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EDMUND G. BROWN JP.
<br />GOVERNOR
<br />CALIFORMI•
<br />Water Boards
<br />
<br />MATTHEW RODRIOUEZ
<br />SECRETARY FOR .
<br />ENVIRONMENTAL PROTECTION
<br />Central Valley Regional Water Quality Control Board
<br />TO: Case File and
<br />Gerald Djuth, C.E.G.
<br />FROM: Amy Terrell, P.E.
<br />DATE: 8 December 2015
<br />SUBJECT: CASE FILE REVIEW OF TRI-AG SERVICE, 20696 SOUTH MANTECA ROAD,
<br />MANTECA, SAN JOAQUIN COUNTY
<br />Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff
<br />reviewed the case file for Tri-Ag Service, also known as Schmiedt Soil Service, at 20696
<br />S. Manteca Road, which is also referred to as 20696 S. Main Street, in Manteca. This site is
<br />listed on Geotracker (SLT5S4823431) as open and inactive. Based on a review of the case file,
<br />Central Valley Water Board staff recommend that additional investigation be conducted to
<br />evaluate if further action is needed.
<br />Between 1946 and 1982, Schmiedt Soil Service primarily provided a fumigation service from a
<br />5- acre parcel that was surrounded by farmland. Fumigants included 1,2-dibromo-3-
<br />chloropropane (DBCP), 1,2-dibromoethane (EDB), and Telone II. Schmiedt Soil Service also
<br />provided fertilizers and pesticides to farmers. Between 1982 and 2001, Tri-Ag Service primarily
<br />operated a fertilizer service on 1.5 acres of this property and also provided fumigants and
<br />pesticides.
<br />In about 2002, the surrounding agricultural area was subdivided into residential developments.
<br />In 2003, an assessment was conducted on 1.5 acres of the 5-acre property. Five soil samples
<br />were taken from 1 foot below ground surface (bgs), three soil samples from 3 feet bgs, and one
<br />round of groundwater samples were taken from three monitoring wells, as described in the
<br />13 February 2004 Limited Soil and Groundwater Investigation Report, prepared by Kleinfelder.
<br />The results showed that in soil, nitrogen concentrations are is elevated , lead, copper and zinc
<br />are elevated in a few samples relative to other on-site samples and may exceed background
<br />concentrations. While DDT, dieldrin, and oryzalin were detected in some soil samples, the
<br />concentrations are below the US EPA's Residential Screening values of June 2015. Other
<br />carbamate urea or organochlorine compounds were not detected, nor were fuel constituents,
<br />volatile organic compounds, or organophosphate compounds.
<br />In groundwater, all the monitoring wells and the supply well contained nitrate above the
<br />maximum contaminant level for drinking water, one monitoring well contained ammonium and
<br />EDB, but other volatile organic compounds, organochlorine, organophosphate, and carbamate
<br />urea compounds were not detected in the monitoring wells. The on-site drinking water well,
<br />however, did contain 4 ug/L 1,2,3-trichloropropane, and 49 ug/L 1,2-dichloropropane, which
<br />exceed the screening levels of 0.005 ug/L and 5 ug/L, respectively.
<br />Central Valley Water Board staff recommend that additional soil and groundwater assessment
<br />be conducted at the Tri-Ag site to evaluate if remediation is needed and if so, to what extent.
<br />KARL E. LONGLEY ScD, P.E., CHAIR PAMELA G. CREEDON P.E. BCEE, EXECUTIVE OFFICER
<br />11020 Sun Center Drive *200, Rancho Cordova, CA 95670 I www.waterboards.ca.govicentralvalley
<br />RECYCLED PAPER
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