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Home My WebLink About20050727.tiff PRELIMINARY GEOTECHNICAL ENGINEERING REPORT PROPOSED FAITH ESTATES WELD COUNTY ROAD 37, NORTH OF HIGHWAY 392 EATON, COLORADO NORTHERN COLORADO GEOTECH PROJECT NO. 185-04 October 21, 2004 Prepared for: Pickett Engineering 808 8th Street Greeley, Colorado 80631 Attn: Mr. Sean Phipps Northern Colorado Geotech 2956 29th Street, Unit 21 Greeley, Colorado 80631 Phone: (970) 506-9244 Fax: (970) 506-9242 2005-0727 Northern Colorado Geotech October 21, 2004 2956 29th Street, Unit 21 Greeley, Colorado 80631 Phone: (970)506-9244 Fax: (970)506-9242 Pickett Engineering 808 8th Street Greeley, Colorado 80631 Attn: Mr. Sean Phipps Re: Preliminary Geotechnical Engineering Report Proposed Faith Estates Northern Colorado Geotech Project No. 185-04 Northern Colorado Geotech has completed a preliminary geotechnical engineering exploration for the proposed Faith Estates to be located on Weld County Road 37, north of Highway 392. This study was performed in general accordance with our proposal number P04049g dated September 21, 2004. The subsurface soils at the site consisted of sandy lean clay, silty sand and well graded sand with silt and gravel. The results of our field exploration and laboratory testing indicate that the soils have low expansive potential and low load bearing capabilities. Based on the anticipated construction and the results of our preliminary engineering exploration, it is our opinion that proposed structures may be supported on spread footing foundations. Standard septic systems appear feasible within the development. This report is preliminary in nature. Additional subsurface exploration should be performed when precise structure and septic system locations are available. If you have any questions concerning this report or any of our consulting services, please do not hesitate to contact us. Sincerely, NORTHERN COLORADO GEOTECH Prepar by: Doug Leafgre , P. President Reviewed by: Gary G. Weeks, P.E. Vice President Copies to: Addressee (4) TABLE OF CONTENTS Page No. Letter of Transmittal SCOPE 1 SITE CONDITIONS 1 PROPOSED CONSTRUCTION 2 SITE EXPLORATION 2 Laboratory Testing 2 SUBSURFACE CONDITIONS 3 Geology 3 Soil and Bedrock Conditions 4 Groundwater Conditions 4 Field Test Results 4 Laboratory Test Results 4 PRELIMINARY DESIGN RECOMMENDATIONS 4 Foundation Design 4 Below Grade Construction 5 Seismic Considerations 5 Septic System Construction 5 General Earthwork 5 Site Preparation 6 Fill Materials and Placement 6 kGENERAL COMMENTS 7 ATTACHMENTS Boring Location Plan Logs of Borings Laboratory Test Results r PRELIMINARY GEOTECHNICAL ENGINEERING REPORT PROPOSED FAITH ESTATES WELD COUNTY ROAD 37, NORTH OF HIGHWAY 392 EATON, COLORADO NORTHERN COLORADO GEOTECH PROJECT NO. 185-04 OCTOBER 21, 2004 SCOPE This report contains the results of our preliminary geotechnical engineering exploration for the proposed Faith Estates to be located on Weld County Road 37, north of Highway 392. The site is located in the southeast quarter of Section 13, Township 6 North, Range 66 West of the 6th Principal Meridian. This report includes descriptions of, and geotechnical engineering recommendations relative to: • subsurface soil conditions • groundwater conditions • preliminary foundation design and construction • basement construction • septic systems • • earthwork The recommendations contained in this report are based upon the results of field and laboratory testing, engineering analyses, and experience with similar soil conditions, structures and our understanding of the proposed project. SITE CONDITIONS The site is currently vegetated with weeds. In the past, the site was used as an agricultural field. Surface drainage is good to the southwest. An existing residence is located on Lot 6 in the northeast corner of the property. The Greeley Number 2 Canal is located along the south and west sides of the site. Weld County Road 37 borders the site to the east. An agricultural field is located north of the property. r Pickett Engineering Faith Estates Northern Colorado Geotech Project No. 185-04 PROPOSED CONSTRUCTION As we understand it, the project will consist of developing the parcel of ground