# TECHNICAL ENGINEERING

EVALUATION REPORT (TEER)

FOR THE

CHITOSAN-ENHANCED

SAND FILTRATION TECHNOLOGY

FOR FLOW-THROUGH OPERATIONS

Developed by Natural Site Solutions, LLC

Redmond, Washington

Prepared By

Gary R. Minton, PhD, PE

Resource Planning Associates

Seattle, Washington

February 28, 2006

# TABLE OF CONTENTS

TOPIC PAGE

PART I – BACKGROUND INFORMATION

Designation sought 1

Current designations 1

Consultant’s role 2

Consultant’s recommendations 3

Regarding approval of the technology 3

Regarding further testing 3

Regarding system specifications 3

Ecology specifications for the flow-through system 6

Technology description 9

General 9

System components 10

Recycle 12

Operation and maintenance manual 12

Test site descriptions 13

Lakeside housing development 13

SeaTac International Airport third runway 14

WSDOT SR-522 road improvement project 16

Test program design 17

PART II – THE CONSULTANT’S EVALUATION

Systems selected for evaluation 18

Compliance with Ecology specifications 18

Compliance with the NSS QAPP 23

Residual chitosan test 23

Toxicity evaluation 23

Laboratory tests of Liqui-Floc 23

In-situ field tests of treated discharge 25

## TOPIC PAGE

Meeting the discharge quality specifications 26

Lakeside housing development 27

SeaTac International Airport third runway 28

WSDOT SR-522 road improvement project 29

Reliability 30

Factors other than performance 31

Discussion of factors 31

Cost 35

References 37

APPENDICES

A. Recommended specifications for CESF-FT facilities 39

B. Recommended Operating Period Information Form 42

C. Examples of completed Daily Operation Log forms 43

D. Operation and Maintenance Manual (separate document)

E. Chitosan test procedure (separate document)

F. Certification of chitosan test by AMTEST Laboratories (separate document)

G. Laboratory tests of toxicity of Liqui-Floc TM 

### (separate document)

H. In-situ field tests of toxicity of CESF-FT discharge (separate document)
Appendices D, E, F, G, and H are contained in one separate document.Not to be released without written approval by NSS 1 

## PART I BACKGROUND INFORMATION

Natural Site Solutions, LLC (NSS) of Redm ond, Washington contracted with Resource Planning Associates, specifically Dr. Gary Minton (referred to as Consultant), to review the ability of the Chitosan-Enhanced Sand Filtration Systems (CESF) to meet conditions set forth by the Washington State Depart ment of Ecology (Ecology, 2003b, 2004), and to prepare a Technical Engineering Evaluation Re port (TEER). The evaluation contained in this report is based on performance of syst ems at three sites: Lakeside Housing Development, WSDOT SR 522 Road Improvement Project, and the third runway at the Seattle-Tacoma International Airport (SeaTac) . These three projects were identified by NSS in its application (NSS, 2004b).

The data were collected following a QAPP Pl an (NSS, 2004a), prepared in accordance with the protocol developed by the Depa rtment of Ecology (Ecology, 2003a). Ecology (2003a) sets forth requirements for the evaluation of technologies that chemically treat

stormwater from construction sites. Ec ology (2003a) requires the preparation and acceptance by Ecology of a QAPP Plan. A QAPP was prepared by Natural Site Solutions (2004a) and accepted by Ecology. The QAPP is ava ilable as a separate report and is not included in the TEER report.

DESIGNATION SOUGHT

Natural Site Solutions of Redmond, Washington seeks General Use Level Designation (GULD) to operate the CESF as a flow-through system (termed “CESF-FT” in this report), meeting the specifications define d by the Washington State Department of Ecology (Ecology, 2004). A flow-t hrough system allows for the continuous discharge of treated construction site stormwater directly to surface waters without intermediate temporary storage of treated stormwater . The Department of Ecology (2003b, 2004)

established conditions to be met if GULD we re to be given to the CESF-FT system.

These conditions are described in this TEER. In October 2003, Ecology gave a GULD designation for batch treatment with the use of Liqui-Floc, TM 

### a special chitosan acetate coagulant. This TEER report documents findi ngs related to seeking designation for the continuous flow-through operation.

CURRENT DESIGNATIONS

In October 2003, NSS received the following designations (Ecology, 2003) with respect to the CESF technology.

1. General Use Level Designation for the CESF tec hnology with the discharge of Chitosan acetate

treated water to retention systems capable of infiltrating all storms to the ground with no discharge to surface water. The design of the in filtration system must be based on the criteria in Volume V of Ecology's 2001 Stormwater Manual for western WA. The design and operational criteria for the CESF specified in this documen t shall also be strictly adhered to. Records showing that total retention was achieved must be kept on site.

2.General Use Level Designation for the CESF technology with a discharge of Chitosan acetate

treated water from a temporary holding pond to su rface water only after the treated stormwaterNot to be released without written approval by NSS 2 is demonstrated to contain less than 0.1 ppm residual Chitosan acetate polymer or is non-toxic

to aquatic organisms (batch treatment). The d esign and operational criteria specified in this document, and in BMP C 250 of Ecology's Western WA Stormwater Manual shall be strictly adhered to. The effluent turbidity and pH shall be monitored at a frequency acceptable to Ecology.

3. Conditional Short-Term Use Designation (CUD) for the CESF technology with the chitosan

acetate treated discharges conveyed directly or indirectly to surface water (flow-through system). This CUD expires on December 31, 2005, unless extended by Ecology and takes effect when all the applicable “Conditions" and "Design and Operational Criteria" specified in this designation document are implemented or satisfied

. This CUD will take effect on March 9, 2004 and will be posted at Ecology’s stormw ater web site as soon as possible.



### The designations were updated in August 2004 (Ecology, 2004).

Ecology (2003b, 2004) established that “ Discharges from the CESF system under these (the above described) designations:

• Shall not cause or contribute to a violation of State Water Quality Standards.

• Shall comply with the discharge requirements of the State of WA Construction

Stormwater General Permit, AKART, and local government requirements, for turbidity and other applicable pollutants. This designation document must be used as the basis of SWPPPs for all construction projects where chitosan treatment is planned.

• Shall be consistent with the guidance in BMP C250, Construction Stormwater

Chemical Treatment, of Ecology's 2001 Stormwater Management Manual for

western WA.

• Are expected to achieve performance goals of a minimum of 95% reduction of NTU

turbidity, a maximum discharge of 10 NTU turbidity, and a discharge pH within a range of 6.5-8.5. If these values are exceeded at any time the responsible site operating personnel shall immediately take appropriate corrective actions.”

CONSULTANT’S ROLE

The TAPE specifies that the applicant is to hire an independent consultant stating “the following work must be performed by an independent professional:

1. Complete the data validation report. 2. Prepare a TEER summary, including a te st results summary and conclusions compared with the supplier’s performance claims. 3. Provide a recommendation of the appropriate technology use level. 4. Recommend relevant information to be posted on Ecology’s website. 5. Provide additional testing recommendations, if needed.”

Item 4 is not presented in this report. In formation to be posted on the website can be generated subsequent to a decision by the Depa rtment of Ecology should it be favorable.Not to be released without written approval by NSS 3 

### CONSULTANT’S RECOMMENDATIONS

Regarding approval of the technology

Recommendation #1: Approve the CESF-FT technology.

The Consultant recommends that the continuous flow system be approved for GULD.

Regarding further testing

The Consultant makes the following recommendations:

Recommendation #2: Bioassays with marine organisms

As yet, bioassays have not been performed on marine organisms. This should occur prior to the use of the CESF-FT where discharge to marine waters is to occur.

Recommendation #3 : In-situ toxicity tests at high turbidity concentrations

As specified by Ecology, an in-situ evaluation of the toxicity of Liqui-Floc was evaluated as a function of dosage and turbidity. The re sults are reported in this TEER. However, the study was conducted only up to a turbidity of 500 NTU. It is recommended that the test be extended to several thousand NTU. It is not uncommon for these higher levels of turbidity to occur in untreated stormwater, necessitating pretreatment with Liqui-Floc.

Regarding system specifications

NSS does not typically design, install, operate or maintain CESF facilities. It is the responsibility of the site contractor. Consequently, each construction site permit for a CESF-FT facility issued by Ecology should c ontain specifications related to design, operation, and maintenance similar to thos e developed previously (Ecology, 2003b, 2004). To support this effort the Consultant has prepared recommended specifications reflecting the experience gained with the test progr am reported in this TEER. The recommended specifications are presented in Appendix A. Pr esented below are the more notable changes to the specifications previously developed by Ecology.

Recommendation #4: Raise the limit for the residual concentration of chitosan to 0.2 mg/L.

Ecology currently specifies that the concentration of residual chitosan not exceed 0.1 mg/L in the discharge. However, AMTEST Laboratories has determined that the test procedure provides a reliable result to 0.2 mg/L only. This residual concentration remains substantially below concentrations at which toxicity occurs. It is therefore recommended that Ecology raise the limit to 0.2 mg/L. Refer to Page 26.Not to be released without written approval by NSS 4 

### Recommendation #5: Allow variances to the maximum allowable dosage rate of chitosan

acetate.

Ecology specifies a maximum dosage of 1 mg/L. The system can be operated within this limitation if the turbidity of the untreated stormwater entering the holding basin is less than 600 NTU. Experience from the test program indicates that despite full implementation of erosion control practices, th e turbidity of the stormwater entering the holding basin can exceed 600 NTU. This necess itates enhanced pretreatment with the use of an initial dosage of chitosan as the stormw ater enters the holding basin. The need for this action will vary with the site. It was f ound necessary at one of the three test sites. Ecology gave variances at these two sites. Although dosages as high as 3 mg/L were used, the effluent residual chitosan was always below the detection limit of 0.2 mg/L.

The variance should be allowed but only fo r pretreatment where the applicant can demonstrate pretreatment with chitosan acetate is necessary because of the type of project or soil conditions. Dosage immediately before the filters should be limited to 1 mg/L. The most common type of project where a varian ce is likely needed is the linear roadway project where equipment movement inhibits full use of source control BMPs.

Recommendation #6: Modify the language of the discharge requirement.

The language currently reads: Are expected to achieve performance goals of a minimum of 95% reduction of NTU turbidity, a ma ximum discharge of 10 NTU turbidity” ... Consider the following: If the influent concentration is only 20 NTU, the discharge requirement becomes 1 NTU. This is not tec hnologically feasible. If the influent is over 200 NTU, the effluent turbidity of 10 NTU must be met and therefore the efficiency must exceed 95%). The words: “minimum of 95%” should be deleted.

Recommendation #7: Modify the language of the discharge monitoring requirements.

Ecology has specified “Water quality influent and effluent shall be continuously monitored for pH and turbidity and the effluent for chitosan concentration and/or aquatic toxicity as follows.” The word “and” in the term “and/or” should be deleted. As written, it states that toxicity must be continuously m onitored even if the chitosan concentration is measured. The following verbiage is recommended: “Water quality influent and effluent shall be continuously monitored for pH and turbidity. The effluent should be periodically monitored as specified in the SWPPP for e ither chitosan concentration or aquatic toxicity”

Recommendation #8: Limit approval at this time to the Liqui-Floc TM 

### polymer for continuous operation.

There are several forms of chitosan acetate. Pr oprietary considerations limit the ability to specify the form of chitosan acet ate developed by each manufacturer. The Consultant therefore recommends that Ecology not give ge neric approval for the use of all potential forms of chitosan acetate. Rather, the treatment effectiveness and toxicity effects of each product must be considered. Each form of chitosan acetate offered for use should undergo full field and laboratory testing, including toxic ity tests. These tests should be conductedNot to be released without written approval by NSS 5 

### through the full ranges of turbidities and pH va lues expected to occur. In addition, the efficacy of the test procedure presented in this report for residual chitosan must be evaluated for each new type of chitosan acetate proposed for use.

