10179096_2103 S. GRAND - Plan (2)

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Former Circuit One 2103 S. Grand Avenue, Santa Ana, California Proiect No. 11-0106 It is expected that the following permits may be required for excavation operations: • A grading and building permit from the City of Santa Ana. • An air district permit. Prior to commencing with excavation activities, Underground Service Alert (USA) will be contacted at least 48 hours in advance to identify the location of utilities that enter the Site. All proposed excavation areas will be clearly marked with white paint as required by USA. USA will contact all utility owners of record within the Site vicinity and notify them of the intent to excavate. All utility owners of record will be expected to clearly mark the position of their utilities on the ground surface throughout the designated area. 4.2 Remove Piping Related to Groundwater Pump and Treat System To access the soil that is required to removed, the piping at the Site related to the P&T system that has been terminated will be removed and the connections of these pipes to the wells will be capped. The excavation will be conducted near wells P-6B and W-1 and precaution will be taken no to damage the wells. Excavation near the wells will be conducted by hand 4.3 Remedial Excavation Under this plan the soil exceeding the copper STLC concentration of 25 mg/L will be removed from the Site by excavation. The excavation and soil handling will be conducted by a qualified, HAZWOPER-trained contractor using conventional earthwork equipment. The contractor will prepare its own Site Specific Health and Safety Plan (HASP), which will address identification of hazards, hazard mitigation, safe work practices and emergency response procedures for the project. The site-specific HASP needs be prepared to comply with 29 CFR 1910.120 and 8 CCR GISO 5192. The contractor will also have to adhere to the HASP prepared by RS. Conventional construction equipment, such as a front-end loader equipped with a backhoe, will be used to remove the soil that is required to be excavated. During the excavation the air will be monitored following air monitoring requirement discussed in the site health and safety plan. The following procedures will be followed to remove the excavated soil. • Access the soil by removing the concrete slab inside the suites. • Excavate the contaminated soil to a depth of about 2.5 feet which is the approximate extent of the soil with copper above its STLC. • Backfill the excavated trench with clean imported soil. • Repair the concrete slab by dowelling it to the existing concrete slab. The thickness and strength of the concrete will be equal or greater than the excising concrete slab. Approximately 1,072 cubic feet of soil will be excavated for this remediation. The excavated soil will be stockpiled in an area that will be cordoned off with temporary fencing in the rear of the suite along the driveway near the boundary of the property west of the existing P&T system compound. The stockpile area will be lined with plastic sheeting and covered daily using plastic sheeting when not actively being worked on and at the end of each workday. Sand bags will be placed in the perimeter of the temporary fence as silt control. The source of the clean backfill material, certification that the fill is clean, and supporting analytical data will be obtained from the excavation subcontractor and submitted to CRWQCB approximately five working days before beginning excavation activities at the site. The clean REMEDIATION SCIENCES 6 .