH value is likely closer to pH 7.5. The hypochlorite dosing is necessary to keep nitrifying bacteria from growing and seeding the final effluent sample. Their presence in the sample will artificially increase the effluent BOD result.

b The County reports that the minimum flow of 45-mgd is artificially low by 6-10 mgd. This low flow

occurred during the summer of 2008 when cali bration of the flow meters was changed.
On November 7, 2008, the wastewater treatme nt plant had an una uthorized, secondary bypass of approximately 1,000 to 2,000 gallons. Primary effluent was unintentionally conveyed to the chlorine cont act channel during preventative maintenance activities on the diversion gates. The County has since modifi ed operational procedures to prevent this incident from reoccurring.

D. Wastewater Effluent, Whole Effluent T oxicity, and Sediment Characterizations
The concentration of pollutants in the discha rge was reported in the NPDES application and in discharge monitoring reports. Table 7 summ arizes those pollutants that the County found in detectable quantitie s as reported in the NPDES form 2A application. Calculations show that none of these pollutants have the potential to exceed the state water quality standard at the edge of the chronic mixing zone based on the reasonable potential calculations provided in Appendix H.Fact Sheet for NPDES Permit WA-002958-1 Page 22 of 101 King County South Wastewater Treatment Plant

Table 7. Wastewater Effluent Characterization

Max. Daily Discharge Average Daily Discharge
POLLUTANT Conc. Units Mass Units Conc. Units Mass Units # of Samples ML/ MDL Antimony 0.67 ug/L 0.45 lbs/d <0.51 ug/L <0.30 lbs/d 32 0.5 Arsenic 1.60 ug/L 1.17 lbs/d 1.26 ug/L 0.76 lbs/d 34 0.5 Cadmium 0.30 ug/L 0.17 lbs/d <0.11 ug/L <0.064 lbs/d 32 0.1 Chromium 4.07 ug/L 2.28 lbs/d 0.87 ug/L 0.51 lbs/d 32 0.4 Copper 42.4 ug/L 24.01 lbs/d 16.5 ug/L 9.51 lbs/d 32 0.4 Lead 2.00 ug/L 1.12 lbs/d 0. 66 ug/L 0.38 lbs/d 32 0.2 Mercury 0.058 ug/L 0.045 lbs/d <0.05 ug/L <0.03 lbs/d 33 0.05 Nickel 4.45 ug/L 2.34 lbs/d 2.99 ug/L 1.78 lbs/d 33 0.3 Silver 0.84 ug/L 0.48 lbs/d <0.35 ug/L <0.21 lbs/d 32 0.2 Zinc 68.0 ug/L 38.5 lbs/d 29. 0 ug/L 17.4 lbs/d 33 0.5 Cyanide 0.028 mg/L 14.61 lbs/d <0.008 mg/L <5.09 lbs/d 33 0.005
Total Phenolic Compounds 0.080 mg/L 47.2 lbs/d <0.011 mg/L <6.55 lbs/d 24 0.005- 0.02 Chloroform 2.18 ug/L 1,565 lbs/d <1.32 ug/L <0.802 lbs/d 23 1.32 Methylene Chloride 7 ug/L 4.16 lbs/d <4.74 ug/L <2.74 lbs/d 23 5 Toluene 3.86 ug/L 1.845 lbs/d <1.45 ug/L <0.78 lbs/d 23 4 1,4-dichlorobenzene 3.93 ug/L 2.82 lbs/d <1.21 ug/L <1.21 lbs/d 15 0.57- 0.6

Whole Effluent Toxicity Testing The County conducted acute and chronic toxici ty tests in February 2008, April 2008, July 2008, August 2008, and October 2008. Acute toxicity tests were conducted with Daphnia pulex (water flea) and Pimephales prom elas (fathead minnow). Chroni c toxicity tests were conducted with Atherinops affinis (topsmelt) and Mysidops is bahia (Mysid Shrimp). Please refer to Appendix G for toxicity test results.

For acute toxicity, the performance standard is th e median survival in 100% effluent being equal to or greater than 80% and no individual test result showing less than 65% survival in 100% effluent. For the above tests, the median surviv al in 100% effluent was 90%. No individual test resulted in less than 65% survival in 100% effl uent. Since the discharge met the performance standard for acute toxicity in the previous permit cycle, the pr oposed permit does not include an acute WET limit and instead includes another effl uent characterization for acute WET to ensure that toxicity has not increased.

For chronic toxicity, the perfor mance standard is no chronic t oxicity test demonstrating a statistically-significant difference in response between the control and a test concentration equal to the acute critical effluent concentration (ACEC) . South WWTP had no chronic toxicity near the previous AC EC of 0.43% effluent in any recent test. No chronic WET limit is needed. The proposed permit includes the same set of chronic tests at the end of the new permit term for submissi on with the application.Fact Sheet for NPDES Permit WA-002958-1 Page 23 of 101 King County South Wastewater Treatment Plant



### Sediment Characterization Ecology has promulgated sediment manageme nt standards under Chapter 173-204 WAC. The sediment management standards contain nu meric chemical and biological criteria that protect benthic organisms that live in the sedi ment of the marine waters of Puget Sound. These standards state that Ecology may require pe rmitted facilities to evaluate the potential for the discharge to cause a viol ation of applicable standards.

In November 2001, King County performed sedime nt sampling from 0 to 2 cm depth at 13 sample locations near the two marine outfalls. Sediment samp les were analyzed for the 47 chemicals with numeric criteria in the sediment management standards. All samples met the sediment quality standards (SQS) numeric criteria. One sample (RT625SD) had a bis(2-ethylhexyl) phthal ate concentration of 43 ppm, comp ared to the SQS criteria of 47 ppm. All other samples had bis(2-ethylhexyl) phthalate concentrations below 10 ppm. Five samples had detection limits for 2-methylpheno l that were slightly above the sediment quality standards criteria, but were not detected in the sediment nor in the effluent. Most of the 47 chemicals were not present at dete ctable levels. The County measured low concentrations of PAH, phthala tes and metals in the sediment, but they were below the numeric criteria for benthic toxicity. 1

In October 1999, King County performed sediment sampling from 0 to 2 cm depth at 13 sample locations near the two outfalls. Se diment samples were analyzed for the 47 chemicals with numeric criteria in the sedime nt management standards. The County did not detect the following four chemicals (2,4-dime thyl phenol, 2-methylphe nol, benzyl alcohol, and hexachlorobutadiene), but most of the sa mples had reported detection limits above the sediment quality standards numeric criteria. Most of the other 47 chemicals were not present at detectable levels below the SQS numeric criter ia. The County measured low concentrations of PAHs, PCBs, phthalates, and metals in the sediment, but they were below the numeric criteria for benthic toxicity. 2

Between 1994 and 1997, King County performed annual sediment sampling from 0 to 2 cm depth at locations ne ar the two outfalls. 3 In October 1997, the County measured concentrations of hexachlorobenzene at th ree locations (RT700NS, RT625ND, RT625SD) that exceeded the sediment quality standards numeric criteria. In October 1995, one location (LSDS02) exceeded CSL numeric criteria fo r benzoic acid. One sample, RT625SD, had bis(2-ethylhexyl) phthal ate concentration of 42 ppm, comp ared to the SQS criteria of 47
ppm. 4 For four chemicals (1,2,4-trichlorobenzene, benzyl alcohol, hexachlorobenzene, and hexachlorobutadiene) many of the samples ha d non-detect concentr ations with reported detection limits above the sediment qua lity standard numeric criteria.

Table 8 shows chemicals detected in sediment samples that approach or exceed the SQS criteria. Figure 6 shows the loca tions of the sampling stations.

1 EIM Data User Study ID RENT01
2 EIM Data User Study ID RENT99
3 EIM Data User Study ID RENT9497
4 Total organic carbon normalized. Sediment Management Standards WAC 173-204-320.Fact Sheet for NPDES Permit WA-002958-1 Page 24 of 101 King County South Wastewater Treatment Plant

Table 8. Detected Chemicals Ab ove or Approaching SQS Criteria

Sampling

Station Sampling Year Chemical Detected in Sediments Sediment Concentration Criteria

RT625SD 2001 Bis(2-ethylhexyl)phthalate 43 ppm OC normalized 47 ppm OC normalized RT625SD 1997 Bis(2-ethylhexyl)phthalate 42 ppm OC normalized RT625SD 1997 Hexachlorobenzene 1.9 ppm OC normalized 0.38 ppm OC normalized RT700NS 1997 Hexachlorobenzene 2.5 ppm OC normalized RT625ND 1997 Hexachlorobenzene 0.95 ppm OC normalized LSDS02 1995 Benzoic acid 1500 ppb dry weight 650 ppb dry weight

Figure 6. Sediment Sampling Locations from 1994-2001Fact Sheet for NPDES Permit WA-002958-1 Page 25 of 101 King County South Wastewater Treatment Plant
In summary, past sediment monitoring does not indicate sediment toxicity or a violation of the sediment management standards at this site. The proposed permit includes additional sediment monitoring to ensure continued compliance because of the large volume of discharge, some past instances of detecti on limits above the SQS numeric criteria, and 1997 concentrations in the chemical analyses of sediments above SQS near the site.

E. SEPA Compliance
Regulation exempts reissuance or modification of any wastewater discharge permit from the SEPA process as long as the permit contains cond itions that are no less stringent than state rules and regulations. The exemption applies only to existing discharges, not to new discharges.



### III. PROPOSED PERMIT LIMITS
Federal and state regulations requ ire that effluent limits in an NPDES permit must be either technology- or water quality-based.

• Technology-based limits are based upon the treat ment methods availabl e to treat specific pollutants. Technology-based limits are set by the EPA and published as a regulation, or Ecology develops the limit on a case-by-case ba sis (40 CFR 125.3, and Chapter 173-220 WAC).

• Water quality-based limits are calculated so that the effluent will comply with the surface water quality standards (Chapter 173-201A WAC), ground water standa rds (Chapter 173-200 WAC), sediment quality standards (Chapter 173- 204 WAC), or the National Toxics Rule (40 CFR 131.36).

• Ecology must apply the most stringent of thes e limits to each parameter of concern. These limits are described below.
The limits in this permit reflect information receive d in the application and from supporting reports (engineering, hydrogeology, etc.). Ecology evalua ted the permit application and determined the limits needed to comply with the rules adopted by the state of Washi ngton. Ecology does not develop effluent limits fo r all reported pollutants

. Some pollutants are not treatable at the concentrations reported, are not c ontrollable at the source, are not listed in regul ation, and do not have a reasonable potential to cau se a water quality violation.
Nor does Ecology usually develop limits for pollu tants that were not reported in the permit application but that may be present in the discharg e. The permit does not authorize discharge of the non-reported pollutants. If significa nt changes occur in any constitu ent of the effluent discharge, King County is required to notify Ecology [40 CFR 122.42(a)]. King County may be in violation of the permit until Ecology modifies the permit to reflect additional discharge of pollutants.

A. Design Criteria
Under WAC 173-220-150 (1)(g), fl ows and waste loadings must not exceed approved design criteria. Ecology-approved design criteria for this facility’s tr eatment plant were obtained from the August 1991 Facilities Plan (Metro’s Regional Treatment Plant in Renton, Enlargement III Program) and the October 1997 East Division Reclamation Plant Stage 2 Liquid Stream Improvements – III2B.1. Both documents were prepared by Brown and Caldwell Consultants and associated firms.Fact Sheet for NPDES Permit WA-002958-1 Page 26 of 101 King County South Wastewater Treatment Plant
Table 9: Design Standards for Kin g County South Wastewater Treatment Plant

Parameter Design Quantity Monthly average flow (max. month) 144 MGD Monthly average dry weather flow (AWDF) 96 MGD Monthly average wet weather flow (AWWF) 115 MGD Instantaneous peak flow 325 MGD
Maximum Month BOD 5 influent loading 251,000 lb/day Maximum Month TSS influent loading 235,000 lb/day Design population equivalent 1,298,000

B. Technology-Based Effluent Limits
Federal and state regulations de fine technology-based effluent lim its for municipal wastewater treatment plants. These effluent limits are gi ven in 40 CFR Part 133 (federal) and in Chapter 173-221 WAC (state). These regulations are perf ormance standards that constitute all known, available, and reasonable methods of prev ention, control, and treatment (AKART) for municipal wastewater.
Chapter 173-221 WAC lists the following techno logy-based limits for pH, fecal coliform, BOD 5 , and TSS:

Table 10. Technology-Based Limits

Parameter Limit pH The pH must measure within th e range of 6 to 9 standard units. Fecal Coliform Bacteria Monthly Ge ometric Mean = 200 organisms/100 mL Weekly Geometric Mean = 400 organisms/100 mL
BOD 5 (concentration) Average Monthly Limit is the most stringent of the following: - 30 mg/L - may not exceed fifteen percent (15%) of the average influent concentration Average Weekly Limit = 45 mg/L
TSS (concentration) Average Monthly Limit is the most stringent of the following: - 30 mg/L - may not exceed fifteen percent (15%) of the average influent concentration Average Weekly Limit = 45 mg/L Chlorine Average Monthly Limit = 0.5 mg/L Average Weekly Limit = 0.75 mg/L
Ecology derived the technology-ba sed monthly average limit for chlorine from standard operating practices. The Water Pollution Cont rol Federation's Chlori nation of Wastewater (1976) states that a properly designed and maintained wast ewater treatment plant can achieve adequate disinfection if a 0.5 mg/L chlorine residual is maintained after fifteen minutes of contact time. See also Metcalf and Eddy, Wastewater Engineering, Treatment,Fact Sheet for NPDES Permit WA-002958-1 Page 27 of 101 King County South Wastewater Treatment Plant
Disposal and Reuse, Third Edition, 1991. A treatment plant that provides adequate chlorination contact time can meet the 0.5 mg/L chlorine limit on a monthly average basis. According to WAC 173-221-030(11)(b), the corresponding weekly average is 0.75 mg/L.
The existing permit has chlorine limits of 0.5 mg/L (average monthly) and 0.75 mg/L (maximum daily), and the facili ty is able to comply with it. The proposed permit includes the same limit.
The technology-based mass limits are based on WAC 173-220-130(3)(b) and 173-221-030(11)(b).
Monthly effluent mass loadings (lbs/day) = maximum monthly desi gn flow (144 MGD) x Concentration limit (30 mg/L) x 8.34 (conve rsion factor) = ma ss limit 36,000 lb/day.
Average weekly effluent mass lo adings (lbs/day) = maximum m onthly design flow (144 MGD) x Concentration limit (45 mg/L) x 8.34 (conve rsion factor) = ma ss limit 54,000 lb/day

. C. Surface Water Quality-Based Effluent Limits
The Washington State surface water quality standards (Chapter 173-201A WAC) are designed to protect existing wate r quality and preserve the bene ficial uses of Washington's surface waters. Waste discharge permits must in clude conditions that ensure the discharge will meet the surface water qua lity standards (WAC 173-201A- 510). Water quality-based effluent limits may be based on an individua l waste load allocation or on a waste load allocation developed during a basin wide total maximum daily load study (TMDL).

Numerical Criteria for the Protection of Aquatic Life and Recreation Numerical water quality criteria are listed in the water quality standards for surface waters (Chapter 173-201A WAC). They specify the maximum levels of pollutants allowed in receiving water to protect aquatic life and re creation in and on the water. Ecology uses numerical criteria along with ch emical and physical data for the wastewater and receiving water to derive the effluent limits in the discharge permit. When surface water quality-based limits are more stringent or pot entially more stringent than technology-based limits, the discharge must meet the water quality-based limits.

Numerical Criteria for the Prot ection of Human Health
The U.S. EPA has published 91 numeric water qu ality criteria for the protection of human health that are applicable to dischargers in Washington St ate (EPA, 1992). These criteria are designed to protect humans from exposur e to pollutants linked to cancer and other diseases, based on consuming fish and shellfis h and drinking contaminated surface waters. The water quality standards also include radionu clide criteria to prot ect humans from the effects of radioactive substances.

Narrative Criteria
Narrative water quality criteria (e.g., WAC 173-201A-240(1); 2006) limit the toxic, radioactive, or other deleterious material concentrations that the facility may discharge to levels below those which have the potential to:Fact Sheet for NPDES Permit WA-002958-1 Page 28 of 101 King County South Wastewater Treatment Plant

• Adversely affect desi gnated water uses.

• Cause acute or chronic toxicity to biota.

• Impair aesthetic values.

• Adversely affect human health.
Narrative criteria protect the specific designated uses of a ll fresh waters (WAC 173-201A-200, 2006) and of all marine waters (WAC 173- 201A-210, 2006) in the state of Washington.

Antidegradation The purpose of Washington's Antidegradation Policy (WAC 173-201A-300- 330; 2006) is to:

• Restore and maintain the highest possible qu ality of the surface waters of Washington.

• Describe situations under which water quality may be lowered from its current condition.

• Apply to human activities that are likely to have an impact on the water quality of surface water.

• Ensure that all human activities likely to cont ribute to a lowering of water quality, at a minimum, apply all known, available, and reasonable methods of prevention, control, and treatment (AKART).

• Apply three tiers of protection (described be low) for surface waters of the state.

Tier I ensures existing and designated uses are main tained and protected and applies to all waters and all sources of pollutions. Ti er II ensures that waters of a higher quality th an the criteria assigned are not degraded unless such lowering of water quality is necessary and in the overriding public interest. Tier II applies only to a specific list of polluting activities. Tier III prevents the degradation of waters formally liste d as "outstanding resource waters," and applies to all sources of pollution.

A facility must prepare a Tier II analysis when all three of the follo wing conditions are met:

• The facility is planning a new or expanded action.

• Ecology regulates or au thorizes the action.

• The action has the potential to cause measurab le degradation to ex isting water quality at the edge of a chronic mixing zone.

This facility must meet Tier I requirements.

• Dischargers must maintain and protect exis ting and designated uses. Ecology must not allow any degradation that will interfere with, or become injurious to, existing or designated uses, except as provided for in Chapter 173-201A WAC.Fact Sheet for NPDES Permit WA-002958-1 Page 29 of 101 King County South Wastewater Treatment Plant
Ecology’s analysis described in th is section of the fact sheet demonstrates that the existing and designated uses of the receiving water wi ll be protected under the conditions of the proposed permit.

Mixing Zones A mixing zone is the defined area in the recei ving water surrounding th e discharge port(s), where wastewater mixes with receiving wa ter. Within mixing zones the pollutant concentrations may exceed water quality numeric standards, so long as the discharge does not interfere with designated uses of the recei ving water body (for example, recreation, water supply, and aquatic life and wildlife habitat, etc.) The pollutant concentrations outside of the mixing zones must meet water quality numeric standards.
State and federal rules allow mixing zones becau se the concentrations and effects of most pollutants diminish rapidly after discharge, due to dilution. Ecol ogy defines mixing zone sizes to limit the amount of time any exposur e to the end-of-pipe discharge could harm water quality, plants, or fish.
The state’s water quality standard s allow Ecology to authorize mi xing zones for the facility’s permitted wastewater discharges only if those discharges already receive all known, available, and reasonable methods of prevention, cont rol, and treatment ( AKART). Mixing zones typically require compliance with water quality criteria within a specified distance from the point of discharge and use no more than 25% of the available width of the water body for dilution. Ecology uses modeling to estimate th e amount of mixing with in the mixing zone. Through modeling Ecology determines the potential for violating the water quality standards at the edge of the mixing zone and derive any neces sary effluent limits. Steady-state models are the most frequently used tools for conducting mixing zone analyses. Ecology chooses values for each effluent and for receiving water variab les that correspond to th e time period when the most critical condition is likely to occur (see Ecology’s Permit Writer’s Manual ). Each critical condition parameter, by itself, has a low probabi lity of occurrence and the resulting dilution factor is conservative. The term “reas onable worst-case” applies to these values.
The mixing zone analysis produces a numerical value called a dilu tion factor (DF). A dilution factor represents the amount of mixing of effluent and receiv ing water that occurs at the boundary of the mixing zone. For example, a dilu tion factor of 10 means the effluent is 10% and the receiving water is 90% of the total volum e of water at the boundary of the mixing zone. Ecology uses dilution factors with the water quality criteria to calculate reasonable potentials and effluent limits. Water quality standards in clude both aquatic life-ba sed criteria and human health-based criteria. The former are applie d at both the acute and chronic mixing zone boundaries; the latter are a pplied only at the chronic boundary. The concentration of pollutants at the boundaries of any of these mixing zones ma y not exceed the numerical criteria for that

zone.
Each aquatic life acute criteri on is based on the assumption that organisms are not exposed to that concentration for more than one hour and more often than one exposure in three years. Each aquatic life chr onic criterion is based on the a ssumption that organisms are not exposed to that concentration for more than f our consecutive days and more often than once in three years.Fact Sheet for NPDES Permit WA-002958-1 Page 30 of 101 King County South Wastewater Treatment Plant

The two types of human health-based water quality criteria dis tinguish between those pollutants linked to non-cancer e ffects (non-carcinogenic) and t hose linked to cancer effects (carcinogenic). The human health-based water quality criteria incorpor ate several exposure and risk assumptions. These assumptions include:

• A 70-year lifetime of daily exposures.

• An ingestion rate for fish or shellfish measured in kg/day.

• An ingestion rate of two liters/day for drinking water

• A one-in-one-million cancer risk for carcinogenic chemicals.

This permit authorizes an acute mixing z one, surrounded by a chronic mixing zone around the point of discharge (WAC 173-201A-400). The water quality standards impose certain conditions before allowing the discharger a mixing zone:

1. Ecology must specify both the allowe d size and location in a permit.
The proposed permit specifies the size a nd location of the a llowed mixing zone.