Recommendation #9: Concerning calibration of the chitosan dosage pump

The current specification is that the pump be calibrated at the onset of each operating period and every four hours. The Consultant’s review of the operating records indicates that the metering pump is very stable. It is therefore recommended that the pump be recalibrated only when the flow and/or influent turbidity changes significantly.

Recommendation #10: Record the rate of discharge

With the CESF-FT system the pH and turbidity of the treated stormwater is continuously and automatically monitored. Should the quality of the treated stormwater not lie within the discharge specifications the system auto matically recycles the stormwater to the holding basin for further treatment by actuating valves.

At the three test sites, the discharge flow rate immediately downstream of the recycle value was monitored. However, only the total flow during the operating period was recorded, not the continuous record. Whether a particular recycle event occurred can only be inferred from the record of pH and turbidity values, rather than by a direct record of discharge flows. Recording the discharge flow would indicate periods when the flow is zero, reflecting the failure to meet the discha rge requirement. Such a record gives the local or state inspector assurance that each tim e the pH or turbidity specification is not met, the recycle mode actually occurred.

Recommendation #11: Require the use of an Operating Period Information Form

A stormwater treatment facility involvi ng continuous discharge should maintain operational records. This allows the regulator to confirm performance. The Consultant makes the following suggestions regarding reco rd keeping. A standard form should be completed for each operating period, called an Operating Period Information Form. The recommended form is presented in Appendix B. Operators at the three tests sites were completing a similar form. Appendix B is simila r to the form that was used, but modified

based on recommendations of the Consultant. The Consultant’s recommendations stem from a review of the records of the three sites, discussed further in this report.

It is further recommended that the superv isor of the operator examine weekly the accumulated completed forms. The supervisor should sign each form to indicate that it has been reviewed, and should also document a ny actions he or she takes in response to any abnormal conditions observed by the operator.

Recommendation #12: The specifications outlined in Appendix A replace BMP C250 in the Department of Ecology stormwater manuals for Washington.

The objective is to avoid confusion and the pot ential for misinterpretation in attempting to resolve any differences with BMP C250 and the proposed specifications.Not to be released without written approval by NSS 6 

### ECOLOGY SPECIFICATIONS FOR THE FLOW-THROUGH SYSTEM

Ecology (2003b, 2004) established conditions fo r the approval of a flow-through system. NSS used these as specifications to guide its test program, embodied in the QAPP document (NSS, 2004).

1. The approved Quality Assurance Project Plan (QAPP), dated January 12, 2004 must be followed and includes:

• A field procedure for detecting a residual of chitosan in stormwater discharges greater than 0.1 ppm which has been accepted by Ecology. It can be downloaded by clicking “Colorimetric Determination of Residual Chitosan in Treated Stormwater.”

• Additional bioassay testing that is accept able to Ecology's Randy Marshall including one

in-situ bioassay test. Laboratory-based EC 25 testing will also be necessary for the following receiving water conditions:

o juvenile salmonid or other fish rearing or habitat, o salmonid or other fish spawning, o lakes,
o marine waters,
o sensitive marine habitat.



### Note: The bioassay test protocols must be pre-approved by Ecology's Randy Marshall and typically will include EC25 and 7-day survival determinations, including testing with embryos. The tests could be conducted once either before a project SWPPP is prepared or ASAP to finish the bioassay testing for the projected receiving waters. If toxicity is revealed NSS will notify Ecology immediately that it set Chitosan use restrictions to the degree applicable for that particular species and receiving water.

• A selection process for pretreatments for influent turbidities above 600 NTU, • A clear

explanation (including appropriate graphics) of the relationship between pH and Chitosan effectiveness for turbidity removal. It is desi rable to illustrate the decrease in effectiveness when the pH approaches the optimum of 6.5-8.5.

• The sand filter operating indicator(s) for switching to the backwash cycle (pressure drop,

effluent turbidity, etc.) The chitosan dose rate shall not exceed 1 mg/L (as chitosan acetate by weight) or 100 mg/L as 1% Liqui-Floc and not exceed 50 mg/L as 2% Liqui-Floc.

2. Water quality influent and effluent shall be continuously monitored for pH and turbidity and the effluent for chitosan concentration and/or aqua tic toxicity as follows: (NOTE: All aquatic toxicity test procedures must be approved by Ecology’s Randy Marshall prior to implementation). For the continuous flow-thr ough discharge to surface water under the CUD the following monitoring and operating procedures sha ll be strictly followed at all sites until a General Use Level Designation is issued by Ecology:

a. The metering pump must be calibrated at startup of the CESF and every four hours during the operation of the Chitosan metering pump to ensure that the dosage is at or below 1.0 ppm at all times. All calibrati on results must be recorded simultaneously with the flow rates and the records kept on site.Not to be released without written approval by NSS 7 b. The discharge from the sand filters must be maintained below 0.1 ppm residual chitosan acetate polymer at all times. At least two discrete grab samples of a homogeneous sand filter discharge must be collected during each operating period (CESF continuous operation up to 24 hours) and analyzed for residual Chitosan polymer. The samples must be collected one and two hours after the onset of each operating period.

c .In the event that the chitosan residual in the discharge is greater than 0.1 ppm, or the discharge exhibits aquatic toxicity based on approved bioassay testing, or when the CESF system is upset or fails a contingency plan to immediately correct the problem must be included in every SWPPP under this CUD. The contingency plan can include any of the following emergency operational me asures, or equivalent measures for the handling of the "off-spec" stormwater:

• temporary storage sized to handle all reasonable failure scenarios, • discharge to a sanitary sewer if available and pre-approved by the sewer authority, • discharge to an infiltration system with no discharge to surface water, or, • truck hauling for proper disposal until the problem is corrected.

d. At one or more construction sites and at any site that is not monitored for residual chitosan in the sand filter discharge operate an insitu bioassay test following a protocol that has been approved by Ecology (Randy Marshall).

e. At all construction sites, at the end of each 8-hour shift, a delegated responsible person

must record his/her assessmen t of the operational efficiency of the CESF process and all upsets, the insitu bioassay results (where applicable), the sand filter discharge chitosan concentrations (where applicable) and any other relevant observations that relate to CESF proper operation and must al so certify the acceptability of the CESF discharge to surface water.

f. Stormwater discharges from the CESF system shall not cause or contribute to receiving surface water quality violations. If the discharge from the CESF will be to a fish spawning area in the stream an approval for t hat discharge must be obtained from the responsible Ecology Regional Office. N SS guarantees that CESF, when used as directed, will not produce treated water whic h exhibits aquatic toxicity caused by Chitosan added as a treatment agent.

3. Source Control procedures will be implemented to the maximum extent feasible to minimize the need for Chitosan treatment and for cont rolling the influent NTU to less than 600.

4. During periods of operation of the CESF syst em a qualified operator acceptable to NSS must be present on-site.



### Additional requirements identified as “Design and Operational” include:

1. The CUD and GULD apply only to Vanson/HaloSource Storm Klear Liqui-Floc (1% and 2% chitosan acetate) Chemical Abstract Service number 9012-76-4

. 2. Because of the high solids loading in water associated with construction siterunoff CESF systems must be designed and operated at a flow rate not to exceed 15 gpm per square foot of sand bed filtration area and should employ a minimum of three (3) sand filter pods to ensure adequate backwashing capacity. The backwash slurry from the sand filters must be discharged to a detention cell that is separate from the temporary storage cell for theNot to be released without written approval by NSS 8 incoming turbid stormwater. The overflow fr om the backwash slurry detention cell can overflow into the detention basin for the turbid stormwater.

3. The maximum suspended sediment (expressed as turbidity) of the influent water should not

exceed 600 NTU.

4. The CESF system treated water output sha ll be equipped with an automatic integrated turbidity and pH sensors capable of shutting the system down if output turbidity or pH exceed preset values. An audible alarm and warning light will be installed on the treatment system to alert the operator in the event of a system failure. NSS is encouraged to include a computerized controller (like the Talus system) to automatically adjust chitosan dosage based on turbidity, flow, and pH.

5. The only filtration media approved is a p re-washed #30 crushed silica sand with a mean effective sand size of 0.34 mm and a filtration quality mesh of 230-400. Minimum sand bed depth shall be 18-inches underlain with a minimu m of 6-inches of 1-inch crushed rock. An intermediate mesh-siz garnet may be added to enhance performance.

6. Chitosan injection shall be performed w ith an LMI-brand C77, high viscosity pump head, electric metering pump, or equivalent. The CESF system shall include a flow-regulating valve on the input to and output of the sand filter. These regulating valves will reduce the maximum output of the pump as required and facilitate proper backwash.

7. The CESF system (including metering pump, ch itosan storage and instrumentation) shall be completely enclosed in a secu re structure with locking door. The Chitosan liquid concentrate tank, metering pump and tubing shall be complete ly contained for secondary containment. The metering pump discharge tubing shall have an anti-siphon valve.

8. Jar tests will be conducted, as needed, to confirm the dosage level of Liqui-Floc.

9. During the planning (SWPPP preparation, etc.) of a project the adverse potential impact on chitosan efficiency of the use of anionic polymers for soil blanketing and stability, will be

evaluated.

10. The CESF system shall only be operate d by a trained tec hnician certified through an approved training program including classroom and fie ld instruction. Training to be provided by Natural Site Solutions to include the following Minimum Training Requirements: Prerequisites:



### • Minimum 1-year experience with, and sound working knowledge of, high pressure sand

filter systems.



### • Experience deploying and troubleshooting pressurized water pumping and piping

systems.



### • Fundamental knowledge of stormwater discharge regulations for applicable

region/locale.



### • Fundamental knowledge of stormwater qua lity testing procedures and methods for

parameters applicable to the region/locale.(not e: class and field content is specified but not included here)Not to be released without written approval by NSS 9 

### TECHNOLOGY DESCRIPTION

The QAPP prepared by Natural Site Solu tions (NSS, 2004a) contains a detailed description of the technology, and the options available in the event that effluent requirements are not met. Provided below is a brief summarization. The reader is referred to the QAPP for the more detailed description.

General

Chitosan-Enhanced Sand Filtration is a sta nd-alone treatment technology for stormwater

from construction sites. Chitosan acetate coa gulates fine suspended sediments, producing larger particles, enhancing their reten tion by the treatment system. Operating the Chitosan-Enhanced Sand Filtration system (CESF-FT) in the flow-through scheme avoids the need for a large and costly holding basin for treated water. If operated as a batch system, a minimum of three holding ba sins would be needed: one for untreated

stormwater and two for treated stormwater . Avoiding the second holding basin increases the number of sites where CESF-FT may be f easible. A schematic is shown in Figure 1, using the system employed at the SeaTac International Airport, one of the three test sites.

