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fth t It is proposed that initial samples be secured at four points`surrounding the excavation site, Cie. on G both ends and either side of the excavation hole, in the native soil]. Samples would be secured approximately one to thee feet away from the original excavation tat three depths at 17, 19, and 27 feet, {see Drawing 1 "Soil Sampling"). An OVM will be used to field check the samples and the samples will be sealed,logged under chain of custody,refrigerated,a.nd transported to an independent certified lab. I 13 The field OVM readings will be used to direct the scope of thesampling, [ie. to determine if the perimeter should be expanded]. The intent is to perform borings moving latterly further and further away from the tank until negative OVM readings are achieved, (see Drawing 1 "Soil Sampling"). { 3.2 Remediation Methods w 3.2.1 General II �! There are two issues which present themselves as potential limiting factors to remediating the site. One is the location/proximity of a school, the other is the location of a building. t - 1. Remediation methods which could potentially cause air emissions, (such as vapor ' extraction), are undesirable due to the proximity of the school. III, { 2. Methods proposing excavation may become complicated if the contamination extends close to or under the building. 5 3. In situ bioremediation may provide a viablel alternative. 3.2.2 -Excavation Should the soil sampling suggest that excavation can be'accomplished in a cost-effective manner the following procedure is proposed. i� To a perimeter, indicated by soil analysis, excavate to a depth of 28 feet. At that depth, perform an OVM measurement. If the OVM indicates negative for volatile organics, a confirming soil sample would be taken. If the confirming' sample shows results which are below action levels, we would request permission from SanJoaquin County Environmental Health to back fill the excavation. i E i I Page 3