SVCSD - NPDES Permit No. CA0037800 Order No. 02-____
CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD
SAN FRANCISCO BAY REGION
1515 CLAY STREET, SUITE 1400
OAKLAND, CA 94612
(510) 622 – 2300 Fax: (510) 622 - 2460
FACT SHEET
for
NPDES PERMIT and WASTE DISCHARGE REQUIREMENTS for
SONOMA VALLEY COUNTY SANITATION DISTRICT
SONOMA, SONOMA COUNTY
NPDES Permit No. CA0037800
PUBLIC NOTICE:
Written Comments
· Interested persons are invited to submit written comments concerning this draft permit.
· Comments should be submitted to the Regional Board no later than 5:00 p.m. on February 28, 2002.
Public Hearing
· The draft permit will be considered for adoption by the Board at a public hearing during the Board’s regular monthly meeting at: Elihu Harris State Office Building, 1515 Clay Street, Oakland, CA; 1st floor Auditorium.
· This meeting will be held on: March 20, 2002, starting at 9:00 am.
Additional Information
· For additional information about this matter, interested persons should contact Regional Board staff member: Ms. Tong Yin, Phone: (510) 622-1008; email:
This Fact Sheet contains information regarding an application for waste discharge requirements and National Pollutant Discharge Elimination System (NPDES) permit for the Sonoma Valley County Sanitation District (SVCSD or District) for discharges of treated wastewater from the treatment facilities. The Fact Sheet describes the factual, legal, and methodological basis for the proposed permit and provides supporting documentation to explain the rationale and assumptions used in deriving the limits.
I. INTRODUCTION
The Sonoma Valley County Sanitation District (SVCSD, hereinafter referred to as the Discharger), has appealed the current permit (Order No. 98-111) to discharge treated wastewater to waters of the State and the United States under the National Pollutant Discharge Elimination System (NPDES). As part of the Settlement Agreement, a new permit will be reissued before Order No. 98-111 expires (October 21, 2003).
The Discharger owns and operates the municipal wastewater treatment plant located at 22675 Eighth Street East near the city of Sonoma, Sonoma County. The Board of Directors of the Sonoma Valley County Sanitation District transferred operating authority for the SVCSD from the Public Works Department to the Sonoma County Water Agency on January 1, 1995. The plant provides secondary level treatment for domestic and light commercial wastewater collected from the cities and unincorporated areas of Sonoma, Glen Ellen, Boyes Hot Springs, and Agua Caliente. The Discharger's service area currently has a population of approximately 34,500 people. The treatment plant has an average dry weather flow design capacity of 3.0 million gallons per day (mgd) and can treat up to 8.0 mgd during the wet weather flow period. Flows higher than 8.0 mgd are bypassed to 35 million gallon equalization basins. During the 1999-2000 wet season, the plant discharged an average of 4.6 mgd of treated wastewater. Approximately 2.8 mgd of the effluent is discharged to holding ponds and most of which was reclaimed during the dry season of 2000.
During the wet weather period from November 1 through April 30, treated wastewater is discharged into Schell Slough (Latitude: 38° 14' 14" and Longitude: 122° 25' 51"). Schell Slough is a tidal estuary, which receives freshwater flow from Schell Creek during the wet weather months. During the dry weather months, Schell Slough is a dead end slough, and is flushed only by limited tidal action. Schell Slough flows into Steamboat Slough, which is tributary to San Pablo Bay by way of the Third Napa Slough, the Second Napa Slough, and the lower reach of Sonoma Creek. Prior to implementation of a reclamation project in May 1992, treated wastewater was discharged into Schell Slough year round. During the dry weather season, treated effluent is now reclaimed for agricultural irrigation and wetland enhancement. In addition to the Schell Slough discharge, this permit allows, under specified conditions, discharge of treated wastewater from the reclamation project to Hudeman Slough, Ringstrom Bay, and several wetland management areas. Hudeman Slough flows into Second Napa Slough and Ringstrom Bay flows into Schell Slough.
During the dry season period from May1 through October 31, the Discharger may discharge treated wastewater stored in R1 and R2 through MU1 and MU3 to Hudeman Slough. The Discharger also has the physical capability of pumping this remaining water back to its Schell Slough discharge point, although this is not the Discharger’s current practice. Starting in 1999, the Discharger made repairs to R1 and R2 which included redirecting local drainage around R1, thereby eliminating the need to drain R1 rapidly at the onset of the wet weather season and eliminating the need for the Discharger to pump remaining water back to its Schell Slough discharge point.
In addition to discharging to Hudeman Slough via Management Units 1 and 3, reclaimed water is discharged to a wetland area owned by the Department of Fish and Game (DFG) known as Ringstrom Bay, located adjacent to the site of the OLF facility. Reclaimed water is discharged to Ringstrom Bay at the request of the Discharger in mid-late summer when the storage reservoirs are at their capacity. Treated wastewater is stored in Ringstrom Bay until discharge to Schell Slough is allowed. Most of the time, Ringstrom Bay is managed as a muted tidal wetland with brackish water entering and leaving the wetland at the tidal sequence through a tide gate controlled by DFG. The new storage reservoir (R4) will be located at the OLF site and will also have a discharge point to Ringstrom Bay.