Stormwater is initially retained in a hol ding basin, which serves two functions. It provides pretreatment by one and possible tw o modes. The common pretreatment mode is simple gravity settling of sediment entering with the untreated stormwater.

Pump Stormwater Detention Pond

Chitosan-Enhanced Sand Filter System Chitosan

Chitosan storage/metered pumping

& water monitoring trailer Construction Site Stormwater Conveyed to Detention Basin

Backwash Water

Treated

Stormwater Discharged to
Snohomish River Figure

Seatac Airport CESF System

Schematic Turbidity and pH Controller

Influent Sample

Port

Effluent Sample Port Automatic Recycle

Valve Automatic Recycle

Valve Influent pH & Turbidity Monitoring

Effluent pH &

Turbidity Monitoring Flow Meter

& Totalizer Flow Meter

& Totalizer Pump Chitosan

Pretreatment

Line

Chitosan

Treatment

Line 20,000-gallon

Pretreatment

Tank 20,000-gallon

Pretreatment

Tank 20,000-gallon Backwash Settling Tank



### FIGURE 1 CESF-FT SchematicNot to be released without written approval by NSS 10 

### System components

The second pretreatment mode is the addition of chitosan acetate as the stormwater enters the basin. This is done only if the incoming st ormwater is extremely turbid, in excess of

600 NTU and if all source control measures have been found incapable of reducing the turbidity below that value. The second func tion is to equalize the flow rate. Moderating the incoming flow allows the CESF-FT to operate at an essentially constant flow rate.

The filters are periodically backwashed automa tically to remove filtered sediment from each pod to maintain the hydraulic capacity of the sand. This feature allows the treatment system to operate on a continuous flow-through basis. As shown in Figure 1, the system typically has four filter pods. The system is equipped with automated sensors for turbidity and pH. If the discharge requirements are not met for either, the treated stormwater is recycled to the holding basin, to receive tr eatment again. Chitosan acetate is added immediately before the filters.

The CESF-FT consists of these components.

Stormwater holding basin(s): Alternatively called the detention/pretreatment basin, these may be either temporary or an elemen t of the permanent drainage system (i.e. detention basin), and may be either ponds or mobile storage tanks.

Pretreatment: Axiomatic to the treatment system is good site erosion control. The objective is to keep the turbidity of th e untreated stormwater less than 600 NTU. When the turbidity of the stormwater ente ring the holding basin exceeds this value,

chitosan acetate is added as the stormwater enters the basin or a pretreatment tank

that follows the basin. The latter has been the more common practice. The pretreated water then enters the basin or tank where the coagulated sediment settles.

Influent pump: Stormwater is pumped from the holding basin to the filter units.

Liqui-Floc injection system: Consists of the following: precision, variable output metering pump, feed and suction tubing, Liqui-Floc product storage container.

Discharge piping or structure: Site and flow rate specific.

Sand filtration units: Various sizes and capacities are shown in Table 1 (NSS, 2004b). The sand size specification (NSS, 2004b) is presented in Table 2, consistent with Ecology (2003b, 2004) requirements. The filters are operated in the range of 5

to 10 GPM/ft 2 

### of media. Eighteen (18) inches of sand is used.

Backwash system: The sand filters are periodically backwashed to retain their hydraulic capacity. The frequency of backwashing is controlled by a timing mechanism, causing backwashing to occur on a regulator schedule. The control system also contains a default value for pr essure loss through the filter. If the default value is reached before the preset time has passed, backwashing occurs. This commonly indicates a need to inspection and possibly maintenance of the filters.Not to be released without written approval by NSS 11 

### TABLE 1 Typical Sand Filtration System Capacities

Manufacturer’s

Recommended

Flow Rate 2

Min./Max.

(gpm) ChitosanEnhanced

Recommended

Max Flow

Rate 3
(gpm) Inlet/

Outlet

Size Backflush

Size Gravel/Sand Required

(Bags) Minimum

Pad Size Required Approx. Ship

Wt.

Less Media (lb)

90 / 132 80 3” 1 1⁄2” 6 / 6 4’ x 7.5’ 396

160 / 237 142 3” 2” 6 / 12 4’ x 9’ 510

255 / 375 225 4” 2” 12 / 15 5’ x 10.5’ 863

357 / 525 315 6” 4” 15 / 21 5’ x 12’ 1208

638 / 938 562 6” 4” 30 / 39 6’ x 15’ 1900

850 / 1250 750 8” 4” 40 / 52 6’ x 19’ 2580



### TABLE 2 Specification for #30 Grade Crushed Silica Sand Media

TABLE 2-2 # 30 GRADE SAND SPECIFICATION

Sieve Size (U.S.) Cumulative Percent Passing Individual Percent
Retained

16 >99.9 Trace

20 99.7 0.3

30 90.6 9.1

40 28.3 62.3

50 4.1 24.2

70 1.4 2.7

100 0.4 1.0

140 0.1 0.3

200 Trace 0.1



### Backwash holding tank: The dirty backwash water does not directly enter the holding basin. Rather, it first enters either a small cell located in the holding basin (separated from the remainder of the basin by a silt curtain) or a separate tank. This keeps most of the filtered sediment from entering the larger basin.

Influent and effluent turbid ity and pH monitoring units: These meters continuously sample the influent and effluent , and directly control the recycle valve.

Data are stored.

Recycle system: If either the effluent turbidity or pH meter indicates that the quality of the effluent has strayed outside the specified discharge requirements, a value automatically shifts to recycle the stormw ater back to the holding basin. Action is

then take to redress the cause.Not to be released without written approval by NSS 12 

### Recycle

Recognizing the importance of recycle, a mo re detailed discussion is presented. The CESF-FS at the Seatac Airport and the WSDOT SR522 sites both have automatic recycle, which puts the system into recycle in the event the stormwater does not meet preprogrammed set points for pH and turbidity. The water is returned to the holding basin and is retreated. The recycle system has th ree components to ensure compliance and to prevent the release of stormwater outside discharge specifications.

• Two electronic-actuated, hydraulic pressure-sustaining valves

• Continuous monitoring consisting of two pH and two turbidity probes

• Electronic controller to control the recycle valves

The CESF-FT system is able to recycle wate r at two points: immediately before and immediately after the filters. Chitosan acetate is injected into the pipe carrying pressurized turbid water from the holding basi n to the filters. The pH and turbidity are measured and recorded by a controller. If the influent pH or turbidity is outside set limits, the controller sends an electronic signal to th e influent recycle valve. The valve opens forcing the water into recycle, returning to the holding basin. The audible and light alarms activate to alert the operator that the system is recycling.

The discharge of treated water from the sand filters is measured for pH and turbidity.

These measurements are sent to the controller and stored. As with the above influent recycle, if the pH or turbidity of the effluent is outside discharge limits the controller sends an electronic signal to the recycle valv e and the valve opens forcing the water into recycle. This water is also recycled back to the holding basin. Should recycle occur, the audible and light alarms are activated to alert the operator.

The recycle valves default to the open position (initiating recycle) in the event of a power failure or other non-ordinary condition. The valves may also be operated manually.

OPERATION AND MAINTENANCE MANUAL

NSS has prepared a standard Operation and Maintenance Manual (NSS, 2003), provided as Appendix D (separate document). The major elements of the manual are:

• Stormwater treatment with chitosan

• Treatment system planning

• Treatment system operation

• Troubleshooting

The manual includes: a typical treatment syst em diagram, system specifications, system capabilities, Liqui-Floc injection rate table, sample system checklist and operation period information form, polymer metering pump speci fications, process control equipment, and MSDS. The manual supplements and does not replace the manual that should be provided by the vendor of the equipment.Not to be released without written approval by NSS 13 

### TEST SITE DESCRIPTIONS

The QAPP specified that the CESF-FT technology was to be evaluated at three sites. Presented in Table 3 are the three sites, the period of operation, and land use. A detailed description of each site follows Table 3.

TABLE 3 Test Sites

SITE PERIOD OF

CESF-FT OPERATION BRIEF DESCRIPTION

Lakeside Housing Development November 2003 – February 2004 80 acre housing development

SeaTac International Airport Third Runway November 2004 to current 150 acre, earth moving and filling project

WSDOT SR 522 Road Improvement Project December 2004 to Current 125 acres



### Lakeside Housing Development

The project was located immediately east of NE 65 th 

### and 188 th 

### Lane NE. in Redmond. Stormwater from the site normally drains eas t to a natural wetland, then to Evans Creek. However, because of the sensitive nature of Evans Creek, all treated stormwater generated during the construction period was pumped to the SR 202 stormwater drainage system, which discharges directly to Lake Sammamish. The CESF-FT facility at the Lakeside Housing Project did not require pr etreatment. Figure 2 presents a schematic and pictorial view of the filter facility.

All stormwater runoff from disturbed portions of the site was directed, via open channels and storm drains, to the stormwater holding basin, which has a capacity of approximately 1 million gallons. Treated water from the CE SF-FT facility was directed to two treated water holding tanks so that the water could be tested prior to discharge.

Recycle Chitosan storage & Metering Shack

Sand Filter

Discharge to
Storm Sewer N

Pumps

Backwash Water Stormwater Holding Basin

(1 Million Gallons)

Lakeside Housing Development

Treatment System Layout



### Figure 2 Lakeside Treatment System Schematic and filter systemNot to be released without written approval by NSS 14 

### Chitosan (1% solution of chitosan acetate) was in jected into a 6-inch pipe about 50-feet upstream of the sand filter at 0.3 to 0.8 millig rams per liter (mg/L), varying with the turbidity of the water. The dose rate of chitosan was calibrated by timing the uptake of chitosan (through the metering pump) from a graduated cylinder and noting the flow rate

of water from the sand filter.

SeaTac International Airport Third Runway

Over 14 million cubic yards of fill dirt are being brought to the west side of Sea-Tac International Airport to form the foundation for the new runway, distributed on 150 acres. There are seven individual CESF-FT units placed at four separate locations, each with holding basins. Their combined capacity is 3,500 GPM. Stormwater can be pumped between ponds to maximize the use of the tota l capacity of the units. Discharge is to

Miller Creek.

Stormwater runoff commonly enters the holdi ng basins at a turbidity level above 1,000 NTU, sometimes as high as 3,000 NTU. The Conditional Use Designation document (Ecology, 2004) limits the chitosan acetate dose rate to 1 mg/L. The contractor was able to keep the dosage within 1 mg/L, despite the high turbidity, by splitting usage between pretreatment and treatment before the filters. At this site, pretreatment occurred in a pretreatment tank immediately following the holding basin, not in the holding basin. The schematic of one of the facilities is presented in Figure 3. Pictorial views are presented in Figures 4 and 5.

Backwash Settling Tank Pretreatment Tank

Sand Filter System # 4

Recycle

Generator Pump Control System Pump

Discharge to Miller Creek N

Pretreatment Tank

Discharge from System #01

Pond G2 Settling Basin Sea Tac Airport

Pond G2 Treatment System # 4 Layout



### Figure 3 Sea-Tac International Airport System Schematic (Facility #04)Not to be released without written approval by NSS 15 

### Figure 4 Aerial view of Facility #4

Figure 5 Ground view of Facility #4 Pond G1 Pond G2 Sand Filter #04 Discharge to
Miller Creek

Backwash Settling Tank Pretreatment
Tanks

Sand Filter #04

Chitosan storage, metered dosing and monitoring box Power SupplyNot to be released without written approval by NSS 16 

### WSDOT SR-522 Road Improvement Project

The Washington Department of Transporta tion (WSDOT) is widening SR-522 between the Echo Lake Road and a bridge across the S nohomish River. The project site is about 125 acres: Discharge is to the Snohomish River. A general view of the site and a filter unit is presented in Figured 6 and 7, respectively.

