Draft Wasteload Allocation Report For McCurtain County Rural Water District #5

Transcription

1 Draft Wasteload Allocation Report For McCurtain County Rural Water District #5 Contents 1. Problem Definition Endpoint Identification Source Analysis Point Sources Non-Point Sources Background Linkage between Sources and Receiving Water Model Inputs Maximum Assimilative Capacity Margin of Safety Allocations Final Recommendations Public Participation References... 5 Appendix A - Desktop Model... 8 List of Tables Table 1. Maximum Assimilative Capacity... 3 Table 2. Allocations for DO... 4 List of Figures Figure 1. McCurtain County RWD#5 WWTF Receiving Stream (Overview)... 6 Figure 2. McCurtain County RWD#5 WWTF Receiving Stream (Detailed View)... 7

2 October 2018 Page 1 of Problem Definition The McCurtain County Rural Water District #5 (RWD#5) requested a sewer discharge permit for a new wastewater treatment facility. Due the increasing demand for services and infrastructure in the area, the McCurtain County RWD#5 plans to add a mechanical treatment plant. The discharge would flow into Yashoo Creek (OK _00). Based on the projected population growth and to ensure compliance with DEQ standards, the McCurtain County RWD#5 requested a discharge flow of 0.40 MGD. Yashoo Creek (OK _00) is listed in the Oklahoma Water Quality Standards (OAC 785:45) as having the following beneficial uses: Aesthetics Agriculture Fish and Wildlife Propagation-Cool Water Aquatic Community Fish Consumption Primary Body Contact Recreation Public and Private Water Supply According to the Oklahoma (d) list, Yashoo Creek was impaired for CWAC and the cause of impairment is Macroinvertebrate Bio. This report addresses dissolved-oxygen demanding substances only and does not address any other pollutant on the State's 303(d) list of impaired waters. This report addresses instream organic enrichment and Dissolved Oxygen (DO) through the use of wasteload allocations of DO-demanding substances (CBOD and Ammonia). This Wasteload Allocation (WLA) has been developed in order to ensure that the limits assigned to the discharge are stringent enough to maintain DO standards under critical conditions. Controls for any necessary pollutants will be established in the permitting process. 2. Endpoint Identification The Oklahoma Water Quality Standards define DO criteria for two flow regimes: critical low-flow and nuisance conditions. The critical low-flow will be either 7Q2 or 1.0 cfs, whichever is greater. Nuisance condition applies only when there is no upstream flow. The following numerical dissolved oxygen criteria for CWAC apply to the receiving stream: Critical Low-Flow Condition (7Q2) Summer (Jun Oct): 6.0 mg/l Spring (Apr May): 7.0 mg/l Winter (Nov Mar): 6.0 mg/l

3 October 2018 Page 2 of 15 In according with OAC 785: , a flow of 1 cfs was used for Yashoo Creek since no flow data are available. Oklahoma s antidegradation policy (OAC 785:45-3) requires protecting all waters of the state from degradation of water quality. The allocated loadings/concentrations in this report were set with regard for all elements of the Oklahoma Water Quality standards, which includes the antidegradation policy. 3. Source Analysis 3.1. Point Sources McCurtain County RWD#5 Wastewater Treatment Facility Facility Legal Description: W1/2, NE1/4, SW1/4, S26, T05S, R24E, McCurtain County, OK (34 9'3.931"N, 94 44'57.96"W) Discharge Location: W1/2, NE1/4, SW1/4, S26, T05S, R24E, McCurtain County, OK (34 8'54.768"N, 94 45'6.95 "W) 3.2. Non-Point Sources The allocations in this waterbody assessment are driven by critical instream dissolved oxygen conditions (low-flow, high temperature) as defined in the Oklahoma Water Quality Standards. Low-flow conditions, by definition, assume little or no runoff Background The following background conditions for the Yashoo Creek were used: Flow (7Q2): CBOD5: Ammonia: DO: 1.0 cfs 2.0 mg/l 0.15 mg/l 85% * temperature * = saturation at the regulatory seasonal temperature 4. Linkage between Sources and Receiving Water The links between sources and the receiving streams can be established through typical water quality models such as spreadsheet mass balance, desktop Streeter-Phelps model, modified Streeter-Phelps model, QUAL2E, QUALTX, SWAT, and HSPF etc. The more complicated a model becomes, the better it represents the system being studied. However, a complex model also requires more data. According the complexity of the problem, available data and policy, Oklahoma s desktop model was chosen for this project. Oklahoma s desktop model is based on the modified Streeter-Phelps equation. The modified Streeter-Phelps model can be found in Oklahoma Continuing Planning Process (CPP).

