ESTACADA And NPDES WASTEWATER DISCHARGE PERMIT …

ESTACADA FACT SHEET

And NPDES WASTEWATER DISCHARGE PERMIT EVALUATION

Oregon Department of Environmental Quality Northwest Region - Portland Office

2020 SW 4th Ave, Suite 400, Portland, OR 97201 Telephone: (503) 229-5263 & FAX 503 229-6957

File Number; 27866

Permit Number: 101542

Permit Application Number: 973277

Permit Application Date: March 26,2008

Permittee: City of Estacada PO Box 958 Estacada, OR 97023

Source Contact: Dave Stone Wastewater Treatment Facility Supervisor Telephone Number: (503)630-8286

Proposed Action: Renewal of aNational Pollutant Discharge Elimination System (NPDES) wastewater discharge permit.

Receiving Stream: Clackamas River (River Mile 23.6)

Stream Location: Clackamas County

Source Location: Adjacent to Timber Park and Hwy 211/224 Estacada, OR 97023

Permit Writer: Garry L. Sage, EIT WQ-NWR- Source Control Section Telephone Number: (503) 229-5690

Source Category: Minor Domestic

Treatment System Class: Level HI

Collection System Class: Level II

City of Estacada Evaluation Report Page 2 of 19

TABLE OF CONTENTS PAGE

Proposed Changes to This Permit 4 Facility Background 4 Introduction 4 Facility Description 4 Biosolids Management and Utilization 5 Inflow and Infiltration (I&I) 6 Pretreatment 6 Pollutants Discharged 6 Beneficial use Analysis 6 Receiving Stream Water Quality (WQ) Impacts 7 Mixing Zone Analysis 7 TMDL Discharge Limits for Temperature, Bacteria, and Mercury 7

TMDL -• Temperature 7 TMDL-Bacteria 9 TMDL-Mercury (Hg) 10

Chlorine Toxicity. 10 Ammonia Toxicity 10 Dissolved Oxygen Reduction 10 Groundwater 1 pH 1 Permit Histoiy 1 Anti-degradation Review 1 Compliance History 1 Permit Discussion 12 Face Page 12

Schedule A - Waste Discharge limitations 12 Treated Effluent Discharged at Outfall 001 12 BOD5 and TSS concentration and mass limits: 12 Bacteria 13 pH 14 Chlorine Residual 14 Ammonia 15 BOD5 and TSS Percent Removal Efficiency 15 Mixing Zone and Zone of Immediate Dilution 15 Groundwater Protection 16

Schedule B - Minimum Monitoring and Reporting Requirements 16 Influent Sampling 16 Effluent Sampling for Outfall 001 16 Biosolids Report Submittal 17 Inflow and Infiltration Report Submittal 17


PAGE Schedule C - Compliance Schedules and Conditions 17

Schedule D - Special Conditions 17 Biosolids Management 17 Changes in Biosolids Standards 18 Operator Certification 18 Groundwater 18 Notification 18

Schedule E - Pretreatment Program 18

Schedule F - General Conditions 18


Proposed Changes to This Permit

Schedule-A 1) Lower summer chlorine daily maximum and monthly average limits, 2) Add summer ammonia daily maximum and monthly average limits, 3) Delete summer thermal load limit requirement/calculations, 4) Lower winter chlorine monthly average limit, 5) Revise pH lower limit, 6) Revise mixing zone (MZ) description to comply with findings of DEQ's MZ study, and 7) Report summer worst-case zone of initial dilution (ZID) = 5 and MZ dilution = 6 (Note-2).

Schedule-B 1) Eliminate summer temperature monitoring of Clackamas River.

Schedule-C 1) Remove Schedule-C (completed conditions or condition moved to Schedule-D).

Schedule-D 1) NO CHANGES PROPOSED.

Schedule-F 1) Schedule-F was extensively revised to comply with recent EPA Region-10 mandated

changes. 2) Clarifies event reporting for permit violations and wastewater overflows.

Facilitv Background

Introduction The City of Estacada operates a wastewater treatment facility located on the east bank of River Mill Reservoir (created by River Mill Dam) in the City of Estacada (Attachment-1). Wastewater (sewage) is treated and discharged to the Clackamas River year-around in accordance with National Pollutant Discharge Elimination System (NPDES) Permit number 101542. The current permit for this facility was issued on September 30,2003 and expired on August 31,2008.

The Department received a permit renewal application on March 26, 2008. A renewal permit is necessaiy to discharge to state waters pursuant to provisions of Oregon Revised Statutes (ORS) 468B.050 and the Federal Clean Water Act. The Department proposes to renew the permit. Currently the permit is under administrative continuation pending its renewal.

Facilitv Description Estacada's wastewater treatment facility was upgraded during Year 2008. Facility additions/replacements include: headworks screen/conveyor/compactor, influent composite sampler, two blowers to improve aeration, two trickling filter pumps, and generator/electrical panel upgrades.