Figure 6 WSDOT SR-522 Project Figure 7 Filter Unit

Two 500 GPM units were deployed, one each at the Echo Lake interchange and at Elliott Road just south of the bridge over the Snohom ish River. The Elliot Road system remains active at the writing of this report, while Echo Lake was decommissioned in early 2005

. The basic overall design of the Elliot Road system, shown in Figure 8, includes:

• Liquid carbon dioxide injection at the pretreatment station to reduce pH

• Liquid chitosan acetate injection for pretr eatment at the pretreatment station

• Holding basin for gravity solids settling

• Chitosan-enhanced sand filtration

SR 522 Backwash Settling Tank Pretreatment Tank

Sand Filter

Recycle

Generator Pump Control System

Pump

Detention/Holding Basin Discharge Manhole to

Snohomish River

CO2 Injection for pH Control Chitosan Injection for Turbidity Pretreatment N

Turbidity Curtain A

B

C Residual Chitosan Sampling Locations 1

Floating Pump

Suction

1- High turbidity stormwater was pretreated with chitosan before entering the holding basin reduce the turbidity load on the sand filter. Sample points A, B and C were tested for residual chitosan to see if any residual chitosan was present in the water. No

residual chitosan was ever detected.



### Figure 8 WSDOT SR522 Elliott Road System Schematic Treatment

System

Construction/ Drainage Area SR 522 Widening ProjectNot to be released without written approval by NSS 17 

### Turbidity levels of incoming stormwater vari ed significantly, less th an 60 NTU to greater than 1,400 NTU. High turbidities were due to th e frequent blasting of shale on the project site. Therefore, chitosan acetate was added to the high-turbidity stormwater immediately prior to the holding basin. It was effective, t ypically reducing the turbidity in the basin to less than 60 NTU. Ecology (2003b, 2004) limits the dose rate to 1 mg/L. A variance was requested for this site, allowing an aggr egate dosage of 3 mg/L, but with 1 mg/L remaining as the immediate dosage before the filters. In practice, about 2.5 mg/L was used in pretreatment when required, added as the runoff entered the basin, and 0.5 mg/L was used immediately prior to the sand filters.

Disturbance of the sedimentary shale rock cr eated a high pH (as high as 9.6) in dewatered groundwater and stormwater. Li quid carbon dioxide was added at the pretreatment station to control pH as it entered the basin. A nother adverse condition was extensive algal blooms occurring in the basin. The atypical gr owth of algae increased the pH of the stored stormwater, necessitating the placement of carbon dioxide as dry ice in the basin. The algae growth was the result of a combina tion of low turbidity (with pretreatment), sunlight penetration, and elevated phosphorus concentrations. The latter was believed due blasting explosives. The treatment system removed the algae from the water without damage to the filters.

TEST PROGRAM DESIGN

The test program is described in Section 3 of the QAPP (NSS, 2004a). Table 4 lists the key elements of the sampling design.

TABLE 4 Major elements of the sampling design a



### ELEMENT
Maintain the residual concentration of chitosan below 0.1 mg/L.

The determination of the residual concentration to occur three times during each operating period. A trout bioassay test is to be conducted at one of the test sites. A minimum of 20 operating periods are to occur. pH and turbidity to be measured at least every 15 minutes. Test sites are to be characterized with respect to perviousness, soil type and vegetation, drainage area, drainage system, catchment flow rates, system specifications, closest receiving water body, pretreatment requirements, site adequacy for opera tion and testing, and any adverse site conditions. That there be sufficient stored water for each operating period to last at least four hours.

Flow meter with a flow rate totalizer. The chitosan metering pump is to be calibrated during each operating period and recorded on the Daily System Operation Log. Other pollutants to be monitored aside from turb idity and pH are TDS, TP, TN, total coliform, metals, pesticides and oil/grease. Turbidity to be sampled by automatic flow-through monitors. Handheld turbidity and pH meters to be calibrated daily, system fl ow meter to be calibrated as per manufacturer’s specifications A Daily System Operation Log is to be ma intained, completed for each operating period. NSS (2004a)Not to be released without written approval by NSS 18 

# PART II – THE CONSULTANT’S EVALUATION

SYSTEMS SELECTED FOR EVALUATION

The three test sites in combination had te n treatment units. The Lakeside site was dismissed because it was operated prior to the final specifications by Ecology (Ecology, 2004). Consequently, its configuration and opera tion did not fully meet the specifications. Three units were selected, Unit 4 at the SeaT ac Airport site which consists of two units,

and the Elliot Road unit at the SR522 site. The former was selected because these two units use the 48-4 sand filter (48” diameter, 4 pods), which is the most popular brand and

size of sand filter in use with chitosan-enhanced sand filtration. It was also selected because pretreatment by chitosan acetate addition is performed in mobile settling tanks (in series), rather than the holding basin (see Figure 5), which has become the primary configuration for the CESF-FT system. SeaT ac Unit 4 represents the best technology and configuration therefore will continue to be recommended to contractors by NSS (MacPherson, pers.com.). The Elliott Road unit was chosen from the two units at the SR522 site because it processed a larger qua ntity of stormwater and continues in operation.

COMPLIANCE WITH ECOLOGY SPECIFICATIONS

Ecology (2003b, 2004) established specificati ons for approval of CESF-FT operation. These specifications are listed in detail in this report beginning on Page 6. Table 5 lists each stipulation with the Consultant’s c onclusions. For many of the specifications,

reference is made to discussions elsewhere in this report. The Consultant evaluated the extent to which these specifications were met by NSS at SeaTac and SR522. Evaluation was accomplished through interviews, site vi sits, and review of operational records

available at the office of NSS.

Ecology specifications required monitoring activities other than just effluent turbidity and pH. Other operational specifications of partic ular interest listed below are discussed by the Consultant, beginning on Page 21.

#5 - If exceeded at any time the responsible s ite operating personnel shall immediately take appropriate corrective actions.

#11 - Chitosan acetate dose rate shall not exceed 1 mg/L

#13 - Chitosan in effluent below 0.1 ppm residual

#15 – Chitosan metering pump calibrated at startup of the CESF-FL and every four hours

#16 - At the end of each 8-hour shift, record a ssessment of operational efficiency, upsets, etc



### The number of each requirement discussed below relates to Table 5. The Consultant examined at random operational records from two sites: SR522 and SeaTac, specifically Unit #4. The entire record of each was not examined: rather, randomly selected months. Each operational record prepared during th e selected months was examined. The following are the Consultant’s findings.Not to be released without written approval by NSS19TABLE 5 ABBREVIATED LIST OF SPECIFICATIONSOF ECOLOGY FOR THE CESF-FT (See Page 5)#STIPULATIONCONSULTANT’S CONCLUSIONS1 Comply with Construction Permit, AKART, etc.This is an expectation placed on the construction permitwith each application of the CESF system, and is notdirectly related to the TEER.2 Be consistent with BMP C250 (Ecology, 2001) This specification was met.395% reduction of NTU turbidity, a maximum of 10NTU, discharge pH of 6.5 to 8.5.This specification was met. See presentation of data beginning on Page 26.4Stormwater discharges from the CESF system shall notcause or contribute to receiving surface water qualityviolations.This specification is met by meeting the discharge requirements specified for turbidity and pH.5If discharge exceeded at anytime, the responsible siteoperating personnel shall immediately take appropriatecorrective actions.”The standard procedure is to recycle the treated water back to the holding basin for re-treatment. Recyclecontrol is automatic, based on continuous monitoring ofeffluent pH and turbidity. See page 12.6 Follow the QAPPConsultant concludes the QAPP was followed with exceptions. See discussion of specifications #11, #13,#15 and #16, beginning on Page 21.7Additional bioassay testing acceptable to Ecology'sRandy Marshall for juvenile salmonid or other fishrearing or habitat, salmonid or other fish spawning,lakes, marine waters, or sensitive marine habitat.Results summarized beginning on Page 23. Studies enclosed in Appendices G and H. The method wasagreed to by Randy Marshall of Ecology. Tests as yethave not been performed with marine organisms asNSS has as yet not been responsible for a site that discharges to marine waters. Tests are currently underway(McPherson, pers. comm.)8Conduct in-situ bioassay test following a protocolapproved by Ecology.Specification was met. See Page 25 and Appendix H.9Explanation of relationship of pH and turbidityremoval.There is no relationship because the two are independent. The CESF dosing systemdoes not affect pH. pHis affected by site conditions such as exposure of freshconcrete to stormwater and algae in the holding basin.10 Use only Vanson/HaloSource Storm Klear Liqui-Floc. This specification is included in each site SWPPP.11 Chitosan acetate dose rate shall not exceed 1 mg/L.The Consultant examined selectedoperational records and confirmed that this specification was met: seePage 21. A variance was received at one ofthe three sites for reasons explained.12Influent and effluent continuously monitored for pHand turbidity.This specification was confirmed bythe Consultant during a site visit to facilities at SR522 and SeaTacAirport Unit 4 on August 12, 2005, and through a reviewof operational records. Continuous monitoring didnot occur at Lakeside because the facility operated before this stipulation was established by Ecology (2004).Effluent testing at this site was manual.13 Chitosan in effluent below 0.1 ppm residual.The Consultant examined selected operating data at random: see Page 22. The Consultant found that thisspecification was always met.14Develop field procedure to detect residual chitosangreater than 0.1 ppm.A method has been developed. See Appendices E and F. AMTEST evaluated the method to establish areliable detection limit. It was determined to be 0.2mg/L. See Page 3 regarding recommendation to changethe allowable residual concentration.15Chitosan metering pump calibrated at startup of theCESF-FL and every four hours of operation.The Consultant examined selected operating data at random: see Page 22. The Consultant found that thisspecification was not always met.Not to be released without written approval by NSS20TABLE 5 ABBREVIATED LIST OF SPECIFICATIONS OF ECOLOGY FOR THE CESF-FT (Continued)#STIPULATIONCONSULTANT’S CONCLUSIONS16At the end of each 8-hour shift,record assessment of operationalefficiency, upsets, etcSee Daily Log form examples in Appendix C. Consultant has recommended changes tothis form to make the specification more explicit to operator. See Page 5.17 Source BMPs to control influent NTU to less than 600.All construction sites are required to implement commonly accepted erosion controlBMPs, as specified in site SWPPPs. Theexperience of NSS has been that thestipulation of 600 NTU cannot be guaranteed.The Consultant can confirm this basedon a report prepared for the City of Redmond (Minton, 1999).18 Pretreatment (procedure) for influent turbidities above 600 NTU,Water entering the holding basin is periodically monitored by hand-held meter. Ifturbidity is above 600 NTU, chitosan is added directly to the stormwater as it entersthe holding basin, preferably several feet “upstream”.19 Qualified operator present on-siteduring operations. This specification is specified in each site SWPPP.20 Flow rate through the filters not to exceed 15 gpm/ft2. Specification met.21 Minimum of three filter pods. Specification met.22 Operating indicator(s) for switching to the backwash cycle.This specification was confirmed by the Consultant during site visits to facilities atSR522 and SeaTac Airport Unit 4 on August 12, 2005 and January 3, 2006.23The backwash discharged to a holding cell within or separate from theholding basin.Specification met.24 Maximum influent turbidity of 600 NTU. See Specification #18 in this table.25Audible alarm and warning light when discharge does not meetrequirements for turbidity or pHSee description of the technology on Page 9. Consultant confirmed the specificationduring site visits.265Filtration media is pre-washed #30 crushed silica sand with a meaneffective sand size of 0.34 mm and a filtration quality mesh of 230-400. Minimum sand bed depth shall be 18-inches underlain with aminimum of 6-inches of 1-inch crushed rock.See description of the technology on Page 10. The Consultant did not conduct agradation test to confirm this specification.27 Use LMI-brand C77metering pump, or equivalent. Consultant confirmed the specification during site visits.28Include flow-regulating valve on the input to and output of the sandfilter.Consultant confirmed the specification during site visits.29 Instrumentation, pumps, chemicalsenclosed in a secure structureThis specification was confirmed by the Consultant during site visits at SR522 andSeaTac Airport (Unit 4) on August 12, 2005.309 Jar tests conducted, as needed, to confirm dosage level. Specified by site owner in each SWPPP.31During the planning (SWPPP preparation,etc) of a project the adversepotential impact on chitosan efficiencyof the use of anionic polymersfor soil blanketing and stability will be evaluated.Specified by site owner in each SWPPP.32CESF system shall only be operated by a trained technician certifiedthrough an approved training programThis specification was met at the three testsites. The responsibility to meet thisspecification at other sites rests with the site owner.Not to be released without written approval by NSS 21 

