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<br />EXHIBIT "A" <br /> <br />Mr. Brian Lee, PE <br />November 21,2005 <br />Page 2 of 13 <br /> <br />€> EarthTech <br /> <br />A Tye. InternatiOl1alltd. Company <br /> <br />obstructions (if any) in the vicinity of proposed drilling locations. As required by law, <br />Underground Service Alert (USA) will also be notified a minimum of 48-hours in advance of field <br />activities. <br /> <br />Permits for well installation/soil borings will be obtained from San Mateo County. Site access <br />(e.g. blocking off nearby parking stalls) will be secured prior to drilling. <br /> <br />Soil and Groundwater Investigations <br /> <br />Prior to drilling activities, Earth Tech will clear borehole locations to a minimum depth of 5 ft bgs <br />using an air knife or similar equipment. Earth Tech will adhere to the details for soil and <br />groundwater sampling as discussed in the Work Plan. Below is a discussion of the proposed soil <br />borings and groundwater sampling locations at the three former UST sites. Attached are Figures <br />3,4, and 5 (see Attachment 1), showing the proposed boring locations at the three UST sites. <br /> <br />923 Jefferson Avenue <br /> <br />Four soil borings are proposed in the vicinity of the former UST at the 923 Jefferson Avenue site <br />(see Attachment 1, Figure 3 of the Work Plan). These borings are intended to facilitate sample <br />collection for the following evaluation purpose: <br /> <br />. Boring B-01. Evaluate the vertical extent of hydrocarbons in soil at the former UST location <br />(at a minimum 2 soil samples will be collected); evaluate the possible presence and <br />concentrations of hydrocarbons in groundwater (1 groundwater grab sample). <br /> <br />. Boring B-02. Evaluate the lateral extent of hydrocarbons in soil northeast of the former <br />UST location (at a minimum 1 soil sample will be collected); evaluate the <br />lateral/downgradient extent of hydrocarbons in groundwater (1 groundwater grab sample). <br /> <br />. Boring B-03. Evaluate the lateral/downgradient extent of hydrocarbons in soil east of the <br />former UST location (at a minimum 1 soil sample will be collected); evaluate the lateral <br />extent of hydrocarbons in groundwater (1 groundwater grab sample). <br /> <br />. Boring B-04. Evaluate the possible presence of hydrocarbons in groundwater southwest <br />and upgradient from the former UST location (1 groundwater grab sample). <br /> <br />1020 Middlefield Road <br /> <br />Five soil borings are proposed in the vicinity of the former UST at the 1020 Middlefield Road site <br />(see Attachment 1, Figure 4 of Work Plan). These borings are intended to facilitate sampling <br />collection for the following evaluation purposes: <br /> <br />. Boring B-05. Evaluate the vertical extent of hydrocarbons and MTBE in soil at the former <br />UST location (at a minimum 2 soil samples will be collected); evaluate the possible <br />presence and concentrations of hydrocarbons in groundwater (1 groundwater grab <br />sample). <br /> <br />. Boring B-06. Evaluate the lateral/downgradient extent of hydrocarbons and MTBE in <br />groundwater relative to the former UST and product pump areas (1 groundwater grab <br />sample). <br />