CHAPTER 2.0 EXISTING FACILITIES

Transcription

1 CHAPTER 2.0 EXISTING FACILITIES

2 CHAPTER 2 EXISTING FACILITIES 2.1 HISTORY OF LANCASTER WATER RECLAMATION PLANT District No. 14 was formed in 1938 and the discharge of treated effluent to Amargosa Creek from the first sewage treatment works constructed began in As District No. 14 grew through the 1950s, it issued bonds to construct new facilities. The LWRP was established at its current location with a treatment capacity of 4.5 mgd in Figure 1-3 shows the incremental capacity expansion stages to date. The original LWRP design provided for primary treatment via settling coupled with secondary treatment via oxidation ponds. In 1961, a dike was built across Amargosa Creek along Avenue C (C Dike) on EAFB property to prevent the treated effluent from flowing onto Rosamond Dry Lake. C Dike created a surface water impoundment that is known as Piute Ponds. Over the years, a significant amount of marsh-type habitat has formed in and around the ponds. Currently, Piute Ponds consists of approximately 400 acres of marsh-type habitat, providing refuse refuge to various species of birds and animals. Originally, Piute Ponds provided sufficient storage and evaporative capacity to prevent the treated effluent discharged to Amargosa Creek from flowing onto Rosamond Dry Lake. However, as flow to the LWRP increased, the capacity of the ponds became insufficient to prevent discharges of effluent to Piute Ponds from overflowing onto Rosamond Dry Lake. In the 1970s, effluent-induced overflows began to occur. The Districts completed a draft EIR in 1977 for the Wastewater Facilities Plan for Sanitation Districts 14 and 20, which identified the facilities necessary to expand the LWRP and prevent effluent-induced overflows from Piute Ponds. A number of comments were received on the draft EIR requesting that Piute Ponds be maintained. Following a series of document revisions, the Districts completed the Supplemental Report Finalizing the Wastewater Facilities Plan for District No. 14 in The recommended facilities identified in the 1981 supplemental report were designed to accommodate an additional 2.0 mgd, for a total influent flow rate of 6.5 mgd, and included agricultural reuse and storage reservoirs. Because water demands for agriculture are seasonal, storage reservoirs were constructed to hold recycled water generated during the winter months for use during the summer months. The storage reservoirs provided sufficient holding capacity for recycled water to support both the needs of Piute Ponds and the agricultural reuse operations, while eliminating effluent-induced overflows from Piute Ponds to Rosamond Dry Lake. To ensure habitat maintenance at Piute Ponds, District No. 14, EAFB, and the DFG entered into an MOULOA on May 6, 1981, requiring District No. 14 to discharge effluent from the Final LWRP 2020 Plan EIR 2-1 May 2004

3 Chapter 2 Existing Facilities LWRP to Piute Ponds at a rate sufficient to maintain a minimum of 200 wetted acres. Appendix D contains a copy of the MOULOA. In 1991, Ducks Unlimited constructed additional impoundments on the south east side of Piute Ponds. Under a Memorandum of Agreement (MOA) signed by EAFB and District No. 14 on March 8, 1991, the Impoundment Areas can be filled each year for duck hunting season, but no discharge is allowed to these impoundments before November 1 or after April 15, unless approved by EAFB. A copy of the MOA is found in Appendix D. Consequently, these impoundments are dry from about June through October. The LWRP has since undergone expansions in 1989, 1992, and 1997, and currently has a design capacity of 16.0 mgd. For each expansion, an Addendum to the 1981 Supplemental Report Finalizing the Wastewater Facilities Plan for District No. 14 or a Negative Declaration has been prepared to comply with CEQA. As the plant influent flow has increased, the LWRP effluent management system has not been able to prevent effluent-induced overflows from Piute Ponds. Discharges of effluent from the LWRP to Piute Ponds have caused the ponds to overflow to Rosamond Dry Lake for up to nine months of the year. In recent years, District No. 14 has modified its effluent management practices, with the annual authorization of EAFB, in order to limit effluent-induced overflows to approximately four months per year. 2.2 EXISTING TREATMENT FACILITIES The LWRP is located at 1865 West Avenue D in an unincorporated area of the County north of the City of Lancaster. The LWRP provides a minimum of undisinfected secondary treatment for all effluent. Raw sewage is gravity fed to the LWRP from the service area through a 42-inch trunk sewer that enters the facility from the south. The influent is pumped through comminutors and aerated grit chambers to remove inorganic solids and gravity flows to the primary sedimentation tanks. The primary effluent then flows by gravity to open-air oxidation ponds, some of which are equipped with surface aerators. These oxidation ponds provide secondary treatment. Sludge is collected from the primary sedimentation tanks and conveyed to the sludge digesters. District No. 14 also owns and maintains the collection system of trunk sewers in its service area. Remaining sewer capacity and physical sewer conditions are checked biennially to determine whether repairs or hydraulic relief is required. In March 2003, District No. 14 completed the Rosamond Outfall and Trunk F Sewer Facilities Plan, which identified current problems in the wastewater conveyance system and recommended sewer relief and replacement projects. Final LWRP 2020 Plan EIR 2-2 May 2004