### • #5 - If exceeded at any time the respons ible site operating personnel shall immediately take appropriate corrective actions.”

NSS was asked by the Consultant to identif y the corrections made by operator in the event that the quality of the discharge is outside the allowable quality. The following was provided (MacPherson, pers. comm..).

If a pH or turbidity excursion causes the system cause to go into recycle, the operator measures the parameters to determin e which is out of compliance. If the pH is too low, the system is kept in recycle while food-grade sodium bicarbonate is added. If the holding pond is large, this may require shutting down the system, and mixing water in the pond with pumps until the desired pH is achieved. The system is restarted in recycle mode. Once the pH is w ithin acceptable limits the system is put back on line. If the pH is too high, dr y ice is hand broadcast into the holding pond until the pH is acceptable. If high pH continues (e.g. extensive concrete pouring), an automated liquid carbon dioxide injection system may be installed. This system reads the incoming and outgoing pH, and automa tically adjusts the rate of carbon dioxide injection. Such a system was inst alled for a period of time on the WSDOT SR522 project due to the high pH caused by the disturbance of alkaline sedimentary shale material by construction.

If the turbidity exceeds the preset limits , one of three adjustments are made: increasing the chitosan dose in a pretreatme nt settling tank, reducing the flow rate of the system to allow more settling time, or more extensive treatment. If, for example, the holding pond suddenly experiences a significant increase in turbidity due to site work or heavy precipitation, the common adjustment is to continue in the recycle

mode while additional chitosan is added to th e stormwater as it enters the basin. If this approach is not adequate due to extreme turbidity the system is shut down, pumps recirculate the entire holding pond c ontents while adding chitosan to reduce the turbidity to levels consistent with filtration (<500 NTU). If this approach is necessary, Department of Ecology and the pr oject contractor are contacted. A plan is developed consistent with Ecology’s regulations and project needs. Typically a quantity of additional chitosan is estimated based on jar testing; that quantity is added while recirculating (mixing) the holding pond with pumps. Once the turbidity has been reduced to acceptable levels the system is restarted in the recycle mode until it has been determined that the effluen t turbidity limits can be met. Once this occurs the system is put back on line. Normally, the holding pond is tested for residual chitosan to ensure there is no excess chitosan present. The actions are documented in a report, summarizing the c ause of the problem and the methods used to bring the system back into compliance.

• #11 - Chitosan acetate dose rate shall not exceed 1 mg/L

A variance to 3 mg/L was given at the SR-522 site, allowing up to 2 mg/L for pretreatment and 1 mg/L immediately prior to the filters. The operational records for the

SR-522 site were examined for the months of January 2005 and October 2005. DosageNot to be released without written approval by NSS 22 

### immediately before the filter was commonly 1 mg/L or less. The Consultant’s review of

the records indicates that the variance c oncentration was not exceeded. As stated previously, the additional dosage above 1 mg/L to pretreat the stormwater as it enters the holding basin.

At the SR-522 chitosan residuals were measured in the holding basin, prior to treatment by the filter (MacPherson, 2006) to ascertain the possible effect of higher chitosan dosages on the residual concentration. Samples were taken at three locations in the holding basin on 38 days from late Ap ril through May 2005. The Consultant has reviewed the data, finding no excursions above 0.2 mg/L of chitosan in either the holding basin or in the discharge from the system during this test period.

• #13 - Chitosan in effluent below 0.1 ppm residual

The same records identified above were examin ed for this stipulation. In no operational period was a residual above 0.1 ppm observe d. However, the test was not always performed each operational period as required. At SeaTac in October and December 2004, and March 2005, the test was not performe d in 25% of the operational periods. However, this omission decreased to essentially 0% in May 2005, and the test was commonly performed twice per operational pe riod. In contrast, at SR522, full compliance was achieved in the two months examined, January and October 2005. Although the residual dosage was maintained at 0.1 mg/L or less, it is recommended that the stipulation be changed to 0.2 mg/L. See the discussion of the test on Page 22.

• #15 – Chitosan metering pump calibrated at startup of the CESF-FL and every four hours

The same records identified above were examin ed for this stipulation. With respect to SeaTac Unit 4, in the early startup month of October 2004 the pump was not typically tested at startup, but two to three hours into the operation. The frequency of early testing improved in March of 2005, but still did not cons istently meet the stipulation. By May 2005, the pump test always occurred, always w ithin one hour of startup and 90% of the time within 15 minutes. In contrast, at SR 522 full compliance was achieved in the two months examined, January and October 2005. At both sites the pumps were not commonly tested if the operational period lasted beyond four hours.

• #16 - At the end of each 8-hour shift, reco rd assessment of operational efficiency,

upsets, etc

The same records identified above were examined for this stipulation. The operator infrequently provided commentary. It is the C onsultant’s view that the language of the form does not make this requirement clear to the operator. The Consultant has made recommendations in this report. The Consultant’s recommended form presented in Appendix B makes the requirement very explicit.Not to be released without written approval by NSS 23 

### COMPLIANCE WITH THE NSS QAPP

Section 3 of the QAPP (NSS, 2000a) was examin ed on this question. All aspects of the program design were met with some excepti ons. As the specifications of the QAPP are essentially the same as the compliance specifications as specified by Ecology (2003b, 2004), summarized in Table 5, the discussion of compliance with both documents is combined in the previous section. The C onsultant discussed the exceptions with the Applicant, and considered the rationale for each.

The subject of dosage limits (1 mg/L) has been discussed. All aspects of the QAPP listed in Table 4 were met with to two exceptions . Turbidity and pH were not monitored continuously at the Lakeside site. But this was because the site was established before Ecology established its operational requirement s (Table 5) or the completion of the QAPP. A second exception was sampling for anal ytes other than pH or turbidity. NSS decided not to sample for phosphorus or meta ls given the inherent awareness, based on studies of stormwater, that little of either me tals or phosphorus are in the dissolved state, given the high influent turbidity concentrations. Hence, high removals of turbidity and TSS will logically in turn substantially re duce phosphorus and metals concentrations.

The Consultant concurs with this view. Th e interest with fecal coliform is with construction sites where mulches are applied for landscaping. However, this did not occur at any of the test sites. Regardless, the Cons ultant’s review of the professional literature indicates that coagulation-filtration systems provide high removals of coliform.

RESIDUAL CHITOSAN TEST

As required by Ecology specifications, N SS worked with a certified laboratory, AMTEST, to confirm the capabilities of a test procedure for chitosan acetate, developed by John MacPherson of NSS. The test procedur e is presented in Appendix E. A report by AMTEST of the test procedure and certifica tion results is presented in Appendix F (AMTEST, 2005)..

TOXICITY EVALUATION

Laboratory tests of Liqui-Floc

A study was conducted by Nautilus Environmental (2004) regarding the toxicity of LiquiFloc. The full report is enclosed as Appendix G. The Consultant has excerpted the full text of two sections of the report: the Execu tive Summary and the Discussion. Each is presented below.Not to be released without written approval by NSS 24 

### Executive Summary: “A toxicity testing progr am was conducted using Storm KlearTMLiqui-FlocTM (chitosan acetate), as manufactured and distributed by Vanson HaloSource, Inc., Redmond, Washington, in ord er to meet the requirements specified in a Washington Department of Ecology docum ent titled “Risk Evaluation of Proposed Treatment Chemicals for Stormwater Runoff”, dated December 8, 2003 (WDOE, 2003). The results of this study are provided in this report.

The program involved conducting a suite of to xicity tests using the product to determine which was the most sensitive species, and to det ermine the “toxic threshold”, defined as the lowest 25% point estimate from the various test s. Rainbow trout were demonstrated to be the most sensitive species, with a 7-day LC25 of 1.21 mg/L Liqui-Floc.

Toxicity tests were subsequently conducted to evaluate the toxicity of the product under the conditions of varying turbidity. This inves tigation was conducted because Liqui-Floc is removed from solution as a result of its acti on on suspended particulate and, therefore, the application rate differs from the discharge concentration in the presence of suspended particulate. Toxicity decreased substantially and linearly with increasing turbidity from a 96-hr LC50 value for rainbow trout of 1.68 mg/L at 0 NTU to 4.52 mg/L at 500 NTU turbidity. After correcting these data using th e ratio between the 96-hr LC50 for rainbow trout and the toxic threshold in non-turbid water, this resulted in a toxic threshold for LiquiFloc ranging from 1.21 mg/L in non-turbid water to 3.25 mg/L in water with a turbidity of

500 NTU.

It should be noted that the actual treatment technology proposed by Natural Site Solutions incorporates a clean-up step involving sand filtration after application of Liqui-Floc to turbid water, which further reduces residual di ssolved chitosan, thus providing an additional safety margin beyond that described in this report.



### Discussion: “The data presented in this study show that rainbow trout were substantially more sensitive to Liqui-Floc than any of the other organisms tested. There was only a minimal difference betw een the results of acute and chronic toxicity tests using rainbow trout, and su rvival was a more sensitive endpoint than growth in the 7-day survival and growth test with this species. The toxic threshold, as defined in WDOE (2003) as the lowest 25% point estimate, was 1.21 mg/L for a 7- day LC25 to rainbow trout.

Toxicity decreased with increasi ng turbidity in a linear manner over the range of turbidities tested from an LC50 of 1.68 mg/L at a turbidity of 0 NTU to an LC50 of 4.52 at a turbidity of 500 NTU. This linear relationship was strong with a R 2 value of 0.997. The reduction in toxicity associated with turbidity is not surp rising, since the product is designed to sorb to particulate materials, therefore reducing its bioavailability.

