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Home My WebLink AboutHILL POND RESIDENCES - Filed GR-GEOTECHNICAL REPORT/SOILS REPORT -CTL ITHOMPSON INCORPORATED September 16, 2014 Catamount Properties 7302 Rozena Street Longmont, Colorado 80501 Attention: Mr. Todd Morgan Subject:Preliminary Geotechnical Investigation Proposed Hillpond Project North of Hillpond Road and Gilgalad Way Fort Collins, Colorado CTL Project No. FC06692-115 We are preparing a preliminary geotechnical investigation report for the Hillpond Project in Fort Collins, Colorado. We have drilled exploratory borings on the site, and laboratory testing is being performed at this time. This letter contains descriptions of the subsurface conditions encountered in our exploratory borings and preliminary discussion of construction at this site as influenced by geotechnical considerations for your use. A subsequent report will include laboratory test results and preliminary geotechnical recommendations for the proposed construction. Site Conditions The site is north of the Hillpond Road and Gilgalad Way intersection in Fort Collins, Colorado (Figure 1). The site is currently occupied by a residence with a garage, two tennis courts, a swimming pool and a shed. Landscaped grass and numerous trees are present. Hillpond Road is located to the south and Gilgalad Way is located to the southeast. Residential properties are present to the west, north and northeast. The ground surface generally slopes down to the south and east. Proposed Construction We understand details of the proposed development are not finalized, but may consist of eight multi-family residential buildings with two to three units each. The buildings will have either basements or at-grade slab-on-grade floors. We were not provided with finished floor levels; we assume that the existing grades within the building areas are near finished first floor elevations. Two interior residential streets are planned which will be privately maintained. Portions of the streets may include permeable pavement. We are assuming that the streets are 400 North Link Lane Fort Collins. Colorado 80524 Telephone. 970-206-9455 Fax 970-206-9441 planned for passenger vehicles, garbage trucks, emergency vehicles, and delivery trucks. Subsurface Conditions Subsurface conditions were investigated by drilling five exploratory borings to depths of approximately 25 to 35 feet. The boring locations are shown on Figure 1. Our representative observed drilling operations, logged the soil and bedrock conditions encountered in the borings, and obtained samples for laboratory testing. Summary logs of the borings, including results of field penetration resistance tests, are presented on Figure 2. Strata encountered in our exploratory borings generally consisted of approximately 0 to 4-1/2 feet of clay and sand fill, underlain by natural sandy clay and clayey sand soils which extended to depths of approximately 18 to 21 feet. The natural soils were underlain by weathered to very hard claystone bedrock which continued to the maximum explored depths. Groundwater was encountered at depths ranging from approximately 14 to 18 feet during drilling. Groundwater depths measured 6 days after drilling ranged from approximately 10 to 15 feet below the existing ground surface. Swell tests on selected samples of the near- surface sandy clay and clayey sand samples are being performed. Discussion Based on the visual observations of the samples obtained from the borings and the subsurface conditions encountered, it appears that the some of the soils and bedrock present at the project site may have expansive potential. Depending on the laboratory test results, there may be low to high expansive soils present. If the soils are of a low expansive potential, then spread footing foundation systems will likely be appropriate for support of the proposed new multi-family residential buildings. If high expansive soils are present, then grade beam and drilled pier foundation systems will be recommended. The risk of differential movement of floor slabs is directly related to the expansive potential of the underlying soils. If high expansive soils are present at slab subgrade elevations, then structurally supported slabs should be considered. Perimeter drainage systems should be constructed for all areas where habitable floor slab elevations are at or below the outside finished grade. Underslab drainage systems should be considered where the groundwater table is within 3 feet of the floor slab elevations. Pavements at this site will include parking areas and access drives. We anticipate that asphalt and concrete pavements will be feasible and pavement CATAMOUNT PROPERTIES 2 HILLPOND PROJECT,FT COLLINS CTLITHOMPSON PROJECT NO.FC06892-115 thickness will not be excessive. We anticipate 4 to 5 inches of asphalt in parking areas, and 5 to 7 inches in drives subject to truck traffic. Six inches of concrete will likely be merited at trash dumpsters and entrance aprons. Proper preparation of the pavement subgrade soils should be performed prior to placement of the asphalt or concrete. For permeable paver design considerations, it is preliminarily estimated that the clay and sand soils would have permeability rates on the order of 1 x104 to 1 x10- centimeters per second cm/sec). If we can be of further service in discussing the contents of this letter or the potential influence of subsurface conditions on the proposed development, please feel free to contact us. CTL I THOMPSON, I O fti.} , ;,, 1 578 t. lDavidM. Nasiatka, P p c/z.fo ct- d'. •', Spencer Schram, PE c S .........•••'•' Senior Geotechnical Eng s .".`-.a Geotechnical Department Man NALENG Attachments: Figures 1 and 2 Via email: Morgantr@Outlook.com nick@northernengineering.com CATAMOUNT PROPERTIES 3 HILLPOND PROJECT,FT.COLLINS CTLITHOMPSON PROJECT NO.FC06692-115 PROSPECT RD J 4r) r K4 SITE LEGEND:In HILL PONDRO 4f T APPROXIMATE B_ INDICATES APPROXIMATE SCALE: =60' LOCATION OF EXPLORATORY 0' 30' 60' BORING VICINITY MAP FORT COLLINS,COLORADO) NOT TO SCALE l,,, A_ 1 B-2 1 •• 1 f-' 1 11 B-1 \ 0 B-4 0a 1 I B-5 1 P O NIt.0 P pNp RD Q' Locations of Exploratory BoringsCATAMOUNTPROPERTIES HILLPOND PROJECT,FT.COLLINS CTL I T PROJECT NO.FC06692-115 FIGURE 1 C) A t P a ! 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