CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD

CENTRAL VALLEY REGION

ORDER NO. 98-184

WASTE DISCHARGE REQUIREMENTS

FOR

STANISLAUS COUNTY DEPARTMENT OF PUBLIC WORKS

FINK ROAD LANDFILL FACILITY

CLASS II AND CLASS III LANDFILLS

CLASS II SURFACE IMPOUNDMENTS

STANISLAUS COUNTY

 

The California Regional Water Quality Control Board, Central Valley Region, (hereafter Board) finds that:

  1. The County of Stanislaus, Department of Public Works, (hereafter Discharger) owns and operates the Fink Road Landfill facility. The facility was previously regulated by WDR No. 94-257 in conformance with Title 27, California Code of Regulations (CCR), Division 2, Subdivision 1 (hereafter Title 27).
  2. On 21 July 1998 the Discharger submitted a Report of Waste Discharge requesting approval of an engineered alternative for the design of LF-2, Cell 3 and future cells, and surface impoundment SI-1.
  3. The Fink Road Landfill facility is a 219-acre disposal site, comprised of Assessor Parcel Number 27-17-40. The site is 3.5 miles west of Crows Landing, in Section 30, T6S, R7E, MDB&M, as shown in Attachment "A", which is incorporated herein and made part of this Order. The area served by the landfill is Stanislaus County.
  4. The waste management facility consists of an inactive 18.3-acre Class III municipal solid waste landfill, (LF-l); an active 92.3-acre Class III municipal solid waste landfill (LF-2) with seven cells; an active 37-acre Class II ash monofill, (LF-3) with six cells; a 1-acre Class II surface impoundment (SI-1) for impoundment of leachate from the leachate collection and removal system (LCRS) of LF-3; and a 1.4-acre Class II surface impoundment (SI-2) for impoundment of leachate from the LCRS of LF-2.
  5. The waste management units (WMUs) at Fink Road are described in the following table:
Unit Classification Description of Liner Components (top to bottom) Status
LF-1 Class III landfill Unlined and no LCRS Filled and closed- final cap constructed in 1997
LF-2 Class III landfill (Cell 1) 1 ft. operations layer, nonwoven fabric, 6 in. LCRS drainage layer, non woven fabric, 1 ft. low permeability soil layer (KS 1 x 10 -6 cm/sec) Filled, with interim cover
LF-2 Class III landfill (Cell 2) 15 in. operations layer, nonwoven fabric, 6 in. LCRS drainage layer, 60 mil textural HDPE, 2 ft. low permeability soil layer (KS 1 x 10 -7 cm/sec) Operating, nearing capacity
LF-3 Class II ash monofill (Cell 1) 12 in. soil operations layer, nonwoven fabric, 8 in. LCRS drainage layer, non woven fabric, 2 ft. low permeability soil layer (KS 1 x 10 -6 cm/sec) At capacity
LF-3 Class II ash monofill (Cell 2) 15 in. operations layer, nonwoven fabric, 6 in. LCRS drainage layer, 60 mil textural HDPE, 2 ft. low permeability soil layer (KS 1 x 10 -7 cm/sec) Operating
SI-1 Class II surface impoundment 1 ft. soil cover, 2 ft. low permeability soil layer (KS 1 x 10-6 cm/sec), nonwoven fabric, 8 in. LCRS drainage layer, nonwoven fabric, 2 ft. low permeability soil layer (KS 1 x 10 -6 cm/sec) Operating
SI-2 Class II surface impoundment 80 mil HDPE, geonet, 80 mil HDPE, 2 ft. low permeability soil layer (KS 1 x 10 -6 cm/sec) Operating

 

  1. Ogden Martin Systems of Stanislaus, Incorporated (OMSS), (formerly Stanislaus Waste-to-Energy Company or SWEC), constructed in 1988, operates a waste-to-energy cogeneration facility (hereafter OMSS plant) at the Fink Road Landfill. The OMSS plant occupies a 16.5 acre area at the southwest corner of the site. The OMSS plant generates electricity from combustion of municipal solid waste. Boiler ash generated as a combustion residue has been discharged to LF-3 since the fall of 1988. The addition of a lime-water mixture to de-acidify contaminated flue gases and the quenching of ashes with water at the OMSS plant results in generation of significant moisture within the boiler ash.
  2. On 25 March 1991, the Discharger submitted a Combustion Ash Moisture Monitoring Plan which was implemented beginning 1 May 1991.