The engineer who designed the facility determined the design average dry weather flow (ADWF). It is the estimated maximum daily average dry weather flow (May 1 to October 31) at which the design engineer expects the treatment facility to consistently meet all effluent limits. Dry weather flows do not include the high levels of infiltration and inflow (I&I) that are associated with Oregon winters on the west side of the Cascade Mountains. Therefore, the design ADWF is used mostly to estimate how much treatment capacity there is for organic loads. For this facility, the design ADWF = 0.54 million gallons per day (MGD). The current actual average dry weather flow (May 1 to October 31) for Year-2009 was 0.297 MGD (Attachment-2). The peak day diy weather flow over the interval May 2008 through May 2010 was 1.370 MGD (May 2008). Currently, this facility operates at 55% of its organic treatment capacity.

Last winter season (Years 2009-2010) the average facility flow was 0.696 mgd and the peak daily flow was 2.23 MGD. For this facility, the design average wet weather flow (AWWF) is 1.55 mgd, and the design peak wet weather flow (PWWF) is 4.50 MGD. Design wet weather flows represent available winter season treatment capacity at this facility. Based on recent treatment performance, this facility is operating at 45% of its winter season average capacity. See the section below on I&I for additional discussion of winter flows and hydraulic capacity.

This facility uses an activated sludge treatment process. Current process design criteria; facility lay-out, instrumentation, and hydraulic profile are included in Attachment-3. Wastewater from the sanitary collection system is transported to the facility's headworks for screening and grit removal. Wastewater then flows to two primary clarifiers for initial solids settling. Decant from the primary clarifiers is pumped to a trickling filter where it is aerated and nutrients are removed. Trickling filter effluent flows to a solids contact tank for additional aeration and nutrient removal. Two secondary clarifiers provide final solids settling. Clarifier decant is filtered, disinfected with sodium hypochlorite, dechlorinated, and discharged through an 18-inch diameter outfall pipe to the Clackamas River at river mile (RM) 23.6.

Biosolids Management and Utilization The permittee's Biosolids Management Plan (BMP) was last updated in 2003. The City has prepared a revised BMP for DEQ's review. The updated BMP will be put out on Public Notice with the renewal permit, and be available for review at DEQ's Northwest Region Office.

Proposed permit Schedule D, Item No. 1 requires that all biosolids must be managed in accordance with the current DEQ approved BMP, and DEQ site authorization letters. Any changes in biosolids management activities that significantly differ from operations specified under the approved plan required prior written approval of the DEQ. All new biosolids application sites must meet the site selection criteria set forth in OAR 340-050-0070, and must be located within DEQ approved application sites in Clackamas County. No new Public Notice is required for continued use of the currently approved sites. Property owners adjacent to any newly approved application sites shall be notified, in writing or by any method approved by DEQ, of the proposed activity prior to the start of application. Proposed new application sites that are deemed by the DEQ to be sensitive with respect to residential housing, runoff potential, or threat to groundwater are subject to public comment in accordance with OAR 340-050-0030.


The permittee produces and land applies at beneficial use rates approximately 60,000 gallons of alkaline stabilized biosolids per year to DEQ approved properties near the City of Estacada. The facility has a 70,000 gallon aerobic digester, and there are two asphalt lined sludge storage ponds with a combined storage capacity of 140,000 gallons. Information in DEQ files and reports from City staff indicate that the two sludge ponds do not have enough storage capacity to hold biosolids for the entire winter season. Decant flows from the sludge digester and biosolids ponds contribute to BOD5 and TSS loading increases on the facility's treatment units and may cause violations of both parameters under certain conditions. Some additional sludge storage capacity, treatment, or handling strategy appears necessaiy to correct capacity deficiencies at the facility.

The renewal permit requires monthly calculation of mean cell residence time, and annual sampling of sludge for total solids, volatile solids, nutrients, pH, and sludge metals content. A record of biosolids sold or given away must be maintained. The quantity and type of alkaline product used to stabilize biosolids and treatment conditions, i.e. pH, temperature, and contact times to comply with vector attraction and pathogen reduction requirements must be reported. The permit also requires the submittal of an annual report.

Inflow and Infiltration (I&I) Based on an evaluation of summer and winter period flows and the peak flow, I&I is not a major problem for the Permittee. The Permittee uses a continuous program of inspection and repair of its collection system components to control the growth of I&I.

Pretreatment Based on Estacada's population and lack of significant industrial sources, a pretreatment program is not needed at this time to protect influent quality.

Pollutants Discharged The current permit allows the City of Estacada to discharge treated effluent from the wastewater treatment plant at Outfall 001 year-around. The current permit sets limits on the following pollutants: Five-day biochemical oxygen demand (BOD5), total suspended solids (TSS), E. coli bacteria, chlorine residual, pH, and pollutant removal efficiency. The proposed permit will regulate the same pollutants; however chlorine and pH limits are more stringent. Additionally, ammonia limits are added for summer season discharges. These proposed limit changes result from a DEQ mixing zone (MZ) study (September 10, 2008) that found summer season dilutions in the zone of immediate dilution (ZID) and MZ to be less than previously calculated. Lower ZID and MZ dilutions increase the potential for effluent chlorine, ammonia, and pl-l toxicity.

