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1.0 INTRODUCTION <br /> 1.1 Previous Work <br /> This report presents the results of a subsurface hydrocarbon <br /> contamination investigation conducted at the Tracy Public Schools <br /> Bus Facility located at 315 East Eleventh Street Tracy, <br /> California (Figure 1) . In September 1987, prior to the present <br /> investigation, a 1000 gallon underground gasoline storage tank <br /> was removed and field inspection indicated the presence of <br /> gasoline contaminated soils and water within the excavated pit. <br /> Tl t n� b1*t ca t x3�ave;"co�ita nec I eit i eari#e a2ffn- :e!R-ddCr <br /> �gs�aaliae A sample of water collected from the pit on September <br /> 16, 198 recorded total volatile petroleum hydrocarbons at a <br /> concentration of 75 parts per million (ppm) and benzene, toluene <br /> and xylene at 15, 39 and 26 ppm, respectively. Laboratory <br /> analysis for lead indicated a 0.012 ppm concentration and <br /> ethylene dibzomide concentration below method detection limits. <br /> The laboratory data sheets and chain of custody form for this <br /> sampling are presented in Appendix 1. <br /> 1.2 Purpose and Scope <br /> This investigation was conducted in response to requirements of . <br /> the San Joaquin Local Health District (SJLHD) as presented to Mr. <br /> Reggie Mersaroli of Tracy Public Schools. The purpose of the <br /> i. investigation was to identify and quantify the extent of the <br /> subsurface contamination and to formulate a remedial action plan, <br /> if necessary. This work was conducted in accordance with the <br /> WaterWork proposal dated December 8, 1987, which was submitted to <br /> b• the SJ'LHD for prior review and comment. This proposal outlined a <br /> program of installing, logging, surveying and sampling three <br /> " monitoring wells in the area around the former tank. <br /> 2.0 INVESTIGATION PROCEDURE <br /> 2.1 Soil Borings <br /> to nzUpparY a 7988..tYrree :soil ox:hgs here ;advanc. al �td�"dept}is' sof <br /> t3tk�g.8 t2 nc1�28�L f e below grade for the purpose of installing <br /> 6. gro-u ,rate Q�t-ito 11 v�ei Research indicated natural <br /> groundwater flow to be in a northerly to northeasterly direction. <br /> As such, boring T-3 was placed in an upgradient location and <br /> borings T-1 and T-2 were positioned in the assumed down <br /> groundwater gradient direction (Figure 2) . Drilling was conducted <br /> with a Mobile B--61 rig using eight inch (O.D.) diameter hollow <br /> stem augers. The drilling was performed under the direction of a <br /> field geologist who maintained a contiuous log cf the aterials _-_ T T <br /> encountered using the Unified Soil Classification System <br /> . (Appendix II) . Soil samples were collected for field <br /> characterization of soil type and inspected for the presence of <br /> hydrocarbon contamination. Core samples were collected in 2 inch <br /> .�" diameter brass tubes 'using a California modified sampler. Select <br /> 1 <br /> ss <br />