SITE INFORMATION AND CORRESPONDENCE CASE 2

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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2003-0141 6_ CALIFORNIA NATURAL PRODUCTS WASTEWATER TREATMENT FACILITY SAN JOAQUIN COUNTY 34. In April 2001, on-site infiltration tests were conducted at the 17.6 acre land application site and at the 16.0 acre land application area. Six double ring infiltrometer tests were performed,using wastewater from the CNP facility. Results ranged from 0.19 to 2.25 in/hr, and averaged 0.80 and 1.09 in/hr at the 17.6 acre site and 16.0 acre site respectively. Based on this information, infiltration rates for the land application area were characterized as moderate. 35. Based on a monthly average application rate of 370,000 gpd and 100-year precipitation data, it is anticipated that less than 2.0 percent of the available infiltration capacity of the application area soil will be utilized during the 100-year precipitation peak month. OTHER WASTE STREAMS 36. Stormwater collected at paved areas and loading docks is piped to the wastewater treatment system. Stormwater that falls on buildings is discharged to stormwater retention basins. 37. Employee showers and the newer restrooms are piped to the domestic wastewater lift station where it is pumped to the City of Lathrop's wastewater collection system. Some of the older restrooms are connected to septic tanks. It is unclear why the Discharger has not connected all of the restrooms to the City collection system, and therefore the Discharger is required to demonstrate whether the use of the domestic septic systems have the potential to impact water quality. Domestic wastewater is not commingled with the process water that is land applied. GROUNDWATER CONDITIONS 38. Three groundwater monitoring wells were installed at the 17.6 acre land application site in July 1988. The locations of the monitoring wells are shown on Attachment B. The Discharger has monitored groundwater levels since June 1994. However, the historic data quality is poor and therefore the data are not reliable. In the year 2001, the existing monitoring wells were resurveyed and Well W-4 was installed at the 17.6 acre land application area. Wells L-1, L-2, and L-3 were installed in the 16.0 acre land application area. Monthly monitoring of all these wells was conducted from May 2001 to February 2002, and quarterly thereafter. In November 2002,Well W-5 was installed as a background well at the 17.6 acre land application area. The Discharger has failed to adequately determine the hydrologic conditions at the land application area and therefore additional analysis of groundwater flow conditions are required in the Provisions section of this Order. 39. The depth to groundwater is approximately 10 to 15 feet bgs and the groundwater gradient is reportedly to the northwest, although locally, groundwater depth and flow may be influenced by local pumping and irrigation patterns. 40. The average analytical results for groundwater samples collected from May 2001 to May 2003 for Wells W-1 through W-5,and L,1 through L-3 are presented below. Earlier analytical data is not presented because it is considered to be poor quality and therefore unreliable.