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Text for response to the letter from the Central Valley Regional Water Quality Control Board (CVRWQCB),dated November 14,2007,which provided comments to the October 31,2007 City of Tracy Wastewater Treatment Plant Treatment, Storage,and Disposal Monitoring Well Network Installation Work Plan. The two comments addressed the following issues: 1. The Work Plan does not address the Holding Ponds(referred to in the November 14, 2007 letter as the Industrial Storage Ponds),particularly with regard to the assessment of background groundwater quality. 2. The proposed background well may be located too close to the sludge drying beds to be considered upgradient This letter responds to these comments. Holding Ponds No additional monitoring wells were proposed for this area for two reasons. 1. The City considers the existing network adequate to monitor groundwater conditions in the immediate vicinity of the holding ponds 2. The original draft Waste Discharge Requirements submitted by the CVRWQCB did not specifically identify the holding ponds,so it was assumed that the Board also considered it adequate. Water quality monitoring(quarterly) is planned to be continued for the existing monitoring wells. The existing wells around the holding ponds are located upgradient(HP-1),downgradient (HP-3 and HP-4) and lateral (HP-2)to the ponds. Adequate groundwater elevation maps can be developed,including the background well(HP-5)located 1,500 feet south of the ponds. The City considers the existing monitoring network at the holding ponds to be adequate and that no additional monitoring wells are needed there. The City plans to re-survey the existing wells,though,to determine the measuring point elevation relative to a standard datum(they are currently surveyed relative to HP-1) when the new wells are surveyed. This will enable the groundwater elevation data to be compared to data collected from the Spreckels/Holly Sugar site and other nearby groundwater investigations. Relative to the question of background groundwater quality,the CVRWQCB's comment that". . .based on the available groundwater data,it was not possible to determine whether ponds were adversely affection groundwater due to insufficient background groundwater quality data." does not fully represent the City's position. The City considers that the extensive background groundwater quality data collected at the Spreckels/Holly Sugar site demonstrates the wide-ranging variability of shallow groundwater quality near the W WTP. This was communicated in the Evaluation of the Tracy WWTP in Response to RWQCB Letter Dated June 14,2004, CH2M HILL April 2005). The attached Figures 10 and 11 from this reports show the wide range of local values for both TDS and specific conductance and supports the position that the assessment of groundwater conditions in the north Tracy area should include not only the data from the onsite background well (HP-5,located at the