Beneficial use Analysis The designated beneficial uses ofthe receiving stream are listed under Oregon Administrative Rule (OAR), Chapter 340, Division 041, Table 340A (Attachments, Designated Beneficial Uses Willamette Basin. Beneficial uses include: public and private domestic water supply, industrial water supply, irrigation, livestock watering, fish & aquatic life, wildlife and hunting, fishing, boating, water contact recreation, aesthetic quality, and hydro power. Division 041, Figures 340A and 340B provide Fish Use Designations, and Salmon and Steelhead Spawning Use Designations, respectively (Attachment-5). Estacada's outfall discharges to core cold-water habitat (year-around)


and is designated for salmon and steelhead spawning use (September 1 - June 15).

Receiving Stream Water Quality (WQ) Impacts

Mixing Zone Analysis On September 10, 2008 DEQ completed a MZ study for Estacada's Outfall 001 that discharges to the River Mill Reservoir behind River Mill Dam. DEQ's MZ study focused on worst-case, summer season conditions in the Clackamas River; i.e. the 7-day average low-flow with a reoccurrence interval of 10-years (7Q10 low-flow). Conductivity measurements were taken to estimate dilution in the ZID and the MZ. Based on the stream conductivity study, worst-case dilution at 7Q10 low-flow was determined to be approximately 5J) at the ZID boundary and 6J0 at the MZ boundary (DEQ MZ report, April 15, 2009). Limits in the current permit (Schedule-A, Note #1) are based on a summer season ZID dilution = 6S and a MZ dilution = 18.0. Given DEQ's recent MZ study, proposed Schedule-A permit limits were adjusted to account for decreased ZID and MZ dilutions. Winter season dilutions listed in the current permit (Schedule-A, Note #1) are carried forward to the proposed renewal permit (Schedule-A, Note #2).

TMDL Discharge Limits for Temperature, Bacteria, and Mercury The City of Estacada's wastewater treatment facility discharges effluent to the Clackamas River. The Clackamas River and its tributaries comprise a subbasin of the main stem Willamette River. Segments of the Willamette River and the Clackamas Subbasin are water quality limited for temperature and bacteria during all or part ofthe year. Total maximum daily load (TMDL) limits for temperature and bacteria were established to correct these water quality problems. The Willamette TMDL sets discharge limits for point and non-point sources to reduce and control temperature and bacteria violations. Temperature and bacteria limits that comply with the Willamette River, Clackamas Subbasin TMDL are proposed for this permit.

Mercury (Hg) contamination is discussed in the Willamette Basin TMDL; however, specific source reductions for Hg are not listed at this time. Each source must comply with the toxics control criteria listed in DEQ's Internal Management Directive (IMD) for Reasonable Potential Analysis for Toxic Pollutants. For Estacada with a design ADWF < 1 MGD, the only toxics identified for reasonable potential analysis (RPA) are ammonia and chlorine. Estacada has no industrial sources that contribute toxics to its sanitary collection/treatment system.

TMDL - Temperature TMDL temperature limits apply from Clackamas RM 23.0 downstream to its confluence with the Willamette River (Willamette Basin, TMDL: Clackamas Subbasin, P. 6-4). Points upstream of RM 23.0 must not contribute to downstream warming of TMDL designated river reaches. The Clackamas Subbasin Temperature TMDL (Table, P. 6-16) states:

Wasteload Allocations (NPDES Point Sources): Allowable heat load based on achieving no greater than a 0.3 °C temperature increase from all sources at the point of maximum impact. This is achieved by limiting stream temperature increases from individual point sources to 0.075 °C. This may also be expressed as a limitation of 0.3 °C increase in 25% of the 7Q10 stream flow. Where multiple point sources discharge to a single receiving


' stream the accumulated heat increase for point sources is limited to 0.2 °C.

OAR Chapter 340, Division 041, Table 340A lists the Clackamas River in the vicinity of Estacada's outfall as "core cold-water habitat." A 16.0 °C temperature criterion applies during times and at locations of core cold water habitat identification (OAR 340-041-0028). Table 340B, "Salmon and Steelhead Spawning use Designations," also applies to this discharge for summer season (September 1-October 31) where the temperature criterion is 13 °C (OAR 340-041-0028). The Department used its standard water quality (WQ) model, the Thermal Calculator spread sheet, to estimate temperature impacts associated with summer season effluent discharges at Outfall 001 (Attachment^). Thermal Calculator results were obtained for both temperature criteria (13.0 °C and 16.0 °C). Each spread sheet run used the 7Q10 summer, low-flow for the Clackamas River at Estacada [595 cubic feet per second (CFS)]; Estacada's treatment facility design ADWF = 0.54 MGD; and the highest 7-day average, summer effluent temperature = 24.6 °C (May 1 -October 31). Both modeling runs produced a "No Reasonable Potential" for a temperature violation using 25% of the river cross-section for mixing (corresponds to mixing with a river flow = 148.8 CFS). Spread sheet results were 13.06 °C and 16.05 °C. When these values are adjusted for full stream mixing, they are 13.015 °C and 16.013 °C, respectively. Both results comply fully with the full stream TMDL limit (0.075 °C) discussed above. The Estacada discharge has no significant impact on downstream temperature during the critical summer season. No beneficial uses are impaired for cold water habitat or for spawning.

