WORK PLANS - Laserfiche WebLink

Home Browse Search

�..1 Envirorunental Mr.Harlin Knoll Resources 23 April 1998 Management Page 4 conductor casing (approximately 3 feet in length) will be installed around the well casing and the wells will be completed with flush mounted vaults. Following installation, the monitoring wells will be developed by the removal of 10 saturated casing volumes of ground water using a disposable bailer. Following development, ground water samples will be collected from each well and analyzed for TPH-g (EPA Method 8015M) and BTEX (EPA Method 8020) consistent with previous ground water samples collected at the site. Pursuant to our phone discussions with the County, ERM also plans to perform additional excavation of soil from the northern and eastern sidewalls of the former UST #1 location. ERM plans to extend the northern and eastern sidewalls of the excavation by another three feet. The scope of work for this activity will be similar to that provided in the 4 March 1998 workplan letter for the additional excavation performed subsequent to tank removal. ERM will sawcut and remove surface pavements along the northern and eastern portions of the tank pit. ERM will then remove and treat ground water from the tank pit. ERM will subsequently excavate soils along the northern and eastern sidewalls of the pit to a depth of approximately 10 feet bgs. Approximately 50 cubic yards of soil will be removed followed by dewatering and disposal of the excavated soils. Following excavation, ERM will collect two sidewall soil samples from the excavation for UST #1, and will submit them for analysis for TPH-g and for BTEX compounds. Following completion of the excavation activities and upon receipt of approval from the County, the excavations will be backfilled. At the request of the County and recommendation by ERM, an oxygen releasing compound (ORC) will be placed in the excavations to stimulate bioremediation prior to backfilling. The tank pits will be backfilled with imported clean fill material as necessary to restore site to existing grade. The backfilling will be performed in accordance with the Underground Storage Tank Removal Workplan (ERM,January 1998). Backfill will be placed in lifts not exceeding 12-inches and will be compacted to 90% maximum density as determined by Modified Proctor Test ASTM D 1557. ERM will provide an independent testing firm to perform in-place compaction tests during backfilling operations. Surface pavements will be replaced to match existing conditions prior to commencement of the work.