4 October 2018 Page 3 of Model Inputs The water quality model used to determine the impact of DO-demanding substances on the instream DO concentration is based on a modified version of the Streeter-Phelps equation. The primary kinetic inputs were derived from literature values and the past WLAs performed by Oklahoma Department of Environmental Quality. Turney-Harris equation was used to calculate the reaeration rates (K2) used in the model. The other primary kinetic inputs were derived from literature values and are as follows: Proposed Permitted Flow: 0.40 MGD CBOD decay rate (K1): 0.30/day Reaeration rate (K2): 15.01/day NBOD decay rate (Kn): 0.30/day CBOD settling rate (Ks): /day Sediment Oxygen Demand (SOD): g/ft 2 /day Hydraulic parameters were estimated using topographic map data and general assumptions. They are as follows: Stream Slope: t/mi Side Slope: 0.10 ft/ft Manning s n : Q2 for the unnamed tributary was assigned 1.0 cfs because there is no data available for the stream. The model inputs were included in the Appendix A Maximum Assimilative Capacity The model was used to determine the stream s maximum assimilative capacity during various seasons under regulatory flow condition of 1.0 cfs for the unnamed tributary. To do this, the concentration of CBOD5 and NH3 of the point source are increased at the same rate until the predicted instream DO reaches the DO criteria. The resultant mass loading represents the maximum assimilative capacity of the stream for DO-demanding substances. The maximum assimilative capacity is measured in terms of DO as shown in the following Table 1. The complete model results are provided in Appendix A. Table 1. Maximum Assimilative Capacity Season Maximum Assimilative Capacity DO (lbs/day) Summer (Jun Oct) Spring (Apr May) Winter (Nov Mar) Margin of Safety The Oklahoma CPP specifies a 20% margin of safety (MOS) for uncalibrated, simple source models. This is implemented in the model by increasing the inputs of DO-demanding substances (CBOD5 and NH3) proportionally just until the DO criteria are met. The quantified MOS is equal to 20% of maximum wasteload allocations. Together with the MOS, load allocation, wasteload allocation and reserved capacity are calculated in the model and will be presented in the next section.

5 October 2018 Page 4 of Allocations There are no other wastewater discharges in the vicinity of the McCurtain County RWD#5 WWTP discharge. The allocation of loads calculated by the desktop model is shown in the following Table 2. Season Load Allocation (lb/day) Table 2. Allocations for DO Wasteload Allocation (lb/day) MOS (20%) (lb/day) Reserved Capacity (lb/day) Summer Spring Winter