Thermal Plume ̂ Requirements Oregon Administrative Rule (OAR) Chapter 340, Division 041 lists temperature control requirements for effluent discharges to waters ofthe State. The proposed Estacada renewal permit must comply with the following "Thermal Plume" language in OAR 340-041-0053.

(2) (d) Temperature Thermal Plume Limitations. Temperature mixing zones and effluent limits authorized under 340-041-0028 (12) (b) will be established to prevent or minimize the following adverse effects to salmonids inside the mixing zone:

(A) Impairment of an active saimonid spawning area where spawning redds are located or likely to be located. This adverse effect is prevented or minimized by limiting potential fish exposure to temperatures of 13 degrees Celsius (55.4 Fahrenheit) or more for salmon and steelhead, and 9 degrees Celsius (48 degrees Fahrenheit) or more for bull trout.

The current and proposed permits require the permittee to collect summer season, maximum effluent temperature data (renewalpermit, Schedule -B, l.d). The Outfall 001 discharge, being slightly warmer than the liver, tends to rise vertically towards the river's surface. The discharge should not directly impact spawning beds that may exist below the outfall pipe. Effluent and river mixing in the vicinity ofthe outfall, keep the overall water temperature at 13.06 °C or cooler (discussion above). This fractional temperature increase above 13.0 °C is, as a practical matter, difficult to measure. Furthermore, during summer spawning season (lSeptember-31 October) the M'orst-case recorded effluent temperature (Attachment-2, P. 14) was 22 °C in September 2007. This


temperature is 2.6 °C lower than that used in the temperature model for spawning use (Attachment, P. 2). Spawning beds should not be affected by warm discharges from Outfall 001 during spawning season.

(B) Acute impairment or instantaneous lethality is prevented or minimized by limiting potential fish exposure to temperatures of 32.0 degrees Celsius (89.6 degrees Fahrenheit) or more to less than 2 seconds).

Estacada's effluent temperature does not reach 32.0 °C (maximum summer temperature — 24.6 °C, as discussed above).

(C) Thermal shock caused by a sudden increase in water temperature is prevented or minimized by limiting potential fish exposure to temperatures of 25.0 degrees Celsius (77.0 degrees Fahrenheit) or more to less than 5 percent ofthe cross section of 100 percent ofthe 7Q10 low flow ofthe water body; the Department may develop additional exposure timing restrictions to prevent thermal shock.

Estacada's effluent temperature has not reached 25.0 °C based on past data collection. Furthermore, MZ dilution provides immediate temperature reduction even under worst-case, low-flow conditions.

(D) Unless the ambient temperature is 21.0 degrees or greater, migration blockage is prevented or minimized by limiting potential fish exposure to temperatures of 21.0 degrees Celsius (69.8 degrees Fahrenheit) or more to less than 25 percent ofthe cross section of 100 percent ofthe 7Q10 low flow ofthe water body.

Estacada's effluent does not violate this criterion based on the Thermal Calculator runs discussed above. The Clackamas River at Outfall 001 is approximately 1000 feet wide.

Past temperature data for this treatment facility and the Clackamas River (beginning in October of Year 2003) are contained in Attachment-2.

TMDL - Bacteria Bacteria control criteria for Estacada's sewage treatment facility are identified in the Willamette Basin TMDL: Clackamas Subbasin, on Page 6-47, per OAR 340-041-0009 (1) (a):

The Oregon Administrative Rules (TMDL Table 6.15) contain bacterial criteria for the waters of the Clackamas Subbasin. Standards were established to ensure that contact recreation (swimming, wading, etc.) does not result in an unacceptable risk to human health. Under the standard, water contact recreation is protected as long as the 30-day log-mean of sample concentrations does not exceed 126 E. coli organisms per 100 mL of water. No single sample is to exceed 406 E. coli Organisms per 100 mL. This TMDL will be based entirely on E. coli data and the current criteria.

The current and proposed renewal permits for Estacada specify the bacteria limits listed above in


Schedule-A of each permit. TMDL compliance is attained.

