SITE INFORMATION AND CORRESPONDENCE

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• ,7a California Regional Water Quality Control Board Central Valley Region Robert Schneider,Chair Winston H.Hickox Gray Davis Secretaryfor Fresno Branch Office Governor Environmental Internet Address: http://www.swrcb.ca.gov/—mgcb5 Protection 1685 E Street,Fresno,California 93706-2020 Phone(559)445-5116 FAX(559)445-5910 24 July 2003 c- Mr. Ben Hall Mr. Nick Musco Musco Family Olive Company Studley Company ?' 17950 Via Nicolo 17950 Via Nicolo Tracy, CA 95376 Tracy, CA 95376 R'v ADDENDUM TO HYDROGEOLOGIC INVESTIGATION WORKPLAN,MUSCO FAMILY OLIVE COMPANY, SAN JOAQUIN COUNTY We reviewed the addendum letter (Addendum), dated 18 March 2003, and prepared by Mr. Joseph Zilles and Mr. Doug Heard of Kleinfelder, Inc. on behalf of Musco Family Olive Company (Discharger) to supplement the 29 October 2002 Additional Hydrogeologic Investigation Workplan (Workplan). The Workplan was submitted in partial fulfillment of Waste Discharge Requirements ()vVDRs) Order . No. R5-2002-0148, Provision G.2.b. The Addendum addresses 22 comments (Items) presented in a 4 December 2002 Regional Board letter, which deemed the Workplan to be incomplete. Provision G.2.b requires, in part, that the Discharger submit a workplan for: additional characterization of groundwater quality around the 84-million gallon storage pond to be determined from a minimum of one well upgradient and two wells downgradient of the storage pond, characterization of percolate quality under the land treatment units (LTUs), and additional studies needed to investigate the groundwater hydrogeology of the facility. At a minimum, these additional studies must include investigation of the high TDS concentrations measured at MW-2, installation of additional wells to replace monitoring wells that have gone dry since installation, and further investigation of the occurrence and quality of groundwater beneath the land application areas. Regional Board staff in the Fresno office has spent considerable effort to become familiar with hydrogeological data submitted to date by Musco relative to what is needed to be confident with decisions that must be made. We have determined that additional specific hydrogeological work is necessary to characterize the site's complex subsurface stratigraphy. As described in the enclosed staff memorandum from Mr. James Dowdall (RG No. 4830), 13 exploratory borings drilled to a depth of 250 feet using the mud rotary drilling method and geophysically logged at specific locations (identified in the enclosed) should provide the necessary information. The logs need to be correlated to more accurately define the site's hydrogeologic framework. The information will confirm whether existing monitoring wells are located properly for compliance purposes and where additional wells should be installed. We will discuss this proposal at our upcoming meeting, during which we will also discuss Musco's proposal for installing pan lysimeters and determining the assimilative capacity of the land application site. California Environmental Protection Agency CO Recycled Paper The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways you can reduce demand and cut your energy costs,see our Web-site at http://www.swreb.ca.gov/rwgcb5