 

WASTES AND THEIR CLASSIFICATION

  1. The 18.3-acre LF-1 was permitted for the disposal of municipal solid waste, infectious waste, and construction debris. These wastes are classified as "nonhazardous solid waste" or "inert waste" using the criteria set forth in Title 27. Since July 1990, LF-1 received about 175 tons per day of municipal solid waste. Landfill operations in LF-1 ceased in June 1993 following the construction and discharge of waste to LF-2, Cell 1.
  2. The 92.3-acre LF-2 is currently used for the disposal of municipal solid waste, treated medical waste, and construction debris. These wastes are classified as "nonhazardous solid waste" or "inert waste" using the criteria set forth in Title 27. LF-2 began receiving wastes in April 1993.
  3. The Discharger also proposes to discharge wastes containing greater than one percent (>1%) friable asbestos for disposal in LF-2. These wastes are classified as ‘hazardous' under Title 22 of the CCR. However, because these wastes do not pose a threat to ground water quality, Section 25143.7 of the Health and Safety Code permits their disposal in any landfill which has WDRs that specifically permit the discharge, provided that the wastes are handled and disposed of in accordance with federal statutes and regulations.

    4.  

  4. About 300 tons per day of boiler ash is generated from the OMSS plant. The Discharger proposes to continue to discharge boiler ash from the OMSS plant to LF-3, a separate monofill unit designed and operated to isolate this waste from putrescible organic matter which could produce acidic leachate. Five additional cells will be constructed within LF-3. LF-3, Cell 1 reached capacity in May 1994. LF-3, Cell 2 is constructed and receiving ash from the OMSS plant.
  5. The OMSS plant ash contains soluble cadmium and lead measured by the California Waste Extraction Test and total lead concentrations that exceed Soluble Threshold Limit Concentrations and Total Threshold Limit Concentrations (STLCs and TTLC) regulatory thresholds, respectively, for toxic and hazardous waste established by the Department of Toxic Substances Control (DTSC) and specified in Title 22, CCR. On 8 February 1990, DTSC approved a request to manage and classify the boiler ash as ‘non-hazardous' because of mitigating characteristics.

    6.  

    DESCRIPTION OF THE SITE

  6. The site is within dissected alluvial fans at the western margin of the San Joaquin Valley with elevations ranging from 240 to 350 feet above mean sea level (MSL).
  7. Land within 1,000 feet of the site is used for agriculture, including grazing, row crops and orchards. The OMSS plant is also adjacent to the landfill areas.
  8. Soils immediately underlying the WMUs are alluvial deposits consisting predominately of interbedded clays, silts, and sands with minor amounts of gravels. Permeabilities of the interbedded layers displayed values ranging from 1x10-4 to 1x10-9 cm/sec based on laboratory tests.
  9. Surface soils consist of 2.5 to 14.5 feet thick of stiff silty clays with traces of sand and gravel. Below the surface soils, interbedded layers of medium dense to very dense sand and gravels and stiff to hard silts and clays of the Tulare formation are present.
  10. Two faults which have the potential to affect the facility are the potentially active Ortigalita fault, about 20 miles south of the site, and the active Calaveras fault, about 28 miles southwest of the site.
  11. Meteorological measurements made in Modesto between 1951 and 1974 were assumed by Stanislaus County to be representative for the Fink Road site. Based on these assumptions the site receives a yearly average of 11.8 inches of precipitation and has a mean evaporation rate of 33.9 inches per year which equates to an annual net evaporation of +22.1 inches.
  12. The 100-year, wet year precipitation for the site is 21.2 inches as calculated by the California Department of Water Resources Bulletin No. 195. The l,000-year, 24-hour precipitation event for the site is 3.53 inches as calculated by the California Department of Water Resources' 1982 "Rainfall-Depth-Duration Frequency for California", Division of Planning.
  13. The site is not within a 100-year floodplain, as determined from Federal Flood Insurance Map, Community Panel No. 060384-0700A.

who own or operate landfill units at which municipal solid waste (MSW) is discharged. The majority of the federal MSW regulations became effective on the "Federal Deadline", 9 October 1993.