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MONITORING AND RE_POAG PROGRAM NO. R5-2015-0810 - 2 - GLENN 2 - GLENN SPRINGS HOLDING, INC. FORMER OCCIDENTAL CHEMICAL CORPORATION, LATHROP FACILITY SAN JOAQUIN COUNTY 5. The treated water is primarily reinjected into a.deeper aquifer through two (2) injection wells under the Waste Discharge Requirements (WDRs) No. R5-2012- 0106 issued by the Central Valley Water Board on 4 October 2012. The majority of treated water is discharged into a confined aquifer beneath a thick confining layer of blue clay, the Concoran Clay, approximately 230 to 300 feet below ground surface-(bgs). The remaining treated water is injected into the upper aquifer. The confined aquifer is isolated from useable groundwaters. Flow distribution of the treated groundwater is not controlled by any means other than the natural receptivity of.the injection wells and hydrogeologic characteristics of the confined aquifer. The injection system operation must comply with the WDRs issued for the Site. 6. The unconfined aquifer system below the Site is generally classified as a four- production zone system: water table zone (approximately 15 to 50 feet below - bgs), shallow zone (approximately 50 to 100 feet bgs), intermediate zone (approximately 100 to 150 ft bgs), and deep zone (approximately 151 feet and 218 ft bgs). A fifth hydrogeologic unit at the Site is the confined injection zone, which is located below the Corcoran Clay layer, at a depth greater than approximately 300 feet bgs. 7. The groundwater monitoring network includes one ninety seven (97) monitoring wells, one multi-level monitoring well with seven (7) sampling ports, eighteen (18) extraction wells, four (4) injection wells, and six (6) municipal supply wells. 8. Existing data and information about the site show the presence of pesticides and fumigants, including 1,2-dibromo-3-chloropropane (DBCP), ethylene dibromide (EDB) and sulfolane resulting from the Dischargers past operations. Groundwater beneath the Site is also contaminated with chloride, nitrate, and sulfate. 9. This Order replaces the requirements listed in MRP No. R5-2004-0800. 10. Prior to construction of any new groundwater monitoring or extraction wells, and prior to abandonment of any groundwater monitoring or extraction wells, the Discharger shall submit plans and specifications to the Central Valley Water Board for review and approval. All well installation and abandonment permits shall be obtained from San Joaquin County Environmental Health Department. Once installed; all new wells shall be added to the monitoring program and shall be sampled and analyzed quarterly per Table 1 and Table 2. The sampling frequency.for these new wells may be re-evaluated after one year. -GeVEL JUL 0 2 2015 ENVIRONMENTAL. 1jr6