It is highly likely that an additional loading of suspended sediment associated with turbidities higher than 500 NTU would provide a further reduction in the LC50 for this product, because the rate of removal of Liqui-F loc from solution is a function of the number of binding sites on the suspended particulate ma terial. Extrapolating the toxicity-turbidity linear relationship would result in a predicted LC50 for rainbow trout of 7.3 mg/L at a turbidity of 1000 NTU and 18.3 mg/L at a turbidity of 3000 NTU, which would correspondNot to be released without written approval by NSS 25 to a toxic threshold for the most sensitive endpoint of 5.2 and 13.2 mg/L, respectively (Table 13).

For application of the product, WDOE requires a three-fold safety margin between the concentration of the product at discharge and the toxic threshold for the product (WDOE, 2003). Thus, the data support application of Liqui -Floc at rates of 0.51, 0.68 and 1.08 mg/L in waters with turbidities of 50, 200 and 500 NTU with no further treatment necessary in order to maintain the safety margin. Based on an extrapolation of the dataset, predicted acceptable maximum application rates at 1000, 2000 and 3000 NTU would be 1.75, 3.07 and 4.40 mg/L, respectively (Table 13).

The application rates proposed here in order to meet the requirements of WDOE (2003) are based solely on Liqui-Floc treated turbid wat er without further treatment. The proposed Liqui-Floc treatment design incorporates a s ubsequent clean-up sand filtration step which has been shown to substantially remove residual dissolved chitosan, in addition to removing Liqui-Floc sorbed to particulate. Thus, the actual application of this product provides a significant further safety margin to the t reatment system, well beyond that required by WDOE (2003).”

Table 1 (in the report) Proposed acceptable applic ation rates based on the toxicity-turbidity data for rainbow trout (50–500 NTU) and an extrapolation of the dataset (>500 NTU).

Turbidity
(NTU) Derived from: 96-hr trout

LC50
(mg/L) Toxic threshold

IC25
(mg/L) Maximum
application rate*
(mg/L)

50 Data 2.11 1.52 0.51

200 Data 2.83 2.03 0.68

500 Data 4.52 3.25 1.08
1000 Extrapolated 

### 7.28 5.24 1.75
2000 Extrapolated 

### 12.82 9.22 3.07
3000 Extrapolated 

### 18.35 13.20 4.40

*based on a three-fold safety margin relative to the toxic threshold.



### The Consultant notes that the three-fold safety margin was specified by Mr. Randy Marshall of the Department of Ecology (MacPherson, pers. comm.)

In-situ field tests of treated discharge

Tests were conducted at the Lakeside constr uction site where the CESF-FT system was employed (ECO-Endeavors, 2004). The full re port is enclosed as Appendix H. Key excerpts from the report are presented below.

Purpose: The purpose of this test is to determin e if there is any chronic mortality to Rainbow trout continually exposed to stor mwater treated by CESF. In-line test chambers will receive water after the polishing filter (the last stage of treatment) and prior to discharge from the site.Not to be released without written approval by NSS 26 

### Discussion: No mortality was observed at anytim e during the 14-day screening in either the test or control chambers. Organisms appeared normal and actively fed.

Days 10-14 had temperature readings over 20  ̊ C, which is well above the 12  ̊ C Whole Effluent Toxicity (WET) testing standard. With the increase in temperature, a marked drop in dissolved oxygen (DO) levels was observed. DO levels in the control chamber were below the 60 percent WET saturation level on days 10 and 11, 58 and 57 percent, respectively. DO levels in the test chamber were below the 60 percent WET saturation level on days 13 and 14, 58 and 56 percent, respectively. However, the organisms continued to actively feed and appeared normal despite the elevated temperatures and decreased DO l evels. Such fluctuations would not be anticipated had the test been performed in the winter months when ambient temperatures are much lower. This situa tion was expected to occur as the test was

started on June 8 , 

### 2002 when temperatures are warmer and was the reason the test was only run for 14-days.

Despite the discrepancies with standard te st temperature and DO levels, survival

rates were 100% in both test and control chambers.

Conclusion: From the data it appears that no chronic toxicity was observed after 14 days of continuous exposure to stormwater treated by the Flow-through Chitosan Enhanced Sand Filtration process.

MEETING THE DISCHARGE Q UALITY SPECIFICATIONS

Ecology’s specifications with regard to effluent quality are “ achieve performance goals of a minimum of 95% reduction of NTU tu rbidity, a maximum discharge of 10 NTU turbidity, and a discharge pH within a range of 6.5-8.5. If these values are exceeded at any time the responsible site operating personnel shall immediately take appropriate

corrective actions.” It is of interest to note that the new NDPES Construction Permit specifies a limit of 25 NTU for all construction sites, irrespective of the BMPs employed.

To meet the QAPP there has to be a mini mum of 20 operating periods, and 480 influent and 480 effluent samples each for turbidity and pH for each site. These numbers have

been exceeded at each site. The total number of operating periods at this time for the ten units at the three sites exceeds 1,500. The total number of data points exceeds 95,000 for each of the two effluent parameters.

The Consultant examined selected data generated at the test sites. Generally, the above specifications were met. Provided below for each site are representative data. The entire data base is not presented given its enormit y. Data for other time periods can be provided if requested. When examining the discharge gr aphs it is important to recognize that the discharge quality always meets the specificati ons. If it does not, the discharge from the filters is recycled to the holding basin. Th e frequency with which the discharge did not meet the discharge limits and was recycled at each site is discussed later in this report.Not to be released without written approval by NSS 27 

### Lakeside Housing Development

Presented Figures 9 and 10 are discharge data fo r this site. The data are over one year, but recognize that operation is not continuous. Th ey represent 65 operating periods and about 700 individual data points for each discharge parameter.

Lakeside Site Influent and Effluent Turbidity

0 1 10 100 1000



### 1

March 2003 to March 2004Turbidity (NTU) Influent

Effluent



### FIGURE 9 Influent and Effluent Turbidity

Lakeside Site Effluent pH

6 6.5

7 7.5

8 8.5

1

March 2003 to March 2004pH



### FIGURE 10 Effluent pHNot to be released without written approval by NSS 28 

### SeaTac International Airport Third Runway

Data from Unit Unit 4 (two systems in parallel) are provided for March through May 2005. During this period there were 24 operating periods and about 2,225 data points each for pH and turbidity. Figure 11 provides turbidity data and Figure 12 presents pH data.

Sea Tac Airport Turbidity Reduction for March, April, May 2005
Logarithmic Scale

0 1 10 100 1000

1

March, April, May 2005Turbidity (NTU) March Influent Turbidity

March Effluent Turbidity

April Influent Turbidity

April Effluent Turbidity

May Influent Turbidity

May Effluent Turbidity



### FIGURE 11 Influent and Effluent Turbidity

Sea Tac Airport Effluent pH Values

6.00 6.50 7.00 7.50 8.00 8.50 9.00

1

March, April, May 2005pH March Effluent pH

April Effluent pH

May Effluent pH



### FIGURE 12 Effluent pHNot to be released without written approval by NSS 29 

### WSDOT SR-522 Road Improvement Project

Data from the Echo Lake interchange facility are provided for period of March through May 2005. Figures 13 and 14 provide turbidity data. Figure 13 presents data for the entire three months. Figure 14 provides the data only for May to further illustrate the high turbidity in the stormwater prior to pre-treatment as it entered the holding basin. Figure 15 presents pH data. The data represent 63 operating periods and about 4,200 points each for turbidity and pH. At this site the pH often rose above 8.5 due to algal activ ity in the holding basin. Liquid carbonic acid was used to lower the pH.

WSDOT SR 522 Turbidity Reduction
Logarithmic Scale

0 1 10 100 1000

1

March, April, May 2005Turbidity (NTU) March Influent Turbidity

March Effluent Turbidity

April Influent Turbidity

April Effluent Turbidity

May Influent Turbidity

May Effluent Turbidity



### FIGURE 13 Influent and Effluent Turbidity

WSDOT SR522 Turbidity

1 10 100 1000 10000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

May 2005Turbidity (NTU)



### FIGURE 14 Turbidity Effluent Before p retreatment

Influent to filtersNot to be released without written approval by NSS 30 WSDOT SR 522 Effluent pH Values

6.0 6.5 7.0 7.5 8.0 8.5 9.0

1

March, April, May 2005Ph March pH

April pH

May pH



### FIGURE 15 Effluent pH

RELIABILITY

The data in Figures 9 through 15 indicate that th e CESF-FT meets the effluent requirements with respect to pH and turbidity, with the inclusion of automatic recycle. Of particular relevance is the frequency in which the discharge quality does not meet the discharge requirements, either turbidity or pH. The Consultant requested NSS to evaluate this question for the SeaTac Airport and WSDOT sites. The Consultant examined the analysis and the data used in the analysis. Presented in Table 6 is the history of recycle fo r these two sites for the time period evaluated in Figures 11 through 15.

TABLE 6 RECYCLE VOLUME HISTORY

Month Seatac System Unit 4 WSDOT SR522

March 4.9% 12.3%

April 8.3% 12.8%

May 6.8% 17%

Both sites experiencing unusual site or system conditions, the later a reflection of new elements in the particular CESF-FT system.

The recycle volume for Unit 4 at the SeaTac Airpor t site ranged from 17 to 27% during the first three months of operation (December 2004 through Fe bruary 2005). The startup of Airport site was complex because of the number of systems involved, the short time frame within which the systems had to be installed, and the occurrence of an extreme storm event that nearly exceeded the total capacity of the treatment systems. The most serious mechanical problem was due to the internal corrosion of the chitosan storage tanks, which caused small pieces of corrosion debris toNot to be released without written approval by NSS 31 

### clog the chitosan metering pumps stopping the flow of the treatment agent. When the chitosan stopped flowing the treatment failed and the syst ems went into recycle mode while operators dismantled and cleaned the metering pumps. This problem was repeated frequently until the chitosan storage tanks were replaced with non-corrosive tanks. Once this problem was corrected the systems ran as designed and no further problems were encountered.

The SR522 site reflected what may be the most ex treme site conditions that the CESF-FT system will experience. Difficulties were faced throughout the treatment period, not just during startup.

• The pH varied from 6.5 to 9.5 based due to the nature of site work and algal production in the holding basin.

• The turbidity varied rapidly from nearly clean to above several thousands NTU.

• The volume of water occasionally exceeded the system’s cpacity, particularly when the turbidity was very high. Pretreatment became a critical factor.

The considerably higher recycle times on the WS DOT SR522 project reflect the fact that this difficult site required times where the system wa s intentionally put into recycle while dosing

with chitosan in an effort to reduce the turbidity of the holding basin before treatment. Because of the nature of the project (linear highway proj ect) there were times when the turbidity rose to thousands of NTU without warning. During these times the only way to reduce the turbidity was to recycle the water while adding chitosan.

The Consultant noted during the fi eld visit that while there is a flow meter on the discharge line,

the data are not recorded. There is therefore no direct record that recycle occurs each time the discharge limits are not met. Rather, it is presum ed that it occurs based on the records of the turbidity and pH, measured immediately in the di scharge of the filter system, and the activation of the alarm system. The above calculations we re made through the examination of the record on turbidity and pH. Where either or both paramete rs were outside the discharge specifications, it was presumed that recycle occurred. Since recycl e occurs automatically, it can only be presumed that the recycle valve functioned satisfactorily in all instances. For this reason, the Consultant has recommended that the discharge flow be recorded.