4 Chapter 2 Existing Facilities The AVTTP provides tertiary treatment to effluent that is then discharged to Apollo Park. The AVTTP provides further treatment to secondary-treated effluent by flocculation, filtration, phosphorus removal, and disinfection to an annual average flow of approximately 0.15 mgd. Photos of Apollo Park and Piute Ponds are shown in Figures 2-1 and 2-2, respectively. Figure 2-3 shows the outer berm of an oxidation pond at the treatment facility. Figure 2-4 shows the ditch that discharges to Amargosa Creek. Table 2-1 summarizes the treatment equipment currently in operation at the LWRP. Figures 2-5 and 2-6 show the existing LWRP site plan. Figure 2-7 provides a schematic flow chart of the existing treatment systems. 2.3 EFFLUENT MANAGEMENT The recycled water from the LWRP is discharged to and/or reused at four sites. Approximately 1.7 mgd is lost via evaporation from the facilities at the LWRP. Disinfected treated effluent enters a ditch that flows to Piute Ponds and the adjacent Impoundment Areas via Amargosa Creek. Table 2-2 summarizes the LWRP effluent management flows for An average of approximately 6.64 mgd of disinfected secondary-treated effluent was discharged from the LWRP into the ditch that leads into the Amargosa Creek and subsequently Piute Ponds in In accordance with the March 1991 MOA, approximately 0.26 mgd of disinfected secondary-treated effluent was discharged to the Impoundment Areas located adjacent to Piute Ponds from November 1 to April 15. In 2002, the AVTTP discharged an average of mgd of tertiary-treated effluent to Apollo Park. An average of approximately 4.0 mgd of undisinfected secondary-treated effluent was discharged to Nebeker Ranch in The deliveries to Nebeker Ranch are substantially reduced during the winter months. The LWRP has a storage capacity of 500 MG (1,534 acre feet). The storage reservoirs are generally empty by October to manage effluent during the winter months when lower evaporation rates result in a reduction in irrigation demand by agricultural operations. Recently implemented modifications to the effluent management scheme during the winter months, with the annual approval of EAFB, has resulted in a minimization of effluent-induced overflows onto Rosamond Dry Lake. 2.4 EXISTING EFFLUENT CHARACTERISTICS The LWRP discharges secondary-treated effluent to Piute Ponds, the adjacent Impoundment Areas, Nebeker Ranch, and the AVTTP. The AVTTP further treats a small portion of the effluent from the LWRP and discharges tertiary-treated effluent to Apollo Park. The discharge to Piute Ponds and the adjacent Impoundment Areas is disinfected with sodium hypochlorite (NaOCl). During specific times of Final LWRP 2020 Plan EIR 2-3 May 2004

5 AVE G SOURCE: Environmental Science Associates, December 2000 LWRP 2020 Plan EIR / Figure 2-1 View of Apollo Park SOURCE: Environmental Science Associates, December 2000 LWRP 2020 Plan EIR / Figure 2-2 View of Piute Ponds 7

6 SOURCE: Districts Photo, December 2000 LWRP 2020 Plan EIR / Figure 2-3 View of Storage Reservoir Berm SOURCE: Districts Photo, December 2000 LWRP 2020 Plan EIR / Figure 2-4 View of Discharge Ditch from Lancaster Water Reclamation Plant to Amargosa Creek 7