2. The facility must fully apply “all know n, available, and reasonable methods of prevention, control and treatmen t” (AKART) to its discharge.
Ecology has determined that the treatm ent provided at King County’s South WWTP meets the requirements of AKART (see “Technology-Based Limits”).

3. Ecology must consider criti cal discharge conditions.
Surface water quality-based limits are derived for the waterbody’s critical condition (the receiving water and waste disc harge condition with the highest potential for adverse impact on the aquatic biota, human health, and exis ting or designated waterbody uses). The critical discharge condition is often pollutant-specific or waterbody-specific.

Critical discharge conditions are those conditions that resu lt in reduced dilution or increased effect of the pollutant. Factors a ffecting dilution include the depth of water, the density stratification in the water column, the currents, and the rate of discharge. Density stratification is determined by the salinity and temperature of the receiving water. Temperatures are warmer in the su rface waters in summer. Therefore, density stratification is generally greatest during the summer months. Density stratification affects how far up in the water column a fr eshwater plume may rise. The rate of mixing is greatest when an effl uent is rising. The effluent stops rising when the mixed effluent is the same density as the surroundi ng water. After the effluent stops rising, the rate of mixing is much more gradual. Water depth can affect dilution when a plume might rise to the surface when there is little or no stratification. Ecology uses the water depth at mean lower low water (MLL W) for marine waters. Ecology’s Permit Writer’s Manual describes additional guidance on crite ria/design conditions for determining dilution factors. The manual can be obtained from Ecology’s website at: http://www.ecy.wa.gov/biblio/92109.html

.Fact Sheet for NPDES Permit WA-002958-1 Page 31 of 101 King County South Wastewater Treatment Plant

Ecology used the following critical c onditions to model the discharge:

• Water depth at MLLW of 625 feet.

• 50 th percentile current speed s of 0.069 m/sec for chronic and human health mixing zones (at Station 46, depth = 191 m).

• 10 th or 90 th percentile current sp eeds of 0.021 and 0.14 m/s ec, respectively for acute mixing zone (at Station 46, depth = 191 m)

• Maximum average monthly effluent fl ow of 144 MGD for chronic and human health non-carcinogen.

• Annual average flow of 106 MGD for human health carcinogen.

• Maximum daily flow of 235 million gallons per day (MGD) for acute mixing zone.

• 1 DAD MAX Effluent temper ature of 22.2 degrees C.

Ambient data at critical conditions in the vi cinity of the outfall was taken from Effluent Dilution Modeling for South Wastewater Tr eatment Plant Outfall study conducted in March 2009.

4. Supporting information must clearly i ndicate the mixing zone would not:

• Have a reasonable potential to cause the lo ss of sensitive or important habitat.

• Substantially interfere with the exis ting or characteristic uses.

• Result in damage to the ecosystem.

• Adversely affect public health.
Ecology established Washington State water qua lity criteria for toxic chemicals using EPA criteria. EPA developed the criteria us ing toxicity tests with numerous organisms and set the criteria to generally protect th e species tested and to fully protect all commercially- and recreationally -important species.

EPA sets acute criteria for toxic chemical s assuming organisms are exposed to the pollutant at the criteria concentration for one hour. They set chronic standards assuming organisms are exposed to the pollutant at th e criteria concentration for four days. Dilution modeling under critical conditions ge nerally shows that both acute and chronic criteria concentrations are reached wi thin minutes of being discharged.
The discharge plume does not impact dr ifting and non-strong swimming organisms because they cannot stay in the plume clos e to the outfall long enough to be affected. Strong swimming fish could maintain a positi on within the plume, but they can also avoid the discharge by swimming away. Mixi ng zones generally do not affect benthic organisms (bottom dwellers) because the buoyant plume rises in the water column. Ecology has additionally determin ed that the effluent will not exceed 33 degrees C for more than two seconds after discharge; and that the temperature of the water will not create lethal conditions or bl ockages to fish migration.Fact Sheet for NPDES Permit WA-002958-1 Page 32 of 101 King County South Wastewater Treatment Plant

Ecology evaluates the cumulative toxicity of an effluent by testing the discharge with whole effluent toxic ity (WET) testing.

Ecology reviewed the above information, the sp ecific information on the characteristics of the discharge, the receivi ng water characteristics, and the discharge location. Based on this review, Ecology concluded that th e discharge does not have a reasonable potential to cause the loss of sensitive or im portant habitat, substantially interfere with existing or characteristics uses, result in da mage to the ecosystem, or adversely affect public health if the permit limits are met.

5. The discharge/receiving water mixture must not exceed water quality criteria outside the boundary of a mixing zone.
Ecology conducted a reasonable potential analysis, using pr ocedures established by the EPA and by Ecology, for each pollutant and c oncluded the discharge/receiving water mixture will not violate wate r quality criteria outside the boundary of the mixing zone if permit limits are met.

6. The size of the mixing zone and the co ncentrations of the pollutants must be minimized.
At any given time, the effluent plume us es only a portion of the acute and chronic mixing zone, which minimizes the volume of water involved in mixing. Because tidal currents change direction, the plume orientat ion within the mixing zone changes. The plume rises through the water column as it mixe s, therefore much of the receiving water volume at lower depths in the mixing zone is not mixed with di scharge. Similarly, because the discharge may stop rising at some depth due to density stratification, waters above that depth will not mix with the disc harge. Ecology determined it is impractical to specify in the permit the actual, much more limited volume in which the dilution occurs as the plume rises and moves with the current.
Ecology minimizes the size of mixing zones by requiring dischargers to install diffusers when they are appropriate to the discharg e and the specific re ceiving waterbody. When a diffuser is installed, the discharge is more completely mixed with the receiving water in a shorter time. Ecology also minimizes th e size of the mixing zone (in the form of the dilution factor) using desi gn criteria with a low probabi lity of occurrence. For example, Ecology uses the expected 95 th percentile pollutant concentration, the 90 th percentile background con centration, the centerline diluti on factor, and the lowest flow occurring once in every ten years to perf orm the reasonable potential analysis.
Because of the above reasons, Ecology has e ffectively minimized the size of the mixing zone authorized in the proposed permit.

7. Maximum size of mixing zone.
The authorized mixing zone does not exceed the maximum size restriction.Fact Sheet for NPDES Permit WA-002958-1 Page 33 of 101 King County South Wastewater Treatment Plant

8. Acute Mixing Zone.

• The discharge/receiving water mixture mu st comply with acute criteria as near to the point of discharg e as practicably attainable. Ecology determined the acute criteria will be met at 10% of the distance of the chronic mixing zone at the ten-year low flow.

• The pollutant concentration, duration, and frequency of exposure to the discharge will not create a barrier to migr ation or translocation of indigenous organisms to a degree that has the potent ial to cause damage to the ecosystem. As described above, the toxicity of any pollutant depends upon the exposure, the pollutant concentration, and the time the orga nism is exposed to that concentration. Authorizing a limited acute mixing zone for this discharge assures that it will not create a barrier to migration. The effluent from this discharge will rise as it enters the receiving water, assuring that the rising effluent will not ca use translocation of indigenous organisms near the point of discharge (below the rising effluent).

• Comply with size restrictions. The mixing zone authorized for this disc harge complies with the size restrictions published in Chapter 173-201A WAC.

9. Overlap of Mixing Zones.
For the marine discharge, please see Appe ndix F for acute and chronic mixing zones diagrams. South WWTP’s mixing zones do not overlap another discharger’s mixing zones

. For the Green River outfall, the mixing zone cannot extend more than 310 feet downstream and more than 100 feet upstream from the diffusers. The mixing zone cannot utilize greater than 25 percent of the flow and cannot occupy greater than 25 percent of the width of the river.

D. Designated Uses and Su rface Water Quality Criteria
Applicable designated uses and surface water qu ality criteria are defined in Chapter 173-201A WAC. In addition, the U.S. EPA set human heal th criteria for toxic pollutants (EPA 1992). Criteria applicable to this facility’s disc harge are summarized belo w in Tables 11 - 14.

Marine Water Discharge (Outfall 001) :

• Aquatic life uses are designated using the following ge neral categories. All indigenous fish and non-fish aquatic species must be protected in waters of the state.

(a) Extraordinary quality salmonid and other fish migr ation, rearing, and spawning; clam, oyster, and mussel rearing and spaw ning; crustaceans and other shellfish (crabs, shrimp, crayfish, scall ops, etc.) rearing and spawning.Fact Sheet for NPDES Permit WA-002958-1 Page 34 of 101 King County South Wastewater Treatment Plant
(b) Excellent quality salmonid and other fish migra tion, rearing, and spawning; clam, oyster, and mussel rearing and spawning; crustaceans and other shellfish (crabs, shrimp, crayfish, scallops, etc.) rearing and spawning.

(c) Good quality salmonid migration and rearing; ot her fish migration, rearing, and spawning; clam, oyster, and mussel reari ng and spawning; crustaceans and other shellfish (crabs, shrimp, crayfish, s callops, etc.) rearing and spawning.

(d) Fair quality salmonid and other fish migration.

The South WWTP’s outfall discharges to Puget Sound at a location that is classified as extraordinary marine waters. The Aquatic Life Uses and associated criteria for extraordinary marine waters are identified below.

Table 11. Aquatic Life Us es and Associated Criteria
Extraordinary quality Temperature Criteria – Highest 1D MAX 13°C (55.4°F) Dissolved Oxygen Criteria – Lowest 1-Day Minimum 7.0 mg/L

Turbidity Criteria • 5 NTU over background when the background is 50 NTU or less; or • A 10 percent increase in turbidity when the

background turbidity is more than 50 NTU. pH Criteria pH must be within the range of 7.0 to 8.5 with a human-caused variation within the above range of less than 0.2 units.

• To protect shellfish harvesting , fecal coliform organism levels must not exceed a geometric mean value of 14 colonies/100 mL, and not have more than 10 percent of all samples (or any single sample when less than ten sample points exist) obtained for calculating the geometric mean value exceeding 43 colonies/100 mL.

• The recreational uses are primary contact recreation and secondary contact recreation.

For the South WWTP’s discharge to Puget Sound, the recreational uses for this receiving water are identified as primary contact, as shown below.

Table 12. Recreational Uses

Recreational use Criteria Primary Contact Recreation Fecal coliform organism levels must not exceed a geometric mean value of 14 colonies/100 mL, with not more than 10 percent of all samples (or any single sample when less than ten sample points exist) obtained for calculating the geometric mean value exceeding 43 colonies/100 mL.

• The miscellaneous marine water uses are wildlife habitat, harvesting, commerce and navigation, boating, and aesthetics.Fact Sheet for NPDES Permit WA-002958-1 Page 35 of 101 King County South Wastewater Treatment Plant
Freshwater Discharge (Maintenance & Emergency Outfall):

• Aquatic Life Uses are designated based on th e presence of, or the intent to provide protection for, the key uses. All indigenous fish and non-fish aquatic species must be protected in waters of the st ate in addition to the key speci es. The Aquatic Life Uses for the Green River at the Emergency Outfall location are identified below.

Table 13. Aquatic Life Uses & Associated Criteria

Salmonid Spawning, Rearing, and Migration Temperature Criteria – Highest 7DAD MAX 17.5°C (63.5°F) Dissolved Oxygen Criteria – Lowest 1-Day Minimum 8.0 mg/L

Turbidity Criteria • 5 NTU over background when the background is 50 NTU or less; or • A 10 percent increase in turbidity when the

background turbidity is more than 50 NTU. Total Dissolved Gas Criteria Total diss olved gas shall not exceed 110 percent of saturation at any point of sample collection. pH Criteria pH shall be within the range of 6.5 to 8.5 with a human-caused variation within the above range of less than 0.5 units.

• The recreational uses are extraordinary pr imary contact recreation, primary contact recreation, and secondary contact recreation. The recreational uses for this receiving water are identified below.

Table 14. Recreational Uses and Associated Criteria

Recreational Use Criteria Primary Contact Recreation Fecal coliform organism levels must not exceed a geometric mean value of 100 colonies /100 mL, with not more than 10 percent of all samples (or any single sample when less than ten sample points exist) obtained for calculating the geometric mean value exceeding 200 colonies/100 mL.

• The water supply uses are domestic, agricultural, i ndustrial, and stock watering.

• The miscellaneous freshwater use s are wildlife habitat, harvesting, commerce and navigation, boating, and aesthetics.

E. Evaluation of Surface Water Quality-Base d Effluent Limits for Numeric Criteria

Puget Sound Outfall No. 001
Pollutants in an effluent may affect the aqua tic environment near the point of discharge (near-field) or at a considerable distance from the point of discharge (far-field). Toxic pollutants, for example, are near-field pollutant s—their adverse effects diminish rapidly with mixing in the receiving water. Conversely, a pollutant such as biological oxygen demand (BOD) is a far-field pollutant whose adverse eff ect occurs away from the discharge even after dilution has occurred. Thus, the method of cal culating surface water qua lity-based effluent limits varies with the point at which the pollutant has its maximum effect.Fact Sheet for NPDES Permit WA-002958-1 Page 36 of 101 King County South Wastewater Treatment Plant
With technology-based controls (AKART), predicted pollutant concentrations in the discharge may exceed water quality criteria. Ecology therefore authorizes a mixing zone in accordance with the geometric configuration, flow restriction, and other restrictions imposed on mixing zones by Chap ter 173-201A WAC.

Chronic Mixing Zone (Outfall No. 001)
WAC 173-201A-400(7)(b) specifies that mixing zones must not extend in any horizontal direction from the discharge ports for a distance greater than 200 feet pl us the depth of water over the discharge ports as measured during MLLW.

The horizontal distance of the chronic mixing zone is 825 feet. The mixing zone extends from the seabed to the top of the water surface.

Acute Mixing Zone (Outfall No. 001)
WAC 173-201A-400(8)(b) specifies that in estuarine waters a zone where acute criteria may be exceeded must not extend beyond 10% of the dist ance established for the chronic zone. The acute mixing zone for Outfall 001 extends 82.5 feet in any direction from any discharge port.

Dilution Factors Ecology provided a thorough review of the Count y’s data, dilution factors, and modeling in June 2009. Ecology verified that the County us ed conservative assumptions and provided rigorous modeling to obtain dilution factors. Th e dilution ratios predicted from the current modeling effort are substantiall y different (lower) from thos e predicted in the previous analysis, and are described in the table below. Ecology revised the dilution factors because the County 1) used new and improved computer models, 2) collected additional density profile data; and 3) updated plant flow rates. Ecology considers the dilution factors in the proposed permit more up-to-date an d representative than the factor s in the previous permit. Note that all of the dilution factors decreased from the previous permit.

Table 15. Comparison of Dilution Ratios

Outfall Chronic Mixing Zone Radius (feet) a Zone of Acute Criteria Exceedance (feet) a Proposed Chronic Dilution

Ratio Current Chronic Dilution

Ratio Proposed Acute Dilution

Ratio Current Acute Dilution

Ratio

South WWTP 825 82.5 225:1 429:1 186:1 233:1

a – as measured horizontally from each port Ecology determined the dilution factors that occur within these z ones at the critical condition using UM3 and NRFIELD/RSB model co mponents. The dilution ratio for this permit is listed in Table 16:Fact Sheet for NPDES Permit WA-002958-1 Page 37 of 101 King County South Wastewater Treatment Plant

Table 16. Dilution Ratio for Outfall No. 001

Criteria Acute Chronic Aquatic Life 186:1 225:1 Human Health, Carcinogen 428:1 Human Health, Non-carcinogen 428:1

Ecology determined the impacts of dissolved oxygen deficiency, temperature, pH, fecal coliform, chlorine, ammonia, metals, nutrients an d other toxics as described below, using the dilution ratios in the above tables. The deri vation of surface water quality-based limits also takes into account the variabili ty of pollutant concentrations in both the effluent and the receiving water.

BOD 5 —With technology-based limits, this discharg e results in a small amount of BOD loading relative to the large amount of dilution in the receiving water at critical conditions. Technology-based limits will ensure that dissolved oxygen criteria are met in the receiving water.
Temperature —The state temperature standard s (WAC 173-201A-200-210 and 600-612) include multiple elements:

• Annual summer maximum threshold cr iteria (June 15 to September 15).

• Supplemental spawning and rearing season criteria (September 15 to June 15).

• Incremental warming restrictions.

• Protections against acute effects.
Ecology evaluates each criterion independently to determine reasonable potential and derive permit limits.

• Annual summer maximum and supplemen tary spawning/rearing criteria.
Each water body has an annual maxi mum temperature criterion [WAC 173-201A-200(1)(c), 210(1)(c), and Tabl e 602]. These threshold criteria (for example, 12, 16, 17.5, 20°C) protect speci fic categories of aquatic life by controlling the effect of human ac tions on summer temperatures.
Some waters have an additional threshold criterion to protect the spawning and incubation of salmonids (9°C for char and 13°C for salmon and trout) [WAC 173-201A-602, Table 602]. These criteria apply during specific date-windows.
The threshold criteria apply at the edge of the chronic mixing zone. Criteria for most fresh waters are expressed as the highest 7-Day average of daily maximum temperature (7-DADMax). The 7-DADMax te mperature is the arithmetic average of seven consecutive measures of daily maximum temperatures. Criteria for marine waters and some fresh waters ar e expressed as the highest 1-Day annual maximum temperature (1-DMax).Fact Sheet for NPDES Permit WA-002958-1 Page 38 of 101 King County South Wastewater Treatment Plant

• Incremental warming criteria.
The water quality standards limit the amount of warming human sources can cause under specific situations [W AC 173-201A-200(1)(c)(i)-(ii), 210(1)(c)(i)-(ii)]. The incremental warming criteria apply at the edge of the chronic mixing zone.
At locations and times when background te mperatures are cooler than the assigned threshold criterion, point sources are permitted to warm the water by only a defined increment. These increments are permitted only to the extent doing so does not cause temperatures to exceed eith er the annual maximum or supplemental spawning criteria.

At locations and times when a threshold cr iterion is being exce eded due to natural conditions , all human sources, considered cumulatively, must not warm the water more than 0.3°C above the naturally warm condition.
When Ecology has not yet completed a TMDL, our policy allows each point source to warm water at the edge of the ch ronic mixing zone by 0.3°C. This is true regardless of the background temperature and even if doing so would cause the temperature at the edge of a standard mi xing zone to exceed the numeric threshold criteria. Allowing a 0.3°C warming fo r each point source is reasonable and protective where the dilution factor is base d on 25% or less of the critical flow. This is because the fully mi xed effect on temperature will only be a fraction of the 0.3°C cumulative allowance (0.075°C or less) for all human sources combined.

• Temperature Acute Effects.
Instantaneous lethality to passing fish: The upper 99 th percentile daily maximum effluent temperature must not exceed 33°C; unless a dilution analysis indicates ambient temperatures will not exceed 33°C 2-seconds after discharge.
General lethality and migration blockage: Measurable (0.3°C) increases in temperature at the edge of a chronic mixing zone are not allowed when the receiving water temperature exceeds eith er a 1DMax of 23°C or a 7DADMax of 22°C.
Lethality to incubating fish: Human actions must not cause a measurable (0.3°C) warming above 17.5°C at locations where eggs are incubating.

• Temperature Chronic Effects.

1. Annual summer maximum.
Ecology calculated the reasonable potentia l for the discharge to exceed the annual summer maximum, the supplementary spawning criterion, and the incremental warming criteria at the e dge of the chronic mixing zone during critical condition(s). No reasonable pote ntial exists to exceed the temperature criterion where:Fact Sheet for NPDES Permit WA-002958-1 Page 39 of 101 King County South Wastewater Treatment Plant
(Criterion + 0.3) > Criterion + [(T effluent95 – Criterion)/DF]. (13 + 0.3) > 13 + [(22.5 – 13)/225]. 13.3 > 13.04
Therefore, the proposed permit does not in clude a temperature limit. The permit requires additional monitoring of effluent and ambient temperatures. Ecology will reevaluate the reasonable potential during the next permit renewal.

2. Incremental warming criteria.

Some waters are naturally incapable of meeting their assigned threshold temperature criteria. At locations and tim es when a threshold criterion is being exceeded due to natural conditions , all human sources, considered cumulatively, must not warm the water more than 0.3°C above the naturally warm condition.

When Ecology has not yet completed a TMDL, our policy allows each point source to warm water at the edge of th e chronic mixing zone by 0.3°C. This is true regardless of the background temperat ure and even if doing so would cause the temperature at the edge of a standard mixing zone to exceed the numeric threshold criteria. Allowing a 0.3°C warm ing for each point source is reasonable and protective where the dilution factor is based on 25 percent or less of the critical flow. This is because the fully mixed effect on temperature will be only a fraction (0.075°C or less) of the 0.3° C cumulative allowance for all human sources combined.

South WWTP reported a maximum effl uent temperature of 22.2°C on their NPDES application. Using the dilution ra tio of 225:1 (receiving water : effluent) and maximum daily temperature of 14.0°C for the receiving water and 22.2°C for the effluent, the predicted maximum daily temperature inside the dilution zone is ((225x14.0)+(1x22.2))/(225+1) = 14.04°C. Thus, under the worst case scenario, the effluent discharge from th is facility results in warming of the ambient temperature by 0.04°C, which is less than the allowable warming temperature of 0.3°C.
Since the discharge does not have a potentia l to violate the water quality standards for temperature in the receiving water, Ecology placed no limits in the permit for effluent temperature. To acquire ambi ent temperature and effluent temperature data, the proposed permit re quires the South WWTP to c ontinue to monitor these temperatures. The need for a limit will be evaluated during the next permit cycle.

pH —Compliance with the technology-based limits of 6.0 to 9.0 will assure compliance with the water quality standards of surface waters because of the high buffering capacity of marine water.