TMDL-Mercury (Hg) As a minor discharger (design ADWF < 1 MGD), Estacada is not required to evaluate its treatment facility effluent for toxics other than ammonia and chlorine (The Department's RPA for Toxic Pollutants IMD, September 2005, Page 16, Fig. 1). The RPA for these two toxics is discussed below. DEQ, however, does have some metals toxicity data for this facility. This data was obtained during DEQ's Estacada MZ study under worst-case, summer low-flow conditions. Attachment-7, Permit Milestones, Table-3, contains a summary of priority pollutant metals testing for DEQ's MZ evaluation conducted on September 10, 2008. Based on a minimum ZID dilution = 5 and MZ dilution - 6, DEQ's metal test data indicates that Estacada's effluent has no potential for acute or chronic toxicity given summer, low-flow conditions. Hg was not included in DEQ's metal testing; however, the test results for other metals indicate very low concentrations (< acute or chronic levels in the ZID and MZ, respectively). This is consistent with low Hg levels and no toxicity potential for this source.

Chlorine Toxicity The Estacada wastewater treatment facility uses chlorine to disinfect its effluent and meet bacterial limits in Schedule-A of the proposed renewal permit. Prior to discharge chlorinated effluent is dechlorinated to remove unacceptable toxicity. Chlorine residual concentration limits (post dechlorination) are listed in Schedule-A ofthe renewal permit.

Chlorine toxicity was evaluated to determine whether permit limits were required (Attachment-8). Recent effluent chlorine residual data is summarized in Attachment-9 for the years January 2008 through June 2010. The RPA for chlorine indicates that permit limits are required. DEQ's Permit Limits spread sheet (Attachinent-8) lists proposed chlorine limits for both summer and winter seasons. Concentration limits for daily maximum and monthly average chlorine residual are listed in Schedule-A, 1 .a ofthe proposed permit. These limits are slightly more stringent than those of the current permit, based on reduced ZID and MZ dilutions, per DEQ's MZ study discussed above.

Ammonia Toxicity The RPA for ammonia determined that summer limits are required for this facility (Attachment-8). Recent effluent ammonia data is summarized in Attachment-9 for the years January 2008 through June 2010. Summer ammonia limits (daily maximum and monthly average) are proposed for Schedule-A ofthe renewal permit.

Dissolved Oxygen Reduction The Department's Streeter-Phelps Dissolved Oxygen Model spread sheet was used to investigate dissolved oxygen (DO) levels associated with a summer season discharge under worst-case conditions (Attachment-10). Source and river temperature data was taken from Attachments-2 & zh Modeling results indicate that DO in the receiving stream drops < 0.1 mg/L after complete mixing with the effluent discharge for the first 1.5 miles of river travel. The DO drop in the first 0.5 miles of river travel is < 0.07 mg/L. River mill Dam is located approximately 0.5 miles below Outfall 001. Spread sheet DO results do not include re-aeration ofthe river as it passes


over the dam, or effluent buoyancy (surface hugging) within and outside of the MZ. Model results are consistent with the allowed DO reduction for this type of point source discharge. DO results (worst-case conditions) comply with OAR 340-041-0016 (1) and (2) for the protection of active spawning beds and for water bodies identified as providing cold-water aquatic life.

Groundwater Appropriate sections ofthe Groundwater Prioritization Worksheet are included in the Department's files for this facility. The Permittee's wastewater treatment and disposal system includes impoundments for sewage solids and biosolids, and the land application of biosolids. Biosolids are discussed above. At this facility, sewage solids and biosolids impoundments are lined to prevent leaching to groundwater. Biosolids are applied at agronomical rates to the approved application sites. This facility poses no risk to groundwater.

m DEQ's pH spread sheet was used to evaluate the facility's discharge. Based on the lower, worst-case MZ dilution discussed above, pH limits must be adjusted (Attachment-11). It is proposed that year-around pH limits be changed to the range 6.1 - 9.0 (Schedule-A, La (3)). This is a minor change that the facility should be able ,to meet by adjusting its operations and/or by chemical addition.

PERMIT HISTORY... Anti-degradation Review An Anti-degradation Review was completed with a recommendation to proceed with this permit action. A copy ofthe review sheet can be found in the DEQ's project file.

Compliance History The Estacada wastewater treatment facility received an upgrade in 2008 (see Facility Description above). Since the current permit was issued (September 30, 2003) the facility has experienced permit violations and enforcement actions, per Attachment-12 as follows:

DATE August 2,2004

February 8,2006

June 13,2007

July 25, 2007

October 29,2007

ACTION Notice of Noncompliance (NON) for permit violations during June 2004.

Warning Letter (WL-NWR/WQ-06-0009) for permit violations during December 2005.

Warning Letter (WL-WQ/M-07-0096) for pennit violations during May 2007.

Warning Letter (WL-WQ/M-07-0109) for peimit violations during June 2007.

Warning Letter (WL-NWR-07-0122) sent for pennit violations during September 2007.

LIMIT VIOLATIONS - One BOD weekly average cone. limit, - One TSS weekly average cone, limit, - BOD monthly average cone, limit, - TSS monthly average cone, limit, and - One CL daily maximum cone, limit. -Two daily bacteria, - Monthly average bacteria, and - One CI daily maximum cone, limit. - Two BOD weekly average cone, limit,

and - BOD monthly average cone, limit. - Two BOD weekly average cone, limit,

and - BOD monthly average cone, limit. - BOD monthly average cone, limit.


