HILL ENGINEERING, INC. 

8 CIBSON STREET NORTH EAST, PENNSYLVANIA 16428 

(814) 725-8659 FAX: (814) 725-3867 

Mt:. Stephen G. Copeland 

Office of Municipal Assistance (3WP41 ) 

U. S. Environmental Protection Agency 

1650 r\ rch Street 

Philadelphia, PA 19103-2029 

RE,-,.....·· ~-

EPP .January 9.,2()1~ 

E . II/ 

" I' NPDtS t, ., (3\ .. "1 

NPDE:S ,CH , , 

Reference: Local Limits Analysis for Ridgway Borough 

NPDES No. PA0023213 

Ridgway Borough 

Elk County, Pennsylvania 

Dear Nlr. Copeland: 

'1 

!inclosed is the Ridgway Borough Local Limits Analysis for your review and approval, for 

the Ridgway Borough Pretreatment Program. 

It is currently the intent of the Borough to implement the results of this analysis on a load 

allocation basis, once the results of the model are approved. 

If you have any questions or comments, please call me. 

EncloSLu:es 

cc: Dave Balog, PA DEP (w/enclosure) 

Paul McCurdy (wi enclosure) 

Sincerely, 

~~'NC 

Richard B. Dodds 
RIDGWAY BOROUGH 

ELK COUNTY, PENNSYL VANIA 

NPDES PERMIT NO. PA0023213 

PRETREATMENT PROGRAM 

LOCAL LIMITS 

PREPARED BY: 

HILL ENGINEERING, INC. 

8 GIBSON STREET 

NORTH EAST, PA 16428 

JANUARY 2014 
RIDGWAY BOROUGH 

LOCAL LIMITS 

TABLE OF CONTENTS 

SECTION NO. 

I. Treatment Plant Description 

II. NPDES Permit Effluent Limits 

III. Regulated Pollutants 

IV. Sampling and Data Collection 

V. Model Parameters 

VI. Sludge Disposal 

VII. Local Limits Summary 

VIII. Proposed Allocation Methodology 

APPENDICES 

Appendix A 

Appendix A"I - EPA Excel Spreadsheet ofPOTW Monitoring Data 

Appendix A"2 - POTW Influent Sampling Data 

Appendix A"3 - POTW Effluent Sampling Data 

Appendix A-4 - Domestic Wastewater Quality Sampling Data 

Appendix B EPA Local Limits Calculation Spreadsheet 

PAGE 

1 

1 

2 

2 

2 

3 

4 

4 
LOCAL LIMITS SAMPLING PLAN 

NPDES PERMIT NO. PA 0023213 

RIDGWAY BOROUGH 

ELK COUNTY, PA 

I. Treatment Plant Description 

Ridgway Borough owns and operates a sewage treatment plant and collection system in 

Ridgway Borough, Elk County, PA. The Ridgway Borough Treatment Plant (RBTP) 

also serves portions of Ridgway Township. 

The treatment plant has a hydraulic design rate of 2.2 MGD as a maximum monthly 

average. The plant discharges to the Clarion River under PA Department of 

Environmental Protection (PA DEP) NPDES Permit No. PA0023213. 

The major components at the treatment plant consist of the following: Barscreen, Grit 

Chamber, Equalization Tank, Aeration Tanks, Clarifiers, Chlorination Feed System, 

Chlorine Contact Tank, Aerobic Digesters, and Belt Filter Press. 

II. NPDES Permit Limits 

The Borough's NPDES Permit No. PA 0023213 contains the following effluent 

limitations: 

Concentration (mglL) 

Monthly 

Parameter 

Mass Loading 

(lbs/day) 

Monthly 

Average Minimum Average Maximum 

CBODs 

TSS 

NH3-N 

pH (s.u.) 