Fecal Coliform —Ecology modeled the numbers of fecal coliform by simple mixing analysis using the maximum day discharge (years 2004- 2008) of 2,075 organisms per 100 ml and a dilution factor of 225.Fact Sheet for NPDES Permit WA-002958-1 Page 40 of 101 King County South Wastewater Treatment Plant
Under critical conditions, modeling predicts no violation of the water quality criterion for fecal coliform. Therefore, the proposed pe rmit includes the technology-based effluent limit for fecal coliform bacteria.

Toxic Pollutants —Federal regulations (40 CFR 122.44) require Ecology to place limits in NPDES permits on toxic chemicals in an effluent whenever there is a reasonable potential for those chemicals to exceed the su rface water quality criteria. Ec ology does not exempt facilities with technology-based effluent limits from m eeting the surface water quality standards.
The following toxic pollutants are present in th e discharge: chlorine, ammonia, and heavy metals. Ecology conducted a reasonable poten tial analysis (see Appendix H) on these parameters to determine whether it would require effluent limits in this permit.
Ammonia's toxicity depends on th at portion which is available in the unionized form. The amount of unionized ammonia depends on the temp erature, pH, and salinity of the receiving marine water. To evaluate ammonia toxici ty, Ecology used the available receiving water information for ambient station LS TN01 and Ecology spreadsheet tools.
Valid ambient background data was available fo r arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc (see Appendix H). Ec ology used all applicable data to evaluate reasonable potential for this discharge to cause a violation of water quality standards.
Ecology determined that ammonia, arsenic, cadmium, chromium, copper, cyanide, lead, mercury, nickel, silver, and zinc pose no r easonable potential to exceed the water quality criteria at the critic al condition using procedures give n in EPA, 1991 (Appendix H) and as described above. Ecology’s determination assumes that this facility meets the other effluent limits of this permit.

Ecology derived effluent limits for the toxic pollutant chlorine, de termined to have a reasonable potential to cause a violation of th e water quality standard s. Ecology calculated effluent limits using methods from EPA, 1991 as shown in Appendix H.

Ecology used new dilution modeling results (more restrictive) to determ ine new total residual chlorine limits for the proposed permit. Ecol ogy derived the new limits based on the state water quality standards of 13 μ g/L for acute and 7.5 μ g/L for chronic along with an acute dilution factor of 186:1 and a chronic dilu tion factor of 225:1 (refer to Appendix H—Technical Calculations ). The resulting permit limits would be an average monthly total residual chlorine limit of 924 μ g/L and a maximum daily total residual chlorine limit of 2,418 μ g/L. However, the technology, guidance-based limit for chlorine is more stringent than the water quality-based limit at 500 μg/L (Average Monthly Limit) and 750 μg/L (Maximum Daily Limit). The anti-backsliding provision under the federal re gulations [CFR 122.44(l)] requires that the chlorine limit be based on the more stringent lim it established in the previous permit since it has been shown to be technologically achievable.

The resultant effluent limits are as follows: Chlorine 0.5 mg/L (average monthl y) and 0.75 mg/L (average weekly)Fact Sheet for NPDES Permit WA-002958-1 Page 41 of 101 King County South Wastewater Treatment Plant

Freshwater Dilution Factors – Green Ri ver Outfall No. 002 (Maintenance Only)
Ecology determined the dilution ratio of effluent to receiving water th at occurs within the freshwater zones based on bulk diluti on. The resultant dilution ratio is:

Table 17. Dilution Ratio - Green River Outfall No. 002

Green River Outfall Acute Chronic Aquatic Life – Maintenance 9:1 Not Applicable Aquatic Life – Emergency Permitted Under S5.F Not Applicable
Ecology determined the acute dilution ra tio based on bulk dilution achieved under the conditions expected during use of the outfa ll for maintenance purposes. King County may discharge only when the river fl ow is at least 1000 cfs (cubic feet per se cond). The rate of discharge anticipated during a maintenance even t is limited to no more than an average of 28 cfs. Ecology used these assumptions for the previous permit and verified them for this permit. Based on these assumptions, the bulk dilution using the entire river is 36:1 (1000/28=36). The regulation permits only 25% of the river width to be utilized; therefore, the effective acute dilution ratio is 9:1 during a maintenance event. Ecology expects that maintenance discharges will only occur for short periods of time and therefore chronic water quality standards would not apply.
Ecology did not determine a mixing zone for the emergency use of the Green River outfall. The Green River outfall is implicitly permitted under Special Condition S5.F and explicitly permitted under Special Condition S1.B for em ergency use. Effluent limits were not imposed for emergency use because it is assumed that such use will occur under extreme and unpredictable circumstances.

BOD 5 —Ecology predicts a violation of the di ssolved oxygen criterion for the receiving water under critical conditions with the tec hnology-based limit. Ecology determined the impact of BOD on the receiving water based on a discharge limit of 15 mg/L and a dilution of 9:1. This discharge limit could produce a drop in dissolved oxygen in the river by as much as 1.67 mg/L based on worst case assump tions. Based on the short duration of this discharge, Ecology believes this limit will protect the receiving water.
Temperature and pH —The impact of pH and temperature were modeled using the calculations from EPA, 1988. Th e input variables were dilution factor 9, upstream temperature 17.2 o C, upstream pH 7.5, upstream alkalinity 50(as mg CaCO 3 /L), effluent temperature 20 o C, effluent pH of 6, and efflue nt alkalinity 68.8 (as mg CaCO 3 /L). (Refer to Appendix H.)

Under critical conditions there is no predicted violation of th e water quality standards for surface waters. Therefore, the no technol ogy-based limit was placed in the permit for temperature. A technology-ba sed effluent limit for pH was placed in the permit.

Fecal Coliform —The numbers of fecal coliform were modeled by simple mixing analysis using the technology-based limit of 200 organism s per 100 ml and a dilution factor of 9. The resulting fecal coliform at the edge of the dilution zone would be 22.1 organisms per 100 ml.Fact Sheet for NPDES Permit WA-002958-1 Page 42 of 101 King County South Wastewater Treatment Plant

Under critical conditions there is no predicted violation of th e water quality standards for surface waters with the technology-based limit. Therefore, the technology-based effluent limit for fecal coliform bacteria was placed in the proposed permit.

Toxic Pollutants —Federal regulations (40 CFR 122.44) require NPDES permits to contain effluent limits for toxic chemicals in an efflue nt whenever there is a reasonable potential for those chemicals to exceed the surface wate r quality criteria. This process occurs concurrently with the derivation of technol ogy-based effluent limits. Facilities with technology-based effluent limits defined in re gulation are not exempted from meeting the water quality standards for surface waters or from having surface water quality-based effluent limits.
Due to the infrequency and short duration of disc harges to the Green River, the only toxicant considered was chlorine. Ecology conducted a r easonable potential analys is (see Appendix H) on chlorine to determine whether or not it w ould require effluent lim its in this permit.
Ecology derived effluent limits for chlorine, wh ich showed a reasonable potential to cause a violation of the water quality standards. Effl uent limits were calculated using methods from EPA, 1991 as shown in Appendix H.

The resultant effluent limits are as follows:

Chlorine 171 μ g/L.

F. Whole Effluent Toxicity
The water quality standards for surface waters fo rbid discharge of effluent that causes toxic effects in the receiving wate rs. Many toxic pollutants ca nnot be measured by commonly available detection methods. However, labora tory tests can measure toxicity directly by exposing living organisms to th e wastewater and measuring th eir responses. These tests measure the aggregate toxicity of the whole efflue nt, so this approach is called whole effluent toxicity (WET) testing. Some WET tests measur e acute toxicity and other WET tests measure chronic toxicity.

• Acute toxicity tests measure mort ality as the significant response to the toxicity of the effluent. Dischargers who monitor their wast ewater with acute toxicity tests find early indications of any potential leth al effect of the effluent on organisms in the receiving
water.

• Chronic toxicity tests measure va rious sublethal toxic responses, such as retarded growth or reduced reproduction. Chronic toxicity tests ofte n involve either a complete life cycle test on an organism with an extrem ely short life cycle, or a partial life cycle test during a critical stage of a test organism's life. Some chronic toxicity tests also measure organism survival.
Ecology-accredited WET testing laboratories use the proper WET testing protocols, fulfill the data requirements, and submit results in the correct reporting format. Accredited laboratory staff knows about WET testi ng and how to calculate an NOEC, LC 50 , EC 50 , IC 25 , etc. Ecology gives all accredited labs the most recent version of Ecology Publication No. WQ-R-95-80, Laboratory Guidance and Whole Effluent Toxicity Test Review CriteriaFact Sheet for NPDES Permit WA-002958-1 Page 43 of 101 King County South Wastewater Treatment Plant
( http://www.ecy.wa .gov/biblio/9580.html ), which is referenced in the permit. Ecology recommends that King County send a copy of the acu te or chronic toxicity sections(s) of its NPDES permit to the laboratory.
WET testing conducted during effluent character ization showed no reas onable potential for effluent discharges to cause receiving water acu te toxicity. All indi vidual acute WET tests had greater than 65% survival in 100% effluent , and the median survival in 100% effluent was 90%. Since the acute toxicity tests pa ssed the performance standard, the proposed permit will not impose an acute WET limit. King County must retest the effluent before submitting an application for permit renewal.

• If this facility makes proce ss or material changes whic h, in Ecology's opinion, increase the potential for effluent toxicity, then Ec ology may (in a regulato ry order, by permit modification, or in the permit renewal) require the facility to conduct additional effluent characterization.

• If WET testing conducted for submittal with a permit application fails to meet the performance standards in WAC 173-205-020, Ecology will assume that effluent toxicity has increased. King County may demonstrate to Ecol ogy that effluent toxicity has not increased, by performing additional WET testing after the process or material changes have been made.
WET testing conducted during effluent character ization showed no reas onable potential for effluent discharges to cause receiving water chronic toxicity. The proposed permit will not impose a chronic WET limit. King County must retest the effluent before submitting an application for permit renewal.

• If this facility makes proce ss or material changes which, in Ecology's opinion, increase the potential for effluent toxicity, then Ec ology may (in a regulato ry order, by permit modification, or in the permit renewal) require the facility to conduct additional effluent characterization

• If WET testing conducted for submittal with a permit application fails to meet the performance standards in WAC 173-205-020, Ecology will assume that effluent toxicity has increased. King County may demonstrate to Ecol ogy that effluent toxicity has not increased by performing additional WE T testing after the pr ocess or material changes have been made.

G. Human Health
Washington’s water quality standards include 91 numeric human health-based criteria that Ecology must consider when writing NPDES perm its. These criteria were established in 1992 by the U.S. EPA in its National Toxics Rule (40 CFR 131.36). The National Toxics Rule allows states to use mixing zones to ev aluate whether discharges comply with human health criteria.
Ecology determined the effluent may contain ch emicals of concern for human health, based on (1) the facility’s status as an EPA majo r discharger, and (2) data or information indicating regulated chemicals occur in the discharge.Fact Sheet for NPDES Permit WA-002958-1 Page 44 of 101 King County South Wastewater Treatment Plant
Ecology evaluated the discharge's potential to vi olate the water quality standards as required by 40 CFR 122.44(d) by following the procedures published in the Technical Support Document for Water Quality-Based Toxics Control (EPA/505/2-90-001) and Ecology's Permit Writer's Manual to make a reasonable potential determination. The evaluation showed that the discharge has no reasonable potential to cause a violation of water quality standards, and an effluent limit is not needed.

H. Sediment Quality
The aquatic sediment standards (Chapter 173- 204 WAC) protect aqua tic biota and human health. Under these standards Ec ology may require a facility to evaluate the potential for its discharge to cause a violation of sediment standards (WAC 173-204-400). You can obtain additional information about sediments at the Aquatic La nds Cleanup Unit website. http://www.ecy.wa.gov/programs/tcp/smu/sediment.html

Ecology determined that the South WWTP disc harge may have the potential to cause a violation of the sediment quality standards because:

• In some of the past testi ng, detection limits were above the SQS numeric criteria.

• In 1997, three locations had detected concentr ations of hexachlor obenzene above the SQS numeric criteria for benthic toxicity.

• King County has previously collected sedime nt samples from the top 2 centimeters of sediment in accordance with past permit requirements. Ecology now bases compliance on the top 10 centimeters of sediment, wh ich is the biologic ally active zone.

• King County has not performed sediment chem ical analysis since 2001, and has not been required to conduct biological tests at locations near the outfalls.

The proposed permit includes a condition requiring King County to:

• Sample and analyze sediments in the vicin ity of South WWTP’s outfall to characterize sediment quality (the nature and extent of chemical contamination and biological toxicity) in the vicinity of the Permittee’s discharge locations. Specifically, sediment sampling will be required for 0 to 10 cm depth at 8 locations near the two outfalls. Chemical analysis of the 47 chemicals in the sediment management standards plus conventional analytes will be required at all 8 sites. Bioassa ys will be performed, if the ch emical concentrations are near or above the sediment management st andards numeric chemical criteria.

• The Permittee must develop a Sampling and Analysis Plan in accordance with the Sediment Sampling and Analysis Plan Appendi x. The Sampling and Analysis Plan must be approved by the Department of Ecology be fore performing sediment sampling. After the sediment sampling is completed, the Permittee must submit a Sediment Data Report and Environmental Information Management (EIM) templates to the Department of Ecology for review and approval.

• If the sediment evaluation shows toxicity at any station, the Permittee must perform additional testing to investigate th e source of sediment toxicity.Fact Sheet for NPDES Permit WA-002958-1 Page 45 of 101 King County South Wastewater Treatment Plant
I. Ground Water Quality Limits
The ground water quality standards (Chapter 173 -200 WAC) protect be neficial uses of ground water. Permits issued by Ecology must not allow violations of those standards (WAC 173-200-100).
King County South WWTP does not discharge wast ewater to the ground. No permit limits are required to protect ground water.

J. Comparison of Effluent Limits With the Previous Permit Issued on September 30, 2004

There were no changes in effluent li mits from the permit issued in 2004.

Table 18. Comparison of Effluent Limits

Basis of

Limit Previous Effluent Limits: Puget Sound Outfall #001 Proposed Effluent Limits: Puget Sound Outfall #001 Average Monthl y Average Weekl y Average Monthl y Average Weekl y Biochemical Oxygen Demand (5-day) Technology 30 mg/L, 36,000 lbs/day, 85% min. removal 45 mg/L, 54,000 lbs/day 30 mg/L, 36,000 lbs/day, 85% min. removal 45 mg/L, 54,000 lbs/day

Total Suspended Solids Technology 30 mg/L, 36,000 lbs/day, 85% min. removal 45 mg/L, 54,000 lbs/day 30 mg/L, 36,000 lbs/day, 85% min. removal 45 mg/L, 54,000 lbs/day

Fecal Coliform Bacteria Technology 200/100 mL 400/100 mL 200/100 mL 400/100 mL

pH Technology 6.0-9.0 6. 0-9.0 6.0-9.0 6.0-9.0 Total Residual Chlorine Technology 0.5 mg/L, 600 lbs/day 0.75 mg/L 1 0.5 mg/L 0.75 mg/L 1

Previous Effluent Limits: Green Rive r -Maintenance Proposed Effluent Limits 2 : Green Rive r -Maintenance Parameter Average Monthl y Maximum Dail y Average Monthl y Maximum Dail y BOD 5 daily maximum NA 20 mg/L NA 20 mg/L

TSS, daily maximum NA 20 mg/L NA 20 mg/L

Fecal Coliform Bacteria, daily max. NA 200/100 mL NA 200/100 mL

pH NA 6.0-9.0 NA 6.0-9.0 Parameter Average Monthl y Maximum Dail y Average Monthl y Maximum Dail y Total Residual Chlorine NA 171 ug/L NA 171 ug/L

1 Represents a Maximum Daily Limit

2 No limits are proposed for an emerge ncy discharge to the Green River.Fact Sheet for NPDES Permit WA-002958-1 Page 46 of 101 King County South Wastewater Treatment Plant


### IV. MONITORING REQUIREMENTS

Ecology requires monitoring, recording, and reporting (WAC 173-220- 210 and 40 CFR 122.41) to verify that the treatment process is functioni ng correctly and that the discharge complies with the permit’s effluent limits.
The monitoring schedule is detailed in the proposed permit under Condition S2. Specified monitoring frequencies take into account the quantity and variability of the discharge, the treatment method, past compliance, significance of polluta nts, and cost of monitoring. The required monitoring frequency is consistent with agency guidance given in the curr ent version of Ecology’s Permit Writer's Manual (Publication Number 92-09) for an ac tivated sludge secondary treatment plant.
Monitoring of sludge quantity and qu ality is necessary to determine the appropriate uses of the sludge. Biosolids monitoring is required by the current state and local solid waste management program and also by EPA under 40 CFR 503.
As a pretreatment publicly-owned treatment work s (POTW), King County is required to sample influent, final effluent, and sludge for toxic pollutant s in order to characteri ze the industrial input. Sampling is also done to determine if pollutants in terfere with the treatment process or pass through the plant to the biosolids or th e receiving water. King County will use the monitoring data to develop local limits which commercial and industrial users must meet.
The proposed permit requires King County to monitor for sediment toxicity to further characterize the sediments near the outfall.

A. Lab Accreditation
Ecology requires that facilities must use a laboratory registered or accredited under the provisions of Chapter 173-50 WAC, Accreditation of Environmental Laboratories, to prepare all monitoring data (with the ex ception of certain parameters)

. Ecology accredited the laboratory at this facility for General Chemistry and Microbiology. The County’s environmental lab at W. Ewing Street is additi onally accredited for trace metals by ICP-OES and ICP-MS, mercury, inorganics, organics by GC and GC-MS, bioassays, and microbiology in matrices, including liquids, sediments, and tissues.Fact Sheet for NPDES Permit WA-002958-1 Page 47 of 101 King County South Wastewater Treatment Plant



### V. OTHER PERMIT CONDITIONS

A. Reporting and Record Keeping

Ecology based permit Condition S3 on our authority to specify any appropriate reporting and record keeping requirements to prevent a nd control waste discha rges (WAC 173-220-210).

B. Prevention of Facility Overloading
Overloading of the treatment plant is a violation of the terms and conditions of the permit. To prevent this from occurring, RCW 90.48.110 and WAC 173-220-150 require King County to take the actions detailed in proposed permit Requirement S4 to plan expansions or modifications before existing capacity is reached and to report and correct conditions that could result in new or increased discharges of polluta nts. Condition S4 restricts the amount of flow.

C. Operation and Maintenance (O&M)
The proposed permit contains Condition S .5 as authorized under RCW 90.48.110, WAC 173-220-150, Chapter 173-230 WAC, and WAC 173- 240-080. Ecology included it to ensure proper operation and regular maintenance of equi pment, and to ensure that King County takes adequate safeguards so that it us es constructed facilities to th eir optimum potential in terms of pollutant capture and treatment.

D. Pretreatment

Duty to Enforce Discharge Prohibitions
This provision prohibits the publicly-owned tr eatment works (POTW) from authorizing or permitting an industrial discharger to discharge certa in types of waste into the sanitary sewer.

• The first section of the pretreatment requi rements prohibits the POTW from accepting pollutants which causes “pass-through” or “i nterference.” This general prohibition is from 40 CFR §403.5(a). Appendix B of this fact sheet defines these terms.

• The second section reinforces a number of specific state and federal pretreatment prohibitions found in WAC 173-216-060 and 40 CFR §403.5(b). These reinforce that the POTW may not accept certain wastes, which:

• Are prohibited due to dangerous waste rules.

• Are explosive or flammable.

• Have too high or low of a pH (t oo corrosive, acidic or basic).

• May cause a blockage such as grease, sand, rocks, or viscous materials.

• Are hot enough to cause a problem.

• Are of sufficient strength or volume to interfere with treatment.

• Contain too much petroleum-based oils , mineral oil, or cutting fluid.

• Create noxious or toxic gases at any point.Fact Sheet for NPDES Permit WA-002958-1 Page 48 of 101 King County South Wastewater Treatment Plant
40 CFR Part 403 contains the regulatory basis for these prohibitions, with the exception of the pH provisions which are based on WAC 173-216-060.

• The third section of pretreat ment conditions reflects stat e prohibitions on the POTW accepting certain types of discharges unless the discharge has rece ived prior written authorization from Ecology. These discharges include:

• Cooling water in significant volumes.

• Stormwater and other di rect inflow sources.

• Wastewaters significantly affecting system hydraulic loading, which do not require treatment.
Ecology delegated author ity to King County for permitting, monitoring, and enforcement over industrial users discharging to their treatment system to provide more direct and effective control of pollutants. Ecology oversees the de legated Industrial Pret reatment Program to assure compliance with federal pretreatment regulations (40 CFR Part 403) and categorical standards and state regula tions (Chapter 90.48 RCW a nd Chapter 173-216 WAC).

E. Solid Waste Control
To prevent water quality problems, the facility is required in permit Condition S7 to store and handle all residual solids (g rit, screenings, scum, sludge, and other solid waste) in accordance with the requirements of RCW 90.48.080 and state water quality standards.
The final use and disposal of sewage sludge from this facility is re gulated by U.S. EPA under 40 CFR 503, and by Ecology under Chapter 70.95J RCW, Chapter 173 -308 WAC “Biosolids Management,” and Chapter 173-350 WAC “Solid Waste Handling Standards.” The disposal of other solid waste is under the jurisdic tion of the King County Health Department.