November 25,2008

June 29,2009

Warning Letter (WL-NWR-08-0095) for peimit violations during September 2008. Warning Letter (WL-NWR-09-0080) sent for permit violations during May 2009.

- BOD monthly average cone, limit.

- Two BOD weekly average cone. limit, - BOD monthly mass load limit, and - BOD monthly average cone, limit.

PERMIT DISCUSSION

Face Page

The Permittee is authorized to construct, install, modify, or operate a wastewater collection, treatment, control, and disposal system. Permits year-around discharge of treated effluent to the Clackamas River at Outfall 001 located at RM 23.6. Discharges from the City of Estacada's wastewater treatment facility must be within limits set by Schedule-A and subsequent permit schedules. All other discharges are prohibited.

Schedule A - Waste Discharge limitations

Treated Effluent Discharged at Outfall 001 The proposed permit sets limits on the wastes discharged from this facility. Limits on the facility's discharge to the Clackamas River include 5-day biochemical oxygen demand (BOD5), total suspended solids (TSS), E. coli bacteria, pH, chlorine residual, ammonia, and BOD5 and TSS removal efficiency.

BOD^ and TSS concentration and mass limits: Based on Willamette Basin minimum design criteria [OAR 340-041-0345 (3)], wastewater treatment resulting in a monthly average effluent concentration of 10 mg/L monthly average for BOD5 and TSS must be provided from May 1 - October 31. From November 1 - April 30, a minimum of secondary treatment or equivalent control is required. Secondary treatment for this facility is defined as monthly average concentration limit of 30 mg/L for BOD5 and for TSS.

The Department is proposing summer concentration limits that match Willamette Basin standards of 10 mg/L monthly average for BOD5 and TSS. During winter season, the Department proposes concentration limits more stringent than secondary treatment; 20 mg/L monthly average for BOD5 and TSS. These design criteria for BOD5 and TSS are protective year-around of water quality and beneficial uses in the Clackamas River, and are the same as those in the existing permit.

The summer and winter season mass load limits for BOD5 and TSS are based on the facility's design ADWF - 0.54 MGD, and the monthly average BOD5 and TSS concentration limits listed above. These limits are in accordance with OAR 340-041-0345 (3).


BODsandTSS

The limits for treated e

Parameter

BOD5

TSS

ffluent at Outfall 001 (May 1 - October 31) are: Average Effluent

Concentrations

Monthly

10 mg/L

10 mg/L

Weekly

15 mg/L

15 mg/L

Monthly

Average

lb/day

45

45

Weekly

Average

lb/day

68

68

Daily

Maximum

Lbs

90

90

Calculations: BODsandTSS (a) 0.54 MGD x 8.34 #/gal x 10 mg/L = 45 lbs/dav monthly average. (b) 45 lbs/day monthly average x 1.5 = 68 lbs/day weekly average. (c) 45 lbs/day monthly average x 2.0 - 90 lbs/dav daily maximum.

The limits for treated e

Parameter

BOD5

TSS

ffluent at Outfall 001 (Novembei Average Effluent

Concentrations

Monthly

20 mg/L

20 mg/L

Weekly

30 mg/L

30 mg/L

• 1 -April 30) are Monthly

Average

lb/day

90

90

Weekly .

Average

lb/day

135

135

Daily

Maximum

Lbs

180

180

Calculations: BODsandTSS (a) 0.54 MGD x 8.34 #/gal x 20 mg/L - 90 lbs/dav monthly average. (b) 90 lbs/day monthly average x 1.5 = 135 lbs/day weekly average. (c) 90 lbs/day monthly average x 2.0 = 180 lbs/day daily maximum.

The City of Estacada's current wastewater treatment facility is capable of meeting the above proposed mass load limits based on composite sampling.

Bacteria

The proposed permit limits discharges of E. coli bacteria to waters of the state. This permit applies the bacteria rule [OAR 340-041-0009 (1) (a)] which sets standards for organisms ofthe Coliform group associated with fecal sources (Escherichia coli or E. coli). The standard is a 30-day log mean of 126 organisms per 100 mL, based on a minimum of 5 samples with no single sample exceeding 406 organisms per 100 mL. The permit proposes a monthly geometric mean of 126 E. coli per 100 mL with no single sample exceeding 406 E. coli per 100 mL.


The proposed permit limits are based on the E. coli standard contained in OAR 340-041-0009 (5). The limits are adequate to comply with the basin water quality standard outside the mixing zone and the contact recreation standard. For Outfall 001, the permit limit for E. coli is based on this standard. It is also the TMDL limit for this source. The proposed limits are a monthly geometric mean of 126 E. coli per 100 mL, with no single sample exceeding 406 E. coli per 100 mL. If a single sample exceeds 406 E. coli per 100 mL, then the permittee may take five consecutive re-samples. Ifthe log mean ofthe five re-samples is less than or equal to 126, a violation is not triggered. The re-sampling must be taken at four hour intervals beginning within 28 hours after the original sample was taken.

