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31 August 2016 AGE Project No. 96-0235 Page 2 of 8 Assessment of deep, dissolved MTBE, east of the former northern UST area has been mostly completed. However, assessment of all dissolved petroleum east of the former UST No. 3, southern area has not been completed and dissolved hydrocarbons are likely migrating east to northeast of the southern UST area. The CRWQCB has directed the limits of the dissolved plumes in the HU2 zone be defined to determine if the remaining dissolved impact meets the criteria established in the Low- Threat UST Case Closure Policy (LTCP), as a requirement for site closure. Based on depth to groundwater measurements collected in 2016 at the site, first-encountered groundwater in the area is approximately 15 feet bsg, while deeper groundwater is significantly impacted between 40 and 60 feet bsg. The site groundwater monitoring well network lacks wells to define the lateral extent of deeper dissolved petroleum hydrocarbons and thus is an impediment to site closure. 2.1. REGIONAL GEOLOGIC/HYDROGEOLOGIC SETTING The property is situated within the Great Valley Geomorphic Province of California; a large, elongate, northwest trending, asymmetric structural trough. The Great Valley Province has been filled with thick sequences of sediment ranging in age from Jurassic to Recent, creating a nearly flat- lying alluvial plain that extends from the Tehachapi Mountains in the south to the Klamath Mountains in the north. The California Coast Range and the Sierra Nevada form the western and eastern boundaries of this province. Rocks composing the basement complex of the province have not been completely defined but are believed to be of metamorphic and igneous origin. The northern and southern portions of the Great Valley Province have been designated the Sacramento and San Joaquin Valleys, respectively. The Modesto, Riverbank, and Turlock Lake Formations and overlying recent alluvium are the principal source of domestic groundwater in the 13,500-square-mile San Joaquin Valley Ground Water Basin (Basin 5-22). This basin is drained primarily by the San Joaquin River. 3.0. SCOPE OF WORK AGE proposes to advance three (3) direct push, soil probe borings to define the lateral down-gradient extent of dissolved petroleum hydrocarbons to deep (HU2) groundwater at the site and installation of a monitoring well for the collection of repeatable groundwater samples proposed at well MW-29 in in Hydrogeologic Unit 3 (HU3). The soil borings are proposed off-site in the City of Stockton Right-of-Way within the sidewalk area on the west side of Harrison Street. Advanced GeoEnvironmental Inc.