F. Spill Plan
This facility stores a quantity of chemicals on-site that have the potential to cause water pollution if accidentally rele ased. Ecology can require a facility to develop best management plans to prevent this accidental release [Section 402(a)(1) of the Federal Water Pollution Control Act (FWPCA) and RCW 90.48.080].
The proposed permit requires this facility to develop and implement a plan for preventing the accidental release of polluta nts to state waters and for minimizing damages if such a spill occurs.

G. Outfall Evaluation
The proposed permit requires King County to conduct an outfall insp ection and submit a report detailing the findings of that insp ection (Condition S13). The inspection must evaluate the physical condition of the discharge pipe and diffusers, and evaluate the extent of sediment accumulations in the vicinity of the outfall.Fact Sheet for NPDES Permit WA-002958-1 Page 49 of 101 King County South Wastewater Treatment Plant

H. General Conditions
Ecology bases the standardized General Conditions on state and federal law and regulations. They are included in all individual municipal NPDES permits issued by Ecology.



### VI. PERMIT ISSUANCE PROCEDURES

A. Permit Modifications
Ecology may modify this permit to impose numeri cal limits, if necessary, to comply with water quality standards for surface waters, with sediment quality standards, or with water quality standards for ground waters, based on new information from sources such as inspections, effluent monitoring, outfall studies, and efflue nt mixing studies.
Ecology may also modify this permit to comp ly with new or amended state or federal regulations.

B. Proposed Permit Issuance
This proposed permit meets all statutory requir ements for Ecology to authorize a wastewater discharge. The permit includes limits and cond itions to protect human health and aquatic life, and the beneficial uses of waters of the state of Washi ngton. Ecology proposes to issue this permit for a term of five years.Fact Sheet for NPDES Permit WA-002958-1 Page 50 of 101 King County South Wastewater Treatment Plant



### VII. REFERENCES FOR TEXT AND APPENDICES
Environmental Protection Agency (EPA)

1992. National Toxics Rule. Federal Register, V. 57, N o. 246, Tuesday, December 22, 1992.

1991. Technical Support Document for Wate r Quality-Based Toxics Control . EPA/505/2-90-001.

1988. Technical Guidance on Supplementary Stream Design Conditions for Steady State Modeling. USEPA Office of Water, Washington, D.C.

1985. Water Quality Assessment: A Screening Procedure for Toxic and Conventional Pollutants in Surface and Ground Water . EPA/600/6-85/002a.

1983. Water Quality Standards Handbook. USEPA Office of Water, Washington, D.C.
Tsivoglou, E.C., and J.R. Wallace.

1972. Characterization of Stream Reaeration Capacity . EPA-R3-72-012. (Cited in EPA 1985 op.cit.)
Washington State Department of Ecology.

2006. Permit Writer’s Manual. Publication Number 92-109 ( http://www.ecy.wa .gov/biblio/92109.html ) Laws and Regulations ( http://www.ecy.wa.gov/laws-rules/index.html )

Permit and Wastewater Related Information ( http://www.ecy.wa.gov/program s/wq/wastewater/index.html )

Water Pollution Control Federation.

1976. Chlorination of Wastewater.
Wright, R.M., and A.J. McDonnell.

1979. In-stream Deoxygenation Rate Prediction. Journal Environmental Engineering Division, ASCE. 105(EE2). (Cited in EPA 1985 op.cit.)Fact Sheet for NPDES Permit WA-002958-1 Page 51 of 101 King County South Wastewater Treatment Plant



### APPENDIX A—PUBLIC INVOLVEMENT INFORMATION
Ecology proposes to reissue a permit to Ki ng County’s South WWTP. The permit includes wastewater discharge limits and other conditions. This fact sh eet describes the facility and Ecology’s reasons for requiring permit conditions.
Ecology placed a Public Notice of Applica tion on April 16, 2009, and April 23, 2009, in The Seattle Times to inform the public about the submitted a pplication and to invite comments on the reissuance of this permit.
Ecology placed a Public Noti ce of Draft on July 31, 2009, in The Seattle Times to inform the public and to invite comments on the proposed draft National Pollutant Discharge Elimination System permit and fact sheet.

The notice –

• Told where copies of the draft permit and fact sheet were available for public evaluation (a local public library, the closest regional or field office, posted on our website).

• Offered to provide the documents in an alte rnate format to accommodate special needs.

• Asked people to tell us how well the proposed permit would protect th e receiving water.

• Invited people to suggest fairer conditi ons, limits, and requirements for the permit.

• Invited comments on Ecology’s determination of compliance with antidegradation rules.

• Urged people to submit their comments, in writing, before the end of the comment period.

• Explained the next step(s) in the permitting process.
Ecology held an informal public meeting and a formal hearing on September 3, 2009, at King County’s regional Bellevue Libr ary to obtain additional comments regarding the South WWTP NPDES Permit.
Ecology has published a document entitled Frequently Asked Questions about Effective Public Commenting which is available on our website at http://www.ecy.wa.gov/biblio/0307023.html

. You may obtain further informa tion from Ecology by telephone, 425-649-7201 , or by writing to the address listed below. Water Quality Permit Coordinator Department of Ecology Northwest Regional Office 3190 160 th Avenue SE Bellevue, WA 98008-5452
The author of this permit and fact sheet is Mark Henley, P.E.Fact Sheet for NPDES Permit WA-002958-1 Page 52 of 101 King County South Wastewater Treatment Plant



### APPENDIX B—GLOSSARY

1-DMax or 1-day maximum temperature —The highest water temperature reached on any given day. This measure can be obtained usi ng calibrated maximum/minimum thermometers or continuous monitoring probes having sampling intervals of thirty minutes or less.

7-DADMax or 7-day average of the da ily maximum temperatures —The arithmetic average of seven consecutive measures of daily ma ximum temperatures. The 7-DADMax for any individual day is calculated by averaging th at day's daily maximum temperature with the daily maximum temperatures of the three days prior and the three days after that date. Acute Toxicity —The lethal effect of a compound on an or ganism that occurs in a short period of time, usually 48 to 96 hours. AKART—The acronym for “all known, available, a nd reasonable methods of prevention, control and treatment.” AKART is a technology-ba sed approach to limiting pollutants from wastewater discharges which requires an engineering judgmen t and an economic judgment. AKART must be applied to all wa stes and contaminants prior to entry into waters of the state in accordance with RCW 90.48.010 and 520, WAC 173-200-030(2)(c)(ii), and WAC 173-216-110(1)(a). Ambient Water Quality —The existing environmental cond ition of the water in a receiving water body.

Ammonia —Ammonia is produced by the breakdown of nitrogenous materials in wastewater. Ammonia is toxic to aquatic organisms, exerts an oxygen demand, and contributes to eutrophication. It also increases the amount of chlorine needed to disinfect wastewater. Annual Average Design Flow (AADF) —The average of the daily fl ow volumes anticipated to occur over a calendar year. Average Monthly Discharge Limit —The average of the measured values obtained over a calendar month's time. Best Management Practices (BMPs) —Schedules of activities, prohibitions of practices, maintenance procedures, and other physical, struct ural and/or managerial practices to prevent or reduce the pollution of waters of the state. BMPs include treatment systems, operating procedures, and practices to c ontrol plant site runoff, spillage or leaks, sludge or waste disposal, or drainage from ra w material storage. BMPs ma y be further categorized as operational, source control, erosion and sediment control, and treatment BMPs.

BOD 5 —Determining the Biochemical Oxygen Demand of an effluent is an indirect way of measuring the quantity of organic ma terial present in an effluent that is utilized by bacteria. The BOD 5 is used in modeling to measure the re duction of dissolved oxygen in receiving waters after effluent is discharged. Stress caused by reduced dissolved oxygen levels makes organisms less competitive and less able to sustai n their species in the aquatic environment. Although BOD is not a specific compound, it is defi ned as a conventional pollutant under the federal Clean Water Act. Bypass— The intentional diversion of waste streams from any portion of a treatment facility.

Chlorine —Chlorine is used to disinfect wastewaters of pathogens harm ful to human health. It is also extremely toxic to aquatic life.Fact Sheet for NPDES Permit WA-002958-1 Page 53 of 101 King County South Wastewater Treatment Plant

Chronic Toxicity —The effect of a compound on an orga nism over a relatively long time, often 1/10 of an organism's lifespan or more. Chr onic toxicity can measure survival, reproduction or growth rates, or other parameters to measure the toxic effects of a compound or combination of compounds. Clean Water Act (CWA) —The Federal Water Pollution Cont rol Act enacted by Public Law 92-500, as amended by Public Laws 95-217, 95-576, 96-483, 97-117; USC 1251 et seq. Compliance Inspection - Without Sampling —A site visit for the pur pose of determining the compliance of a facility with the terms and conditi ons of its permit or with applicable statutes and regulations. Compliance Inspection - With Sampling —A site visit for the purpose of determining the compliance of a facility with the terms and conditi ons of its permit or with applicable statutes and regulations. In addition it includes as a minimum, sampling and analysis for all parameters with limits in the permit to asce rtain compliance with those limits; and, for municipal facilities, sampling of influent to ascertain compliance with the 85 percent removal requirement. Ecology may conduct additional sampling. Composite Sample —A mixture of grab samples collect ed at the same sampling point at different times, formed either by continuous sa mpling or by mixing discrete samples. May be "time-composite" (collected at constant time intervals) or "flow-proportional" (collected either as a constant sample volume at time inte rvals proportional to str eam flow, or collected by increasing the volume of each aliquot as the flow increased while maintaining a constant time interval between the aliquots). Construction Activity —Clearing, grading, excava tion, and any other activity which disturbs the surface of the land. Such activities may include road building; construction of residential houses, office buildings, or industrial buildings; and demolition activity.
Continuous Monitoring —Uninterrupted, unless otherw ise noted in the permit.

Critical Condition —The time during which the combination of receiving water and waste discharge conditions have the highest potential for causing toxicity in the receiving water environment. This situation usually occurs wh en the flow within a water body is low, thus, its ability to dilute effluent is reduced. Dilution Factor (DF) —A measure of the amount of mixing of effluent and receiving water that occurs at the boundary of the mixing zone. Expr essed as the inverse of the percent effluent fraction, for example, a dilution factor of 10 means the effluent comprises 10% by volume and the receiving water 90%. Engineering Report —A document which thoroughly examines the engineering and administrative aspects of a particular domestic or industrial wastewater facility. The report must contain the appropriate informa tion required in WAC 173-240-060 or 173-240-130.

Fecal Coliform Bacteria —Fecal coliform bacteria are used as indicators of pathogenic bacteria in the effluent that are harmful to humans. Pa thogenic bacteria in wast ewater discharges are controlled by disinfecting the wastewater. Th e presence of high numbers of fecal coliform bacteria in a water body can indicate the recent release of untreated wastewater and/or the presence of animal feces.Fact Sheet for NPDES Permit WA-002958-1 Page 54 of 101 King County South Wastewater Treatment Plant
Grab Sample —A single sample or measurement taken at a specific time or over as short a period of time as is feasible.

Industrial Wastewater —Water or liquid-carried waste from industrial or commercial processes, as distinct from domestic wastewater. These wastes may result from any process or activity of industry, manufacture, trade or business; from the developmen t of any natura l resource; or from animal operations such as feed lots, poultry houses, or dairies. The term includes contaminated storm water and, also, l eachate from solid waste facilities. Major Facility —A facility discharging to surface water with an EPA rating score of > 80 points based on such factors as flow volume, toxic pollutant potential, and public health impact. Maximum Daily Discharge Limit —The highest allowable daily discharge of a pollutant measured during a calendar day or any 24-hour period that reas onably represents the calendar day for purposes of sampling. The daily discharg e is calculated as the average measurement of the pollutant over the day. Maximum Day Design Flow (MDDF) —The largest volume of flow anticipated to occur during a one-day period, expresse d as a daily average. Maximum Month Design Flow (MMDF) —The largest volume of fl ow anticipated to occur during a continuous 30-day period, e xpressed as a daily average. Maximum Week Design Flow (MWDF) —The largest volume of fl ow anticipated to occur during a continuous 7-day period, ex pressed as a daily average. Method Detection Level (MDL) —The minimum concentration of a substance that can be measured and reported with 99 percent confidence that the pollutant c oncentration is above zero and is determined from analysis of a samp le in a given matrix containing the pollutant. Minor Facility —A facility discharging to surface water with an EP A rating score of < 80 points based on such factors as flow volume, toxic pollutant potential, and public health impact. Mixing Zone —An area that surrounds an effluent discha rge within which wa ter quality criteria may be exceeded. The area of the authorized mi xing zone is specified in a facility's permit and follows procedures outlined in st ate regulations (Cha pter 173-201A WAC). National Pollutant Discharge Elimination System (NPDES) —The NPDES (Section 402 of the Clean Water Act) is the federal wastewater permitting system for discharges to navigable waters of the United States. Many states, in cluding the state of Washington, have been delegated the authority to issue these permits . NPDES permits issued by Washington State permit writers are joint NPDES/ State permits issued under both state and federal laws. pH —The pH of a liquid measures its acidity or alkalinity. It is the negative l ogarithm of the hydrogen ion concentration. A pH of 7 is defined as neutral, and large variations above or below this value are considered harmful to most aquatic life. Peak Hour Design Flow (PHDF) —The largest volume of flow anticipated to occur during a one-hour period, expressed as a daily or hourly average. Peak Instantaneous Design Flow (PIDF) —The maximum anticipated instantaneous flow.Fact Sheet for NPDES Permit WA-002958-1 Page 55 of 101 King County South Wastewater Treatment Plant
Quantitation Level (QL) —The smallest detectable concentr ation of analyte greater than the Method Detection Limit (MDL) where the accu racy (precision &bias) achieves the objectives of the intended purpose.

Reasonable Potential —A reasonable potential to cause a water quality violation, or loss of sensitive and/or im portant habitat. Responsible Corporate Officer —A president, secretary, treasure r, or vice-president of the corporation in charge of a principal busine ss function, or any other person who performs similar policy- or decision-mak ing functions for the corporati on, or the manager of one or more manufacturing, production, or operating facilities employing more than 250 persons or have gross annual sales or expenditures ex ceeding $25 million (in second quarter 1980 dollars), if authority to sign documents has b een assigned or delegated to the manager in accordance with corporate procedures (40 CFR 122.22). Technology-Based Effluent Limit —A permit limit that is based on the ability of a treatment method to reduce the pollutant. Total Suspended Solids (TSS) —Total suspended solids is the particulate materi al in an effluent. Large quantities of TSS discharged to receivi ng waters may result in solids accumulation. Apart from any toxic effects attr ibutable to substances leached out by water, suspended solids may kill fish, shellfish, and other aquatic organisms by causing abrasive injuries and by clogging the gills and respiratory passages of various aquatic fauna. Indirectly, suspended solids can screen out light and can promote and maintain the development of noxious conditions through oxygen depletion.

Solid Waste —All putrescible and non-putrescible solid and semisolid wastes including, but not limited to, garbage, rubbish, ashes, industria l wastes, swill, sewage sludge, demolition and construction wastes, abandoned vehicles or parts thereof, contaminated soils and contaminated dredged material , and recyclable materials.

State Waters —Lakes, rivers, ponds, streams, inland wa ters, underground waters, salt waters, and all other surface waters and watercourses within the jurisdiction of the state of Washington.

Stormwater —That portion of precipitation that does not naturally percolate into the ground or evaporate, but flows via overland flow, interflow, pipes, and other features of a storm water drainage system into a defined surface wate r body, or a constructed infiltration facility. Upset —An exceptional incident in which there is unintentional and temporary noncompliance with technology-based permit effluent limits because of factors beyond the reasonable control of the Permittee. An upset does not include noncompliance to the extent caused by operational error, improperly designed treatment f acilities, lack of preventative maintenance, or careless or improper operation. Water Quality-Based Effluent Limit —A limit on the concentration of an effluent parameter that is intended to prevent the concentrati on of that parameter from exceeding its water quality criterion after it is discharged into receiving waters.Fact Sheet for NPDES Permit WA-002958-1 Page 56 of 101 King County South Wastewater Treatment Plant



### APPENDIX C—SOUTH WWTP APPLICATION PRIORITY POLLUTANT DATA SUMMARY

POLLUTANT MAXIMUM DAILY DISCHARGE A VERAGE DAILY DISCHARGE
ANALYTICAL METHOD ML/MDL Conc. Units Mass Units Conc. Units Mass Units Number of Samples
METALS (TOTAL RECOVERABLE), CYANIDE, PHENOLS, AND HARDNESS.

ANTIMONY 0.67 μg/L 0.45 lbs/d <0.51 μg/L <0.30 lbs/d 32 EPA200.8 0.5

ARSENIC 1.60 μg/L 1.17 lbs/d 1.26 μg/L 0.76 lbs/d 34 EPA200.8 0.5

BERYLLIUM <MDL μg/L <0.18 lbs/d <MDL μg/L <0.12 lbs/d 32 EPA200.8 0.2

CADMIUM 0.30 μg/L 0.17 lbs/d <0.11 μg/L <0.064 lbs/d 32 EPA200.8 0.1

CHROMIUM 4.07 μg/L 2.28 lbs/d 0.87 μg/L 0.51 lbs/d 32 EPA200.8 0.4

COPPER 42.40 μg/L 24.01 lbs/d 16.5 μg/L 9.51 lbs/d 32 EPA200.8 0.4

LEAD 2.00 μg/L 1.12 lbs/d 0.66 μg/L 0.38 lbs/d 32 EPA200.8 0.2

MERCURY 0.058 μg/L 0.045 lbs/d <0.05 μg/L <0.03 lbs/d 33 CVAA EPA245.1 0.05

NICKEL 4.45 μg/L 2.34 lbs/d 2.99 μg/L 1.78 lbs/d 33 EPA200.8 0.3

SELENIUM <MDL μg/L <1.35 lbs/d <MDL μg/L <0.89 lbs/d 33 EPA200.8 1.5

SILVER 0.84 μg/L 0.48 lbs/d <0.35 μg/L <0.21 lbs/d 32 EPA200.8 0.2

THALLIUM <MDL μg/L 0.18 lbs/d <MDL μg/L <0.117 lbs/d 33 EPA200.8 0.04-0.2

ZINC 68.0 μg/L 38.5 lbs/d 29.0 μg/L 17.4 lbs/d 33 EPA200.8 0.5

CYANIDE 0.028 mg/L 14.61 lbs/d <0.008 mg/L <5.09 lbs/d 33 SM4500-CN-I,E 0.005

TOTAL PHENOLIC COMPOUNDS 0.080 mg/L 47.2 lbs/d <0.011 mg/L <6.55 lbs/d 24 EPA 420.1 & 420.2 0.005- 0.02

HARDNESS (AS CaCO3) 99.4 mg/L 105,50 0 lbs/d 64.8 mg/L 44,632 lbs/d 75 SM2340C 0.1

Use this space (or a separate sheet) to provide information on other metals requested by the permit writerFact Sheet for NPDES Permit WA-002958-1 Page 57 of 101 King County South Wastewater Treatment Plant

POLLUTANT MAXIMUM DAILY DISCHARGE A VERAGE DAILY DISCHARGE
ANALYTICAL METHOD ML/MDL Conc. Units Mass Units Conc. Units Mass Units Number of Samples

VOLATILE ORGANIC COMPOUNDS

ACROLEIN <MDL μg/L <3.886 lbs/d <MDL μg/L <2.902 lbs/d 23 EPA 624 5

ACRYLONITRILE <MDL μg/L <3.886 lbs/d <MDL μg/L <2.902 lbs/d 23 EPA 624 5

BENZENE <MDL μg/L <0.777 lbs/d <MDL ug/L <0.580 lbs/d 23 EPA 624 1

BROMOFORM <MDL μg/L <0.777 lbs/d <MDL ug/L <0.580 lbs/d 23 EPA 624 1

CARBON TETRACHLORIDE <MDL μg/L <0.777 lbs/d <MDL ug/L <0.580 lbs/d 23 EPA 624 1

COLORBENZENE <MDL μg/L <0.777 lbs/d <MDL μg/L <0.580 lbs/d 23 EPA 624 1

CHLOROBIDBROMOMETHANE <MDL μg/L <0.777 lbs/d <MDL μg/L <0.58 lbs/d 23 EPA 624 1

CHLOROETHANE <MDL μg/L <0.777 lbs/d <MDL μg/L <0.580 lbs/d 23 EPA 624 1

2-CHLOROETHYLVINYL ETHER <MDL μg/L <0.777 lbs/d <MDL μg/L <0.580 lbs/d 23 EPA 624 1

CHOLOROFORM 2.18 μg/L 1.565 lbs/d <1.32 μg/L <0.802 lbs/d 23 EPA 624 1.32

DICHLOROBROMOMETHANE <MDL μg/L <0.777 lbs/d <MDL μg/L <0.58 lbs/d 23 EPA 624 1

1,1- DICHLOROETHANE <MDL ug/L <0.777 lbs/d <MDL ug/L <0.580 lbs/d 23 EPA 624 1

TRANS-1,2-DICHLOROETHYLENE <MDL ug/L <0.777 lbs/d <MDL ug/L <0.580 lbs/d 23 EPA 624 1