for nine "estate- style" lots that will be serviced by individual sewage disposal systems. SITE EXPLORATION A total of six test borings were drilled on September 27, 2004. The borings were drilled to approximate depths of 3 to 15 feet at the locations shown on the Site Plan, Figure 1. Three soil borings were drilled at various locations within the development and a preliminary percolation test boring was drilled adjacent to each soil test boring. All borings were advanced with a truck- mounted drilling rig utilizing 4 and 6-inch diameter solid stem augers. The borings were located in the field by pacing from property lines and/or existing site features. The accuracy of boring locations should only be assumed to the level implied by the methods used. Lithologic logs of each boring were recorded by an engineering geologist during the drilling operations. At selected intervals, samples of the subsurface materials were taken by driving split- spoon and/or ring samplers. Standard penetration measurements were recorded while driving a split-spoon and/or ring sampler into the subsurface materials. The standard penetration test is a useful index in estimating the density of the materials encountered. Groundwater conditions were evaluated in each boring at the time of subsurface exploration, and 14 days after the drilling. We also reviewed the results of a soil and percolation test performed for the existing residence located on Lot 6 (Northern Colorado Geotech Project No. 151-02, dated October 4, 2002). Laboratory Testing The samples retrieved during the subsurface exploration were returned to our laboratory for observation by the project manager. The soils were classified in general accordance with the Unified Soil Classification System. At that time, the field descriptions were confirmed or modified and an applicable laboratory testing program was formulated. Boring logs were prepared and are attached with this report. Laboratory tests were conducted on selected samples and are presented on the boring logs and attached laboratory test sheets. The test results were used for the geotechnical engineering analyses, and the development of foundation and earthwork recommendations. 2 Pickett Engineering Faith Estates Northern Colorado Geotech Project No. 185-04 Selected samples were tested for the following engineering properties: • Water Content • Grain size • Dry Density • Compressive Strength • Consolidation • Expansion SUBSURFACE CONDITIONS Geology The proposed area is located within the Great Plains physiographic province. The Colorado Piedmont is located near the western border of the Great Plains province and was formed during Late Tertiary and Early Quaternary time (approximately 2,000,000 years ago). The Colorado Piedmont is a broad, erosional trench which separates the Southern Rocky Mountains from the High Plains. Structurally, the site lies near the axis of the Denver Basin. During the mountain building of the Laramide Orogeny (approximately 70,000,000 years ago), intense tectonic activity occurred, causing the uplifting of the Front Range and associated downwarping of the Denver Basin to the east. Due to the erosional action of wind and streams, relatively flat uplands and broad valleys characterize the present-day topography of the Colorado Piedmont in this region. The bedrock at the site is anticipated to be the Cretaceous Laramie Formation. The Laramie consists of interbedded sandstone, siltstone and claystone units. Significant coal units are also found in the Laramie Formation in southern Weld County. Based on our borings and a literature review, it is our opinion that there are not economic quantities of sand or gravel aggregate at the site. Due to the type of bedrock formation(s) which underlie the site, it is our opinion that no economic quantities of quarry rock are available at the site. Based on the review of maps in the area, we are unaware of coal mines in the immediate vicinity of the site. Therefore, it is our opinion that there are no economic quantities of minerals or aggregate at the subject site. Due to the relatively flat nature of the site, geologic hazards at the site are anticipated to be low. Seismic activity in the area is