7 PLANT CAPACITY COMMINUTORS Table 2-1 Lancaster Water Reclamation Plant Design Criteria ITEM Chapter 2 Existing Facilities Average Flow (mgd) 16.0 Peak Sanitary Flow Capacity (mgd) 28.8 Peak Storm Flow Capacity (mgd) 40.0 Number 2 Capacity, each (mgd) 26 AERATED GRIT CHANNELS Number 4 Capacity (mgd) 28.8 PROCESS AIR STATION AERATED GRIT BLOWERS Number of Blowers 2 PRIMARY SEDIMENTATION TANKS Number 6 PRIMARY SLUDGE PUMPS DIGESTION TANKS Number 2 Primary Sludge Flow (gpd) 80,552 Total Number of Digesters 5 DIGESTED SLUDGE TRANSFER PUMPS Number 5 FERROUS CHLORIDE SYSTEM Number of Pumps 2 SLUDGE DRYING BEDS Number 12 Design Loading Rate (lbs dry solids/sqft-yr) 45 OXIDATION PONDS Number 8 Average Surface Area (acres)/pond 30.3 Surface Aerators 24 STORAGE RESERVOIRS Number 4 Total Surface Area (wetted acres) 160 Average Capacity, each (MG) 125 Total Capacity (MG) 500 AGRICULTURAL IRRIGATION PUMP STATION & FORCE MAIN Number of Pumps 3 Source: LWRP 2020 Plan Final LWRP 2020 Plan EIR 2-6 May 2004

8 Detail shown in Figure EQUALIZATION BASIN OXIDATION OXIDATION POND NO. 9 POND NO.10 OXIDATION POND NO. 1 OXIDATION POND NO.3 OXIDATION POND NO.5 OXIDATION POND NO.7 OXIDATION POND NO.4 OXIDATION POND NO.6 OXIDATION POND NO.8 AVENUE D SOURCE: County Sanitation Districts of Los Angeles County 20TH STREET WEST OXIDATION POND NO. 2 Not to Scale SIERRA HWY STORAGE RESERVOIR NO.1 STORAGE RESERVOIR NO.3 STORAGE RESERVOIR NO.2 STORAGE RESERVOIR NO.4 LWRP 2020 Plan EIR / Figure 2-5 Site Plan for Lancaster Wastewater Reclamation Plant UNION PACIFIC RR

9 FH OXIDATION POND NO. 9 EQUALIZATION BASIN PUMP STATION DRYING BEDS SLUDGE PROPERTY LINE Not to Scale SOURCE: County Sanitation Districts of Los Angeles County SLUDGE DRYING BEDS CLEANOUT PUMPING DIGESTER CONTROL BLDG DIGESTION TANKS CLEANOUT PUMPING OXIDATION POND NO. 1 DIVERSION STRUCTURE OXIDATION POND NO. 2 PRIMARY SEDIMENTATION TANKS ANTELOPE VALLEY TERTIARY TREATMENT PLANT PROPERTY LINE LWRP 2020 Plan EIR / Figure 2-6 Detail of Site Plan for Lancaster Wastewater Reclamation Plant

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11 Chapter 2 Existing Facilities Table 2-2 Average Annual Effluent Flow for 2002 AVERAGE ANNUAL EFFLUENT FLOW (mgd) Piute Ponds 6.64 Impoundment Areas 0.26 Nebeker Ranch 4.0 Apollo Park 0.16 In-Plant Evaporation (oxidation ponds and storage 1.74 reservoirs) TOTAL 12.8 Source: CSDLAC, 2002 the year, such as duck hunting season, the quantity of NaOCl is increased. Table 2-3 summarizes the average monthly flow treated at the LWRP and AVTTP for In compliance with the WDRs issued for the LWRP by the RWQCB-LR, effluent is monitored for 3 constituents on a daily basis, 7 constituents on a weekly basis, 4 constituents on a monthly basis, 15 on a quarterly basis, and 132 more constituents on an annual basis. Tables 2-4 through 2-8 summarize the LWRP and AVTTP effluent quality for the year Table 2-3 Influent Flow Rates for 2002 LWRP AVTTP MONTH AVERAGE MONTHLY MAXIMUM MONTHLY AVERAGE MONTHLY FLOW RATE FLOW RATE FLOW RATE (mgd) (mgd) (mgd) January February March April May June July August September October November December YEARLY AVERAGE Source: LWRP2020 Plan Final LWRP 2020 Plan EIR 2-10 May 2004

