WORK PLANS - Laserfiche WebLink

Home Browse Search

SECTION 2 Monitoring Well Destruction Rationale and Destruction Procedures Because of low nitrogen concentrations in groundwater samples collected from these wells in the last 2 years,Water Board approval for properly destroying monitoring wells KP-4, KP-41), and KP-6D is requested. Historical concentrations for samples collected at these monitoring wells are presented in Table 2-1,at the end of this section. Following is a summary of the nitrate-N and ammonia-N concentrations in groundwater samples collected from these wells shown on Figure 1-1. Monitoring Well KP-4 Monitoring well KP-4 was installed in 1996, and groundwater samples were collected at this well from July 1996 through August 2013. • Nitrate-N concentrations ranged from less than 0.044 milligram per liter(mg/L) (August 2013)to 94.4 mg/L(November 1996).The most recent concentration was less than 0.044 mg/L(August 2013), which is the historical low for this monitoring well.Concentrations have decreased since August 2000 and have been detected below the groundwater cleanup goal of 10 mg/L since September 2004. • Ammonia-N concentrations ranged from less than 0.3 mg/L(March 2000)to 94 mg/L(July 1996).The most recent concentration was 1.4 mg/L(August 2013). Concentrations have decreased since August 2008 and were detected below the groundwater cleanup goal of 1.5 mg/L in August 2013. Monitoring Well KP-41) Monitoring well KP-4D was installed in 2010, and groundwater samples were collected from October 2010 through August 2013. • Nitrate-N concentrations were below the laboratory detection limits(0.02 to 0.1 mg/L) in all groundwater samples collected,which are less than the cleanup goal of 10 mg/L. • Ammonia-N concentrations ranged from 0.21 mg/L(August 2013)to 0.26 mg/L(October 2010),which are all below the groundwater cleanup goal of 1.5 mg/L. Monitoring Well KP-61) Monitoring well KP-61)was installed in 2000,and groundwater samples were collected from August 2000 through August 2013. • Nitrate-N concentrations ranged from less than 0.11 mg/L(August 2013)to 420 mg/L(September 2004). The most recent concentration was less than 0.11 mg/L(August 2013),which is the historical low for this monitoring well. Concentrations have decreased since September 2004 and have been below the groundwater cleanup goal of 10 mg/L since August 2011. • Ammonia-N concentrations ranged from 0.04 mg/L(August 2013)to 3.7 mg/L(August 2006).The most recent concentration was 0.04 mg/L(August 2013),which is the historical low for this monitoring well. Concentrations have generally been below the groundwater cleanup goal of 1.5 mg/L since sampling began in August 2000,with the exception of samples collected between 2005 and 2007. Monitoring wells KP-4 and KP-4D are located in the stormwater pond area,which the Water Board is considering for no further action (Water Board, 2014). Monitoring wells KP-41)and KP-6D are the only two remaining deep monitoring wells at the Site, and nitrogen concentrations at these wells have been below cleanup goals for at least 2 years. Because of the information presented above,Water Board approval for destroying monitoring wells KP-4, KP-4D,and KP-6D is requested. RDD/140100001(NLH4947.DMX) 2-1 M=1311N2MW