anticipated to be low; and from a structural standpoint, the property should be relatively stable. With proper site grading around proposed structures, erosional problems at the site should be minimal. r 3 Pickett Engineering Faith Estates Northern Colorado Geotech Project No. 185-04 Soil and Bedrock Conditions Soils at the site generally consisted of sandy lean clay, silty sand, clayey sand and well graded sand with silt and gravel to depths of 15 feet. Summary boring logs are attached with this report. Groundwater Conditions Groundwater was encountered at approximate depths of 8 to 10 feet in Test Borings 1 and 2 at the time of field exploration. When checked 14 days after the drilling, groundwater was measured at approximate depths of 8% to 10 feet. These observations represent groundwater conditions at the time of the field exploration, and may not be indicative of other times, or at other locations. Groundwater levels can be expected to fluctuate with varying seasonal and weather conditions. Field Test Results Field test results indicate that the clay soils vary from medium stiff to stiff in consistency. The sand soils vary from loose to medium dense in relative density. /~ Preliminary percolation testing conducted is summarized as follows: Percolation Test Results Test Hole Depth Soil Percolation Rate (inches) Classification (minutes/inch) 1 36 CL 10 2 36 CL 15 3 36 CL 30 The soils appear to have fair percolation rates. M Laboratory Test Results Laboratory test results indicate that the soils have low expansive potential and low load bearing capabilities. PRELIMINARY DESIGN RECOMMENDATIONS Foundation Design Based on the results of our subsurface exploration and the results of the laboratory testing, it is our .-" opinion that spread footing foundations may be used for support of proposed structures. Footings 4 Pickett Engineering Faith Estates Northern Colorado Geotech Project No. 185-04 should be placed on undisturbed soils and/or engineered fill material. Relatively shallow groundwater along the northern side of the property will require particular attention in the design and construction. The footings may be preliminarily designed for maximum bearing pressures of 1,000 to 2,000 psf. The design bearing pressure applies to dead loads plus design live load conditions. The design bearing pressure may be increased by one-third when considering total loads that include wind or seismic conditions. Exterior footings should be placed a minimum of 30 inches below finished grade for frost protection and to provide confinement for the bearing soils. Finished grade is the lowest adjacent grade for perimeter footings. Below Grade Construction Groundwater was encountered on the northern portion of the site at depths of 8 to 10 feet below existing grade. Basement construction is considered feasible on the site provided that basement subgrade is placed a minimum of 3 feet above the groundwater. Site specific subsurface explorations should be performed to determine groundwater levels at the precise building locations. Seismic Considerations The project site is located in Seismic Risk Zone I of the Seismic Zone Map of the United States as indicated by the 1997 Uniform Building Code. Based upon the nature of the subsurface materials, a soil profile type Se should be used for the design of structures for the proposed project (1997 Uniform Building Code, Table No. 16-J). Septic System Construction 1 A Field test results indicate that a standard septic system wilt likely be feasible throughout the entire development. Site specific soil percolation testing will be necessary for each lot within the development. The systems should be designed in accordance with applicable state and county requirements and should be located at the minimum distances from all pertinent ground features described in Weld County regulations. General Earthwork All earthwork on the project should be observed and evaluated by Northern Colorado Geotech. The evaluation of earthwork should include observation and testing of 5 Pickett Engineering Faith Estates Northern Colorado Geotech Project No. 185-04 engineered fill, subgrade preparation, foundation bearing soils, and other geotechnical conditions