FACTORS OTHER THAN PERFORMANCE

Discussion of factors

This aspect of the TAPE protocol is presented in a table format in Table 7 with responses to each item listed in the protocol. Costs are discussed separately from the table, following the table.Not to be released without written approval by NSS32TABLE 7 SUMMARY DISCUSSION OF OTHER FACTORSFACTORDISCUSSIONTECHNOLOGY DESCRIPTIONDescribe the treatment technology including process diagrams, primary equipment drawings,sketches, etc. Include details on the relevant treatment mechanisms such as: Filter media grainsize distribution, clean media hydraulic conductivity, hydraulic conductivity versus sedimentloading (provide sediment grain size distribution and dry density used in analysis), providetypical and maximum operational hydraulic gradient.See Page 9. Hydraulic gradients are meaningless with the technologyas it is a pumped system.APPLICATIONSFor which applications (e.g., land uses such as roadways, high-use sites, commercial,industrial, residential runoff areas) does the vendor recommend this technology.There are no inherent factors limiting the use of this technology. It isapplicable to all construction sites of any soil characteristics and size.What are the pretreatment requirements.Treat when influent to holding pond exceeds 600 NTU, despite allefforts at effective source control.Provide a list of the facilities that are installed in the United States. Include addresses and sizeof each facility. Provide at least three references with names and telephone numbers.The CESF-FT system has or is being used at over 100 sites in the U. S.wiith about 50 are in Washington.A complete list is not provided asNSS is not involved at all sites. Site owners for the three test sites:Lakeside Larry Darnell, (425)-313-2653; SeaTac, Port of Seattle, JimThorwart (253)831-7102; SR522, WSDOT Carl Vogt, (206) 660-1511.SITE CHARACTERISTICSDo any site characteristics or safety considerations favor or limit the technology’s use: climate,rainfall, steep slopes, high groundwater, seepage/baseflows, tidal action, soil type includingorganics and pH, proximity to wells, septic systems and buildings, facility depth limits foraccess and safety, hazardous materials spill risk,driving head requirements, and power.There are no inherent factors limiting the use of this technology. It ispotentially applicable for all construction sites of any soilcharacteristics and acreage.DESIGN CRITERIA FOR SIZINGPollutant removal at design flow and for representative stormwater characteristics. See discussion beginning on Page 26.Design hydraulics (design flow and/or volume, by-pass flow, hydraulic grade line, scourvelocities, etc.).Design flow rate is set by the discharge requirements. Hydraulicgradients are meaningless as it is a pumped system.Design residence time, vertical/horizontal velocities, etc. Residence time in the filters is about one minute.Stormwater constituent limitations (pollutants and other constituents), fouling factors. None, as pretreatment addresses the issue of high influent turbidity.Specific media flow rate (design velocity). Operate at less than 15 GPM/ft2of filter surface area.Media head loss curves.This relationship has not been developed, given the complexity ofthe tests and variable conditions between sites.Not to be released without written approval by NSS33TABLE 7 SUMMARY DISCUSSION OF OTHER FACTORS (continued)FACTORDISCUSSIONMinimum media contact time and minimumthickness. Contact time is about one minute. Filter thickness is 18 inches.Estimate system/system components design lifebefore major overhaul. Components receiveoverhaul as needed between site installations.Media specifications ensuring adequate media quality at all times. A physical/chemical andimpurity specifications list should be provided.See Page 11. Impurity specificationsare irrelevant in the case ofsand media as it meets a specific gradation, is mined, and washed.CONSTRUCTIONWhat role does the vendor take in design and construction.NSS provides the polymer, training, and technical consultation. Itis the responsibility of the operator with the assistance of thevendor of the equipment to design and install the system.How is the technology installed. How long does it take.Standard construction procedures. Entire system is generallyinstalled within a few days to two weeks.How are factors such as structural integrity, water tightness, and buoyancy addressed. “Off-the shelf” equipment with years ofexperience is used.What types of problems can occur/have occurred in designing and installing the technology. None. System components are well established in the industry.How are potential problems diagnosed and corrected, and by whom.Monitoring of turbidity, pH, and filter backwash frequency.Problems are corrected by the site operator.If problems go uncorrected, how does this affect the technology’s effectiveness.NA. Operator on site at all times. If problem requires corrections,system is shut down. Holding pond stores water in the interim.How available is the technology (e.g., where do the major components come from and howmuch lead time is needed).“Off-the-shelf” equipment is used and therefore lead time is not anissue. Replacement parts are available within hours.COSTS ...See Page 40.OPERATION AND MAINTENANCEDescribe the level of training personnel shallhave to operate and maintain the technology?Who provides the training, is a certification available.NSS provides training. Each operator receives on-site, on-handstraining for one year before being certified as an operator.Describe how operation and maintenance personnel are supervised. By immediate superior who conducts weekly operation check.How are inspections performed and how often. By operator. Occurs essentially continuous each operating period.How do you tell know when maintenance will beneeded, i.e., what is the "trigger." Whenthe frequency of filter backwash is above the norm.How is maintenance performed. Standardindustrial procedures for each component.Are all maintenance areas accessible by peopleand equipment. Are special equipment ormethods needed for access? Any confined space entry areas.Yes, no confined space entry.34TABLE 7 SUMMARY DISCUSSION OF OTHER FACTORS (continued)FACTORDISCUSSIONWhat is the estimated maintenance frequency and on what information/tests do you base thisestimated maintenance frequency.Varies with each component. pHand turbidity meters calibratedeach operating period and twice annually by manufacturer.What maintenance equipment and materials are required. System element is disassembled and cleaned.Does the vendor offer a maintenance service contract? If so, provide cost information,including mobilization, equipment rental, mileage, solids/spent media disposal, etc.Maintenance is the responsibilityof the site operator and theprovider of the equipment, not NSS.How are solids/spent media classified (waste type) and disposed. Inorganic sediment. Disposed to the cell in the holding basin.Can the technology be damaged due to delayedmaintenance, and if so, how is it restored.Excessive loading and failure to properly backwash can result intotal clogging of the sand,requiring replacement.How many years have you been in business?If vendor goes out of business or product modelchanges, how/where will facility owner find needed parts, materials, and service.Vendors, not NSS, provides equipment. Components, widely usedfor other applications,are readily available.RELIABILITYWhat factors can cause the technology to notperform as designed. Highinfluent turbidity, runoff ofsome soil stabilizer agents.Can the technology add, transform,or release accumulated pollutants.The system may discharge residual chitosan but as yet has notbeen observed above the detection limit.Is the technology sensitive to heavy or finesediment loadings—is pretreatment required. Yes, asindicated in this report.How is underperformance diagnosed and treated. Monitoring ofeffluent pH and turbidity, and backwash frequency.What is the warranty. Provider of equipment provides the warranty.What initial/ongoing user support is provided.Does the vendor charge for support.NSS gives technical advice if requested. Equipment vendorresponsible for advising site contractor.ROBUSTNESSHow sensitive is the technology’s performance tonot being maintained correctly. Sensitive.How are problems diagnosed and treated.Monitoring of effluent pH and turbidity, filter pressure differenttial; frequency of automatic backwash and recycle. See Page 21.Are system components durable, expected to last a reasonable length of time before repair. YesOTHER FACTORSDoes the technology provide benefits or present challenges in other ...areas, such as groundwater recharge, thermal effects,habitat creation, aesthetics, vectors, safety, communityacceptance, recreational use, andefficacy on redevelopment sites.The technology is used only temporarily and therefore theseaspects do not apply.Not to be released without written approval by NSS 35 

### Cost

The TAPE (Ecology, 2003a) asks for the following information.

• Installation-removal, operation and Lease (if applicable) costs: Base the cost analysis on

the test results.



### • Indicate approximate seasonal system capital/operating costs for flow-through system models on a “design cfs treated basis” (not p er cfs hydraulic capacity), or a dollar per TSS removed and/or turbidity reduced basis, using typical stormwater TSS concentrations (see earlier footnote). Batch treatment costs should be determined based on volume treated, gallon or cubic foot.



### The following is an analysis of the fixed a nd variable costs associated with operating a chitosan-enhanced sand filtration system including pretreatment. All assumptions are listed. The cost analysis was prepared by Natural Site Solutions.

Assumptions for a 240,000 gallon per day facility

Sand Filter (48” dia., 4-pod sy stem) $3,000/month Sand (#30 grade crushed silica) + under rock $1,000/once only Mobilization cost $500/once only Demobilization cost $500/once only

Chitosan $9.00/10,000 gallons treated at 1 ppm $27.00/10,000 gallons treated at 3 ppm Diesel cost $1.75 per gal with an average consumption of 6 gph 20,000-gal pretreatment tank $900/month Mobilization cost $500/once only Demobilization cost $500/once only Pumps (2- 30 HP electric submersible w/ float level controllers, combined cost) $2,400/month Secondary metering pump for pretreatment $1,000/once only Controller Module (Brain Box) $3,500/month Mobilization/Demobilization $500/once only 100 KVA Generator (diesel powered) $2,000/month System assembly (40 hours @ $50/hr) $2,000/once only System disassembly (20 hours @ $50/hr) $1,000/once only System operator $65/hr System performance data monitoring and reporting costs 20 hrs/month @$75 $1,500/month



### Once only costs excluding site preparation

Sand Filter Mobilization cost + sand filling $1000 Demobilization cost $500

Pretreatment Tank Mobilization cost $500 Demobilization cost $500 Secondary metering pump for pretreatment $1,000 Controller Module (Brain Box) Mobilization/Demobilization $500 System assembly (40 hours @ $50/hr) $2,000 System disassembly (20 hours @ $50/hr) $1,000 Total $7,000Not to be released without written approval by NSS 36 

### Reoccurring Monthly Costs

Sand Filter (48” dia., 4-pod system au to backwash 400 gpm output) $3,000 20,000-gal pretreatment tank $900 Pumps (2- 30 HP electric submersible w/ float level controllers) $2,400 100 KVA Generator (diesel powered) $2,000 Controller Module (Brain Box) $3,500 Removal and disposal of sediments from se ttling cell 20 hrs @$150/hr plus fee $3,500 System performance data monitoring and reporting costs 20 hrs/mo @$75 $1,500 Total $16,300



### Estimating Total Monthly System Costs for Three Scenarios

The cost to treat is directly related to the quantity of water treated. Three scenarios are provided in Table 8, differing by the level of use.

• Light use: defined as operating the system for four hours per day for ten days per month (total 960,000 gallons treated per month)

• Moderate use: defined as operating the system six hours per day 15 days per month (total 2,160,000 gallons treated per month)

• Heavy use: defined as operating the system ten hours per day 20 day per month (total 4,800,000 gallons treated per month)

As an average assumption a chitosan acetate dos e rate at 2 mg/L is used, 1.5 mg/L for pretreatment and 0.5 mg/L for filtration. H eavy use is most often associated with continuous dewatering activities, dredging, a nd unusually heavy and prolonged periods of precipitation.

