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v California Regional Water Quality Control Board Central Valley-_ Recrlon Robert Schneider,Chair Terry Tamminen Sacramento blain Office Arnold Schw irzenegger Secretary for Internet Address: http:llwr«v.sivrcb.ca.govlrwgcb5 Governor Environmental 11020 Sun Center Drive#200 Rancho Cordova,CA 95670-6114 Protection Phone(916)464-3291 Fax(916)464-4797 _ _ - — - ,- 22 October 2004 2004 Mr. Bud den Ouden -1 Ripon Farm Service P.O. Box 806 Ripon, CA 95366-0806 MONITORING WELL WORK PLAN, RIPON FARM SERVICE, 228 71 HIGH11'A Y 99 S., RIPON, SAN JOAQ UIN COUNTY The domestic water supply well at Ripon Farm Service has contained high concentrations of nitrate, and in a 16 July 2004 letter, Central Valley Regional Water Quality Control Board (Regional Board) staff. requested that Ripon Farm Service conduct a subsurface investigation to evaluate'«vhether on-site activities have affected.local groundwater. In response, your consultant, Advanced GeoEnvironmental Inc. (AGE) transmitted the 30 August 2004 Monitoring Mell Installation TV ork Plan (Work Plan). Background The Work Plan states that Ripon Farm Service has been operating a fertilizer formulation and retail outlet at this location for about 45 years. In the western portion of the site, four underground fuel tanks were removed in 1987, and investigation and remediation are Underway. Eight monitoring wells are associated with the fuel tanks, and an air sparging/soil vapor extraction remediation system has been operational since 1994. The fertilizer handling facilities are predominately in the central and eastern portion of the site. The City of Ripon has installed a municipal water supply well (Well 12) about 700 feet due east-of Ripon Farm Service which has contained increasing concentrations of nitrate since 2003. As of July 2004, this well contained 62 mg/l nitrate (as nitrate). The City of Ripon is concerned that Ripon Farm Service operations maybe contributing to the increased concentrations observed in this well. San Joaquin County Environmental Health Department is concerned about concentrations of nitrate (as nitrate) as high as 800 mg/l identified in the on-site water supply well serving Ripon Farm Service. In 2004, the concentrations of nitrate in this well ranged from 60 to 317 mg/l nitrate (as nitrate), depending upon which laboratory obtained and ran the analyses, according to a 14 October 2004 telephone conversation with Mr. Bud den Ouden of Ripon Farm Service. Mr. Den Ouden stated that when a single sample was split between two laboratories, the results were 60 and 70 mg/l. In a 15 October 2004 telephone conversation with Mr. William Little of AGE, he related that a residence adjacent to Ripon Farm Service, upgradient of and adjacent to its water suppI'y well,had had a failed septic system and that.the residence has been removed. California Environmental Protection Agency Q.J Recycled Paper