exposed during the construction of the project. Site Preparation Strip and remove existing vegetation, debris, and other deleterious materials from proposed building and pavement areas. All exposed surfaces should be free of mounds and depressions which could prevent uniform compaction. Stripped materials consisting of vegetation and organic materials should be wasted from the site, or used to revegetate landscaped areas or exposed slopes after completion of grading operations. If unexpected fills or underground facilities are encountered, such features should be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction. It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment. Depending upon depth of excavation and seasonal conditions, groundwater may be encountered in excavations on the site. Pumping from sumps may be utilized to control water within excavations. Well points may be required for significant groundwater flow, or where excavations penetrate groundwater to a significant depth. The individual contractor(s) is responsible for designing and constructing stable, temporary excavations as required to maintain stability of both the excavation sides and bottom. All excavations should be sloped or shored in the interest of safety following local, and federal regulations, including current OSHA excavation and trench safety standards. Fill Materials and Placement All exposed areas which will receive fill should be scarified to a minimum depth of eight inches, conditioned to near optimum moisture content, and compacted. The placement of soils on the site should be observed by Northern Colorado Geotech. The fill should be assessed for suitability of use in the proposed fill and tested for placement including compaction percentage and moisture content. 6 Pickett Engineering Faith Estates Northern Colorado Geotech Project No. 185-04 Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift. Recommended compaction criteria for engineered fill materials are as follows: Clean on-site soils or approved imported materials may be used as fill material. Imported soils (if required) should conform to the following: Percent fines by weight Gradation (ASTM C1361 6" 100 3" 70-100 No. 4 Sieve 50-100 No. 200 Sieve 60 (max) • Liquid Limit 30 (max) • Plasticity Index 15 (max) Minimum Percent Material (ASTM D6981 Scarified subgrade soils 95 On-site and imported fill soils: Beneath foundations 95 Beneath slabs 95 Beneath pavements 95 � A A On-site or imported clay soils should be compacted within a moisture content range of 2 percent below, to 2 percent above optimum. Granular soils should be compacted within a moisture range of 3 percent below to 3 percent above optimum unless modified by the project geotechnical engineer. GENERAL COMMENTS The analysis and recommendations presented in this report are based upon data obtained from borings performed to obtain representative subsurface conditions at the site. Variations in the soil 7 r n r Pickett Engineering Faith Estates Northern Colorado Geotech Project No. 185-04 between borings will occur. Northern Colorado Geotech should be present during construction to observe the excavation and construction procedures and confirm or modify our recommendations. The scope of services for this project does not include either specifically or by implication any environmental assessment of the site. This report has been prepared in accordance with generally accepted geotechnical engineering practices in this area at this time. No warranties, either express or implied, are intended or made. r • . ........, LOT 1 LOT 2 LOT 3 LOT 5 LOT 6 LOT 4 No.1 S \ No.29 . \ LOT 7 R re re LOT 8 \ i No.3& LOT 9 Y 4 BORING LOCATION PLAN N PROPOSED FAITH ESTATES WELD COUNTY ROADS 37,NORTH OF HWY 392 EATON,COLORADO ,/"+,1 FOR PICKETT ENGINEERING Northern P o. 165-00- Colorado �° 1•-300• Geotech Daro. 10-20-04 2956 29th Stree4 Unit 21 PojeU MgT Greeley,Colorado 80631 DML DIAGRAM IS FOR GENERAL LOCATION ONLY. Phone: (970)5069244 AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES , Fax: (970)506 Fguro N0. 9242 .1 LOG OF BORING No. 1 Sheet 1 of 1 .---- CLIENT ARCHITECT/ENGINEER Pickett Engineering SITE WCR 37 and Hwy 392 PROJECT Eaton,Colorado Faith Estates Preliminary SAMPLES TESTS o (0 t7 rr ae a w Z O LL N W0 K Z WW MZF U ' !