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Section 1 Introduction and Background 1.1 INTRODUCTION The City of Ripon (City) provides sanitary sewer collection, treatment and disposal for approximately 3,600 residential and commercial connections and two industrial connections in southern San Joaquin County incorporated City of Ripon. The City wastewater treatment and disposal facility (WWTF) is regulated by the Central Valley Regional Water Quality Control Board (Regional Board) and the Regional Board Waste Discharge Requirements Order No. 94- 263 (WDRs). The City's service area is adjacent to and north of the Stanislaus River and west of US Highway 99. The WDRs contain monitoring and reporting requirements, which include quarterly and annual monitoring of groundwater. This report proposes the installation of new groundwater monitoring wells namely to establish a minimum of two background groundwater monitoring locations, outside the influent of wastewater treatment and disposal operations. Data obtained from monitoring these wells will likely be used to establish site specific groundwater quality limitations for the facility. This workplan also proposes and identifies the location of one additional compliance monitoring well, down gradient of the wastewater treatment ponds, filling in an identified data gap. The following provides a brief summary of the regulatory background leading up to this proposed expansion of the groundwater monitoring network: • The City of Ripon Hydrogeologic Investigation(August 2005) identified inadequacies in the existing groundwater monitoring network, specifically that current up gradient monitoring locations may not be completely outside the influence of wastewater treatment and disposal operations,thus limiting the ability to assess background groundwater quality at the site. In addition,the current network does not monitor impacts occurring directly down gradient of the wastewater treatment ponds; ■ The Hydrogeologic Investi ag tion(August 2005) and subsequent quarterly and annual monitoring reports have recommended that additional monitoring wells be installed to address these inadequacies; • The City is currently undergoing an evaluation of the best practicable treatment and control of their industrial wastewater discharge, in which the characterization and quality of background groundwater is a key factor; and, ■ Similarly, continued growth in the City will result in the need to expand permitted wastewater flows, and assessment of background groundwater quality is an integral part of any increased discharge. April 2007 City of Ripon Wastewater Treatment Facility 1-1 Groundwater Monitoring Well Installation Workplan