The beneficial uses of Sonoma Creek, as identified in the Basin Plan and based on known uses of the receiving waters in the vicinity of the discharges, are:
· Water Contact Recreation
· Non-contact Water Recreation
· Cold Freshwater Habitat
· Warm Freshwater Habitat
· Wildlife Habitat
· Preservation of Rare and Endangered Species
· Fish Migration
· Fish Spawning
· Estuarine Habitat
The beneficial uses of San Pablo Bay identified in the Basin Plan, are:
· Industrial Service Supply
· Navigation
· Water Contact Recreation
· Non-contact Water Recreation
· Ocean Commercial and Sport Fishing
· Wildlife Habitat
· Preservation of Rare and Endangered Species
· Fish Migration
· Fish Spawning
· Shellfish Harvesting
· Estuarine Habitat
Beneficial uses for the wetlands are determined site specifically and per discussions with Department Fish and Game (DFG) personnel and biologists within the Board staff. The Basin Plan (page2-7) states the following “[T]ere are many potential beneficial uses of wetlands. …because of the large number of small and non-contiguous wetlands, it will probably not be practical to delineate and specify beneficial uses for every wetland area. Therefore, beneficial uses may be determined site specifically, as needed”.
Based on best professional judgment (BPJ), the following beneficial uses are supported by the wetland units (MU1 and MU3) and Ringstrom Bay:
· Wildlife Habitat
· Preservation of Rare and Endangered Species
· Estuarine Habitat
· Non-contact Water Recreation (birding)
· Water Contact Recreation (hunting)
· Fish Migration
· Fish Spawning
· Groundwater Recharge
Because Schell and Hudeman Sloughs and Ringstrom Bay are tidally influenced, with freshwater input during the rainy season, the effluent limitations specified in this Order for discharges to Schell and Hudeman Sloughs, Ringstrom Bay, are the lower of the marine and fresh water limitations.
II. DESCRIPTION OF EFFLUENT
Board Order No. 98-111, adopted by the Board on October 21, 1998, currently regulates the discharge from the treatment plant.
1. Effluent Characteristics
The Discharger’s treated wastewater has the characteristics summarized in Table A. The data in Table A represent at least monthly monitoring performed from March 1998 through August 2001. Results for detected organic constituents are included in Table A. All other organic constituents were not detected. The average values in Table A reflect the averages of only the detected values for each parameter.
Table A. Summary of Effluent Data for Outfall E001
Constituent / Average / or Detected Value (1) / Maximum /BOD5 (mg/l) * / 6.80 / 24
TSS (mg/l) * / 7.62 / 23
pH* / 6.70 / 6.9 (max) / 6.6 (min)
DO (mg/L) * / 7.55 / 6.0 (minimum)
Oil & Grease (mg/L) * / <5 (median) / 70
Settable Matter (mg/L) * / <0.1 (median) / 15
Arsenic (mg/l) / 2.7 / 3.3
Copper (mg/l) / 8.1 / 24
Mercury (mg/l) / 0.013 / 0.41
Nickel (mg/l) / 3.11 / 5.5
Silver (mg/l) / 0.55 / 1.1
Zinc (mg/l) / 57.5 / 140
Cyanide (mg/l) / 7.5 / 13
Chlorodibromomethane (mg/l) / 1.48 / 3.8
Chloroform (mg/l) / 39.4 / 150
Dichlorobromomethane (mg/l) / 7.4 / 17
Methyl Chloride (mg/l) / 31 / 3
Tetrachloroethylene (mg/l) / 0.611 / 0.6
Toluene (mg/l) / 0.91 / 1.3
Phenol (mg/l) / 0.92 / 1.7
Acenaphthene (mg/l) / 21 / 2
Benzo(a)Anthracene (mg/l) / 0.031 / 0.03
Benzo(a)Pyrene (mg/l) / 0.031 / 0.03
Benzo(ghi)Perylene (mg/l) / 0.021 / 0.02
Chrysene (mg/l) / 0.071 / 0.07
Fluorene (mg/l) / 0.031 / 0.03
Indeno(1,2,3-cd)Pyrene (mg/l) / 0.031 / 0.03
Phenanthrene (mg/l) / 0.11 / 0.12
Pyrene (mg/l) / 0.11 / 0.1
gamma-BHC (mg/l) / 0.02 / 0.022
Dieldrin (mg/l) / 0.02 / 0.03
Tributyltin (mg/l) / 0.006 / 0.017
* Monthly averages are used to calculate the average, maximum or minimum;
1 Where constituents were detected only once, this is presented as the average value.
2. Solids Treatment
Wastewater solids removed during the treatment process are directed to a small circular clarifier which is used to thicken the sludge, after which, the sludge is dewatered by a belt filter press. All dewatered sludge is taken to a landfill.