12 Table 2-4 Semi-Annual Undisinfected Secondary Effluent Monitoring Results Chapter 2 Existing Facilities CONSTITUENT RANGE AVERAGE Sulfate (mg/l) Chloride (mg/l) Source: LWRP 2020 Plan Table 2-5 Undisinfected Secondary Effluent Monitoring Results for Constituents Monitored Annually a CONSTITUENT ANALYTICAL RESULT Total Cyanide (mg/l) Total Hardness (mg/l) 143 Total Phosphate (mg/l) 12.5 Fluoride (mg/l) 0.57 Boron (mg/l) 0.58 Total Organic Carbon (mg/l) 55.8 Chloroform (mg/l) 7 Toluene (mg/l) 1 Calcium (mg/l) 37.3 Magnesium (mg/l) 12.7 Arsenic (mg/l) Barium (mg/l) Copper (mg/l) Lead (mg/l) Manganese (mg/l) 0.02 Sodium (mg/l) 149 Zinc (mg/l) 0.13 Antimony (mg/l) Source: LWRP 2020 Plan (a) Constituents with detections. Table 2-6 Disinfected Secondary Effluent Monitoring Results CONSTITUENT RANGE AVERAGE PERMIT LIMIT Total Coliform, Daily Grab (MPN/100mL) < 2 a - 2 < 2 23 (maximum) b Total Coliform, 7 Day Median (MPN/100mL) < 2-2 < (maximum) Total Suspended Solids N/A Sulfate (mg/l) N/A Chloride (mg/l) N/A MBAS (mg/l) < (maximum) Oil & Grease (mg/l) < N/A Source: LWRP 2020 Plan (a) < x indicates constituent was not detected, with the detection limit being x. (b) The number of coliforms must not exceed 23MPN/100mL in more than one sample during any 30-day period. Final LWRP 2020 Plan EIR 2-11 May 2004

13 Chapter 2 Existing Facilities Table Antelope Valley Tertiary Treatment Plant Routine Effluent Monitoring Results CONSTITUENT RANGE AVERAGE PERMIT LIMIT Total Coliform, Daily Grab (MPN/100mL) < 1 a - < 1 < 1 23 (maximum) b Total Coliform, 7 Day Median (MPN/100mL) < 1 - < 1 < (maximum) Turbidity, 24-Hour Composite (NTU) N/A Turbidity, 30-Day Mean (NTU) (maximum) Turbidity, Time > 5 NTU (minutes) (maximum) MBAS (mg/l) (maximum) Soluble BOD (mg/l) (average) 45 (maximum) Soluble COD (mg/l) N/A Nitrate Nitrogen (mg/l-n) N/A Ammonia Nitrogen (mg/l-n) < < 0.3 N/A Kjeldahl Nitrogen (mg/l-n) < 0.7 N/A Source: LWRP 2020 Plan (a) < x indicates constituent was not detected, with the detection limit being x. (b) The number of coliforms must not exceed 23MPN/100mL in more than one sample during any 30-day period. Table Lancaster Water Reclamation Plant Routine Undisinfected Secondary Effluent Monitoring Results CONSTITUENT RANGE AVERAGE PERMIT LIMITS Soluble Carbonaceous BOD (mg/l) < 3 a - 18 < 7 N/A Soluble BOD (mg/l) (30-day average) 45 (maximum) Soluble COD (mg/l) N/A ph (ph units) (minimum) 9.0 (maximum) Dissolved Oxygen (mg/l) (minimum) Total Dissolved Solids (mg/l) N/A Total Suspended Solids (mg/l) N/A MBAS (mg/l) (average) 2.0 (maximum) Oil & Grease (mg/l) < N/A Kjeldahl Nitrogen (mg/l) N/A Nitrate Nitrogen (mg/l) N/A Ammonia Nitrogen (mg/l) N/A Source: LWRP 2020 Plan (a) < x indicates constituent was defected, with the detection limit being x. Final LWRP 2020 Plan EIR 2-12 May 2004