-W W >O 7 W C.W �UZ I-01 - m W KW N p Om 0F-W < 0- OQ 2 a 0D: >-u zo 7N0 0 mZ 2 R oa =H Og zz �aa 6"TOPSOIL .o`i, 13 1 SS 18 10 0.5 SANDY LEAN CLAY '{� Tan to brown, moist, medium stiff to stiff %// fJy/� 13 2 SS 12 21 31/10/66 5 /�/ .` 6.0 / WELL GRADED SAND WITH SILT AND GRAVEL Tan, moist to wet, medium dense 13 3 SS 12 14 T. 10 • • V 1 13 4 SS 12 16 15.0 15 BOTTOM OF BORING WATER LEVEL OBSERVATIONS Northern STARTED 9/27/04 FINISHED 9/27/04 "OV/orado WL 1__Z 8.0 W.D. Geotech DRILL Co. Drilling Eng DRILL RIG CME-55 2 wt. Y $ 5 A.B. 2956 29th Street,Unit 21 LOGGED BY DBC APPROVED DML u Greeley,Colorado 80631 When Checked 14 Days A.B. Phone: 970-506-9244 NCG PROJECT No. 185-04 0 Fax: 970.506-9242 LOG OF BORING No. 2 Sheet 1 of 1 '' CLIENT ARCHITECT/ENGINEER Pickett Engineering SITE WCR 37 and Hwy 392 PROJECT Eaton,Colorado Faith Estates Preliminary SAMPLES TESTS ❑ 1.3 re `e w n -i F N cc Z> W V! Z W LL 'W Z >W N ❑ 7 in a E~ 3� m w K ❑0_ < w 0? 2 o_ ❑ O >- <a o ❑ mz z ?? ❑o. xH 6"TOPSOIL 1 i. 14 1 SS 18 7 0.5 SANDY LEAN CLAY Tan to brown, moist, medium stiff to stiff 9 -II f/ l 5 2 RS 12 6 116 6000 7.0 SILTY SAND Tan, moist to wet,loose 6 3 SS 12 6 10.0 Y 10— WELL GRADED SAND WITH SILT AND GRAVEL Tan,wet, medium dense ti — � I 20 4 5S 12 9 15.0 - 15 gyl�l BOTTOM OF BORING WATER LEVEL OBSERVATIONS STARTED 9/27/04 FINISHED 9/27/04 tli(orthern oforado WL g 10.0 W.D. Geotech DRILL co. Drilling Eng DRILL RIG CME-55 0- WL 1 10.0 A.B. 2956 29th Street,Unit 21 LOGGED BY DBC APPROVED DML u Greeley,Colorado 80631 When Checked 14 Days A.B. Phone: 970-506-9242 Fax: 970.506-9242 NCG PROJECT NO. 185-04 • LOG OF BORING No. 3 Sheet 1 of 1 CLIENT ARCHITECT/ENGINEER Pickett Engineering SITE WCR 37 and Hwy 392 PROJECT Eaton,Colorado Faith Estates Preliminary SAMPLES TESTS C O n o E • _ �0 W ≥o F w [Liu O. F 5J Ill W CW `II 0 OM a 0 OK K W J> 6"TOPSOIL ;W'i, 29 1 SS 18 7 0.5 SANDY LEAN Tan o brown, ry toYmoist,very stiff r 18 2 RS 12 7 102 9000 5- 5.5 CLAYEY SAND Tan, moist,loose • . —� 8 3 SS 12 12 10.0 � 10 SILTY SAND Tan, moist, medium dense - 11 4 SS 12 8 15.0 15 BOTTOM OF BORING .-� WATER LEVEL OBSERVATIONS Northern STARTED 9/27/04 FINISHED 9/27/04 t‘olorado WL None W.D. Geotech DRILL co. Drilling Eng DRILL RIG CME-55 WL None A.B. 2956 29th Street,Unit 21 LOGGED BY DBC APPROVED DML Greeley,Colorado 80631 xi When Checked 14 Days A.B. Phone: 970-506-9244 NOG PROJECT NO. 185-04 J Fax: 970-506-9242 -3 , -2 0 z•Tt °.:I----------------------r-----T-r-----"--:- -------- I 71"----7"N\--- , 3 ' ' E I - 4 i i 5 -- 0.1 1 10 STRESS,kst Specimen Identification Classification Yd MC% • 2 3.0 SANDY LEAN CLAY 115 6 r-• CONSOLIDATION TEST Northern 2956 29th Street,Unit 21 Client: Pickett Engineering Number: 185-04 Colorado Greeley,Colorado 80631 Phone: 970 506 9244 Project: Faith Estates Preliminary Geotech Fax: 970-506-9242 Location: WCR 37 and Hwy 392 _ I -3 — - - -2 -1 • 1 co 2' r 3; 4 5 - -- L 0.1 1 10 STRESS,ksf Specimen Identification Classification Ya MC% • 3 3.0 SANDY LEAN CLAY '102 7 CONSOLIDATION TEST Northern 2956 29th Street,unit 21 Client: Pickett Engineering Number: 185-04 Colorado Greeley,Colorado 80631 Phone: 970-506-9244 Project: Faith Estates Preliminary Geotech Fax: 970-506-9242 Location: WCR 37 and Hwy 392 • U.S.SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER 6 4 3 2 1.5 13/4 1/23/8 3 4 6 810 1416 2 30 0 40 50 60 100140200 100 I II IlliNkl 11111 I I I - 95 __ I _ 1 90 - 85 - 80 I I 75 70 —_IIIIR_I— I 65 H60 _��-�_ >-CO 55 et _ _ — La 50 z M I- 45 z w U 40 0: a - w a - 35 30 , _ 25 - NJ 20 15 10 • 5 0 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS GRAVEL SAND COBBLES SILT OR CLAY coarse fine coarse I medium I fine Specimen Identification Classification LL PL PI Cc Cu • 1 8.0 WELL GRADED SAND WITH SILT AND GRAVEL 1.17 18.29 Specimen Identification D100 D60 D30 D10 %Gravel %Sand %Silt I %Clay • 1 8.0 12.5 1.984 0.501 0.108 16.9 75.2 7.9 GRAIN SIZE DISTRIBUTION Northern 2956 29th Street,Unit 21 Client: Pickett Engineering Number: 185-04 Colorado Greeoad 80431 0. Phonele:y,970-506-924Colro 4 Project: Faith Estates Preliminary Geotech Fax: 970-506-9242 Location: WCR 37 and Hwy 392 Hello