3. Shallow Water Discharge Prohibition & Wastewater Reclamation
The Basin Plan prohibits the discharge of any wastewater which has particular characteristics of concern to beneficial uses at any point at which the wastewater does not receive an initial dilution of at least 10:1, or into any nontidal water, deadend slough, similar confined waters, or any immediate tributaries thereof. Discharges of wastewater to the sloughs, Ringstrom Bay, and the wetland management areas are contrary to this prohibition, due to the tidal nature of the receiving waters and limited upstream, fresh water flows. The discharge is classified as a shallow water discharge, and effluent limitations are calculated assuming no dilution.
The Basin Plan provides that exceptions to the above prohibition will be considered for discharges where: 1) an inordinate burden would be placed on the discharger relative to beneficial uses protected, and an equivalent level of environmental protection can be achieved by alternate means such as an alternative discharge site, a higher level of treatment, and/or improved treatment reliability; or, 2) the discharge is approved as a part of a reclamation project; or, 3) it can be demonstrated that net environmental benefits will be derived as a result of the discharge.
In addition to the criteria stated above for exceptions, the Basin Plan requires that the Board consider the reliability of the discharger's system in preventing inadequately treated wastewater from being discharged to the receiving water, and the environmental consequences of such discharges.
The Discharger currently reclaims treated wastewater for irrigation of agricultural lands. Discharges of treated wastewater to land are regulated by Wastewater Reclamation Requirements in Order No. 92-067, adopted by the Board on June 17, 1992.
The water reuse program implemented by the Discharger complies with the exception provision of the Basin Plan, as the discharge is approved as part of a reclamation project.
III. GENERAL RATIONALE
The following documents are the bases for the requirements contained in the proposed Order, and are referred to under the specific rationale section of this Fact Sheet.
· Federal Water Pollution Control Act, as amended (hereinafter the CWA).
· Federal Code of Regulations, Title 40 - Protection of Environment, Chapter 1, Environmental Protection Agency, Subchapter D, Water Programs, Parts 122-129 (hereinafter referred to as 40 CFR specific part number).
· Water Quality Control Plan, San Francisco Bay Basin, adopted by the Board on June 21, 1995 (hereinafter the Basin Plan). The California State Water Resources Control Board (hereinafter the State Board) approved the Basin Plan on July 20, 1995 and by California State Office of Administrative Law approved it on November 13, 1995. The Basin Plan defines beneficial uses and contains WQOs for waters of the State, including San Pablo Bay.
· California Toxics Rules, Federal Register, Vol. 65, No. 97, May 18, 2000 (hereinafter the CTR).
· National Toxics Rules 57 FR 60848, December 22, 1992, as amended (hereinafter the NTR).
· State Board’s Policy for Implementation of Toxics Standards for Inland Surface Waters, Enclosed Bays, and Estuaries of California, May 1, 2000 (hereinafter the State Implementation Policy, or SIP).
· Quality Criteria for Water, USEPA 440/5-86-001, 1986.
· Ambient Water Quality Criteria for Bacteria – 1986, USEPA440/5-84-002, January 1986.
IV. SPECIFIC RATIONALE
Several specific factors affecting the development of limitations and requirements in the proposed Order are discussed as follows:
1. Recent Plant Performance
Section 402(o) of CWA and 40 CFR 122.44(l) require that water quality-based effluent limits (WQBELs) in re-issued permits be at least as stringent as in the previous permit. The SIP specifies that interim effluent limitations, if required, must be based on current treatment facility performance or on previous permit limitations whichever is more stringent. In determining what constitutes “recent plant performance”, best professional judgment (BPJ) was used. Effluent monitoring data collected from March 1998 to August 2001 are considered representative of recent plant performance. It specifically accounts for flow variation due to wet and dry years.
2. Impaired Water Bodies in 303(d) List
The USEPA Region 9 office approved the State’s 303(d) list of impaired waterbodies on May 12, 1999. The list was prepared in accordance with section 303(d) of the CWA to identify specific waterbodies where water quality standards are not expected to be met after implementation of technology-based effluent limitations on point sources. San Pablo Bay is listed for copper, mercury, nickel, selenium, exotic species, dioxin and furan compounds, total PCBs, dioxin-like PCBs, chlordane, DDT, dieldrin, and diazinon. The TMDLs will establish waste load allocations (WLAs) and load allocations for point sources and non-point sources, respectively, and will result in achieving the water quality standards for the water body. Depending upon whether the Discharger is found to be impacting water quality in San Pablo Bay, the TMDLs may include WLAs for the dischargers. If the TMDLs address the Discharger, the final effluent limitations for this discharge would be based on the applicable WLAs.