TABLE 8 THREE COST SCENARIOS

Scenario One - Light use



## Variable Cost Element Duration Cost
Operating Labor @ $65/hr Reasonably expect 50 hours $3,250 Fuel consumption (diesel) 40 hours @ 6 gph $420 Chitosan consumption 2 mg/L based on previous assumption $1,760 System performance data monitoring and reporting 10 hrs/mo @$75 $750

Senior operator project oversight Assume 2 site visits (1 hour each)@$120/hr $240 Meeting with regulatory pe rsonnel 2 hours @ $120.hr $240
Total Variable Costs $6,660

Hard Cost Elements $13,300

Total Hard & Variable Costs $19,960 Total cost of $19,960.00 divided by the amount of water treated gives a cost per gallon of $0.021.Not to be released without written approval by NSS 37 

### TABLE 8 (Continued)

Scenario Two – moderate use

Variable Cost Element Duration Cost Operating Labor @ $65/hr Reasonably expect 105 hours $6825 Fuel consumption (diesel) 90 hours @ 6 gph $945 Chitosan consumption 2 mg/L based on previous assumption $3,956 System performance data monitoring and reporting 15 hrs/mo @$75 $1,125

Senior operator project oversight Assume 2 site visits (1 hour each)@$120/hr $240 Meeting with regulatory pe rsonnel 2 hours @ $120.hr $240
Total Variable Costs $13,331

Hard Cost Elements $13,300

Total Hard & Variable Costs $26,631 Total cost of $26,631.00 divided by the total amount of water treated gives a cost per gallon of $0.012.



### Scenario Three - Heavy use

Variable Cost Element Duration Cost Operating Labor @ $65/hr Reasonably expect 240 hours $15,600 Fuel consumption (diesel) 200 hours @ 6 gph $2,100 Chitosan consumption 2 mg/L based on previous assumption $8,800 System performance data monitoring and reporting 20 hrs/mo @$75 $1,500

Senior operator project oversight Assume 4 site visits (2 hour each)@$120/hr $960 Meeting with regulatory pe rsonnel 2 hours @ $120.hr $240
Total Variable Costs $28,984

Hard Cost Elements $13,300

Total Hard & Variable Costs $42,284 Total cost of $42,284.00 divided by the total amount of water treated gives a cost per gallon of water
$0.009.



### REFERENCES

AMTEST, 2005, Residual chitosan test procedure.

ECO-Endeavors, 2004 (June 2), Rainbow trout (Oncorhynchus mykiss) Chronic Toxicity Screening of Stormwater Treated by Chito san Enhanced Sand Filtration Flow-Through System-Redmond, Washington, for Natural Site Solutions

, Redmond, Washington.

Ecology, 2001, Stormwater Management Manual for western Washington

.

Ecology (Department), 2003a (September), Guidance for Evaluating Emerging Stormwater Treatment Technologies at Construction Sites, Chemical Technology Assessment Protocol – Ecology (CTAPE), Olympia, Washington.

Ecology (Department), 2003b (October 27), Engineering Summary, Use Designations For Chitosan-Enhanced Sand Filtration, Olympia, Washington.Not to be released without written approval by NSS 38 

### Ecology (Department), 2004 (February 26, updated August 18), Engineering Summary, Use Designations For Chitosan-Enhanced Sand Filtration, Olympia, Washington.

MacPherson, J., 2005, personal communication.

MacPherson, J., 2006, memo to Consultant on chitosan pretreatment, February 27, 2006.

Minton, G.R., and A. Benedict, 1999, Polymer-assi sted clarification of stormwater from construction sites, Resource Planning Associ ates, for the City of Redmond, Washington.

Natural Site Solutions, LLC (NSS), 2003, Chitosan-Enhanced Sand Filtration System – Operation and Maintenance Manual, Redmond, Washington.

NSS, 2004a (January 12), Quality Assurance Project Plan, Chitosan-Enhanced Sand Filtration, Redmond, Washington.

NSS, 2004b (June 24), Application for General Use Designation: Chitosan-Enhanced

Sand Filtration Stormwater Treat ment Technology, Redmond, Washington.

Nautilus Environmental LLC, 2004 (September 30), Toxicity testing for Liqui-Floc, Final Report, for Natural Site Solutions

, Redmond, Washington.Not to be released without written approval by NSS 39 

### APPENDIX A

RECOMMENDED SPECIFICATIONS FOR PERMITTED FACILITIES

CHITOSAN-ENHANCED SAND FILTRATION TECHNOLOGY

FOR FLOW-THROUGH OPERATIONS

The following specifications identify elements of the SWPPP for each construction site.

1. Stormwater discharges from the CESF-FT system shall not cause or contribute to receiving surface water quality violations.

2. If the discharge from the CESF-FT system will be to a fish spawning area in the stream an approval for that discharge must be obt ained from the responsible Ecology Regional

Office.

3. The CESF-FT facility contractor shall guarantee that CESF-FT system, when used as directed, will not produce treated water which exhibits aquatic toxicity caused by chitosan added as a treatment agent.

4. The CESF-FT system shall only be operated by a trained technician certified through an approved training program that includes classroom and field instruction. Training to be provided by a qualified trainer. The tec hnician shall have the following Minimum Training Requirements.

• Minimum 1-year experience with, and sound working knowledge of, high pressure sand filter systems.

• Experience deploying and troubleshooti ng pressurized water pumping and piping
systems.

• Fundamental knowledge of stormwater di scharge regulations for applicable region/locale.

• Fundamental knowledge of stormwater quality testing procedures and methods for parameters applicable to the region/locale.(note: class and field content is specified but not included here)

5. The facility shall employ a minimum of three (3) sand filter pods to ensure adequate backwashing capacity. The backwash slurry fro m the sand filters must be discharged to a holding cell that is separate from the tempor ary storage cell for the incoming turbid

stormwater. The overflow from the backwash slurry holding cell can overflow into the holding basin for the turbid stormwater.

6. The operating flow rate shall not exceed 15 GPM per square foot of sand bed filtration

area.

7. The filtration media shall be pre-washed #30 crushed silica sand with a mean effective sand size of 0.34 mm and a filtration quality mesh of 230-400. Minimum sand bed depth

shall be 18-inches underlain with a minimum of 6-inches of 1-inch crushed rock.

8. The CESF-FT system shall include a flow-regulating valve on the input to and output of the sand filter. These regulating valves will reduce the maximum output of the pump as required and facilitate proper backwash.Not to be released without written approval by NSS 40 9. Water quality influent and effluent shall be continuously monitored and recorded for flow, pH and turbidity.

10. The CESF-FT system treated water output sha ll be equipped with an automatic integrated turbidity and pH sensors capable of shutting the system down if output turbidity or pH exceed preset values. An audible alarm and warning light shall be installed on the treatment system to alert the operator in the event of a system failure.

11. The discharge flow rate shall be metered and recorded.

12. The CESF-FT control system (including metering pump, chitosan storage and instrumentation) shall be completely enclo sed in a secure structure with locking door. The chitosan liquid concentrate tank, mete ring pump and tubing shall have secondary containment. The metering pump discharge tubing shall have an anti-siphon valve.

13. Chitosan injection shall be performed with an LMI-brand C77, high viscosity pump head, electric metering pump, or equivalent. The metering pump must be calibrated within 15 minutes of the beginning of each operating peri od. It is to be recalibrated when a significant change occurs in either flow or influent turbidity.

14. The maximum suspended sediment (expressed as turbidity) of the influent water entering the holding basin(s) should not exceed 600 NTU. Source control procedures shall be implemented to the maximum extent feasible to minimize the need fo r the use of chitosan acetate for the pretreatment of stormwater entering the holding basin.

15. The chitosan acetate dose rate for water ente ring the filters shall not exceed 1 mg/L (as chitosan acetate by weight). All calibration resu lts must be recorded simultaneously with the flow rates and the records kept on site. •

16. A variance can be sought to use additi onal chitosan acetate for pretreatment of stormwater entering the holding basin. It shall be demonstrated, however, that source control BMPs are unable to meet the pretreatment requirement of 600 NTU.

17. Only those forms of chitosan acetate approved by the Department of Ecology shall be

used.

18. Jar tests will be conducted, as needed, to confirm the dosage level of chitosan acetate.

19. The SWPPP is to include a field procedure, accepted by the Department of Ecology, for detecting a residual of chitosan in the discharge, sensitive to 0.2 mg/L.

20. .The discharge from the sand filters shall be maintained below 0.2 ppm residual chitosan at all times. A discrete grab sample of a homogeneous sand filter discharge must be collected and analyzed within 30 minutes of th e onset of operation. The test is to be repeated whenever there is a change in do sage, or a significant change in influent turbidity of flow rate.

21. An operation and maintenance manual sh all be prepared and available on-site.

22. A contingency plan to immediately correct the problem must be included in each SWPPP and Operation and Maintenance manual in th e event that the above specified residual chitosan is exceeded, exhibits aquatic toxic ity based on approved bioassay testing, or when the CESF system fails to meet discharge quality requirements.

23. During the planning (SWPPP preparation, etc.) of a project the adverse potential impact on chitosan efficiency of the use of anionic polymers for soil blanketing and stability,

will be evaluated.Not to be released without written approval by NSS 41 24. An Operating Period Information Form shall be completed for each operating period. The recommended format is included with these specifications. At a minimum, the form

shall include the following information.

• A record of each recycle event

• A record of each backwash event

• Actions taken when a recycle event occurs

• Actions taken when excessive backwashing is occurring

• A record of pump calibration

• A record of chitosan use for pretreatment

• A record of chitosan dosage imme diately prior to the filters

• A record of test results for ch itosan residual in the effluent

The supervisor of the operator shall examin e weekly the forms completed the previous week. The supervisor shall sign each daily fo rm indicating it has been reviewed, and also

document actions he or she has taken in r esponse to any abnormal conditions observed by the operator.

25. At all construction sites, at the end of each operating period, a delegated responsible person shall record his/her assessment of the operational efficiency of the CESF process and all upsets, the sand filter discharge chito san concentrations and any other relevant observations that relate to CESF proper ope ration and must also certify the acceptability of the CESF discharge to surface water.

26. These stipulations supersede BMP C-250.Not to be released without written approval by NSS 42 

### APPENDIX B OPERATING PERIOD INFORMATION FORM


## CESF Treatment System Shift Log

Treatment Unit Startup Time Date Startup Totalizer Operator #1 Startup Flowrate Operator #2 Operator #3 Shutdown Time

Shutdown Totalizer

Total Gallons Treated

Initial System Checkout Chitosan Polymer

Level F 3⁄4 1⁄2 1⁄4

General System Integrity Grab Sample Confidence Checks

Influent Turbidity = Influent Turbidity Influent pH = Influent pH Effluent Turbidity = Effluent Turbidity Effluent pH = Effluent pH

pH & Turbidity Reading from Controller (4 sample measurements per shift 1 )

#1 Time: #2 Time: #3 Time #4 Time: pH Turbidity (NTU)

Residual Chitosan Test (15 min. & 4 hours after startup) Time Result - positive (>0.2 mg/L) / negative (<0.2 mg/L) Sample #1 Sample #2

Backwash Settings: Default time interval (minutes) Differential pressure (psid) Starup: If changed: If changed:

Notes/Observations:

Did recycle occur because the discharge quality did not meet discharge requirements? Give time,
duration and corrective action:

Operator comments : Acceptable / Unacceptable (circle one) Operator Signature :

1 For reporting purposes 4 pH and turbidity readings are n eeded per day. Because only one shift may be run, 4 readings are needed each shift. The pH and turbidity readings may be taken directly from the digital

readout on the Hach controllers.Not to be released without written approval by NSS 43 

### APPENDIX C EXAMPLES OF COMPLETED DAILY LOG FORMSNot to be released without written approval by NSS 44Not to be released without written approval by NSS 45