Loading...
HomeMy WebLinkAboutMASON STREET INFRASTRUCTURE PROJECT - FDP230016 - SUBMITTAL DOCUMENTS - ROUND 6 - Geotechnical (Soils) Report CTL|Thompson, Inc. Denver, Fort Collins, Colorado Springs, Glenwood Springs, Pueblo, Summit County – Colorado Cheyenne, Wyoming and Bozeman, Montana April 19, 2024 1311 North College, LLC 262 East Mountain Avenue Fort Collins, Colorado 80524 Attention: Colin Vito Subject: Groundwater Investigation Fort Collins Rescue Mission 1311 North College Avenue Fort Collins, Colorado Project No. FC10520.002-112-L1 We performed a Geotechnical Investigation for Fort Collins Rescue Mission initially called Hibdon/Mason 24/7 Shelter and presented results in a report (Project No. FC10,520-125-R1, dated November 20, 2023). During the investigation, ground- water was encountered at depths of 8 to 9.5 feet or approximate elevations 4970.5’ to 4973’. We indicated that groundwater may be encountered during sub-excavation or deep utility installation. We were requested to drill additional borings to further evaluate the groundwater levels near the proposed detention pond. This letter pre- sents the results of our additional groundwater measurements. The scope was de- scribed in a proposal DN 24-0094R dated March 1, 2024. Investigation We drilled two borings on March 21st 2024, to a depth of about 15 feet below existing grade using a truck-mounted drill rig and 8-inch continuous flight hollow- stem auger at the approximate locations shown on Fig. 1 . Machine-slotted PVC pipe was installed in the lower 10 feet and the upper 5 feet is solid PVC riser pipe. An ad- ditional 3.5 feet of riser pipe was installed above-grade with a stick-up well protector. Silica sand was placed from a depth of 3 feet to 15 feet. A bentonite seal was con- structed in the upper 3 feet of each monitoring well. Our field representative was pre- sent to observe drilling, log the strata encountered, and log monitoring well construc- tion. Monitoring well logs are presented in Appendix A. Subsurface Conditions Strata found in our exploratory borings consisted of about 7 to 9.5 feet of sandy gravelly clay underlain by silty gravelly sand. We measured groundwater at the time of drilling and once again, several days later on March 29, 2024. The groundwater measurements are presented in the table below. Additional groundwa- ter measurements will be obtained on a monthly basis through the fall of 2024 and measurements will be transmitted in subsequent letters. 1311 NORTH COLLEGE, LLC 2 FORT COLLINS RESCUE MISSION – 1311 NORTH COLLEGE AVENUE CTL | T PROJECT NO. FC10520.002-112-L1 Monitoring Well March 21, 2024 Depth to GW During Drilling (ft) March 29, 2024 Depth to GW (ft) GW Elev. (shallow- est measurement) (ft) P-1 6 5.5 4974 P-2 5 8 4971.5 We believe this investigation was conducted with that level of skill and care ordinarily used by geotechnical engineers practicing under similar conditions. No warranty, express or implied is made. If we can be of further service in discussing the contents of this letter or in the analysis of the influence of subsoil conditions on design of the structures, please call. CTL | THOMPSON, INC. Abhinav Jakilati Staff Engineer Reviewed by: Erin Bouchet, P.E., P.G. Associate Engineer| Denver Engineering Manager Via e-mail: Andy.Reese@kimley-horn.com Blaine.Mathisen@epsgroupinc.com 4/22/2024 © 2024 Microsoft Corporation © 2024 Maxar ©C | 1311 NORTH COLLEGE, LLC FORT COLLINS RESCUE MISSION – 1311 NORTH COLLEGE AVENUE CTL | T PROJECT NO. FC10520.002-112-L1 APPENDIX A MONITORING WELL LOGS WELL DETAILWELL CONSTRUCTION Monitoring Well Construction Summary Project Name Drilling Contractor Soil DescriptionDepth To 4' From Project No. Drilling Method Borehole Diameter (in) Sand Pack DEPTH/HEIGHT FROM GROUND SURFACE DEPTH (FT)Cap Type Well Protector Type Annular Sealant Type Seal Material Type Sand Pack Type Riser Pipe Length (ft) and Type Riser Pipe Diameter (in) Screen Length (ft) and Type Screen Slot Size Gallons Removed (purge) Other Ground Water Depth (ft) Ground Elevation Date Drilled Engineer Well No. Soil Type CTL/THOMPSON, INC.(303) 825-0777 0' 0' 8" HOLLOW STEM AUGER 3' 3' 5' 12' 10' 15' 15' 8" 0' 0' 3.5' Top of Well Protector Top of Riser Pipe Ground Surface J-PLUG STICK UP BENTONITE CHIPS BENTONITE CHIPS SILICA 10/20 5' PVC 40 2" 10' PVC 40 0.010" N/A N/A 15' REMARKS: 1971 WEST 12TH AVENUE DENVER, COLORADO 80204 TS NATURAL GRASS CL 9.5' SPG SAND, GRAVELLY, VERY MOIST, BROWN, DARK BROWN. CLAY, SANDY, MOIST, DARK BROWN. Bottom of Screen Bottom of Borehole Top of Seal Total Seal Interval Top of Sand Top of Screen Total Screen Interval DEPTH (FEET) FC10520.002-112 9.5' FORT COLLINS RESCUE MISSION TERRACON TSK/DENVER 3/21/24 0' P-1 4979.81' 6' FIG. A-1 WELL DETAILWELL CONSTRUCTION Monitoring Well Construction Summary Project Name Drilling Contractor Soil DescriptionDepth To 4' From Project No. Drilling Method Borehole Diameter (in) Sand Pack DEPTH/HEIGHT FROM GROUND SURFACE DEPTH (FT)Cap Type Well Protector Type Annular Sealant Type Seal Material Type Sand Pack Type Riser Pipe Length (ft) and Type Riser Pipe Diameter (in) Screen Length (ft) and Type Screen Slot Size Gallons Removed (purge) Other Ground Water Depth (ft) Ground Elevation Date Drilled Engineer Well No. Soil Type CTL/THOMPSON, INC.(303) 825-0777 0' 0' 8" HOLLOW STEM AUGER 3' 3' 5' 12' 10' 15' 15' 8" 0' 0' 3.5' Top of Well Protector Top of Riser Pipe Ground Surface J-PLUG STICK UP BENTONITE CHIPS BENTONITE CHIPS SILICA 10/20 5' PVC 40 2" 10' PVC 40 0.010" N/A N/A REMARKS: 1971 WEST 12TH AVENUE DENVER, COLORADO 80204 TS NATURAL GRASS CL CLAY, SANDY, MOIST, DARK BROWN. Bottom of Screen Bottom of Borehole Top of Seal Total Seal Interval Top of Sand Top of Screen Total Screen Interval DEPTH (FEET) FORT COLLINS RESCUE MISSION TERRACON TSK/DENVER 3/21/24 0' P-2 4979.46' 5' 2.5' 2.5' 7' 7' 15' CL/GC SP SAND, GRAVEL, VERY MOIST CLAYEY, GRAVELLY, SANDY FC10520.002-112 FIG. A-2