WORK PLANS - Laserfiche WebLink

Home Browse Search

1.. _ �E { 2.1 Soil and Groundwater Assessments at Highiet/Monterosso Parcel GEvnna'rRix Environmental assessments at the Highiet/Monterosso parcel were performed by others on behalf of previous property owners between 1988 and 1990. As described below, a limited area of soil was F found to be affected by petroleum hydrocarbons and groundwater was found to be unaffected by petro- leum hydrocarbons. f.1 1988 Soil Assessment FA soil assessment was performed at the site in 1988 by Terrestrial Technology,Inc. (TTI); however, the reports describing the results of the assessment were not available to Geomatrix. Levine-Fricke (L-F) reported that the TTI assessments were performed after petroleum hydrocarbon-affected soil was en- countered during the installation of a water line for the City of Tracy (L-F, 1990). L-F reported that TTI advanced nine soil borings in a row along the northern portion of the site approximately 125 feet south of Byron Road and three borings closer to the northern property boundary at distances of 11, 28, and 53 feet south of Byron Road. The locations of the nine TTI soil borings farther from the road are shown on Figure 2; the locations of the three borings nearest the road were not shown in the L-F report. Petroleum hydrocarbons were detected in a sample collected from 6 feet below ground surface (bgs) in the boring located l I feet from Byron Road. Petroleum hydrocarbons were not detected in samples r collected from the other i 1 soil borings advanced at the site. F1989 Soil Assessment ' In January 1990, L-F performed a soil assessment on behalf of Sunboro Development Corporation. Results of the assessment were presented in the L-F 5 September 1989 "Soil-Quality Investigation, F Sunboro Development Corporation Parcel B, Tracy, California." The assessment consisted of advanc- ing 13 soil borings to depths of 15 to 25 feet bgs at the locations shown on Figure 2. In addition, a soil J sample was collected from approximately 5 feet bgs in an excavation associated with the installation of 3 a water line at the location shown on Figure 2. Groundwater was encountered at depths ranging from 7.5 to 11 feet bgs. k Petroleum discoloration or odor was observed in soil samples collected at depths ranging from 5 to F 16 feet from soil borings D, J, and L. Soil samples were analyzed for total recoverable petroleum hy- drocarbons (TRPH) using EPA Method 418.1. Soil analytical results are summarized in Table 1. FSamples collected from boring D at depths of 7 and 10 feet bgs contained TRPH at concentrations of 81 and 1,100 milligrams per kilogram (mg/kg), respectively. The sample collected from I 1 feet in bor- ing J contained TRPH at a concentration of 420 mg/kg. Two.samples collected from boring L at depths Fi of 11 and 16 feet bgs contained TRPH at concentrations of 230 and 270 mg/kg, respectively. TRPH was not detected in the remaining 18 soil samples submitted for chemical analysis. Based on the re- ! 1 sults of their assessment,L-F recommended that groundwater monitoring wells be installed at the site. L.1 2 F]