6 October 2018 Page 5 of Final Recommendations The following changes are recommended for inclusion in the Oklahoma Water Quality Management Plan (208 Plan). Proposed Design Flow: Summer (Jun Oct): Spring (April May): Winter (Nov Mar): McCurtain County RWD#5 Wastewater Treatment Facility Limits 0.40 MGD 15.0 mg/l CBOD 5; 7.0 mg/l NH 3; 5.0 mg/l DO 18.0 mg/l CBOD 5; 12.0 mg/l NH 3; 6.0 mg/l DO Secondary Treatment (25 mg/l CBOD 5, 30 mg/l TSS) 8. Public Participation This Draft WLA report will be submitted to EPA for technical approval. After technical approval is received, the proposed permit limits will be sent for public comments. Public comments received during this period will be responded to and become part of the WLA report. The proposed limits will be implemented through the Oklahoma Pollutant Discharge Elimination System (OPDES) permit for the McCurtain County RWD#5, which represents an adequate implementation of the wasteload allocation. The water quality model in this report shows clearly that the recommended allocation of DO-demanding substances effectively addresses the DO problem that can be potentially caused by the proposed discharge of the facility. The McCurtain County RWD#5 will be required to submit monthly Discharge Monitoring Reports (DMR) to the Oklahoma Department of Environmental Quality. The DMR will ensure that the beneficial uses will be maintained in Yashoo Creek. 9. References 1. Title 785, Oklahoma Administrative Code, Chapter 45 Oklahoma s Water Quality Standards, State Of Oklahoma, Oklahoma Desktop Model One Reach, version 3.0, Watershed Planning Section, Oklahoma Department of Environmental Quality, Oklahoma City Oklahoma, Oklahoma Continuing Planning Process, 2012 edition, Oklahoma Department of Environmental Quality, State of Oklahoma, 2013.

7 October, 2018 Page 6 of 15 Figure 1. McCurtain County RWD#5 WWTF Receiving Stream (Overview)

8 October, 2018 Page 7 of 15 Figure 2. McCurtain County RWD#5 WWTF Receiving Stream (Detailed View)

9 October, 2018 Page 8 of 15 Appendix A - Desktop Model

10 October, 2018 Page 9 of 15 INPUT PARAMETERS FOR MODIFIED STREETER-PHELPS MODEL CITY: McCurtain Co. Rural Water District #1 PERFORMED BY: Ying DATE: 7/16/2018 I DISCHARGE INFORMATION LOCATION: W 1/2 /NE¼/SW¼-S26-T05S-R24E BASIN: COUNTY: McCurtain PROPOSED PERMIT FLOW: Summer Spring Winter MGD II RECEIVING STREAM STREAM NAME Yashoo Creek MODELED LENGTH 6.80 MILES NUMBER OF SEGMENTS 40 Summer Spring Winter UPSTREAM FLOW (7Q2) CFS STREAM SLOPE (S) FT/MILE SIDE SLOPE (P) 0.10 FT/FT MANNING'S N VELOCITY COEFFICIENT (Cv) DEPTH COEFFICIENT (Ch) Summer Spring Winter Upstream Flow Velocity (fps) Q2 (cfs) Depth (ft) Upstream Flow Velocity (fps) (cfs) Depth (ft) III IV WATER QUALITY CRITERIA OF RECEIVING STREAM AQUATIC COMMUNITY FLAG 3 COOL WATER AQUATIC COMMUNITY AVERAGE D.O. REQUIREMENT SUMMER 6.00 MG/L SPRING 7.00 MG/L WINTER 6.00 MG/L UPSTREAM CONDITIONS D.O. SATURATION % UPSTREAM CBOD MG/L UPSTREAM NH3-N 0.15 MG/L V RATE CONSTANTS at 20 C Summer Spring Winter CBOD DECAY RATE (K1) (/DAY) UPSTREAM FLOW UPSTREAM FLOW UPSTREAM FLOW REAERATION RATES (K2) 1.0 (cfs) 0.0 (cfs) 1.0 (cfs) 0.0 (cfs) 1.0 (cfs) 0.0 (cfs) 1). TURNEY-HARRIS 2). TEXAS SUMMER SPRING WINTER K2=1.33*S^0.32/n^ K2=4.022*V^0.273/H^ SELECTTED K2 FORMULA Flag Formula Flag Formula Flag Formula 1 TURNEY-HARRIS 1 TURNEY-HARRIS 1 TURNEY-HARRIS SUMMER SPRING WINTER CBOD SETTLING RATE (Ks) KS /DAY NBOD DECAY (Kn) KN /DAY SEDIMENT OXYGEN DEMAND SOD G/FT2/D

