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ti.,r 23 July 1999 AGE-NC Project No. 99-0628 Page 3 of 5 a utility clearance obtained through Underground Service Alert. 3.2. EXCAVATION OF DRY WELLS AND FORMER DRAIN LINE Prior to initiating excavation work.,the concrete around each dry well and the former drain line will be removed to expose the areas. Each dry well will then be excavated using a truck-mounted drill rig equipped with a large diameter earth auger bit (`'bucket auger"). The bucket auger will be advanced to depths of approximately 25 feet below surface grade (bsg) or until the entire depth of the dry well has been reached and the contents removed. The excavated materials will be placed on- site in an appropriate container (bin) or placed on plastic sheeting, pending sample collection and analysis. In other areas of sample collection, shallow borings will be advanced using hollow-stem augers. The borings will be advanced to depths of approximately 5 feet bsg with the collection of soil samples at depths of 2 and 5 feet bsg. However, if obvious contamination is present, all boring slexcavatioils may be advanced to greater depth. Field procedures for the excavation or advancement of borings are included in Section 4.1. 3.3. SOIL SAMPLE COLLECTION AND ANALYSIS Samples will be collected fi-om the bottom of each dry well; from the area of the former clarifier; and from the excavated soil. It is not believed that any additional "joint"or connections were present in the original drain system from the clarifier to the dry wells,therefore, no additional samples will be collected. However, if additional potential connection points or areas of obvious contamination are encountered, additional soil samples will be collected. Discrete soil samples will be collected at depths of 2 and 5 feet below each dry well, drain line or clarifier location. Field procedures for collection of soil samples are presented in Section 4.2. Selected soil samples will be analyzed by a California Department of Health Services (DHS)- certified laboratory for the following constituents: • Total petroleum hydrocarbons ("TPH-all") in accordance with EPA Methods 8015 Modified15030: ■ Benzene, toluene, ethylbeiizene, and total xylenes (BTEX) in accordance with EPA Method 8020; ■ Volatile organics in accordance with EPA Method 8260; Advanced C.eilEnvlroyimenIBI,1nc.