14 Chapter 2 Existing Facilities 2.5 SOLIDS PROCESSING Biosolids Management Solids removed from the influent during primary treatment are treated on site. The LWRP produced approximately 853 dry tons of Class B biosolids in the year Primary sludge and skimmings are anaerobically digested in the on site digesters. Dewatered biosolids are stockpiled on site until removed for reuse and/or disposal. The LWRP is permitted to stockpile solids for up to two years. In 2002, approximately 990 dry tons of biosolids were hauled to the San Joaquin Composting Facility in Kern County to be processed into soil amendments. The solids content of transported biosolids is typically in excess of 80 percent. Annual biosolids monitoring reports are submitted to EPA. Biosolids Regulatory Background Biosolids are regulated under the Code of Federal Regulations (CFR) 40, Part 503. The regulations contain standards for management of wastewater residuals that are (1) beneficially reused for soil enhancement through land applicationpurposes, (2) disposed of at dedicated sites or landfills, or (3) incinerated. Part 503 regulations identify criteria for evaluating the quality of biosolids based on pollutant thresholds, pathogen quantity, and vector attraction reduction. Any biosolids exceeding the established criteria thresholds cannot be directly land-applied. Part 503 classifies biosolids into two classes: Class A and Class B. Class A biosolids have been treated sufficiently for all pathogens to be essentially eliminatedto be considered essentially pathogen free. Class B biosolids have been treated sufficiently for the level of pathogens to be substantially reduced but not completely removedeliminated. Reuse of Class B biosolids requires adherence to more restrictions have a much more restricted use than use of Class A biosolids. In addition, the EPA published the Standards for the Use or Disposal of Sewage Sludge, known as the Round One regulation, in February 1993 in compliance with Section 405 of the CWA. The Round One regulation sets limits for metals, pathogens, and total hydrocarbons for land application, surface disposal, and incineration of sewage sludge. Section 405 of the CWA also requires Round Two regulation for pollutants not previously regulated under the Round One regulation. As the result of a citizen s suit, EPA was required to propose Round Two regulations by December 15, 1999, and to take final actions by December 15, In November 1995, EPA notified the court that, based on risk assessment results, they were considering Final LWRP 2020 Plan EIR 2-13 May 2004

15 Chapter 2 Existing Facilities further regulations only for dioxins. 1 However, the EPA recently decided not to regulate dioxin in landapplied biosolids. The SWRCB regulates the land application of biosolids through either General Order permits or site specific WDRs issued by the RWQCB. The SWRCB issued Water Quality Order No DWQ, which covers the general waste discharge requirements for discharging biosolids to land for use as a soil amendment in agricultural and for land reclamation activities. The SWRCB standards for land application are more stringent than currently follows EPA guidelines (Part 503) on land application of biosolids. 2.6 INFLOW AND INFILTRATION Infiltration occurs when groundwater enters the sewer system through cracks and holes in the sewer pipes. Since groundwater levels are generally low in the LWRP service area, infiltration has not been a large problem. The LWRP 2020 Plan estimated the average wastewater generation rate due to infiltration to be 100 gpcd during the winter of , the winter with the highest recorded rainfall at the LWRP in recent years. This compares favorably to the annual average infiltration wastewater generation rate of 94 gpcd. Inflow, on the other hand, results from excessive flow into the sewer system and usually occurs during and after storms through manhole covers. Substantial storm water inflow has occurred within the District No. 14 service area in the past, increasing the LWRP's peak flow capacity needs. The LWRP 2020 Plan estimated that, during the winter of , the peak wastewater generation rate was 226 gpcd. As a result, District No. 14 has pursued a policy of maintaining and sealing manholes to reduce inflow as much as possible. 2.7 CONSERVATION Local water purveyors have the primary responsibility for implementing water conservation measures. The reuse of effluent for agricultural purposes at Nebeker Ranch results in an equivalent reduction in the volume of groundwater that would otherwise be extracted. Providing low-flow toilets and showers has resulted in a substantial portion of the conservation credits experienced by the wastewater treatment facilities in the southern portions of the County. Since development is relatively newer more recent in the Antelope Valley, these low-flow devises are generally already installed. 1 U.S. Environmental Protection Agency. Accessed on 15 August Final LWRP 2020 Plan EIR 2-14 May 2004