1,1- DICHLOROPROPANE <MDL μg/L <0.777 lbs/d <MDL μg/L <0.58 lbs/d 23 EPA 624 1

ETHYLBENZENE <MDL ug/L <0.777 lbs/d <MDL ug/L <0.58 lbs/d 23 EPA 624 1

METHYL BROMIDE <MDL ug/L <3.49 lbs/d <MDL ug/L <1.92 lbs/d 23 EPA 624 5

METHYL CHLORIDE <MDL ug/L <0.78 lbs/d <MDL ug/L <0.58 lbs/d 23 EPA 624 1

METHYLENE CHLORIDE 7 ug/L 4.164 lbs/d <4.74 ug/L <2.74 lbs/d 23 EPA 624 5

1,1,2,2-TETRACHLOROETHANE <MDL ug/L <0.777 lbs/d <MDL ug/L <0.580 lbs/d 23 EPA 624 1

TETRACHLOROETHYLENE <MDL μg/L <0.777 lbs/d <MDL μg/L <0.58 lbs/d 23 EPA 624 1

TOLUENE 3.86 ug/L 1.845 lbs/d <1.45 ug/L <0.78 lbs/d 23 EPA 624 4Fact Sheet for NPDES Permit WA-002958-1 Page 58 of 101 King County South Wastewater Treatment Plant

POLLUTANT MAXIMUM DAILY DISCHARGE A VERAGE DAILY DISCHARGE
ANALYTICAL METHOD ML/MDL Conc. Units Mass Units Conc. Units Mass Units Number of Samples
1,1,1- TRICHLOROETHANE <MDL ug/L <0.777 lbs/d <MDL ug/L <0.580 lbs/d 23 EPA 624 1

1,1,2- TRICHLOROETHANE <MDL ug/L <0.777 lbs/d <MDL ug/L <0.580 lbs/d 23 EPA 624 1

TRICHLOROETHYL ENE <MDL ug/L <0.777 lbs/d <MDL ug/L <0.580 lbs/d 23 EPA 624 1

VINYL CHLORIDE <MDL ug/L <0.777 lbs/d <MDL ug/L <0.580 lbs/d 23 EPA 624 1

Use this space (or a separate sheet) to provide information on other metals requested by the permit writer

ACID-EXTRACTABLE COMPOUNDS

P-CHLORO-MCRESOL <MDL μg/L <1.48 lbs/d <MDL μg/L <1.14 lbs/d 24 EPA 3520C/625 1.9-2.4

2-CHLOROPHENOL <MDL μg/L <1.48 lbs/d <MDL μg/L <1.14 lbs/d 24 EPA 3520C/625 1.9-2.4

2,4- DIMETHYLPHENOL <MDL μg/L <0.74 lbs/d <MDL μg/L <0.56 lbs/d 24 EPA 3520C/625 0.94-1.2

4,6-DINITRO-OCRESOL <MDL μg/L <1.48 lbs/d <MDL μg/L <1.14 lbs/d 24 EPA 3520C/625 1.9-2.4

2,4- DINITROPHENOL <MDL μg/L <1.48 lbs/d <MDL μg/L <1.14 lbs/d 24 EPA 3520C/625 1.9-2.4

2-NITROPHENOL <MDL μg/L <0.74 lbs/d <MDL μg/L <0.56 lbs/d 24 EPA 3520C/625 0.94-1.2

4-NITROPHENOL <MDL μg/L <1.48 lbs/d <MDL μg/L <1.14 lbs/d 24 EPA 3520C/625 1.9-2.4

PENTA CHLOROPHENOL <MDL μg/L <0.74 lbs/d <MDL μg/L <0.56 lbs/d 24 EPA 3520C/625 0.94-1.2

PHENOL <MDL μg/L <2.95 lbs/d <MDL μg/L <2.27 lbs/d 24 EPA 3520C/625 3.9

2,4,6-TRICHLORO PHENOL <MDL μg/L <2.95 lbs/d <MDL μg/L <2.27 lbs/d 24 EPA 3520C/625 3.8-4.7

Use this space (or a separate sheet) to provide information on other metals requested by the permit writer

BASE-NEUTRAL COMPOUNDS

ACENAPHTHENE <MDL μg/L <0.30 lbs/d <MDL μg/L <0.23 lbs/d 24 EPA 3520C/625 0.38-0.47

ACENAPHTYLENE <MDL μg/L <0.44 lbs/d <MDL μg/L <0.34 lbs/d 24 EPA 3520C/625 0.57-0.71

ANTHRACENE <MDL μg/L <0.44 lbs/d <MDL μg/L <0.34 lbs/d 24 EPA 3520C/625 0.57-0.71

BENZIDINE <MDL μg/L <17.88 lbs/d <MDL μg/L <13.72 lbs/d 24 EPA 3520C/625 23-28

BENZO(A) ANTHRACENE <MDL μg/L <0.44 lbs/d <MDL μg/L <0.34 lbs/d 24 EPA 3520C/625 0.57-0.71Fact Sheet for NPDES Permit WA-002958-1 Page 59 of 101 King County South Wastewater Treatment Plant

POLLUTANT MAXIMUM DAILY DISCHARGE A VERAGE DAILY DISCHARGE
ANALYTICAL METHOD ML/MDL Conc. Units Mass Units Conc. Units Mass Units Number of Samples

FLUORANTHENE <MDL μg/L <0.44 lbs/d <MDL μg/L <0.34 lbs/d 24 EPA 3520C/625 0.57-0.71

FLUORENE <MDL μg/L <0.44 lbs/d <MDL μg/L <0.34 lbs/d 24 EPA 3520C/625 0.57-0.71

HEXACHLORO BENZENE <MDL μg/L <0.44 lbs/d <MDL μg/L <0.34 lbs/d 24 EPA 3520C/625 0.57-0.71

HEXACHLOROBUT ADIENE <MDL μg/L <0.74 lbs/d <MDL μg/L <0.57 lbs/d 24 EPA 3520C/625 0.94-1.2

HEXACHLOROCYCLOPENTADIENE <MDL μg/L <0.74 lbs/d <MDL μg/L <0.57 lbs/d 24 EPA 3520C/625 0.94-1.2

HEXA CHLOROETHANE <MDL μg/L <0.74 lbs/d <MDL μg/L <0.57 lbs/d 24 EPA 3520C/625 0.94-1.2

INDENO(1,2,3-CD) PYRENE <MDL μg/L <0.74 lbs/d <MDL μg/L <0.57 lbs/d 24 EPA 3520C/625 0.94-1.2

ISOPHORONE <MDL μg/L <0.74 lbs/d <MDL μg/L <0.57 lbs/d 24 EPA 3520C/625 0.94-1.2

NAPHTHALENE <MDL μg/L <1.17 lbs/d <MDL μg/L <0.90 lbs/d 24 EPA 3520C/625 1.5-1.9

NITROBENZENE <MDL μg/L <0.74 lbs/d <MDL μg/L <0.57 lbs/d 24 EPA 3520C/625 0.94-1.2

N-NITROSODI-NPROPYLAMINE <MDL μg/L <0.74 lbs/d <MDL μg/L <0.57 lbs/d 24 EPA 3520C/625 0.94-1.2

N-NITROSODIMETHYLAMINE <MDL μg/L <2.95 lbs/d <MDL μg/L <2.72 lbs/d 24 EPA 3520C/625 3.8-4.7

N-NITROSODIPHENYLAMINE <MDL μg/L <0.74 lbs/d <MDL μg/L <0.97 lbs/d 24 EPA 3520C/625 0.94-1.2

PHENANTHRENE <MDL μg/L <0.44 lbs/d <MDL μg/L <0.34 lbs/d 24 EPA 3520C/625 0.57-0.71

PYRENE <MDL μg/L <0.44 lbs/d <MDL μg/L <0.34 lbs/d 24 EPA 3520C/625 0.57-0.71

1,2,4- TRICHLOROBENZENE <MDL μg/L <0.44 lbs/d <MDL μg/L <0.44 lbs/d 24 EPA 3520C/625 0.57-0.71

Use this space (or a separate sheet) to provide information on other metals requested by the permit writer

Use this space (or a separate sheet) to provide information on other metals requested by the permit writerFact Sheet for NPDES Permit WA-002958-1 Page 60 of 101 King County South Wastewater Treatment Plant



### APPENDIX D—SOUTH WWTP DI SCHARGE MONITORING REPORT SUMMARY TABLES

Discharge Monitoring Data – October 2004 to April 2009Fact Sheet for NPDES Permit WA-002958-1 Page 61 of 101 King County South Wastewater Treatment Plant

DateBOD, mg/LBOD, mg/LBOD, ppdBOD, ppdTSS, mg/LTSS, mg/LTSS, ppdTSS, ppd

Mnthly

Ave Max day Mnthly Ave Max day Mnthly Ave Max Day Mnthly Ave Max day 1-Oct-04 205 213 115655 123429 231 259 132103 152714
1-Nov-04 217 237 141967 153571 286 300 186667 2000714 1-Dec-04 209 245 157385 166000 277 297 207933 222000
1-Jan-05 236 288 167407 184000 289 351 207500 224000 1-Feb-05 258 293 163100 18000 238 261 150929 179000 1-Mar-05 257 301 167458 182000 251 293 161700 181000 1-Apr-05 217 275 144286 172000 234 247 157310 164000 1-May-05 208 217 123214 131000 248 261 146069 165000 1-Jun-05 271 289 155267 165000 284 307 162800 172000 1-Jul-05 266 285 140500 15100 293 308 154710 162000 1-Aug-05 259 284 133586 147000 255 295 131194 15000 1-Sep-05 217 231 111000 117000 243 266 123862 139000 1-Oct-05 203 238 104083 125000 241 276 124500 145000
1-Nov-05 195 217 130737 142000 228 242 155519 175000 1-Dec-05 178 207 121667 128000 213 251 153484 173000 1-Jan-06 106 134 114095 120000 145 163 157033 167000 1-Feb-06 149 191 117684 125000 195 217 149808 160000
1-Mar-06 166 179 113789 121000 197 212 134310 145000 1-Apr-06 131 150 73125 87000 210 246 114733 126000 1-May-06 178 200 88643 98000 234 274 117600 135000
1-Jun-06 159 184 88517 101000 251 292 139533 159000 1-Jul-06 167 179 82161 88000 233 241 114839 123000 1-Aug-06 171 18 77750 85000 234 263 107033 121000 1-Sep-06 163 187 76400 90000 239 258 112615 121000 1-Oct-06 183 203 91037 108000 271 302 135000 161000
1-Nov-06 119 176 115760 128000 198 299 190667 209000
1-Dec-06 125 154 114791 130000 188 211 170516 185000 1-Jan-07 194 254 171936 207273 202 234 181675 194047 1-Feb-07 228 260 175349 189959 214 258 163499 188819 1-Mar-07 200 222 173264 188278 190 210 163790 172649 1-Apr-07 223 248 161646 177289 236 300 171296 217415 1-May-07 261 291 169684 183530 284 314 184373 206998 1-Jun-07 266 305 155759 185908 280 302 163794 184306
1-Jul-07 266 281 154919 165367 274 288 159404 162066 1-Aug-07 267 304 150752 178668 279 297 157276 174574 1-Sep-07 258 287 143860 157492 265 279 149373 159556 1-Oct-07 245 286 153475 181750 248 306 155068 193760
1-Nov-07 251 258 167336 175401 252 287 166792 195538 1-Dec-07 208 233 187630 212502 205 218 183212 197848 1-Jan-08 230 253 185376 194462 222 255 179970 207100
1-Feb-08 246 261 180033 182851 234 255 172707 179393 1-Mar-08 251 276 195478 206004 248 265 190174 196611 1-Apr-08 250 275 173840 187373 249 258 176737 187316 1-May-08 272 285 155043 164240 280 304 160027 174982 1-Jun-08 270 317 157417 175848 267 300 156557 166613 1-Jul-08 291 308 128112 139850 284 309 125001 131251 1-Aug-08 276 302 132284 146017 263 279 128507 151526 1-Sep-08 271 287 142891 149496 259 272 136316 141808 1-Oct-08 285 300 152221 161913 264 292 140785 150531
1-Nov-08 253 289 178953 191857 257 284 184084 216825 1-Dec-08 266 305 191900 240824 216 250 155366 173750 1-Jan-09 252 301 214073 225037 216 233 185616 232900 1-Feb-09 290 305 196211 207194 260 278 175071 184177
1-Mar-09 266 302 207950 222730 242 251 189248 191276 1-Apr-09 242 283 159607 206371 259 348 170167 225204

AVE: 223 248 144231 152763 243 270 156587 203983 MIN: 106 18 73125 15100 145 163 107033 15000 MAX: 291 317 214073 240824 293 351 207933 2000714 Limit 251000 235000 85% 213350 199750 InfluentFact Sheet for NPDES Permit WA-002958-1 Page 62 of 101 King County South Wastewater Treatment Plant

DateFlow, MGDFlow, MGDBOD, mg/LBOD, mg/LBOD, ppdBOD, ppdBOD, %RemovalTSS, mg/LTSS, mg/LTSS, ppdTSS, ppdTSS, %RemovalPHPHFecalColiform,FecalColiform,Cl, mg/LCl, mg/LCal. Cl, ppd

Mnthly

Ave Max day Mnthly Ave Wkly Ave Mnthly Ave Wkly Ave Mnthly Ave Mnthly Ave Wkly Ave Mnthly Ave Wkly Ave Mnthly Ave Day Min Day Max GEM GM7 Ave Monthly Max day Monthly Ave 1-Oct-04 67.9 76.9 14.8 15.3 8371 8543 93 13.9 16.1 8013 10143 94 7 9.8 33 80 0.003 0.02 1.5
1-Nov-04 78 106.9 14 15 9117 9800 93 18 20 11910 14300 94 7 8.2 153 208 0 0.01 0 1-Dec-04 91.3 109.6 15.6 17 12074 15100 93 17 20.3 12910 15400 94 6.4 8.9 67 83 0 0.01 3
1-Jan-05 91 118 15 17 11118 13100 94 17 22 12603 15000 94 6.8 8.3 107 320 0.02 0.19 22
1-Feb-05 75 82 16 19 10315 13000 94 21 24 13425 16300 91 6.9 7.5 64 99 0 0 0 1-Mar-05 78 100 20.5 23.5 13483 15180 92 15.4 17.7 9952 11500 94 6.9 7.3 48 206 0 0 0 1-Apr-05 81 82 15 18 10369 12200 93 13.5 14 9160 9400 94 6.8 8.5 17 22 0 0 0 1-May-05 70 73 10.9 12 6397 7000 95 13.7 18 8100 11000 94 6.8 7.3 37 88 0 0 0 1-Jun-05 68 70 14 18 7787 10000 95 12.5 18 7117 9900 96 6.7 7.2 121 196 0 0 0
1-Jul-05 63 63.7 20.7 23 10924 12000 92 17.3 19 9126 10100 94 6.8 7.4 75 265 0 0 0 1-Aug-05 61.3 61.9 16 18 8155 9100 94 13 14 6687 7500 95 6.4 7.2 108 148 0 0 0 1-Sep-05 61 62.2 14 17 7155 8600 94 15.8 16.6 8043 8400 93 6.8 7.2 95 180 0 0 0 1-Oct-05 62 62.4 12.2 13 6321 6700 94 14.7 17 7703 9000 94 6.8 7.3 50 70 0 0 0
1-Nov-05 81 86.2 14 15 8891 9500 93 20.8 22 14030 14900 91 6.9 7.1 59 134 0 0 0 1-Dec-05 91 133.4 14.4 20 10867 21600 92 25.3 36 20645 40500 88 6.6 7.3 54 115 0 0 0
1-Jan-06 133 158 14.7 23 16855 24700 86 20.4 34 23097 36700 86 6 7.3 66 125 0 0 0
1-Feb-06 96 148 11 11 8835 12400 93 14 15 11311 18200 93 6.5 7 48 76 0 0 0 1-Mar-06 81 90 13.8 16 9333 10500 92 16.4 18.4 11090 11900 92 6.6 7 130 329 0 0.01 0 1-Apr-06 65 78 10 13.7 5720 7900 92 14.2 19 7853 11000 93 6 7.4 88 197 0.01 0.05 3 1-May-06 60 70 14.4 20 7161 9700 92 12.9 14.8 6448 7400 94 6.4 7.8 51 67 0 0.03 2 1-Jun-06 66 77 12 15 6514 8000 93 9.9 11 5480 6200 96 6.5 7.2 86 100 0 0.02 2
1-Jul-06 59 65 11.9 13.4 5835 6600 93 16.1 18.9 7865 8700 93 6.8 7.1 134 294 0 0.03 0 1-Aug-06 55 58 9.7 11 4426 5000 94 11.7 16 5345 7000 95 6.1 7.5 42 108 0 0.05 2 1-Sep-06 56 62 9 10 4293 4800 94 14.5 17 6803 8300 94 6.6 7.4 79 156 0 0.03 1 1-Oct-06 59 74 11.4 14.1 5664 7500 94 11.7 13.9 5794 7300 96 6.5 8.6 40 44 0 0 0
1-Nov-06 119 183 15 18 15569 22157 88 30 41 32357 50971 85 6.3 7 56 135 0 0.03 2
1-Dec-06 111 193 14 18 14133 21700 89 23 30 22455 35000 88 6.3 6.9 41 86 0 0 0 1-Jan-07 104 142.7 22 26 18777 21394 89 25 34 22760 36308 87 6.3 7.1 110 249 0.05 0.05 43.5
1-Feb-07 89.1 115.2 20 21 15262 17447 91 17 18 12850 14838 92 6.7 7.2 49 105 0.05 0.05 37.2
1-Mar-07 100.7 131.5 18 19 15154 17003 91 18 21 15494 18647 91 6.6 7 32 116 0.05 0.05 42 1-Apr-07 82.9 95.8 25 30 16969 20271 89 22 25 15192 16891 91 6.6 8.8 96 300 0.05 0.05 34.6 1-May-07 72.8 81 18 29 10918 19169 94 17 22 10587 13766 94 6.6 7.8 57 85 0.05 0.05 30.4
1-Jun-07 66.5 70.3 18 21 10191 11651 93 13 15 7296 8111 95 6.6 7.2 110 355 0.05 0.05 27.7 1-Jul-07 67.3 77.2 12 14 6595 8178 96 8 9 4651 5108 97 6.2 6.8 56 173 0.05 0.08 28.6 1-Aug-07 64.7 70 15 19 8072 9890 95 12 15 6430 7847 96 6.5 6.9 85 241 0.06 0.17 30 1-Sep-07 62.7 84.2 15 17 7906 8987 94 16 18 8302 9642 94 6.5 7.2 105 247 0.05 0.14 27.8 1-Oct-07 70.4 82.8 15 17 9063 10124 94 13 19 7615 11394 95 6 7.3 150 308 0.05 0.05 29.4
1-Nov-07 74.4 95.8 17 21 10934 12993 93 15 21 9411 13286 94 6.6 7.2 170 254 0.05 0.15 34.2
1-Dec-07 99.4 234.9 23 24 19843 29360 90 25 27 21218 32134 89 6.6 7.3 141 363 0.29 0.75 231.3 1-Jan-08 89.7 116.6 22 26 16617 18282 91 24 29 17989 20585 90 6.7 7.2 35 39 0.07 0.17 49.2
1-Feb-08 79.9 104.1 23 28 15193 20311 92 24 30 16590 21710 90 6.7 7.4 35 62 0.05 0.05 33.3
1-Mar-08 81.6 106.5 20 21 13795 15267 93 23 25 15653 18520 92 6.9 7.3 37 78 0.06 0.16 44.8 1-Apr-08 75.6 89.1 17 22 10405 17768 94 21 28 13513 21306 92 7 7.4 135 259 0.05 0.05 31.5 1-May-08 60.4 65.8 19 21 9811 10519 94 16 18 8214 9073 95 7.1 7.5 106 145 0.05 0.07 25.6
1-Jun-08 62.4 74.2 18 20 9145 10226 94 13 14 6962 8126 95 7.1 7.5 84 171 0.05 0.12 28 1-Jul-08 45.2 55.1 17 19 6547 7584 95 17 20 6578 8192 95 7.3 7.5 48 66 0.05 0.07 19.1 1-Aug-08 52.1 76.7 17 18 7143 8777 95 15 19 6731 9291 95 7.2 7.5 20 23 0.05 0.07 22 1-Sep-08 57.7 64.6 13 13 6151 6578 96 9 11 4388 4999 97 6.8 8.4 25 43 0.05 0.11 25.1 1-Oct-08 59.2 65.3 16 25 8188 12753 16 22 7908 11281 6.9 7.6 34 53 0.06 0.22 28.7
1-Nov-08 80.5 144.4 22 25 15108 19881 18 20 12195 15558 6.8 6.9 85 185 0.06 0.18 39.3
1-Dec-08 81.6 132.6 23 27 15799 21514 23 26 15517 24360 6.7 6.9 38 56 0.06 0.17 39.9 1-Jan-09 100.8 200.7 23 26 20186 29891 27 30 23121 32420 6.3 6.9 35 104 0.06 0.19 53.4
1-Feb-09 73.5 84.4 19 24 11865 14750 19 20 11405 13378 6.5 6.9 23 56 0.05 0.05 30.6
1-Mar-09 87.7 105.8 20 22 14582 18491 24 30 17672 24443 6.5 6.8 94 145 0.05 0.05 36.6 1-Apr-09 75 124.4 18 20 11231 15467 19 24 11958 16810 6.3 6.9 43 80 0.05 0.05 31.3