Based on the above discussion, the permit limits for bacteria are: Other Parameters (Year-around) E. coli Bacteria

Limitations Shall not exceed 126 organisms per 100 mL monthly geometric mean. No single sample shall exceed 406 organisms per 100 mL.

pH The Willamette Basin Water Quality Standard for pH is found in OAR 340-041-0345 (1). The allowed range is 6.5 to 8.5. The proposed permit limits pH to the range 6.1 - 9.0: where pH is adjusted slightly upward on the low end relative to the current permit. Within the Permittee's mixing zone, the water quality standard for pH does not have to be met. Given worst-case 7Q10 low-flow conditions in the Clackamas River and a minimum MZ dilution = 6.0 (see discussion above), it appears that effluent with an initial pH of 6.1 - 9.0 should not violate the Willamette Basin Water Quality pH Standard listed above. See Attachment-11 (Estacada pH RPA Spread Sheet) for an estimate of MZ boundary pH based on current data.

Other Parameters (Year-around) PH

Limitations Shall be within the range of 6.1 - 9.0.

Chlorine Residual Proposed chlorine residual limits are generally more stringent than current limits. Chlorine limits were adjusted to account for lower dilutions during summer season and RPA results for low-flow and high-flow conditions in the Clackamas River (see Attachment-8)

May 1 - October 31: Parameter Chlorine Residual, Daily Maximum Chlorine Residual, Monthly Average

Limitations Shall not exceed 0.10 mg/L. Shall not exceed 0.03 mg/L.

November 1 - April 30: Parameter Chlorine Residual, Daily Maximum Chlorine Residual, Monthly Average



Ammonia Based on a RPA (Attachment-8) for acute and chronic ammonia toxicity at the edge ofthe ZID and at the RMZ boundary, the following ammonia limits are proposed for summer season:

May 1-October 31: Parameter Ammonia as N, Daily Maximum Ammonia as N, Monthly Average


BOD5 and TSS Percent Removal Efficiency A minimum level of percent removal for BOD5 and TSS for municipal dischargers is required by the Code of Federal Regulations (CFR) secondary treatment standards (40 CFR, Part 133). An 85 percent removal efficiency limit (85%) is included in the proposed permit to comply with federal requirements. The BOD5 and TSS monitoring frequency under the Renewal Permit is 2/week.

Other Parameters BOD5 and TSS Removal Efficiency

Limitations Shall not be less than 85% monthly average for BOD5 and 85% monthly average for TSS.

Mixing Zone and Zone of Immediate Dilution

No wastes may be discharged or activities conducted that cause or contribute to a violation of water quality standards in OAR 340-041 applicable to the Willamette Basin, except as provided for in OAR 340-045-0080.

The current permit defines the ZID and RMZ as follows:

The allowable mixing zone is a rectangle 75-ft upstream and downstream from the end-of-pipe and 75-feet wide centered on the outfall discharge point. The Zone of Immediate Dilution (ZID) is a 7.5-foot radius from end-of-pipe.

Based on a recommendation from DEQ staff (MZ study report published April 15, 2009), it is proposed to redefine the MZ and ZID as follows:

The allowable mixing zone is a rectangle extending 75-ft upstream and downstream from the end ofthe discharge pipe; and 75-feet wide measured from the discharge point towards the center ofthe river on a line perpendicular to the bank. The zone of immediate dilution (ZID) is a 7.5-foot radius from the end ofthe pipe.

The Department believes that the mixing zone, as described above, is appropriate for this discharge. Beneficial uses ofthe receiving stream will be protected, and the mixing zone meets the criteria in rule.


Groundwater Protection The renewal permit proposes to prohibit all activities at this facility that could cause an adverse impact on the existing or potential beneficial uses of groundwater.

Schedule B - Minimum Monitoring and Reporting Requirements

The renewal permit proposes that the laboratory used by the permittee to analyze samples have a quality assurance/quality control (QA/QC) program to verify the accuracy of sample analysis. If QA/QC requirements are not met for any analysis, the results shall be included in the report, but not used in calculations required by the proposed permit. When possible, the permittee shall re-sample in a timely manner for parameters failing the QA/QC requirements, analyze the samples, and report the results.

In 1988, the Department developed a monitoring matrix for commonly monitored parameters. Proposed monitoring frequencies for all permit parameters are based on this matrix. They correspond to those applied to facilities of similar size and complexity in the state. Proposed monitoring frequencies are unchanged from the current permit.

Influent Sampling Influent parameters must be monitored as specified in the permit at the indicated locations. The permit proposes that grab samples, measurements, and composite samples be taken at the headworks just downstream ofthe Parshall flume after raw screening and grit removal and before any return flows to the headworks. All measurements for influent temperature (summer season) and samples for toxics are taken in the same location.

It is proposed that influent measurement and sampling include: • Total flow (daily measurement), • Flow meter (annual calibration), • BOD5 and TSS (2 days/week by composite sampler), • , BOD5 and TSS (weekly average calculation for each), • pH (3 days/week by grab sample), and • Influent daily maximum temperature measurement (3 days/week).

