The URL can be used to link to this page

Home My WebLink AboutSILVERBERG PUD PRELIMINARY - 12 92A - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTENGINEERING GEOLOGY REPORT FOR SILVERBERG P.U.D., CITY OF FORT COLLINS, LARIMER COUNTY, COLORADO FOR GEFROH-HATTMAN, INC. CDS ENGINEERING CORPORATION LOVELAND, COLORADO PROJECT NUMBER - 96-8832 OCTOBER 18, 1996 � s .. OL: :z • n ■ I — --j ' I 1 I I• — ,III 1111�1�1 �I N i V; _ )sC_L3TbItY•r07 , O � '1 i d i B 5 1 � �In II I i I 1 D'D 0wool DD 00 ilv19 I I1 n 1 SITE AREA G1•aGY DRAWN BY: EODRAWING W Qe -- Qugternary Eol an Deposits above ire+oceou5 Pierre N0' SCALE : r " - i - Iro ± 5%ale Upper er UNI (k-,P 1 DATE: 10-18-96 CDS ENGINEERING CORP. 0.OJECT 96-8832 TABLE OF CONTENTS 1 Paae Letter of Transmittal i Table of Contents Scope 1 Site Investigation 1 Geology 2-4 - Regional and Local Setting 213 - Economic Geology 3 - Potential Geologic Hazards 4 Groundwater Resources 5 Sewage Disposal 5 Summary, Conclusions, and Recommendations 516 Site Area Geology Drawing No. 1 October 18, 1996 Project No. 96-8832 Mr. Rick Hattman GEFROH-HATTMAN, INC. 145 W. Swallow Road Fort Collins, CO 80525 Dear Rick: Enclosed is the Engineering Geology Report for Silverberg P.U.D., City of Fort Collins, Larimer County, Colorado. If you have any questions concerning the information in this report, please contact this office. sincerely, CDS E06 N� AJW/pkw Enclosures "BONA L t 165 2nd Street S.W.. Loveland, CO 80537 . (970)667-8010 .. Fax: (970) 667-8024 1 SCOPE This report presents geologic data, interpretation, and evaluation which pertains to the development of the proposed Silverberg P.U.D., in the City of Fort Collins, Larimer County, Colorado. The Silverberg P.U.D..is a proposed 9± acre development located in the east part of the City of Fort Collins, Larimer County, Colorado. More particularly, the site is located in the NW; of the NW; of Section 22,.,Township 7 North, Range 68 West of. the 6th P.M., Larimer County, Colorado. The intent of this subdivision is to provide a site for commercial development. Six (6) lots are anticipated. SITE INVESTIGATION This investigation was carried out by means of site inspection by the author of this report, and information obtained from "Sand, Gravel, and Quarry Aggregate Resources - Colorado Front Range Counties", "Guidelines and Criteria for Identification and Land -Use Controls of Geologic Hazard and Mineral Resource Areas" and "Proceedings of the Fifteenth Forum on Geology of Industrial Minerals" by the Colorado Geological Survey,"Geologic Map of Colorado", by the U.S.G.S. and "Soil Survey of Larimer County Area, Colorado", by the U.S.D.A. Soil Conservation Service.. Information of economic constraints for sand and gravel mining were from verbal communications with local gravel pit operators. J GEOLOGY Regional and Local Setting The site lies in the Colorado Piedmont Section of the Great Plans Physiographic Province. The Colorado Piedmont is an elongated trough in the Great Plains, adjacent to the Front Range of the Southern Rockies. The Colorado Piedmont was formed when, uplift of the area in Miocene -Eocene times (20-50 million years ago) produced an increase of stream erosion resulting in scouring next to the foothills and outlying areas. -The Piedmont is bordered by the Southern Rockies to the west, Great Plains escarpment to the northeast, and Palmer Divide to the south. „ More particularly, the site lies in the east part of the City of Fort Collins, Larimer County, Colorado, just east of Interstate 25 and south of E. Prospect Drive, northeast of the Cache'La Poudre River. Structurally, the site lies on the western edge of the Denver Basin, a thick accumulation of sediments involved with downwarping in the basin area and uplift of the adjacent highland areas in late Cretaceous and early Cenozoic. Small anticlinal folds occur adjacent to the Front Range in the sedimentary rocks and are conducive to the accumulation of oil and gas deposits. The closest known faults to the site are the Thompson Canyon Fault and Milner Mountain Fault, which are approximately 9 j 3 miles to the southwest. Both faults are believed to be inactive since no recent records of fault movement or earthquakes exist. Slopes at the site are slight to moderate with drainage flowing predominately to the west with a maximum slope of approximately three percent (3%). The site is not located within the 100-year or 500-year flood plain. Groundwater levels appear to be seasonably high to a 2011- 30" depth in the area during part of the growing season. Economic Geology Mineral resources at the site are upland gravel deposits underlying pediments and high Tertiary surfaces. Because of the high groundwater area, local development and size of the property, the —area of. the site was determined to be unmineable. Based on the above data and criteria used in determining economic feasibility of local gravel operations, we feel that the site is not large enough and does not contain enough gravel to be economic for mining. Information on oil and gas deposits at the site were not available at this time; however, oil and gas wells are located near this area. 4 Potential Geologic Hazards Geologic hazards caused by gravity, such as landslides, rockfall, mud and debris flows and snow avalanches, are not anticipated in the present state of the site. Utility trenches may require shoring or bracing in order to create -safe working conditions during construction. The SCS described the soils at the site as Nunn Clay Loam. These soils are described by the SCS as having 1 to 3 percent slopes. Some of the Nunn Clay Loams have high seasonal groundwater and poor drainage.' The soils, which are to support foundations will be comprised of clays with varying amounts of sand and gravel, and should be able to support foundation loads. Each building site should have a complete geotechnical investigation and engineered foundation so as to minimize the effects of structures on the soils and to review the groundwater depths. The groundwater depths across the site can then be addressed. 5 GROUNDWATER RESOURCES Potable water is to be supplied by the East Larimer County Water District. Shallow groundwater at the site should not be used as potable water. Pollution of the groundwater caused by individual sewage disposal systems at the site should not exist because Boxelder Sanitation or the City of Fort Collins sewage system will be used. SEWAGE DISPOSAL The sewage disposal will be handled by Boxelder Sanitation or the City of Fort Collins sewage system. SUMMARY. CONCLUSIONS, AND RECOMMENDATIONS The site is underlain with some gravels; although it was not found to be in sufficient quantities to be economical to mine. Oil and gas wells are not located in the area although sufficient information was not obtainable to determine the economic feasibility for.oil and gas production at the site. Possible high groundwater and potential trench caving are hazards which will require attention prior to and during the construction process.. Potential hazards can be minimized or eliminated by 1) a geotechnical investigation being performed for each building site and following the recommendations in the report and 2) following the present construction codes. 6 Based on the data mentioned in this report, we feel that the site is suitable for the proposed Silverberg P.U.D., provided the recommendations in this report are met. This report does not reflect any variations in surface and subsurface conditions either natural or man-made.