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Lang-vton 's Market
<br /> 15615 Seventh Street, Lathrop, California
<br /> Phase 11 Latera' & Vertical Extent
<br />' of Second Groundwater A u fer wk
<br /> ;CEIVIED
<br />' DEC 13 1995
<br /> IRONMENrTAL HEALTH
<br /> 10 Project Identification ✓? PERMIT/SERVICES
<br /> This project will involve lateral and vertical defirutron of the second aquifer with the installation of three
<br />' (3) monitoring wells This ,work is associated with the former underground tank failure at Langston's
<br /> Market, 15615 Seventh Street, Lathrop, Cahforma (Figure 1)
<br />' 2.0 Site Description wid History
<br />' A preliminary enviionmental investigation of the property was completed by Murray & Associates
<br /> at the request of Mr Langston in Apr.] 1902 Tnis preliminary investigation includrd the dulling
<br /> of several exploratory soil borings by hand auger and rotary crammer in the vicinity of a failed
<br /> 4,000 gallon underground gasohne tank (UST) The tank failure occurred in [tine 1940 following
<br /> a helium piessuj,, test Approxrr-iately 1,200 gallons of unleaded gasoline �as lost horn the tank
<br />' The purpose of the, pr,:,hinrrrary invc�tjgation vwm to quickiy and inexpensively e,-alnate the extent
<br /> of soil contamination <<s a result of Ihre US", fa.liue and to determine the potential fir grotrtrdwarer
<br />' contamination TI,e -.w.,esttgation conw,�ted f m.nually, drrlhnr, eight 2-inch diameter soil borings
<br /> to a depth of 17 feet Giot..>ckvatt:: ac the attc; r;, enrou.,Ier ed at a depth of 17 5 to 18 feat I tit
<br /> borings demonstrated that soil comamutatioa to ;tie vicinity of the former UST extGndea dOw17 tO
<br /> the capillary fruige zone, and the water table, with 1-tile literal sp,eading prgur+,- 2 shows [tie
<br /> lateral extent of both the cod and groundwater contamination as detcrrnin-_d by the April 1992
<br /> investigation Although no groundwater rionrtor rng wells were installed at that time, soil vapor
<br />' samples were collected from alcove the wla.er table in all bot-rigs acid screenen in the field using a
<br /> 580B OVM Although not conclusive, this preliminaty investigation provided a reasonable
<br /> estimate of the extent of contamination in both the soil and groundwater, and has formed the basis
<br />' for the location of exploratory soil borings and groundwater monitoring wells The drilling
<br /> activities were performed and,-r the ,upernsion of a California Registcied Geologist who selected
<br /> the boring locations .and logged d.- borings as they were di filled Duj ung drilling, soil samples
<br />' were collected at app,opi rate icptl, inter-�als 1,9, 14, and 17 feet) trsaig a driven tube sampler
<br /> equipped with extension rods and a :angle clear one-trick diameter starrtic,.s Stec I Wbtl
<br />' The results of the field OVN1 scrcening (if ,oil samples collected are press:nted below Soil
<br /> samples were c,ollectcd at 9, 14 an L 17 feet below the ground swfaoe The 9-toot sample would
<br /> correspond to a depth, aprjlo.. irrartely equal tc, }ne bottom of the tank, while Me 17-foot �atr►l�lu
<br /> would be representative of the capillary fringe zone The prt�senc. cif,„ontamination in the sample
<br /> collected from 17 feet ,%owd ndicatc that groundwater at that holai10n is c:,rttanrrnated
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