11 October, 2018 Page 10 of 15 VI PROPOSED WASTELOAD ALLOCATIONS ( WLA ) EFFLUENT MINIMUM MINIMUM Reserved CBOD5 NH3-N D.O. TEMP D.O. D.O. Capacity? (MG/L) (MG/L) (MG/L) ( C ) 0.00 CFS 7Q2 / 1.0 CFS SUMMER MG/L 6.18 MG/L YES SPRING MG/L 7.14 MG/L YES WINTER MG/L 6.02 MG/L YES VII MARGIN OF SAFETY AND ALLOCATIONS WLAs and Multiplier CBOD5 NH3-N D.O. Factor (MG/L) (MG/L) (MG/L) 1 SUMMER SPRING WINTER Margin Of Safety Required MOS 20.0% SUMMER SPRING WINTER Maximum Wasteload Allocations Maximum Wasteload (lbs/day) Dissolved Oxygen Maximum Assimilative Capacity Max Assimilative Capacity (lbs/day) Dissolved Oxygen SUMMER SPRING WINTER Allocations (in Dissolved Oxygen) Load Allocation Wasteload Allocation Margin Of Safety (20%) Reserved Capacity SEASON (lbs/day) (lbs/day) (lbs/day) (lbs/day) SUMMER SPRING WINTER Locations of D.O. Sags MINIMUM RIVER MINIMUM RIVER D.O. MILE D.O. MILE 0.0 CFS 1.0 CFS SUMMER 6.18 MG/L MG/L 0.00 SPRING 7.14 MG/L MG/L 0.00 WINTER 6.02 MG/L MG/L 0.00

12 DO (mg/l) DO (mg/l) DO (mg/l) Draft Wasteload Allocation Report for the McCurtain County Rural Water District #5 October, 2018 Page 11 of 15 Plots for 7Q2 Headwater Flow: SUMMER Distance (mi) DO Standards SPRING Distance (mi) DO Standdards WINTER Distance (mi) DO Standards

13 October, 2018 Page 12 of 15 OKLAHOMA DEPARTMENT OF ENVIRONMENTAL QUALITY S DESKTOP WASTELOAD ANALYSIS - SUMMER McCurtain Co. Rural Water District #1 SUMMER ALLOCATION PROPOSED PERMIT FLOW = 0.4 MGD 1.0 CFS UPSTREAM FLOW PROPOSED PERMIT FLOW = 0.4 MGD 0.0 CFS UPSTREAM FLOW 29 C TEMPERATURE 29 C TEMPERATURE INITIAL CONDITIONS ARE AS FOLLOWS... INITIAL CONDITIONS ARE AS FOLLOWS... REACH LENGTH (MILES): 6.80 REACH LENGTH (MILES): 6.80 NUMBER OF SEGMENTS: 40 STREAM VELOCITY: 6.70 MILES/DAY NUMBER OF SEGMENTS: 40 STREAM VELOCITY: 6.70 MILES/DAY NUMBER OF REACHES: 1 STREAM DEPTH: 0.31 FEET NUMBER OF REACHES: 1 STREAM DEPTH: 0.31 FEET REACH NUMBER: 1 REACH CL CONC: MG/L REACH NUMBER: 1 REACH CL CONC: MG/L BODU/CBOD5 RATIO: 2.30 D.O. SATURATION: 7.67 MG/L BODU/CBOD5 RATIO: 2.30 D.O. SATURATION: 7.67 MG/L NODU/CBOD5 RATIO: 4.30 D.O. TARGET: 6.00 MG/L NODU/CBOD5 RATIO: 4.30 D.O. TARGET: 2.00 MG/L EFFLUENT FLOW: 0.40 MGD UPSTREAM FLOW: 0.65 MGD EFFLUENT FLOW: 0.40 MGD UPSTREAM FLOW: 0.65 MGD EFFLUENT CBOD5: 15.0 MG/L UPSTREAM CBOD5: 2.00 MG/L EFFLUENT CBOD5: 15.0 MG/L UPSTREAM CBOD5: 2.00 MG/L EFFLUENT NH3N: 7.0 MG/L UPSTREAM NH3N: 0.15 MG/L EFFLUENT NH3N: 7.0 MG/L UPSTREAM NH3N: 0.15 MG/L EFFLUENT D.O.: 5.0 MG/L UPSTREAM D.O.: 6.90 MG/L EFFLUENT D.O.: 5.0 MG/L UPSTREAM D.O.: 6.90 MG/L RATE CONSTANTS(1/DAY, BASE E) 20 DEGREES 29 DEGREES THETA RATE CONSTANTS(1/DAY, BASE E) 20 DEGREES 29 DEGREES THETA K1: K1: K2: TURNEY-HARRIS K2: TURNEY-HARRIS KN: KN: KS: KS: SOD (G/FT2/DAY): SOD (G/FT2/DAY): RESULTS ARE AS FOLLOWS... RESULTS ARE AS FOLLOWS... DISTANCE CBOD5 ULT BOD NH3-N ULT NOD D.O. FLOW DISTANCE CBOD5 ULT BOD NH3-N ULT NOD D.O. FLOW (MILES) (MG/L) (MG/L) (MG/L) (MG/L) (MG/L) (MGD) (MILES) (MG/L) (MG/L) (MG/L) (MG/L) (MG/L) (MGD)