Effluent Sampling for Outfall 001 The permit proposes to take effluent grab and composite samples, and measurements at the effluent metering manhole (EMM). Composite samples, samples for toxics, and effluent temperature measurements are taken at the same location.

Proposed measurement and sampling of effluent parameters includes: ® Total flow (daily measurement); ® Flowmeter (annual calibration); » BOD5 and TSS (2 days/week concentration by composite sampler); • BOD5 and TSS (weekly average concentration calculation); * BOD5 and TSS (monthly average concentration calculation);


BOD5 and TSS (daily mass load calculation); BOD5 and TSS (weekly average mass load calculation); BOD5 and TSS (monthly average mass load calculation); BOD5 and TSS (monthly average percent removal calculation); pH (3 days/week grab sample); E. coli (weekly grab sample); E. coli (monthly average calculation by geometric mean); Chlorine (pounds used daily for disinfection); Chlorine residual (daily maximum concentration); Chlorine residual (monthly average concentration); Ammonia as N (2 days/week concentration by grab sample); Ammonia as N (monthly average concentration calculation); Effluent daily maximum temperature measurement (3 days/week); and Whole Effluent Toxicity (WET) testing per Schedule D, Item #6.

Biosolids Report Submittal A Biosolids Report must be submitted by February 19n ofthe following year whenever biosolids are land applied. The report must describe biosolids handling activities for the previous year, and at a minimum include the required information outlined in OAR 340-050-0035 (6) (a)-(e).

Inflow and Infiltration Report Submittal The permittee shall have in place a program to identify and reduce inflow and infiltration (I&I) into its sewage collection system. An annual report shall be submitted to the Department by February 19 each year. The report must detail sewer collection maintenance activities aimed at reducing I&I. It must state those activities that were completed in the previous year, and those activities planned for the following year.

Schedule C - Compliance Schedules and Conditions

Schedule C is not used in this permit.

Schedule D - Special Conditions

Schedule D ofthe proposed permit includes five Special Conditions.

1. Biosolids Management. All biosolids shall be managed in accordance with the current, DEQ approved Biosolids Management Plan, and the site authorization letters issued by the DEQ. Any changes in biosolids management activities that significantly differ from operations specified under the approved plan require the prior written approval ofthe DEQ.

All new biosolids application sites shall meet the site selection criteria set forth in OAR 340-050-0070 and must be located within DEQ approved application sites in Clackamas County. No new Public Notice is required for continued use ofthe currently approved sites; however,


a copy ofthe latest approved Biosolids Management Plan is included for review with renewal permit documentation during the Public Comment Period. Property owners adjacent to any

2. Changes in Biosolids Standards. This permit may be modified to incorporate any applicable standard for biosolids use or disposal promulgated under Section 405(d) of the Clean Water Act, if the standard for biosolids use or disposal is more stringent than any requirements for biosolids use or disposal in the permit, or controls a pollutant or practice not limited in this permit.

3. Operator Certification. The permittee shall comply with Oregon Administrative Rules (OAR), Chapter 340, Division 049, Regulations Pertaining to Certification of Wastewater System Operator Personnel. The permittee shall have its wastewater system supervised by one or more operators who are certified in a classification and grade level specified in the permit. The permittee's wastewater system may not be without supervision for more than thirty (30) days; and the permittee is responsible for ensuring the wastewater system has a properly certified supervisor available at all times to respond on-site.

4. Groundwater. The permittee shall not be required to perform a hydro-geologic characterization or groundwater monitoring during the term of this permit provided the facilities are operated in accordance with the permit conditions; and there are no adverse groundwater quality impacts (complaints or other indirect evidence) resulting from the facility's operation.

5. Notification. The permittee shall notify the DEQ Northwest Region - Portland Office in accordance with the response times noted in the General Conditions of this permit, of any malfunction so that corrective action can be coordinated between the permittee and the Department.

Schedule E - Pretreatment Program The proposed permit does not require a pretreatment program based on documentation submitted during the current permit cycle.

Schedule F - General Conditions

The General Conditions were revised and issued on September 18, 2009. A summary ofthe changes is as follows:

(1) There are additional citations to the federal Clean Water Act and CFR, including references to standards for sewage sludge use or disposal;

(2) There is additional language regarding federal penalties; (3) Bypass language has been made consistent with the Code of Federal Regulations; and (4) Overflow language has been modified;


o Formerly the language stated that overflows in response to the five or ten year event would not violate the permit,

© Now it states that overflows are prohibited, and * DEQ will continue to exercise enforcement discretion with respect to overflows

consistent with the provisions ofthe Bacteria Rule (OAR 340-041-0009).

These General Conditions are standard additions to NPDES permits of this type. Their inclusion is proposed for this draft permit.

GLS: Estacada NPDES Fact Sheet. 1, 03Augl0.docx Revised: 07Sep2010

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