CORRESPONDENCE_1990-1993 - Laserfiche WebLink

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WASTE DISCHARGE REQUIREMENTS -4- FORWARD INC.,FORWARD LANDFILL SAN JOAQUIN COUNTY DESCRIPTION OF SITE 14. Land within 1,000 feet of the site is primarily used for agriculture. The City of Stockton's municipal solid waste landfill is about 1000 feet north of the Forward facility. The City of Stockton may expand its facility to include the property adjacent to Forward's northern boundary. 15. The shallow ground water beneath the site is contained in the Victor Formation. These sediments generally have moderate permeabilities with locally high permeabilities in the sandy and gravelly lenses. Ground water in the Victor Formation is unconfined and flows in a north-northeasterly direction beneath the site.Locally,ground surface is about 40 feet in elevation. The regional ground water table is about 60 to 70 feet below ground surface or-20 to -30 feet in elevation. The quality of this water is suitable for domestic or agricultural use. 16. Low levels of volatile organic compounds (VOCs) have been found in monitoring wells (MWs) at the facility between June 1988 and June 1993. Based on 1992 monitoring results,wells MW 2A/B, 5A/5B, 13A/B and 14A/B were impacted by a release of VOCs from the landfill. These VOCs included halogenated compounds such as trichloroethene,tetrachloroethane, 1,1-dichloroethane, 1,2-- dichloroethane, 1,1-dichloroethene,cis-l,2-dichloroethene,chloroethane and dichlorodifluoromethane in concentrations between 0.2 and 3.0µg/1. Phenolics (total phenols)were reported in wells MW-1B, 3B, 8, 13B, 14, 19 and 20 at levels between 6 and 50 µg/l. Other aromatic VOCs including benzene, toluene and xylenes were also found in ground water samples. Inorganic constituents, such as chloride, were elevated in wells MW-1, 2, 3, 13, 14 and 15 compared to background well MW-12. In general, the 1992 monitoring results indicated a trend of increasing contaminants in ground water. Results for the first two quarters of 1993,however, suggest halogenated VOC occurrences and concentrations are decreasing.Evidence collected to date does not identify which waste management unit is the source of the contaminants. 17. The beneficial uses of ground water are municipal, domestic, agricultural, and industrial supply. 18. The site receives an average of 14.27 inches of precipitation per year based on precipitation data from the Stockton WBAP Station number B00-8560 approximately 8 miles northwest of the site. The mean evaporation for this site is 78.43 inches per year as measured at Oakdale Woodard Reservoir between the years 1919 and 1968. Based on these data, average annual net evaporation at the site is 64.16 inches. 19. The 1,000-year, 24-hour precipitation event for the site is 4.11 inches. The 100-year, 24-hour precipitation event is 3.25 inches. The estimated 100-year annual precipitation is 25.42 inches. 20. The site is not within a 100-year floodplain as shown on Federal Insurance Rate Map for San Joaquin County, dated 15 May 1980. 21. Surface drainage is to the South Fork of South Littlejohn Creek, which is tributary to South Littlejohn Creek, which flows into Littlejohn Creek, tributary to French Camp Slough, hence San Joaquin River and the Delta.