AVE: 76.34 98.36 16 19 10665 13545 93 17 21 11696 15615 93 6.6 7.4 73 152 0 0 8 MIN: 45.20 55.10 9 10 4293 4800 86 8 9 4388 4999 85 6.0 6.8 17 22 0 0 0 MAX: 133.00 234.90 25 30 20186 29891 96 30 41 32357 50971 97 7.3 9.8 170 363 0 0 44 Limit 144.00 30 45 36000 54000 85 30 45 36000 54000 85 6.0 9.0 200 400 0.5 0.75 85% 122.40 EffluentFact Sheet for NPDES Permit WA-002958-1 Page 63 of 101 King County South Wastewater Treatment Plant



### APPENDIX E

— SOUTH WWTP DISCHARGE MONITORING REPORT GRAPHS

South WWTP – Influent TSS (Mass Basis)

South WWTP – Influent TSS (Concentration Basis) 0 50,000 100,000 150,000 200,000 250,000Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07Dec-07Feb-08Apr-08Jun-08Aug-08Oct-08Dec-08Feb-09Apr-09Influent TSS, lbs/day Monthly Avg

85% of Design Loading

100% Design Loading

0 50 100 150 200 250 300 350Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07Dec-07Feb-08Apr-08Jun-08Aug-08Oct-08Dec-08Feb-09Monthly Average Influent TSS, mg/LFact Sheet for NPDES Permit WA-002958-1 Page 64 of 101 King County South Wastewater Treatment Plant

South WWTP – Influent BOD 5 (Mass Basis)

South WWTP – Influent BOD 5 (Concentration Basis) 0 50,000 100,000 150,000 200,000 250,000 300,000Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07Dec-07Feb-08Apr-08Jun-08Aug-08Oct-08Dec-08Feb-09Influent BOD5, lbs/day Monthly Avg

85% of Design Loading

100% Design Loading

0 50 100 150 200 250 300 350Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07Dec-07Feb-08Apr-08Jun-08Aug-08Oct-08Dec-08Feb-09Monthly Average Influent BOD5, mg/LFact Sheet for NPDES Permit WA-002958-1 Page 65 of 101 King County South Wastewater Treatment Plant

South WWTP – Influent Flow

South WWTP – Effluent pH 0 20 40 60 80 100 120 140 160Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07Dec-07Feb-08Apr-08Jun-08Aug-08Oct-08Dec-08Feb-09InfluentFlow, MGD Average Monthly Flow

85% of Max Month Flow

100% of Max Month Flow

5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5Jan-04Aug-04Feb-05Sep-05Mar-06Oct-06Apr-07Nov-07Jun-08Dec-08Jul-09Effluent pH, Std. Units Day Min

Day Max permit range: 6.0 - 9.0Fact Sheet for NPDES Permit WA-002958-1 Page 66 of 101 King County South Wastewater Treatment Plant
South WWTP – Effluent TSS (Mass Basis)

South WWTP – Effluent TSS (Concentration Basis) 0 10000 20000 30000 40000 50000 60000Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07Dec-07Feb-08Apr-08Jun-08Aug-08Oct-08Dec-08Feb-09Effluent TSS, ppd Monthly Avg Weekly Avg Monthly Avg permit limit Weekly Avg permit limit

0 5 10 15 20 25 30 35 40 45 50Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07Dec-07Feb-08Apr-08Jun-08Aug-08Oct-08Dec-08Feb-09Effluent TSS, mg/L Monthly Avg Weekly Avg Monthly Avg permit limit Weekly Avg permit limitFact Sheet for NPDES Permit WA-002958-1 Page 67 of 101 King County South Wastewater Treatment Plant

South WWTP – Effluent BOD 5 (Mass Basis)

South WWTP – Effluent BOD 5 (Concentration Basis) 0 10000 20000 30000 40000 50000 60000Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07Dec-07Feb-08Apr-08Jun-08Aug-08Oct-08Dec-08Feb-09EffluentBOD5, ppd Monthly Avg Weekly Avg Monthly Avg permit limit Weekly Avg permit limit

0 5 10 15 20 25 30 35 40 45 50Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07Dec-07Feb-08Apr-08Jun-08Aug-08Oct-08Dec-08Feb-09EffluentBOD5, mg/L Monthly Avg Weekly Avg Monthly Avg permit limit Weekly Avg permit limitFact Sheet for NPDES Permit WA-002958-1 Page 68 of 101 King County South Wastewater Treatment Plant

South WWTP – Effluent Fecal Coliform Bacteria

0 50 100 150 200 250 300 350 400 450Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07Dec-07Feb-08Apr-08Jun-08Aug-08Oct-08Dec-08Feb-09Effluent Fecal Coliform, #/100 mL GEM

GM7
GEM permit limit
GM7 permit limitFact Sheet for NPDES Permit WA-002958-1 Page 69 of 101 King County South Wastewater Treatment Plant



### APPENDIX F—OUTF ALL DIAGRAMSFact Sheet for NPDES Permit WA-002958-1 Page 70 of 101 King County South Wastewater Treatment PlantFact Sheet for NPDES Permit WA-002958-1 Page 71 of 101 King County South Wastewater Treatment PlantFact Sheet for NPDES Permit WA-002958-1 Page 72 of 101 King County South Wastewater Treatment Plant

Pipe length=10,000 ft. Pipe Dia. = 8 ft. Diffuser length = 500 ft. Diffuser Dia. = 64in. with 168 - 4in. Diameter Ports. Plan View 2,150 ft

Side View

-625 ft MLLW 0 ft MLLW Acute Mixing Zone Boundary

South WWTP Marine Outfall Mixing Zones – North Diffuser. 665 ft Chronic Mixing Zone Boundary 1,650 ft 165 ft 665 ft

Not to Scale

Pipe length=10,000 ft. Pipe Dia. = 8 ft. Diffuser length = 500 ft. Diffuser Dia. = 64in. with 168 - 4in. Diameter Ports. Plan View 2,150 ft

Side View

-625 ft MLLW 0 ft MLLW Acute Mixing Zone Boundary

South WWTP Marine Outfall Mixing Zones – South Diffuser. 665 ft Chronic Mixing Zone Boundary 1,650 ft 165 ft 665 ft

Not to ScaleFact Sheet for NPDES Permit WA-002958-1 Page 73 of 101 King County South Wastewater Treatment Plant



### APPENDIX G—WHOLE EFFLUENT TOXI CITY (WET) TESTING RESULTS
ACUTE TEST

King County South Plant Acute WET Test Results as % Survival in 100% Effluent

Test Code Collected Start Date Organism Endpoint % Survival
RMAR1177 2/8/2008 2/8/2008 Daphnia pulex 48-hour Survival 75% RMAR1178 2/11/2008 2/11/2008 Fathead Minnow 96-hour Survival 88% RMAR1210 4/2/2008 4/2/2008 Daphnia pulex 48-hour Survival 100% RMAR1208 4/7/2008 4/7/2008 Fathead Minnow 96-hour Survival 78% RMAR1298 7/9/2008 7/9/2008 Daphnia pulex 48-hour Survival 100% RMAR1296 8/18/2008 8/18/2008 Fathead Minnow 96-hour Survival 85% RMAR1327 10/8/2008 10/8/2008 Daphnia pulex 48-hour Survival 100% RMAR1325 10/13/2008 10/13/2008 Fathead Minnow 96-hour Survival 93%
Median = 90%

CHRONIC TEST

King County South Plant Chronic WET Test Results as NOEC/LOEC in % Effluent Test Code Collected Start Date Organism Endpoint NOEC LOEC PMSD RMAR1180 2/6/2008 2/6/2008 Atlantic Mysid 7-day Survival 12.5 25 15.43% Biomass 0.43 12.5 15.46% Weight 0.43 12.5 14.99% RMAR1179 2/6/2008 2/7/2008 Topsmelt 7-day Survival 12.5 25 12.80% Biomass 0.43 12.5 16.27% Weight 0.43 12.5 11.28% RMAR1209 4/2/2008 4/2/2008 Topsmelt 7-day Survival 25 50 11.96% Biomass 12.5 25 15.36% Weight 12.5 25 13.46% RMAR1207 4/2/2008 4/2/2008 Atlantic Mysid 7-day Survival 50 100 11.63% Biomass 12.5 25 13.90% Weight 0.43 12.5 12.22% RMAR1299 7/9/2008 7/9/2008 Atlantic Mysid 7-day Survival 50 100 12.88% Biomass 12.5 25 12.92% Weight 12.5 25 11.83% RMAR1297 7/9/2008 7/9/2008 Topsmelt 7-day Survival 50 100 14.56% Biomass 25 50 22.16% Weight 25 50 18.74% RMAR1326 10/8/2008 10/8/2008 Topsmelt 7-day Survival 50 100 7.29% Biomass 50 100 20.18% Weight 50 > 50 18.53% RMAR1328 10/8/2008 10/8/2008 Atlantic Mysid 7-day Survival 50 100 15.90% Biomass 25 50 15.32% Weight 25 50 12.41% For Acute toxicity, the performance standard is the median survuval in 100% effluent being equal to or greater than 80% and no individual test result showing less than 65% survival in 100% effluent.

Median survival in 100% effluent = 90%. All Acute WET Tests had greater than 65% survival in 100% effluent. Therefore, no Acute WET limit required. Permit requires another effluent characterization for acute WET ( WAC 173-245 )

.

For Chronic toxicity, the performance standard is no chronic toxicity test demonstrating a statistically significant difference in response between the control and a test concentration equal to the acute critical effluent concentration (ACEC). For the tests below, the previous ACEC of 0.43% effluent was used.

The proposed permit includes lower (more restrictive) dilution factors than the previous permit. This results in a new ACEC of 0.54% and CCEC of 0.44%, which w ill be used in the pr oposed permit for WET testing. If there is no chronic toxicity at the acute mixing zone boundary, then there is no reasonable potential for chronic toxicity a t the edge of the chronic mixing zone boundary. To review, Ecology compares the Lowest Observed Effects Concentration (LOEC) to the ACEC. If the LOEC is always above the ACEC, we can assume that there is no chronic toxicity. Based on the above data, the LOEC is always greater than the ACEC (0.43 %). Therefore, no chronic WET limit is needed.Fact Sheet for NPDES Permit WA-002958-1 Page 74 of 101 King County South Wastewater Treatment Plant



### APPENDIX H—TECHNI CAL CALCULATIONS

Several of the Excel ® spreadsheet tools used to evaluate a discharger’s ability to meet Washington State water quality standard s can be found on Ecology’s homepage at http://www.ecy.wa.gov/programs/eap/pwspread/pwspread.html

.Fact Sheet for NPDES Permit WA-002958-1 Page 75 of 101 King County South Wastewater Treatment Plant
Table H-1: South WWTP – Water Quality Criteria for Detected Pollutants

FACILITY: South Plant WWTP FILENAME: RUN DATE:4/17/2009
PREPARED BY: M. Henley

Red font = National Toxics Rule (40 CFR 131.36) Blue font = EPA National Recommended Water Quality Criteria:2002 (EPA 822-R-02-47) Green font = Other source - see comment Black font = WAC 173-201A (Nov. 1997)

Input Required Data Units 0 mg/L S 99.4 mg/L at CaCO 3

WATER QUALITY CRITERIA (in ug/L unless otherwise noted)
Pollutant Detected input "y" Pollutant CAS No. NPDES
A pplication Reference No. Hardness or pH dependent Conversion Factor Conversion Factor Chronic Priority Pollutants Carcinogen Water Quality Criteria - Marine - Acute Water Quality Criteria - Marine - Chronic Human Health Criteria - Marine

48.70 AMMONIA mg/L N N 233 35 0.67 ANTIMONY (INORGANIC) 7440360 1M Y N 4300 1.60 ARSENIC (dissolved) 7440382 2M Y Y 69 36 0.30 CADMIUM 7440439 4M 50.0 0.97 0.94 Y N 42.00 9.3 750.00 CHLORINE (Total Residual) 7782506 N N 13 7.50 2.18 CHLOROFORM 67663 11V Y Y 470 4.07 CHROMIUM(HEX) 18540300 Y N 1100 50 42.40 COPPER 744058 6M 50.0 Y N 4.80 3.10 28.00 CYANIDE 57125 14M Y N 1.00 1.00 220000 3.93 1,4 DICHLOROBENZENE 106467 22B Y N 2600 2.00 LEAD 7439921 7M 50.0 0.89 Y N 210.00 8.10 7.00 METHYLENE CHLORIDE 75092 22V Y Y 1600 0.058 MERCURY 7439976 8M Y N 1.80 0.0250 0.15 4.45 NICKEL 7440020 9M 50.0 Y N 74.00 8.20 4600 0.84 SILVER 7740224 11M 50.0 Y N 1.90 NA 1.40 TETRACHLOROETHYLENE 127184 24V Y Y 8.85 3.86 TOLUENE 108883 25V Y N 200000 68.00 ZINC 7440666 13M 50.0 Y N 90.00 81.00VALUE PRESENTED IS TH L.O.E.LENTER RECEIVING WATER TSS (IF IF RECEIVING WATER TSS IS ANNUAL HARDNESS VALUE USED FOR HARDNESS DEPENDENT LIMITS>>>> * = INSUFFICIENT DATA TO DEVELOPFact Sheet for NPDES Permit WA-002958-1 Page 76 of 101 King County South Wastewater Treatment Plant
Table H-2: South WWTP – Ammonia Calculation Spreadsheet

Ammonia Calculation Spreadsheet

Calculation of seawater fraction of un-ionized ammonia from Hampson (1977). Un-ionized ammonia criteria for
salt water are from EPA 440/5-88-004. Revised 19-Oct-93. Facility: South Plant WWTP
Permit No: WA-002958-1
INPUT*

1. Temperature, deg C (90th percentile): 14.0 Max.

2. pH, (90th percentile): 8.0

3. Salinity, g/Kg (90th percentile): 31.1 Max.

OUTPUT

1. Pressure (atm; EPA criteria assumes 1 atm): 1.0

2. Molal Ionic Strength (not valid if >0.85): 0.640

3. pKa8 at 25 deg C (Whitfield model "B"): 9.319

4. Percent of Total Ammonia Present as Unionized: 2.066%

5. Unionized ammonia criteria (mg un-ionized NH3 per liter) from EPA 440/5-88-004 Acute: 0.233 Chronic: 0.035

6. Total Ammonia Criteria (mg/L as NH3) Acute: 11.28 Chronic: 1.69

7. Total Ammonia Criteria (mg/L as NH3-N) Acute: 9.27 9269.35 ug/L Chronic: 1.39 1392.39 ug/L
* Data from ambient monitoring station LSNT01, South Plant Outfall

fn: TSDCalc10.clsFact Sheet for NPDES Permit WA-002958-1 Page 77 of 101 King County South Wastewater Treatment Plant

Table H-3: South WWTP – Reasonable Potentia l to Exceed the Water Quality StandardsState Water QualityStandardMax concentrationat edge of...MetalCriteriaTranslator asdecimalMetalCriteriaTranslatoras decimalAmbientConcentration(metals asdissolved)Acute ChronicAcuteMixingZoneChronicMixingZoneLIMITREQ'D?Effluentpercentilevalue95th %effluentconc.measured(metals astotalrecoverable)CoeffVariation# ofsamplesMultiplierAcuteDil'nFactorChronicDil'nFactorParameter Acute Chronicug/L ug/L ug/Lug/L ug/L Pnug/L CVsnCOMMENTSAmmonia 11.0 9269 1392 212.55 177.62 NO 0.95 0.997 375000.2100.21 934 1 186 225ARSENIC (dissolved) 1.00 1.4400 69.0 36.0 1.44 1.44 NO 0.95 0.916 1.5160.1010.10 34 1 186 225CADMIUM 0.994 0.994 0.0746 42.0 9.3 0.07 0.07 NO 0.95 0.911 0.0770.7560.67 32 1 186 225CHLORINE (Total Residual) 13.0 7.5 0.27 0.22 NO 0.95 0.998 50.0000.7510.67 1553 1 186 225CHROMIUM(HEX) 0.993 0.993 0.4510 1100.0 50.0 0.46 0.46 NO 0.95 0.911 1.4800.7230.65 32 1 186 225COPPER 0.83 0.83 0.5740 4.8 3.1 0.71 0.69 NO 0.95 0.911 31.3400.4750.45 32 1 186 225CYANIDE 1.0 1.0 0.00 0.00 NO 0.95 0.913 0.0190.9030.77 33 1 186 225LEAD 0.951 0.95 0.1630 210.0 8.1 0.17 0.17 NO 0.95 0.911 1.2540.5220.49 32 1 186 225MERCURY 0.85 0.000621 1.8 0.025 0.00 0.00 NO 0.95 0.913 0.0510.3060.30 33 1 186 225NICKEL 0.99 0.99 0.6830 74.0 8.20 0.70 0.70 NO 0.95 0.913 4.0040.1830.18 33 1 186 225SILVER 0.85 1.9 NA 0.00 0.00 NO 0.95 0.911 0.5960.4230.41 32 1 186 225ZINC 0.946 0.946 0.8880 90.0 81.0 1.13 1.09 NO 0.95 0.913 49.3400.4140.40 33 1 186 225This spreadsheet calculates the reasonable potential to exceed state water quality standards for a small number of samples. Theprocedure and calculationsare done per the procedure in Technical Support Document for Water Quality-based Toxics Control, U.S. EPA, March, 1991 (EPA/505/2-90-001) on page 56.User input columns are shown with red headings. Corrected formulas in col G and H on 5/98 (GB)Fact Sheet for NPDES Permit WA-002958-1 Page 78 of 101 King County South Wastewater Treatment Plant

Table H-4: South WWTP – Chlorine Limit to Meet Water Quality Limit

Permit Limit Calculation Summary

Acute Dil'n Factor Chronic Dil'n Factor Metal Criteria Translat

or Metal Criteria Translat

or Ambient Concentr

ation Water Quality Standard

Acute Water Quality Standard Chronic Average Monthly Limit (AML) Maximum Daily Limit

(MDL) Comments PARAMETER Acute Chronic ug/L ug/L ug/L ug/L ug/L

Chlorine 186.00 225.00 13.00 7.50 923.7 2418.0 New DF

500.0 750.0 Technology-Based

Waste Load Allocation (WLA) and Long Term Average (LTA) Calculations Statistical variables for permit limit calculation

WLA Acute WLA Chronic LTA Acute LTA Chronic LTA Coeff. Var. (CV) LTA Prob'y Basis Limiting LTA Coeff. Var. (CV) AML Prob'y Basis MDL Prob'y Basis # of Sample

s per Month ug/L ug/L ug/L ug/L decimal decimal ug/L d ecima l decimal decimal n

2418 1687.50 776.4 890.0 0.60 0.99 776.4 0.60 0.95 0.99 30.00 1.00Fact Sheet for NPDES Permit WA-002958-1 Page 79 of 101 King County South Wastewater Treatment Plant

Table H-5: South WWTP – Reasonable Potent ial to Exceed Human Health CriteriaFact Sheet for NPDES Permit WA-002958-1 Page 80 of 101 King County South Wastewater Treatment Plant
Table H-5 (Continued): South WWTP – Reas onable Potential to Exceed Human Health CriteriaFact Sheet for NPDES Permit WA-002958-1 Page 81 of 101 King County South Wastewater Treatment Plant
Table H-6: South WWTP – Ambient Monitoring Data Summary

King County Water Quality Data Station LSNT01 - Central Basin 1999 through 2008 - Conventionals Salinity Temperature Dissolved Oxygen Fecal Coliform Bacteria

(PSS) (°C) (mg/L) (# organisms/100 mL) Minimum 27.0 7.5 4.5 0.0 Maximum 31.1 14.0 13.6 4.0

Average 30.1 10.3 7.2 0.2 90% 30.8 12.4 8.6 1.0 95% 30.8 13.0 9.0 1.0Fact Sheet for NPDES Permit WA-002958-1 Page 82 of 101 King County South Wastewater Treatment Plant

Table H-7: South WWTP – Dilution Assessment for Temperature

The Water Quality temperature guidance document may be found at: http:// www.ecy.wa.gov/ biblio/ 0610100.html

INPUT May-Sep Oct-Apr

1. Chronic Dilution Factor at Mixing Zone Boundary 225 225
2. Annual max 1DADMax Ambient Temperature (Background 90th percentile) 14.0 °C 12.5 °C Max.
3. 1DADMax Effluent Temperature (95th percentile) 22.2 °C 18.9 °C Max.
4. Aquatic Life Temperature WQ Criterion 16.0 °C 16.0 °C

OUTPUT

5. Temperature at Chronic Mixing Zone Boundary: 14.04 °C 12.53 °C
6. Incremental Temperature Increase or decrease: 0.04 °C 0.03 °C
7. Incremental Temperature Increase 12/(T-2) if T< crit: 1.00 °C 1.14 °C
8. Maximum Allowable Temperature at Mixing Zone Boundary: 15.00 °C 13.64 °C
A. If ambient temp is warmer than WQ criterion 9. Does temp fall within this warmer temp range? NO NO

10 . Temp increase allowed at mixing zone boundary, i f required: --- ---

B. If ambient temp is cooler than WQ criterion but within 12/(T amb -2) and within 0.3 °C
of the criterion 11. Does temp fall within this incremental temp. range? NO NO
12. Temp increase allowed at mixing zone boundary, if required: --- ---
C. If ambient temp is cooler than (WQ criterion-0.3) but within 12/(T amb -2) of the criterion

13. Does temp fall within this Incremental temp. range? NO NO
14. Temp increase allowed at mixing zone boundary, if required: --- ---

D. If ambient temp is cooler than (WQ criterion - 12/(T amb -2)) 15. Does temp fall within this Incremental temp. range? YES YES
16. Temp increase allowed at mixing zone boundary, if required: NO LIMIT NO LIMIT
17. Do any of the above cells show a temp increase? NO NO
18. Temperature Limit if Required? NO LIMIT NO LIMIT Marine T-mix T-Mix is based on WAC 173-201A-200(1)(c)(i)--(ii) and Water Quality Program Guidance.

