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SECTION 3 Monitoring Well Location and Destruction The 2012 Annual Report(CH2M HILL, 2012) recommended that Monitoring Wells KP-75, KP-71),and KP-8S be properly destroyed because they are no longer sampled as part of the annual groundwater monitoring program. Monitoring Wells KP-7S and KP-7D were covered with road base during routine grading by the Port of Stockton, and need to be located and uncovered before they can be destroyed. Monitoring well KP-9S is also buried beneath road base and needs to be located for future sampling. Monitoring well locations are shown on Figure 1. Monitoring Wells KP-75, KP-7D,and KP-8S were installed in 1999. Groundwater samples were routinely collected from Monitoring Wells KP-75 and KP-7D from June 1999 through March 2004 and from Monitoring Well KP-8S from June 1999 through August 2006. Following is a summary of the nitrate-N and ammonia as nitrogen (ammonia-N)concentrations in groundwater samples from these wells: • KP-7S: — Nitrate-N—Concentrations ranged from 142 meligrams per liter(mg/L) (February 2003)to 22.4 mg/L (August 1999);the most recent concentration was 4.43 mg/L(March 2004). — Ammonia-N—Concentrations were be4aw due Itbaatory detection limit(0.3 mg/L) in all groundwater samples collected. • KP-7D: — Nitrate-N—Concentrations were belee ow w6wa.ry detection limit(0.1 mg/L) in all groundwater samples collected. — Ammonia-N—Only two samples had 4ae1rr4!!:4M■.91wations,0.34 mg/L(February 2002)and 0.7 mg/L (February 2003).All other sample co•trews afw swe below the laboratory detection limit(0.3 mg/L). • KP-8S: — Nitrate-N—Concentrations ranged fta� bolter"I*tatoratory detection limit(0.1 mg/L) in samples from August 2003 and March 2004 to a m4•r•Arsa d 4 t +n6/L(June 1999);the most recent concentration was 2.5 mg/L(August 2006). — Ammonia-N—The most recent groundwater sarnpte in August 2006 had an estimated detectable concentration of 0.05 mg/L.All other sampie concentrations were below the laboratory detection limit (ranged from 0.2 to 0.3 mg/L). The Water Board approved suspending groundwater quaky monitoring at Monitoring Wells KP-7S, KP-71), and KP-85 under Monitoring and Reporting Program No RS-2004-0835 because of the low nitrogen concentrations at these wells(Water Board, 2007).These wells are no tonger sampled as part of the annual groundwater moni- toring;therefore, in accordance with Monitoring and Reporting Program No. R5-2004-0835(Water Board, 2004), Water Board approval for locating and properly destroying these wells is requested. 3.1 Well Location As mentioned in the 2012 Annual Report(CH2M HILL, 2012),an attempt to locate Monitoring Wells KP-7S, KP-7D, and KP-9S on March 27, 2012, using a handheld global positioning system instrument, metal detector,and shovel was unsuccessful.The Port of Stockton suggested that the wells might be buried beneath 18 inches or more of road base(Port of Stockton,2012).A land surveyor will be contracted to precisely locate the monitoring wells. Once the monitoring wells are exposed, Monitoring Wells KP-75 and KP-7D will be destroyed and monitoring well KP-9S will be staked so that it can be easily found in the future for gauging and sampling. Monitoring Well KP-85 was accessed during the 2012 annual groundwater monitoring event to measure the depth to groundwater,and is assumed to still be accessible. RDD/131490001 (CM5152=X) 3-1 SS052913233837