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Approach: Task 35.1 Alluvial Well Construction and Testing in the Denver Basin and the Lower South Platte Regions. Phase 2 Task program is an extension of Phase 1 and will include the installation, testing and monitoring at 25 alluvial aquifer locations, from wells completed in unconsolidated alluvial deposits. Existing wells and new wells that are being installed by others and that are located in areas where data gaps exist will be the focus for data collection activities. If access to the existing wells is unavailable or if after making reasonable effort to contact up to 75 well owners, there is no strong indication of cooperation, then up to 25 new wells will be installed by the Consultant.. The drilling, installation and testing of wells by the Consultant under this Task will commence after the State provides written approval of the Field Study Workplan (Task 33). • Information on the location and the owners of wells drilled and installed by others in the areas of interest will be provided through well permit applications collected from the SEO. It is anticipated that the State will provide limited assistance to the Consultant, such as discussing the Consultant's purposes with the applicant and assisting the Consultant administratively with site access, as needed. • Locations of new wells drilled by the Consultant will, if possible, be located on public rights- of-way and accessible for the duration of the SPDSS program and thereafter, under agreements to be negotiated by Consultant with assistance from the State. Sites will be selected that do not require grading for either road construction or drilling. The State will be consulted if suitable locations for drilling cannot be found on public rights-of-way. • Approved site locations will be staked in the field and cleared for drilling by a commercial utility locating service. • The Consultant will apply for monitoring well permits on behalf of the CWCB as owner, and will prepare a bid package consisting of well design, technical specifications, and contract documents for well drilling, sampling, logging, testing, and completion. As determined in Phase 1, fees for State Engineer's Office well permits are not required. • Drilling and well installation will be performed by a qualified drilling subcontractor, with oversight provided by a registered Colorado professional engineer or a professional geologist according to CRS 34-1-201(3). It is anticipated that the driller selected for the Phase 1 sub- contract will be retained for the Phase 2 work. However, separate drilling contractors may be selected for different areas, at the Consultant's discretion and approval by the State. • Drilling will commence when access is available at a sufficient number of sites to cost- effectively implement field mobilization, and when weather conditions are suitable. (All alluvial wells will be constructed using either direct-push technology or hollow-stem auger equipment, and if conditions warrant (i.e. heaving sands) drilling fluids may be used. • All boreholes will be drilled to approximately thirty feet below the water table, with an estimated maximum depth of 80 feet, and an average depth of 60 feet. SPDSS Groundwater SOW, Phase 2 4