Notes: All Data inputs must meet WQ guidelines.Fact Sheet for NPDES Permit WA-002958-1 Page 83 of 101 King County South Wastewater Treatment Plant

Table H-8: South WWTP – Dilution A ssessment for Fecal Coliform Bacteria

South Plant WWTP Receiving Water Calculations
Chronic Dilution Factor 225 1
Acute Dilution Factor 186 Facility Design Max Month Flow 144.00 mgd 222.82 cfs

Fecal Coliform Dilution Calculation Receiving Water Fecal Coliform 4 #/100 ml Ambient Monitoring LSNT01 Effluent Fecal Coliform - worst case 2075 #/100 ml Max. Daily Discharge (2004-2008) Downstream Fecal Coliform 13 #/100 ml Difference between mixed and ambient 9 #/100 ml Primary Contact and Shellfish Habitat Surface Water Criteria 14 #/100 ml Current state WAC designation

Conclusion: At design flow, the discharge has no reasonable potential for violation of water quality standards for fecal coliform.Fact Sheet for NPDES Permit WA-002958-1 Page 84 of 101 King County South Wastewater Treatment Plant

Table H-9: South WWTP – Assessment for Impacts to Dissolved Oxygen

South WWTP Dissolved oxygen concentration following initial dilution. References: EPA/600/6-85/002b and EPA/430/9-82-011

INPUT Source 1. Dilution Factor at Mixing Zone Boundary: 225 Chronic dilution factor 2. Ambient Dissolved Oxygen Concentration (mg/L): 4.5 Min. at LSNT01

3. Effluent Dissolved Oxygen Concentration (mg/L): 4.5 NPDES permit application - Min. value

4. Effluent Immediate Dissolved Oxygen Demand (mg/L): 45 DMR Data Max BOD 5-day OUTPUT Dissolved Oxygen at Mixing Zone Boundary (mg/L): 4.30

Decrease of 0.2 mg/L = No Measurable Change 0.20Fact Sheet for NPDES Permit WA-002958-1 Page 85 of 101 King County South Wastewater Treatment Plant
Table H-10: South WWTP – Assessment for pH

Calculation of pH of a mixture in seawater. Based on the CO2SYS program (Lewis and Wallace, 1998) http://cdiac.esd.ornl.gov/oceans/co2rprt.html

INPUT

1. MIXING ZONE BOUNDARY CHARACTERISTICS Dilution factor at mixing zone boundary 225.000 Depth at plume trapping level (m) 2.000

2. BACKGROUND RECEIVING WATER CHARACTERISTICS Temperature (deg C): 14.00 Max pH: 7.80 Avg. 2007 EB Monit. Sta

. Salinity (psu): 31.10 Max Total alkalinity (meq/L) 2.40

3. EFFLUENT CHARACTERISTICS Temperature (deg C): 22.20 Max pH: 8.80 Max Salinity (psu) 0.00 Total alkalinity (meq/L): 3.00

4. CLICK THE 'calculate" BUTTON TO UPDATE OUTPUT RESULTS >>>

OUTPUT

CONDITIONS AT THE MIXING ZONE BOUNDARY Temperature (deg C): 14.04 Salinity (psu) 30.96 Density (kg/m^3) 1023.07 Alkalinity (mmol/kg-SW): 2.35 Total Inorganic Carbon (mmol/kg-SW): 2.25 pH at Mixing Zone Boundary: 7.81Fact Sheet for NPDES Permit WA-002958-1 Page 86 of 101 King County South Wastewater Treatment Plant



### APPENDIX I—INDUSTRIAL DISCHARG ERS TO COUNTY’S SOUTH WWTP

F.1. Pretreatment program . Does the treatment works have, or is subject to, an approved pretreatment program? - Yes F.2. Number of Significant Industrial Users (SIUs) and Categorical Industrial Users (CIUs) . Provide number of each of the following types of industrial users that discharge to the treatment works. a. Number of non-categorical SIUs. 36 b. Number of CSIUs. 29 F.3. Mailing Address F.7. A. O. Smith Water Products Company 820 SW 41ST STREET RENTON 98057 METAL FINISHING - CFR 433 Aero Controls, Inc. 1602 PIKE STREET NW AUBURN 98001 METAL FINISHING - CFR 433 Aero Controls, Inc. 1610 20TH STREET NW AUBURN 98002-3459 METAL FINISHING - CFR 433 Aerojet-General Corporation 11441 WILLOWS ROAD NE REDMOND 98052 METAL FINISHING - CFR 433 Aramark Uniform & Career Apparel, LLC 7810 SOUTH 228TH STREET KENT 98032 LAU NDRY-INDUSTRIAL B.S.B. Diversified Company Inc. S. 200 ST. AND 81ST ST. KENT 98032 GROUNDWATER REMEDIATION - ORGANICS Baker Commodities Inc. 5795 S. 130TH PLACE SEATTLE 98178 RENDERING Bakery Chef Company -Ralcorp Frozen 6320 S. 190TH STREET KENT 98032 FOOD PROC ESSING Black Oxide, LLC 131 30TH STREET NE, SUITE 25 AUBURN 98002 METAL FINISHING - CFR 433 Boeing Commercial Airplane - Auburn 700 15TH ST. SW AUBURN 98002 METAL FINISHING - CFR 433 Boeing Commercial Airplane - Renton 801 LOGAN AVE. N. RENTON 98055 METAL FINISHING - CFR 433 Boeing Electronics Center 616 SW 41ST STREET, BLDG.7-107 RENTON 98055 METAL FINISHING - CFR 433 Burlington Environmental, LLC 20245 77TH AVE. S. KENT 98032 CENTRALIZED WASTE TREATMENT 437B PSES Cedar Grove Composting, Inc. 17825 CEDAR GROVE RD. SE MAPLE VALLEY 98038 COMPOSTING-YARD WASTE Circuit Services WorldWide 13000 BEL-RED ROAD, NO. 105 BELLEVUE 98005 ELECTROPLATING - CFR 413 Coca-Cola Bottling Company of Washington 1150 124TH AVE NE BELLEVUE 98005 FOOD PROC ESSING-SOFT DRINKS Davis Wire Corporation 19411-80TH AVENUE SOUTH KENT 98032-1190 IRON AND STEEL MANF - CFR 420 Electrofinishing, Inc. 22630 88TH AVENUE S., UNIT A KENT 98031 METAL FINISHING - CFR 433 Exotic Metals Forming Company 5411 S. 226TH STREET KENT 98032 METAL FINISHING - CFR 433 Express Finishing 15046 NE 95TH STREET REDMOND 98052 METAL FINISHING - CFR 433 G & K Services 1001 SW 34TH ST. RENTON 98055 LAU NDRY-INDUSTRIAL Genie Industries - Bld. 2 - Moosewerks 7140 180TH AVENUE NE REDMOND 98052 METAL FINISHING - CFR 433 Genie Industries - Bld. 3 & 4 18340 NE 76TH STREET REDMOND 98052 METAL FINISHING - CFR 433 Genie Industries - Bld. 6 & 7 - Scissors Plant 18700 & 18750 NE 65TH STREET REDMOND 98052 METAL FINISHING - CFR 433 GKN Aerospace Chem-tronics Inc. 20231 72ND AVENUE SOUTH KENT 98032 METAL FINISHING - CFR 433 Green Garden Food Products, Inc. 5851 S. 194TH ST. KENT 98032 FOOD PROC ESSING Hexcel Corporation 19819 84TH AVE. S. KENT 98032 GROUNDWATER REMEDIATION - ORGANICS Honeywell International Inc. 15001 NE 36TH STREET REDMOND 98073 METAL FINISHING - CFR 433 Hytek Finishes Company 8127 S. 216TH STREET KENT 98032 METAL FINISHING - CFR 433 International Paper Company (fka Weyerhaeuser) 1899 120TH AVENUE NE BELLEVUE 98005 CORRUGATED CONTAINER January Company 9844 40TH AVE. S. SEATTLE 98118 FOOD PROC ESSING-MEATS Kenworth Truck Company - Renton 1601 N. 8TH STREET RENTON 98057 METAL FINISHING - CFR 433 King County CIP - Juanita Bay Pump Station 9304 JUANITA DRIVE NE KIRKLAND 98034 CONST RUCTION DEWATERING King County DOT - Renton Decant Fac ility 155 MONROE AVE. NE RENTON 98056- 4199 DECANT STATION King County SWD - Cedar H ills Landfill 16645 228TH AVENUE SE MAPLE VALLEY 98038 SOLID WASTE - LANDFILL King County SWD - Factoria Transfer Station 13800 SE 32ND ST. BELLEVUE 98005 SOLID WASTE - TRANSFER FAC King County SWD - Houghton Transfer Station 11724 NE 60TH STREET KIRKLAND 98033 SOLID WASTE - TRANSFER FAC King's Command Foods, Inc. 7622 S. 188TH ST. KENT 98032 FOOD PROC ESSING-MEATS Metro Transit South Base 12100 E MARGINAL WAY SOUTH TUKWILA 98168 TRANSPORTATION FACILITY Mikron Industries 1034 SIXTH AVENUE NORTH KENT 98032 PLASTIC PRO DUCTS MANF. 463 Oberto Sausage Company - Kent 7060 SOUTH 238TH STREET KENT 98032 FOOD PROC ESSING-MEATS Pacific Metallurgical Inc. 925 5TH AVENUE SOUTH KENT 98035 METAL FINISHING - CFR 433 Pacific Propeller International, LLC 5802 SOUTH 228TH STREET KENT 98032-1810 ELECTROPLATING - CFR 413 Port of Seattle, Seattle-Tacoma International Airport, BW 17025 AIR CARGO ROAD SEATAC 98188 CHEMICAL TOILET Port of Seattle, Seattle-Tacoma International Airport, IWS 17801 INTERNATIONAL BOUL EVARD SEA TAC 98188 GENERAL TYPE Protective Coatings Inc. 1215 N. SECOND AVENUE KENT 98032 ELECTROPLATING - CFR 413 Prototron Circuits Inc. 15225 NE 95TH STREET REDMOND 98052 METAL FINISHING - CFR 433 Puget Sound Recycling 523 A STREET SE AUBURN 98002 CENTRALIZED WASTE TREATMENT 437 PSNS Quala Systems, Inc. 19929 77TH AVENUE SOUTH KENT 98032 TRANSPORTATION FACILITY Quality Finishing Inc. 12704 NE 124TH STREET, #42 KIRKLAND 98034 ELECTROPLATING - CFR 413 Rexam Beverage Can Company 1220 NORTH SECOND AVENUE KENT 98032 COIL COATING - CFR 465 Safeway, Inc. - Bellevue Beverage Plant 1500 124TH AVE NE BELLEVUE 98005 FOOD PROC ESSING-SOFT DRINKS Safeway, Inc. - Milk Plant 1723 124TH AVENUE NE BELLEVUE 98005 FOOD PROC ESSING-DAIRY Seattle, City of-SWD - Kent Highlands 23240 MILITARY ROAD S. KENT 98032 SOLID WASTE - LANDFILL Shasta Beverages 1227 ANDOVER PARK EAST TUKWILA 98188 FOOD PROC ESSING-SOFT DRINKS Skills, Inc. - Auburn Facility 715 - 30TH STREET NE AUBURN 98002 METAL FINISHING - CFR 433 Smith Fabrication Inc. 1609 S. CENTRAL AVE. NO. 11 KENT 98032 METAL FINISHING - CFR 433 Stoller Metals, Inc. 22809 86TH AVENUE S KENT 98031 METAL FINISHING - CFR 433 Tri-Way Industries, Inc. (Auburn) 506 44TH STREET NW AUBURN 98001 METAL FINISHING - CFR 433 Truesoups Division of H.J. Heinz Company, L. P. 26401 79TH AVENUE SOUTH KENT 98032 FOOD PROC ESSING-SOUPS TTM Technologies, Inc. 17550 NE 67TH COURT REDMOND 98052 METAL FINISHING - CFR 433 Vectra Fitness Inc. Kent Facility 19021 80TH AVENUE SOUTH KENT 98032 METAL FINISHING - CFR 433 Western Metal Art and Sign 7042 SOUTH 188TH STREET KENT 98032 METAL FINISHING - CFR 433 Western Pneumatic Tube 835 6TH SOUTH KIRKLAND 98033 METAL FINISHING - CFR 433 WestFarm Foods/Darigold - Issaquah 611 FRONT STREET NORTH ISSAQUAH 98027 FOOD PROC ESSING-DAIRYFact Sheet for NPDES Permit WA-002958-1 Page 87 of 101 King County South Wastewater Treatment Plant



### APPENDIX J—RESPONSE TO COMMENTS



### Comments Received During Public Hearing – September 3, 2009

Betsy Cooper, King County Wastewater Treatment Division

My name is Betsy Cooper. I am the NPDES Pe rmit Administrator for the Wastewater Treatment Division. King County’s address is 201 S Jackson Street in Seattl e. I am pleased to give comments tonight in reference to the draft South Plant permit.

I want to thank the Department of Ecology for running this public hearing.

More than 40 years ago, the Metropolitan Se wer Authority and now King County began the process of helping to protect public health and the citizens and the environment by beginning wastewater treatment in this region.

Before South Plant, basically there were, you know, wastewater from ho mes or industries was flowing directly into Lake Washington or in to Puget Sound and the beaches were affected by those discharges and the people who used them and fishing and swimming was not necessarily the thing you wanted to do all the time in this ar ea. However, the region decided to address that issue and in 1958, the region pulled together to create a regional govern ment called METRO and that is now incorporated into King County’s Wastewater Treatment Division.

In reference to the South Plant, South Plant began, as Mark noted earlier in his pr esentation, as a secondary treatment plant in 1965 and fairly soon after additional upgrades began to increase the capacity of that secondary treatment. Initially th ere was a discharge into the Green River of this effluent but in the late 80s a new 12 mile tunne l was built to Duwamish Head and then outfalls were built there approximately 10,000 feet long and they discharged our tr eated effluent into about 625 feet of water.

The South Plant today treats approximately 94 mill ion gallons of wastewater every day for the residents and businesses of the area and that treatment removes tons of pollutants and creates resources for our region. I’ll talk a little about bo th the treatment at the plant and those resources that we are involved in creating

And we also at the plant, we treat septage, as well the materials that are removed from septic tanks and in 1998 about 20 million gallons of se ptage was also treated at the plant.

So, South Plant as Mark mentioned, really does create a high quality effluent and in compliance with all the existing requirements of the permit a nd we consistently exceed those requirements.

We also, as part of the wastewater treatment program, have an industr ial wastewater program that is involved in trying to remove pollutants be fore they reach the influent to the plant. One example of that, a very successful example, is the dental waste program, were the County determined that it was important to remove mercury from the sources, the main sources of mercury to our system, which are dental offi ces. So that program, since 2003, has removedFact Sheet for NPDES Permit WA-002958-1 Page 88 of 101 King County South Wastewater Treatment Plant
approximately 375 pounds of mercury, from what w ould have been in our influent and perhaps moving through our system and into our environment.

One of the other major things that King Count y does to protect against pollution is vigorous environmental education programs that we try to invite people to the plant so that they understand where that water goes, as well we try to inform peopl e about what kinds of choices they can make to improve the environment.

One other component of King County’s efforts to try and protect Puget Sound, in addition to the way we operate the plant, really is to participate in a variety of different activities that Ecology and other organizations such as the Puget Sound Partnership are doing to try to protect Puget Sound. We feel that being a partner in regiona l efforts is important and we put substantial resources and effort to do that.

But, the other large component that we mentione d, was we create resources from wastewater. It is a recycling plant as well. As we talked about the effluent leaving the outfall, we also generate about 6500 wet tons of biosolids every year and t hose are used as fertili zer for enriching soils and they alone represent a significant removal of nutrients and a reuse of those nutrients for beneficial use.

Also the gas system that has been created at South Plant uses digester gas to run specific equipment in the plant as well as to send scrub gas back to Puget Sound Energy for its use. An example that has been given of the amount of ga s we send back can typically light 2500 homes.

The one other very important recycling program we have is the reclaimed water program where approximately 80-94 million gallons of reclaimed wate r is used in the plant every year or on-site and then 2-6 million gallons is sent off-site for irrigation uses and other uses. And the Wastewater Treatment Division is looking is looking to create a sort of larger vision for that reclaimed water program and our other plants will be participating in that and we are looking to expand that reclaimed water program so that th ere will be less flow to Puget Sound from our system.

So in conclusion, we are very proud of our role th at South Plant plays in the protection of Puget Sound and we are happy to give comments tonight. Thank you.

End of Public Hearing Comments

Ecology’s response to King County’s Oral Testimony:

Comments noted.Fact Sheet for NPDES Permit WA-002958-1 Page 89 of 101 King County South Wastewater Treatment Plant



### Comments from People For Puget Sound (via e-mail)

September 18, 2009

Karen Burgess Mark Henley Department of Ecology Northwest Regional Office 3190 - 160th Avenue SE Bellevue, WA 98008-5452 Via E-mail: kbur461@ecy.wa.gov, mahe461@ecy.wa.gov, tmil461@ecy.wa.gov

RE: King County South Wastewater Treatment Plant draft NPDES Perm it (No. WA-002958-1)

To Karen and Mark,

We are writing to comment on the King County South Wastewater Treatment Plant draft NPDES Permit (No. WA-002958-1), dated July 28, 2009.

People For Puget Sound is a nonprofit, citizens’ organization whose mission is to protect and restore Puget Sound and th e Northwest Straits.

We are attaching our recent (February 13, 2009) West Point Permit comment letter because most of the background information and the commen ts apply to the South Plant as well.

The King County South Plant is a ma jor facility with pot ential adverse impacts to the health of Puget Sound. Together with the King County West Point facility, these two plants discharge about 50 percent of the treated sewage wastewat er to the surface wate rs of the Puget Sound basin.

We are pleased that Ecology has incorporated into this draft permit many of the same requirements that have been included in the ne w West Point facility permit based on our and other stakeholder concerns. These requirement s include improved industrial user monitoring, a trigger for a nutrient reduction feasibility an alysis if the current Ecology-led Puget Sound dissolved oxygen studies show that South Plant is contributing to the nutrient loading problem, and improved water and sediment monitoring.

In addition, we would like to e xpress appreciation for the improve d Fact Sheet. This Fact Sheet is well written, more detailed and overall is s ubstantially improved over other Fact Sheets we have reviewed and also includes improved maps, photos, graphs, etc. The mixing zone diagrams are excellent. The changes in the permit and the justifications are well explained. The wastewater effluent characterization is the m odel that we hope all Ecology Fact Sheets will follow.Fact Sheet for NPDES Permit WA-002958-1 Page 90 of 101 King County South Wastewater Treatment Plant

Our comments follow:

1. Omission of relevant ongoing studies and reports . We recommend that the Fact Sheet should include mention of important studies being undertaken by Ecol ogy that relate to the permit such as the toxic loadings studies.

Ecology’s response : Generally, the fact sheet is used to provide information specific to the permit, and we do not typically include regional or statewide studies in in dividual fact sheets. The best source for information regarding broad studies is the Ecology we bpage. These studies are ongoing and only the webpage provides the most up-to-date information. The web links to these studies was provided in the Public Notice as follows: Puget Sound Water Quality: http://www.ecy.wa.gov/puget_sound/index.html South Sound Dissolved Oxygen Study: http://www.ecy.wa.gov/puget_sound /dissolved_oxygen_study.html Control of Toxic Chemicals in Puget Sound http://www.ecy.wa.gov/programs/wq/pstoxics/index.html

Special Condition S17 has been added to the perm it to address possible outcomes of the South Sound Dissolved Oxygen Study and the Puget Sound Hydrodynamic Modeling.

2. Endocrine disrupters. People For Puget Sound requests that Ecology include monitoring of emerging chemicals including pharmaceuticals (at a minimum, the chemicals currently being assessed in Ecology’s study), PBDEs and additional chemicals that were detected in King County’s surface water study in the new permit. A baseline is needed so that the success of future work on source reduc tion/pollution preventi on can be assessed.

Ecology’s response : At this time, Ecology is not putting requirements for EDC testing in individual permits. Ecology is awaiting the re sults of our current study on pharmaceuticals and personal care products (PPCPs) before making pr ogrammatic decisions concerning PPCPs.

3. S6.E. Source Tracking Characterization . We are pleased that Ecology has included our request to require King County to begin the process of looking at sources of toxic chemicals in a more systematic way. At this point, Ki ng County does not have an inline characterization of the toxic chemical loads in each section of their system (i.e., areas in the system where lead, mercury, phthalates, etc. have higher c oncentrations) and so does not know where the problems are in terms of being able to reduce so urces of toxic chemicals to the facility.

Our concerns are:

a. One report is inadequate. We request that Ecology request that a source tracing plan be submitted by 6 months from the permit star t date and that a ye arly progress update be due by June 1 of each year of the permit cycle. Furthermore, the plan and progress reports should be sent to interested stakeholders, including People For Puget Sound by King County.Fact Sheet for NPDES Permit WA-002958-1 Page 91 of 101 King County South Wastewater Treatment Plant

b. Our key goal in requesting this study in the first place was that the sewer line itself be tested, branch by branch. This propos ed S6.E.study does not include that key requirement and we request that it do so.

