Laserfiche WebLink
South Platte Decision Support System Groundwater Component Task 33 Field Study Work Plan <br />for Alluvial and Bedrock Well Installation, Testing, and Water Level Monitoring <br />3.2.4 Bedrock Well Installation <br />It is anticipated that the bedrock well will be completed with 5-inch schedule 80 PVC <br />casing with up to 200 feet of 0.040-inch slot factory-milled screen as shown in the <br />figure in Appendix F. However, if a shallower depth is required or alternate <br />construction materials and methods are approved by CDM and the State, the well will <br />be constructed of other materials capable of meeting the objectives described above. <br />Well screen placement will be determined in a way that allows monitoring of the <br />same completion intervals as the nearby production well. Drilling mud in the boring <br />will be thinned with clean water and an 8-12 grade coarse filter pack will be installed <br />via tremie pipe in the annulus and will extend at least 8 feet above the screened <br />interval to prevent migration of grout into the filter pack adjacent to the screen. To <br />prevent melting of the PVC casing due to a cement-based grout mixture's heat of <br />hydration, the annulus will be filled with high-solids bentonite mixed with clear <br />water to the surface within the grouted surface casing. A steel protective surface <br />casing with a lid and locking hasp will be installed over the PVC well casing to <br />provide well security. If necessary, up to three protective steel bollards will be <br />installed around the well. Details of bedrock well construction are provided in <br />Appendix F. Well completion will be in accordance with State of Colorado Division of <br />Water Resources regulations. <br />Surveying of the ground surface and a water level measuring datum will be <br />performed with vertical control to within 0.10 foot and horizontal accuracy will be to <br />within 2 feet. In the event that another well is installed in a different aquifer at the <br />same location and can be used to determine whether a vertical hydraulic gradient <br />exists between the respective aquifers, its water level measuring point will be <br />surveyed to within 0.01 feet of the bedrock well's measuring point. <br />3.2.5 Bedrock Well Development, Aquifer Testing, and Water Level Data <br />Collection <br />The well will be developed by surging and pumping and the produced water will be <br />discharged to the surface. The procedure for well development is presented in <br />Appendix G. No single-well pumping test is anticipated for this new well, since it will <br />serve only as an observation well to a nearby production well. <br />A multi-well aquifer pumping test will be conducted after the well is completed and <br />developed. A nearby large-capacity well will be used as the pumping well, with the <br />well constructed by CDM used as the observation well. Pumping from the high- <br />capacity well will be conducted at a constant rate for a period between 8 and 72 hours <br />with an anticipated test duration of 36 hours. If an existing flow meter is not already <br />certified, flow meter certification will be performed according to State of Colorado <br />regulations. Pumping well discharge will be measured and logged for up to 72 hours. <br />The specification for flow meter certification is presented in Appendix J. If constant <br />pumping occurs for more than 72 hours, the well operator's daily totalizing flow <br />records will be obtained to provide a record of pumping discharge after 72 hours. <br />~.~.-~ <br />17 <br />Z:\SPDSS\10-CDM DELIVERABLES\PHASE 2 FIELD WORKPLAN\FINAL DRAFT\FINAL SPDSS TASK 33 2 WORK PLAN.DOC <br />