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a preliminary conceptual model of groundwater conditions in the basins. The report will include working drawings, maps and cross sections, findings, conclusions, and recommendations for characterization to support the basin cleanup effort. Plume Interception Design Based on the conceptual model and information collected during the data collection phase discussed in Task 2.2, a design will be prepared to implement the plume containment strategy for contamination sourced from the "160 -Acre Parcel'. The County has already completed its design associated with the 'Bunker Area" and is currently installing the first system. This process will be performed for the "160 -Acre Parcel" and includes: development of remedial investigation and feasibility study documents, preparation of a remedial action plan, and preparation of detailed construction plans. One important aspect of this design will include analysis of options and development of plans to facilitate disposition of treated groundwater. The estimated costs for this sub -task are illustrated in Table 1, where it has been assumed that the system for contamination from the "160 Acre Parcel' will require 50% more effort than the system being installed by the County. 4.2.2 TASK 2.2: DATA COLLECTION AND CHARACTERIZATION SUB -TASK A data collection effort is necessary to support the process of cleaning up groundwater in the basins and to provide critical information for successive remedies. This program will be based on the conceptual model and design data from Task 2.1 and is anticipated to consist of three primary aspects: 1) providing recommendations related to soil and groundwater source -area remediation at, or immediately near, source areas; 2) collecting design information to control contaminant migration from the former RABSP property; and 3) expanding the downgradient hydrogeologic database to support optimal wellhead treatment and/or down -plume remediation. A brief description of each sub -task is given below: Providing Recommendations for Source Area Remediation The sources of the perchlorate contamination must be identified, characterized and effectively remediated by the Responsible Parties (RPs). However, source control efforts will involve close cooperation between the regulatory agencies to encourage source area investigations and implementation of soil and groundwater remedies including_on the former RABSP site. It is essential to expeditiously characterize and remediate source contamination before it reaches groundwater, to prevent continued migration of contamination off -Site. This source site remediation will decrease overall costs and shorten regional groundwater cleanup times. The RCBTC will make recommendations regarding RP efforts to investigate and remediate source areas. Data Collection for Design of Plume Control for Contamination Emanatina From RABSP Area The County is currently implementing a remediation program that is designed to capture contaminated groundwater that originates on properties on and adjacent to the former 'Bunker Rialto -Colton Basin Technical Committee— White Paper Revised 2/22/2006 6