Ecology’s response : At this time, Ecology believes that Special Condition S6.E is an appropriate requirement for source characterization. King C ounty relies on their Industrial Waste Program (KCIW) to regulate permitted and authorized discha rges from significant industrial users. Ecology has delegated pretreatment authority to King County and inspects their program annually.

4. Pretreatment. The permit or the Fact Sheet should lis t in an appendix the name and type of industry for each pretreatment facility.

Ecology’s response : The draft permit included Appendix I which listed the name and type of industries that discharge into th e County’s South conveyance system . Appendix I is retained for the final fact sheet.

5. Mailing list. Stakeholder and interested persons list for permit should be added as an appendix.

Ecology’s response : In regard to the draf t South Plant NPDES permit, comments were received by only three stakeholders: People For Puget Sound, City of Everett and King County. Ecology does not believe that a separate appendix is neces sary as there was limited public participation in this draft permit.

6. Public Participation. As a final note, we are concerned that the public hearing for this permit was held on the Thursday before the La bor Day holiday weekend. For future public hearings associated with major permits, we re quest that key stakeholders be contacted to help determine the optimal date for holding hearings.

Ecology’s response : It is often difficult to select a da te for the public hearing that works for everyone and that fits the timeline for the issuan ce of the permit. In an e-mail dated August 3, 2009, we invited someone from your organization to attend the informal public meeting and to provide testimony on your behalf. No other stakeholders expre ssed reservations regarding the hearing date.

Thank you for the opportunity to comment. Please contact me with questions at (206) 382-7007 X215.

Sincerely,

Heather Trim Urban Bays and Toxics Program Manager
AttachmentFact Sheet for NPDES Permit WA-002958-1 Page 92 of 101 King County South Wastewater Treatment Plant



### Comments from King County (v ia e-mail and USPS letter)

September 18, 2009

Tricia Miller Water Quality Permit Coordinator Northwest Regional Office Dept. of Ecology 3190 160 th Avenue SE Bellevue, WA 98008-5452

RE: Comments on the Draft South Plant NPDES Permit (No. WA-002958-1) Renewal

Dear Ms. Miller:

Thank you for the opportunity to comment on the South Plant Permit Renewal. King County’s comments are below.

Permit Comments

• Page 14 - S2.C – Sampling and Analytical Procedures - For consistency, after the reference to 40 CFR 136 in the second paragraph of S2.C, pl ease add: "Methods iden tified in Appendix A may be used." This is the same langua ge that was added to section S6B.

Ecology’s response : Additional requested language is not necessary. Special Conditions S2.A and S2.B explicitly allow for labor atory methods in Appendix A to be used.

• Page 32 – S11.1 or 2 – Receiving Water Characterization - The analysis of Total and Dissolved Metals in a saltwater matrix will required methods and detection limits that are not in Appendix A. Therefore, please add, to either #1 or #2 of these sections: "Conduct all chemical analysis using the methods and detection levels identified in the approved SAP/QAPP". This will allow the methodologies to be specified and approved by Ecology through the SAP/QAPP, givi ng Ecology in either case, the final approval.

Ecology’s response : Additional requested language is not necessary. S11.9 explicitly allows for chemical analyses using methods and detec tion levels identified in Appendix A, or as identified in the Sampling and Quality Assurance Plan.

• Page 33 – S12C – Source of Sediment Toxicity Study - This section calls for King County to undertake an analysis of the source of sediment toxicity for which Ecology has no guidance. The absence of guidance on this issue is understandable as the relationship between sediment-bound and deposited chemicals and toxicity is not as well studied asFact Sheet for NPDES Permit WA-002958-1 Page 93 of 101 King County South Wastewater Treatment Plant
water column relationships. The process and procedures used in traditional Toxicity Reduction Evaluation studies are not directly tr ansferable or possibly even appropriate for sediments. Further, since there has not been a ny indication that there is a toxicity concern at this site, it is presumptive and premature to have such a requ irement in the permit at this time; particularly so if there is no defined proc ess to assess such a concern. Including this requirement in this permit, prior to any indica tion of toxicity concer ns near South Plant’s outfall is unwarranted and we request this requirement be removed.

A more appropriate approach to addressing this concern would be to work with the County if any toxicity was observed to determine what ne xt steps would be appropriate. Next steps would likely vary dependant on the specific fi ndings. They could range from verification and further characterization of the problem, to an attempt to identify the source of toxicity or even to determine if a sediment impact zone would be appropriate. In addition, guidance development and rule making to define such a toxicity evaluation program for sediments is needed so that such guidance would be availa ble for those sites where sources of toxicity needed to be pursued.

Ecology’s response : This permit requirement only applies if toxicity is found in the sediment. It is in the permit so that if toxicity is found, actions to investigate may be taken immediately without a permit revision. Ecology will work with the County to determine what next steps are appropriate, if toxicity is found in the sediments. We agree that the next steps may vary depending on the nature and severity of the probl em. Ecology does not plan to develop specific guidance or rule revision to addres s this topic because this type of activity is varied, occurs very infrequently, and should be based on the most cu rrent science. USEPA has published a guidance document on Sediment Toxicity Identifica tion Evaluation (EPA/600/R-07/080 September 2007) that can be used for this purpose.

• Page 33 – S12.C – Source of Sediment Toxicity Study - If this section remains in the permit the 30-day period for commencement of toxici ty source evaluation is much too short, especially if additional sampling needed to occur. We request, at a minimum, a 90-day period to allow adequate time for discussion of fi ndings to determine that such a step is the appropriate action and a clarification that commencement means starting development of a sampling plan or starting furthe r studies with existing materials, as appropriate. We further request that the clock would not run during the period of tim e required for development of what an appropriate sediment toxicity eval uation would comprise. Based on the timeframe for Ecology’s development of whole effluent toxi city identification pro cedures in the 1990’s, this could be a considerable period of up to one to two years. As the period of time is not discernable, the only implementable approach in the permit is to suspend the clock during this process.

Ecology’s response : Conditions may change during the time that samples are stored, including loss of volatile constituents and changes in redox state. Toxicity evaluations should begin as soon as possible after toxicity is detected, or there is increased potential for inconclusive results. There are already existing Sediment Toxicity Id entification Evaluation procedures published by the USEPA. Thirty days to begin toxi city identification is reasonable.Fact Sheet for NPDES Permit WA-002958-1 Page 94 of 101 King County South Wastewater Treatment Plant

• Page 33 – S12.C- Also, if this section remains in the permit, please change the final sentence of Section S12.C to read: "The Permittee must submit to Ecology the results of the sediment toxicity investigation within three months of completion of testing."

Ecology’s response: The permit has been modified with the additional language.

Fact Sheet Comments

• Page 23 – Sediment Characterization - In the second paragra ph, please correct the first sentence to read: "In November 2001, King Count y performed sediment sampling from 0 to 2 cm depth at 13 ( rather than 10 ) sample locations near the two marine outfalls."

Ecology’s response : The fact sheet has been corrected.

• Page 23 – In the second paragraph, it is not clear why a Bis(2-et hylhexyl)phthalate concentration of 43 ppm at Sta tion RT625SD is presented in text here and in the Table 8 on page 24, since the reported concentration did not exceed the SMS chemical criterion and, the datum is further qualified with a "B" flag. Su ch data should be considered at best, an estimate. In addition, all other sample s during that sampling period had Bis(2- ethylhexyl)phthalate concentrations below 10 ppm. Therefore, it is requ ested that the fourth and fifth sentences be deleted from this paragraph.

Ecology’s response: The table title is “Detected Ch emicals Above or Approaching SQS Criteria.” This sample is close to the SQS criteria. Since it is qualified with a “B” flag, it is less precise than other measurements, and may actually be at a level that can cause effects. There is nothing incorrect in the representation of the facts in the fact sheet.

• Page 23 – In the third paragraph, please corr ect the first sentence to read: "In October 1999, King County performed sediment samp ling from 0 to 2 cm depth at 13 ( rather than 12 ) sample locations near the two outfalls."

Ecology’s response : The fact sheet has been corrected.

• Page 23 – In the fourth paragraph, please corre ct the second sentence to read: "In October 1997, the County measured concentrations of hexachlorobenzene at three locations (RT700NS, RT625ND, RT625SD) that exceeded the Sediment Quality Standards numeric criterion”. ( There were no exceedances of benzoic acid in 1997. There was one exceedance of the SQS/CSL criterion for Benzoic Acid at one location (LSDSO2) in 1995 but 1997, 99, and 2001 data have shown no such exceedances.) Then, add the following sentence after the second sentence: "During both the 1999 and 2001 sediment monitoring events, hexachlorobenzene was not detected at thes e three locations, nor any of the other 10 locations sampled and, the method detection lim its were all below the associated Sediment Quality Standard chemical criterion."Fact Sheet for NPDES Permit WA-002958-1 Page 95 of 101 King County South Wastewater Treatment Plant
Ecology’s response: The fact sheet has been modified with the correct date for the benzoic acid exceedance. The requested additional sentence is not necessary and does not fit in this paragraph since this paragraph speaks to the timeframe of 1994-1997.

• Page 24 – We do not feel that Table 8 should re main in the Fact Sheet. The three locations that exhibited some exceedances of Hexachloro benzene in 1997, exhibited no exceedances in two subsequent sampling events. As menti oned above, the Benzoic acid datum mentioned was from 1995, not 1997, and data from 1997, 19 99, and 2001 do not exhibit and exceedances for Benzoic acid. Finally, the Bis(2-ethylhexyl)phthalate data listed in the table are not exceedances of the standard. Therefore, we requ est the table be deleted from the Fact Sheet.

Ecology’s response : Table 8 provides a historical summary of exceedances or chemicals approaching the criteria. Once th e date is changed from 1997 to 1995 for benzoic acid, this is an accurate representation of the facts. The table will be retained in the fact sheet.

• Page 44 – Sediment Quality – Please delete the second bulle t under the second paragraph of this section as it is an inco rrect statement. As menti oned above, Benzoic acid was not detected in any of the 8 sediment sample s collected during the 1997 sediment-monitoring event. Dry-weight normalized detection lim its for the 8 samples ranged from 338 to 368 μg/Kg, which is well below the SQS/CSL criterion of 650 μg/Kg. Benzoic acid was not detected in any of the 13 samples collected during the 1999 monitoring event, at a similar range of dry-weight normalized detection limits . During the 2001 sediment monitoring event, analytical detection limits had improved signifi cantly for benzoic acid and this compound was detected in all 13 samples at concentrations ranging from 342 to 553 μg/Kg, all below the SQS/CSL criterion.

Ecology’s response: The draft fact sheet was intended to note hexachlorobenzene as an exceedance, and not benzoic acid, under the second bu llet. The fact sheet has been corrected to mention hexachlorobenzene instead of benzoic acid.

• King County certainly accepts the idea that Ec ology would require additional sampling at the outfalls to check sediment conditions as these sites not been sampled for almost 10 years. However, as noted in earlier comments on th is matter, it is incorrect and misleading to represent the current sediment dataset as indicating that there has been sediment contamination at these sites and we request th at this section not present that impression because it is not supported by the data.

Ecology’s response: This section is intended to provide a factual summary of existing data. There have been past exceedances of the chemical criteria. We also state in a summary on page 23 that past sediment monitoring does not generally indicate sedi ment toxicity or violation of SMS criteria.Fact Sheet for NPDES Permit WA-002958-1 Page 96 of 101 King County South Wastewater Treatment Plant

• Page 44 – With regard to the fourth bullet under the second paragraph which describes the requirement for the sample to be of th e top 10 centimeters rather than the top 2 centimeters - this is a significant paradigm sh ift. The most-recent version of the Sediment Sampling and Analysis Plan Appendix (Ecol ogy 2008) still recommends the 0- to 2-cm depth stratum when sampling sediment around pe rmitted outfalls. It states: “In some cases, monitoring data may be used to interpret tem poral changes in sediment conditions. Such cases may include, for example, ambient monitoring programs, monitoring of conditions in the vicinity of a permitted discharge, or m onitoring of a cap placed over contaminated sediments as part of remediation. In such cas es, it would be more appropriate to limit the sampling to the uppermost 2 cm of sediment , which would represent the most recently deposited particulate matter. If deeper (e .g., 10 cm) sediment samples were collected and analyzed, older sediment would be included in the samples, making it more difficult to detect temporal changes in sediment conditions.” (SAPA, Ecology 2008).

If, as was suggested in discussions with Ecology staff, the purpose of 10 cm sampling is really a one-time assessment for compliance with water quality standards (the Sediment Management Standards), we recomme nd that this is clarified in th e permit and fact sheet. It would also be helpful to identify that follo wing a demonstration of compliance; future sampling will revert to the 2-cm depth consistent with existing guidance. This will provide a clearer demonstration of intent for the next permit.

Ecology’s response : The top 10 centimeters of sediment is considered the biologically-active zone for Puget Sound and is used for compliance with the Sediment Management Standards. Sediment samples from the top 2 cm have been used in the past for trend analysis. In the past several years, we have been asking for 10 cm de pth samples at NPDES outfalls so that we may evaluate compliance with the Sediment Manageme nt Standards. It is not just a one-time assessment of compliance. Ecology has discreti on whether to request 10 cm or 2 cm samples depending on the purpose of the sampling study.

The SAPA was updated in 2008 to add a new appendi x with procedures for entering data into the EIM database. Other sections of th e SAPA were not updated at that time.

• Page 44 – Please add the following language to the fifth bullet under the second paragraph: "Although not required, King Count y has performed benthic comm unity analysis during two previous sediment monitoring events. Analys is of the benthic data indicates a healthy benthic community, typical of deep, depos itional environments in Puget Sound."

The benthic community proximal to the South Tr eatment Plant outfalls was characterized in both 1999 and 2001, with triplicate sa mples collected from 5 stations proximal to the outfalls and one reference station, located 2,500 feet fr om the outfalls, at a similar depth. During both monitoring years, the benthic community showed no impact from the outfalls and no apparent gradient in benthic community indices exists, with respect to proximity to or distance from the outfalls. Tables of the bent hic indices may be found at the following links: http://your.kingcounty.gov/dnrp/ library/2001/kcr64/99sec3.pdf http://your.kingcounty.gov/dnrp/ library/2002/kcr 64/Section3.pdfFact Sheet for NPDES Permit WA-002958-1 Page 97 of 101 King County South Wastewater Treatment Plant
Ecology’s response: Although the Sediment Management Standards require submittal of any existing sediment data (WAC 173-204-610), thes e benthic community data have not been submitted to Ecology’s EIM database. If King C ounty wanted these data included in the fact sheet summary, the data should have been subm itted to Ecology and brought to our attention with the permit renewal application or during entity review of the draft fact sheet and permit. Since we do not have this data, nor do we have ad equate time to review it before permit issuance, we can not include the requested quote as it is not confirmed at this time. Please provide EIM benthic community data, summary report, and be nch sheets to Ecology for review, verification, and approval.

• Page 44 – We recognize that Ecology can re quire additional sedime nt testing above its regular tiered approach paradigm. However, to indicate that the Ecology will be expecting four bioassays analyses be undertaken without specific SMS exceedances is another significant paradigm shift and one that again does not seem warranted based on the existing data that has clearly demonstrated there is little indication of toxicity in the vicinity of the outfalls (as presented below):

o Sediments in the vicinity of the South Plan t outfalls have been tested for sediment contamination since the mid- 1990’s. Each sampling event have taken sediments from multiple sites – as many as 13 in the most r ecent sampling events, with an overall total of 48 samples. In the last two events, the benthic community was also sampled. In total these samples represent a significant data set.

o The two most recent sampling events (2001 and 1999), had no de tected sediment chemical concentrations that exceeded any Sediment Management Standards chemical criterion. During the 2001 monitoring event, analytical method detection limits had improved to the point that all method detection limits (MDLs) met SQS chemical criteria with one exception. The dry- weight normalized MDL for 2-Methylphenol exceeded the SQS of 63 ug/Kg DW in four of 13 samples, ranging from 64 to 67 ug/Kg DW. This is merely an artifact of slightly lower percent solids concentrations in these four samples as 2-Methylphenol was not detect ed in any of the 13 samples, 9 of which had MDLs that met the SQS criterion.

o The only detected exceedances found in earlier sampling events are summarized below and do not indicate any pattern of exceedance s or the existence of current toxicity

concerns:

 Hexachlorobenzene detected in samples co llected from three stations proximal to the outfalls during th e 1997 monitoring event. Two of these concentrations (0.954 and 1.87 mg/Kg OC exceeded the SQS chemical criterion of 0.38 mg/Kg OC. The third concentration of 2.52 mg/Kg OC exceeded the CSL chemical criterion of 2.3 mg/Kg OC. All three of these stations were sampled again in both 1999 and 2001, during which hexachlorobenzene was not detected, with a method detection limit that met the SQS chemical criterion.Fact Sheet for NPDES Permit WA-002958-1 Page 98 of 101 King County South Wastewater Treatment Plant

 Benzoic acid was detected at a concen tration of 1,480 ug/Kg DW in one sample collected during the 1994 monitoring event. This concentration exceeded the SQS/CSL chemical criterion of 650 ug/Kg DW. The station from which this sample was collected was located approximately 3,000 feet from the outfall. Benzoic acid was not detected at the stat ion that was located equidistant between the two outfalls.

o The benthic community proximal to the Sout h Treatment Plant outfalls, characterized in both 1999 and 2001, showed no impact from the outfalls and no apparent gradient in benthic community indices exists, with re spect to proximity to or distance from the outfalls (see comment above).

o Whole Effluent Toxicity Tes ting has been performed cons istently since 1986 on South Plant effluent. No concerns regarding effl uent toxicity have been identified. No toxicity-based requirements have been determined to be needed in this permit. Limits earlier imposed on metals concentrations where removed in the 1990’s because metals data demonstrated they were no longer warranted.

We contend that if such an significant and e xpensive bioassay requirement is being added to this permit that there needs to be a compelling case to suspect that sediment contamination, and thus toxicity, is present. We submit that no such case can be made and, in fact, that the data support a compelling case that toxicity is not indicated at this site. We therefore request that the expectation of bioassays should continue to be trigge red only if a sediment quality exceedance is observed as has been t ypical for NPDES permits to date.

Ecology’s response: The Sediment Management Standa rds provide Ecology with specific authority to evaluate NPDES discharges in cons ideration of multiple factors including discharge characteristics, receiving water characteristics, and cost mitigating factors. Ecology’s request for toxicity testing at this location was not based solely on past chemistry data, but also because of the size of the discharge and consistency with permits at other wastewater treatment plants of this size. The West Point Wastewater Treatment Plant, wh ich has a similar size discharge, has had many bioassays performed near the outf all and has found toxicity, even when concentrations are below the chemical criteria.

However, in this case Ecology has considered yo ur request, and will only require bioassays to be performed if the chemical concentrations are near or above the numeric ch emical criteria in the Sediment Management Standards.

Thank you for consideration of our comments. If you have any questions regarding these comments, please contact me at 206-263-3728.
Sincerely,

Betsy Cooper
NPDES Coordinator Cc: Mark Henley, Permit Manager, Dept of Ecology NWROFact Sheet for NPDES Permit WA-002958-1 Page 99 of 101 King County South Wastewater Treatment Plant



### Comments from the City of Everett (via USPS letter)Fact Sheet for NPDES Permit WA-002958-1 Page 100 of 101 King County South Wastewater Treatment PlantFact Sheet for NPDES Permit WA-002958-1 Page 101 of 101 King County South Wastewater Treatment Plant

Ecology’s response to Issue #1: The Sediment Management St andards provide Ecology with specific authority to evaluate NPDES discharges in consideration of multiple factors including discharge characteristics, receiving water characte ristics, and cost mitigating factors. Ecology’s request for toxicity testing at th e South plant outfalls was not base d solely on past chemistry data, but also because of the size of the discharge a nd consistency with permits at other wastewater treatment plants of this size. The West Point Wastewater Treatment Plant, which has a similar size discharge, has had many bioassays performed near the outfall and has f ound toxicity, even when concentrations are below th e chemical criteria.

However, in this case Ecology has considered th e County’s request, and will only require bioassays to be performed if the chemical concentrations are near or above the numeric chemical criteria in the Sediment Management Standards.

Ecology’s response to Issue #2: The top 10 centimeters of sedi ment is considered the biologically-active zone for Puget Sound and is used for compliance with the Sediment Management Standards. Sediment samples from the top 2 cm have been used in the past for trend analysis. In the past several years, we have been asking for 10 cm depth samples at NPDES outfalls so that we may evaluate compliance with the Sediment Management St andards. It is not just a one-time assessment of compliance. Ecology has discretion whether to request 10 cm or 2 cm samples depending on the purpose of the sampling study.

The SAPA was updated in 2008 to add a new appendix with procedures for en tering data into the EIM database. Other sections of the SAPA were not updated at that time.

Ecology’s response to Issue #3: This permit requirement only applie s if toxicity is found in the sediment. It is in the permit so that if toxi city is found, actions to investigate may be taken immediately without a permit revision. Ecology will work with the County to determine what next steps are appropriate, if t oxicity is found in the sediments. Ec ology acknowledges that the next steps may vary depending on the nature and severity of the problem. Ecology does not plan to develop specific guidance or rule revision to address this topic becau se this type of activ ity is varied, occurs very infrequently, and should be based on the most current science. USEPA has published a guidance document on Sediment Toxicity Identif ication Evaluation (EPA /600/R-07/080 September 2007) that can be used for this purpose.