Fecal Coliform 

(5/ 1-9/30) 

(I 0/1-4/30) 

Fluoride 

Copper 

Total Dissolved Solids 

Total Chlorine 

460 

550 

1,945 

2,035 

1.65 

76,299 

6.0 

25 

30 

108 

200 

2,000 

0.09 

0.5 

50 

60 

216 

9.0 

1,000 

10,000 

0.18 

1.6 

The permitted flow capacity of the treatment plants is 2.2 MGD. The flow rate for local 

limits analysis was 1.04 MGD based on the average annual flow rate for the 2007 through 

2011 period. 

I 
III. Regulated Pollutants 

Guidelines from EPA recommend regulating the following pollutantsl

: 

Arsenic Lead Cyanide 

Cadmium Mercury Selenium 

Chromium Nickel Hex. Chromium2 

Copper Silver Zinc 

The Borough intends to also regulate the following pollutants where its NPDES Permit 

also contains numerical limits: 

CBODs 

Ammonia 

Total Dissolved Solids 

Fluoride 

Total Suspended Solids 

In addition, the Borough also included the following pollutants into the Local Limits 

analysis, but they may not require regulation3

: 

Chloride 

Barium 

IV. SIGNIFICANT INDUSTRIAL USERS 

Sulfate 

Based on the reported information for four (4) of the SIUs tributary to the Borough's 

wastewater treatment facility NPDES application, their process discharge quantity is: 

Permittee 

Allegheny Coatings 

Metal Powder Coatings 

Diversified Coatings 

Ion Technologies 

gpd 

618 

35 

256 

843 

I The Borough does not intend to monitor or regulate molybdenum through the EPA Pretreatment Program since the 

basis for its control is limited to the Clean Sludge requirements associated with the land application ofbiosolids. 

Without land application requirements, the development of Local Limits for molybdenum is unnecessary since there 

are no federal or state discharge limits for this contaminant, nor are there inhibition values associated with this 

rarameter. 

PLEASE NOTE: Since virtually all the levels of Total Chromium were significantly lower than the LOD (50 ppb) 

available for Hexavalent Chromium, data for Total Chromium were used in replacement for Hexavalent Chromium 

values throughout the entire analysis. 

3 As stated in the approved Local Limits Monitoring Plan, the Borough is not including pollutants such as strontium, 

bromide, or specific radionuclides in this analysis since there are no known sOurces of these parameters in general 

domestic wastewater (the offset source of the analysis). In addition, there are also no inhibition values for these 

parameters in the published EPA guidance. 

2 
In addition, there is a fifth SIU, Alpha Sintered Metals, Inc., which has an approximate 

annual average industrial discharge quantity of 31 gpd. Also, based on the 2011 Annual 

Pretreatment Report, the treatment facility receives approximately 1,860 gpd for hauled 

in wastes from Chattanooga Labeling Company, 309 gpd of wastewater from GKN 

Sintered Metals, 508 gpd of municipal wastewater sludge, 870 gpd of septage, and an 

average of 13,589 gpd of hauled in gas industry brine waste. 

V. Sampling and Data Collection 

The Borough collected samples for ten (10) consecutive days at the following locations: 

POTW Influent 

POTW Effluent 

Domestic Sample Location 

The results of these samples were used, along with the results of previous influent and 

effluent sampling results from quarterly monitoring results from 2012 and part of20 13, 

to calculate removal rates4

• 

The samples for all pollutants was 24-hour composites, except cyanide which was four 

(4) grab samples over a 24-hour period. The sampling for POTW Influent and Effluent 

was 24-hour flow proportional. The domestic sampling in the sewer system was 24-hour 

time proportional as proposed in the approved sampling plan. 

An additional ten (10) sampling days were collected from the same domestic wastewater 

sampling location, on non-consecutive days, for a total of twenty (20) sampling events. 

VI. Model Parameters 

A. Model Inputs. 

Based on the 2011-12 flow monitoring data, the Borough's plant has an average 

flow of 1.04 mgd. Approximately 0.020 mgd of the flow is attributable to 

tributary industrial facilities, as discussed in Section IV of this documents. The 

results of the sampling for influent, effluent and domestic wastewater, were 

included in the spreadsheet under the "Monitoring Data" worksheet. 