14 October, 2018 Page 13 of 15 DESKTOP WASTELOAD ANALYSIS - SPRING McCurtain Co. Rural Water District #1 ALLOCATION PROPOSED PERMIT FLOW = 0.4 MGD 1.0 CFS UPSTREAM FLOW PROPOSED PERMIT FLOW = 0.4 MGD 0.0 CFS UPSTREAM FLOW 22 C TEMPERATURE 22 C TEMPERATURE INITIAL CONDITIONS ARE AS FOLLOWS... INITIAL CONDITIONS ARE AS FOLLOWS... REACH LENGTH (MILES): 6.80 REACH LENGTH (MILES): 6.80 NUMBER OF SEGMENTS: 40 STREAM VELOCITY: 6.70 MILES/DAY NUMBER OF SEGMENTS: 40 STREAM VELOCITY: 6.70 MILES/DAY NUMBER OF REACHES: 1 STREAM DEPTH: 0.31 FEET NUMBER OF REACHES: 1 STREAM DEPTH: 0.31 FEET REACH NUMBER: 1 REACH CL CONC: MG/L REACH NUMBER: 1 REACH CL CONC: MG/L BODU/CBOD5 RATIO: 2.30 D.O. SATURATION: 8.72 MG/L BODU/CBOD5 RATIO: 2.30 D.O. SATURATION: 8.72 MG/L NODU/CBOD5 RATIO: 4.30 D.O. TARGET: 7.00 MG/L NODU/CBOD5 RATIO: 4.30 D.O. TARGET: 2.00 MG/L EFFLUENT FLOW: 0.40 MGD UPSTREAM FLOW: 0.65 MGD EFFLUENT FLOW: 0.40 MGD UPSTREAM FLOW: 0.65 MGD EFFLUENT CBOD5: 18.0 MG/L UPSTREAM CBOD5: 2.00 MG/L EFFLUENT CBOD5: 18.0 MG/L UPSTREAM CBOD5: 2.00 MG/L EFFLUENT NH3N: 12.0 MG/L UPSTREAM NH3N: 0.15 MG/L EFFLUENT NH3N: 12.0 MG/L UPSTREAM NH3N: 0.15 MG/L EFFLUENT D.O.: 6.0 MG/L UPSTREAM D.O.: 7.85 MG/L EFFLUENT D.O.: 6.0 MG/L UPSTREAM D.O.: 7.85 MG/L RATE CONSTANTS(1/DAY, BASE E) 20 DEGREES 22 DEGREES THETA RATE CONSTANTS(1/DAY, BASE E) 20 DEGREES 22 DEGREES THETA K1: K1: K2: TURNEY-HARRIS K2: TURNEY-HARRIS KN: KN: KS: KS: SOD (G/FT2/DAY): SOD (G/FT2/DAY): RESULTS ARE AS FOLLOWS... RESULTS ARE AS FOLLOWS... DISTANCE CBOD5 ULT BOD NH3-N ULT NOD D.O. FLOW DISTANCE CBOD5 ULT BOD NH3-N ULT NOD D.O. FLOW (MILES) (MG/L) (MG/L) (MG/L) (MG/L) (MG/L) (MGD) (MILES) (MG/L) (MG/L) (MG/L) (MG/L) (MG/L) (MGD)

