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Farmington Groundwater Recharge Program STC Work Plan—Hammer Site 2.4. Pilot Scale Test Construction Activities The PRTP will be one of two designs; a flooded field type consisting of undisturbed ground contained by earthen berms (Figures 5 and 6) or a deepened pit (Figures 7 and 8). The deepened pit would be applied to penetrate hardpan sediments if encountered at shallow depths. Flooded field recharge test plot design will cover an approximate area of 100 by 100 feet and water level will be maintained between 0.5 and 1 foot within the berms. The PRTP bottom will follow natural contours of the topography and be separated by soil berms ranging in height from I to 3 feet. If a deepened pit is chosen to be the recommended pilot recharge test method at the site, a small scale excavation will be made within a certain area of the site. Pit depth may extend to 10 feet below initial ground surface and will have sloped embankments at each edge. The bottom of the pit will be 50 by 50 feet or less. Pond height will be maintained at a constant depth of 1 to 5 feet. Source water will be conveyed to the site by pumping from a source existing nearby agricultural well or diversions from "Big John" Creek. Selection of a source water conveyance type will be made following the first stage of field data collection. Flow will be controlled by means of a check structure at the inlet of the recharge test plot. 2.5. Field Data Collection #2—Pilot Recharge Test The objective of the pilot recharge test is to assess infiltration rates at the site for a 6-week period and determine if long term (greater than 6 month) recharge is feasible at this location. Specific types of data collected during pilot recharge testing will be recorded according to the schedule presented in Appendix D and will include the following: • Water level elevation; • Inflow rate; • Pond height; and • Source water quality(field measurements). Additional data that will be monitored includes evaporation, precipitation, pond height, and inflow rate. Pilot recharge testing will begin after baseline groundwater elevation, source and groundwater quality data is collected and PRTP construction activities are completed. Monitoring will continue for a 4-6 week period and will cease I week after water is no longer conveyed to the PRTP. Following this posttest-monitoring period, collected data will be analyzed and compiled into a technical memo summarizing results and recommendations. MWH 2-9 July 2004