B. Water Oualitv Criteria 

4 The 2011 data set was not utilized due to significant differences in detection levels and changes in influent 

sampling points that resulted in substantial differences in influent data characteristics. 

, Since hauled-in waste was not sampled separately, but were included in the influent sampling, the total flow from 

these sources were included into the existing industrial sources. 

3 
Ridgway Borough's NPDES permit limits were included in the spreadsheet model 

for CBOD, TSS, TDS, arrunonia-N, copper, and fluoride6 In addition, human 

health criteria values were also included. Since the DEP evaluated the discharge 

limits for the NPDES permit based on the states chronic and acute water quality 

criteria, these values were not include into the model. Chapter 93 instream 

concentration water quality limits for chloride and sulfate were assessed in Table 

4 of the spreadsheet 7

• 

C. Removal Rates 

Removal rates for the following parameters were based on actual data collected 

during this survey: 

Cadmium 

Lead 

Zinc 

TSS 

Chromium 

Nickel 

Ammonia 

Barium 

Copper 

Silver 

CBOD 

The removal rates for the above listed parameters are listed in Table 3 of the 

EP A's spreadsheet. 

Standard removal rates for activated sludge wastewater treatment facilities were 

assumed for the following parameters: 

Arsenic 

Chromium (VI) 

Cyanide 

Selenium 

Mercury 

In the event that there was no apparent removal rates shown during the survey and 

no standard removal rates reported in EPA guidance, no (zero) removal 

percentage was assumed. Specifically, zero (0) percent removal was assumed for: 

Chloride 

TDS 

Sulfate Flouride 

Based on Option 1, in Table 5-1 of the manual, all data that was below the level 

of detection was considered to be of y, the value of the level of detection. 

The values for primary removal efficiencies (Rprim) used in Table 8 of the 

accompanying EPA Local Limits spreadsheet were the median values for each 

respective parameter reported in the table entitled "Priority Pollutant Removal 

Efficiencies (%) Through Primary Treatment" on page R-I of the EPA's "Local 

Limits Development Guidance" manual. 

6 Although there is no concentration limit for fluoride, ammonia-N, or TDS, a concentration value was derived by 

dividing the respective monthly mass load limit by the 1.04 mgd average flow. 

, Table 4 of the EPA spreadsheet was used for the Chapter 93 evaluation since it is based on Q,.IO flows. 

4 
D. Inhibition Values 

The inhibition values for activated sludge were assumed to be the median values 

listed in the EPA Guidance Manual. Inhibition values are shown on Table 8. 

VII. Sludge Disposal 

Ridgway Borough currently disposes of all of its sludge through landfill disposal. 

Since Ridgway Borough does not currently utilize land application of sludge and 

continues to have no interest in instituting the land application program, sludge disposal 

land application has not been considered as a factor in determining local limits. As such, 

the land application ceiling and cumulative application rates from 40 CFR Part 503.13 

were not used in determining the local limits reported in this document. 

VIII. Local Limits Summary 

The local limits were determined using the EPA computer spreadsheet model on Excel 

available for download during 2013. The local limit utilized was the most restrictive of 

the values calculated based on NPDES Permit, human health criteria, and activated 

sludge inhibition. Safety and expansion factors of 10% were assumed for all pollutants, 

with the exception ofTSS, ammonia, CBODj , and TDS, which were assumed at 5%. 

Allowable growth rates of 5 percent were assumed for all parameters. 

The proposed "Allowable Industrial Loading(s)" are summarized in Table 15 of the 

printout of the EPA Excel spreadsheet. 

IX. Proposed Allocation Methodology 

The local limits will be allocated to industrial users in accordance with EPA guidelines. 

Currently, the Borough's local limits are allocated based on the mass proportional 

method whereby the allowable loadipg is allocated to the existing users based on current 

loadings. As is currently the case, the mass proportional method of allocation will be 

subject to existing or future agreements with industries regarding capacity utilization of 

the POTW. Local limits will be superseded if categorical limits are more stringent. 

5 
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