15 October, 2018 Page 14 of 15 OKLAHOMA DEPARTMENT OF ENVIRONMENTAL QUALITY DESKTOP WASTELOAD ANALYSIS - WINTER McCurtain Co. Rural Water District #1 PROPOSED PERMIT FLOW = 0.4 MGD 1.0 CFS UPSTREAM FLOW PROPOSED PERMIT FLOW = 0.4 MGD 0.0 CFS UPSTREAM FLOW 18 C TEMPERATURE 18 C TEMPERATURE INITIAL CONDITIONS ARE AS FOLLOWS... INITIAL CONDITIONS ARE AS FOLLOWS... REACH LENGTH (MILES): 6.80 REACH LENGTH (MILES): 6.80 NUMBER OF SEGMENTS: 40 STREAM VELOCITY: 6.70 MILES/DAY NUMBER OF SEGMENTS: 40 STREAM VELOCITY: 6.70 MILES/DAY NUMBER OF REACHES: 1 STREAM DEPTH: 0.31 FEET NUMBER OF REACHES: 1 STREAM DEPTH: 0.31 FEET REACH NUMBER: 1 REACH CL CONC: MG/L REACH NUMBER: 1 REACH CL CONC: MG/L BODU/CBOD5 RATIO: 2.30 D.O. SATURATION: 9.45 MG/L BODU/CBOD5 RATIO: 2.30 D.O. SATURATION: 9.45 MG/L NODU/CBOD5 RATIO: 4.30 D.O. TARGET: 6.00 MG/L NODU/CBOD5 RATIO: 4.30 D.O. TARGET: 2.00 MG/L EFFLUENT FLOW: 0.40 MGD UPSTREAM FLOW: 0.65 MGD EFFLUENT FLOW: 0.40 MGD UPSTREAM FLOW: 0.65 MGD EFFLUENT CBOD5: 25.0 MG/L UPSTREAM CBOD5: 2.00 MG/L EFFLUENT CBOD5: 25.0 MG/L UPSTREAM CBOD5: 2.00 MG/L EFFLUENT NH3N: 15.4 MG/L UPSTREAM NH3N: 0.15 MG/L EFFLUENT NH3N: 15.4 MG/L UPSTREAM NH3N: 0.15 MG/L EFFLUENT D.O.: 2.0 MG/L UPSTREAM D.O.: 8.51 MG/L EFFLUENT D.O.: 2.0 MG/L UPSTREAM D.O.: 8.51 MG/L RATE CONSTANTS(1/DAY, BASE E) 20 DEGREES 18 DEGREES THETA RATE CONSTANTS(1/DAY, BASE E) 20 DEGREES 18 DEGREES THETA K1: K1: K2: TURNEY-HARRIS K2: TURNEY-HARRIS KN: KN: KS: KS: SOD (G/FT2/DAY): SOD (G/FT2/DAY): RESULTS ARE AS FOLLOWS... RESULTS ARE AS FOLLOWS... DISTANCE CBOD5 ULT BOD NH3-N ULT NOD D.O. FLOW DISTANCE CBOD5 ULT BOD NH3-N ULT NOD D.O. FLOW (MILES) (MG/L) (MG/L) (MG/L) (MG/L) (MG/L) (MGD) (MILES) (MG/L) (MG/L) (MG/L) (MG/L) (MG/L) (MGD)