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Home My WebLink About971116.tiff GEOTECHNICAL INVESTIGATION REPORT Scotch Pine Estates LA SALLE, COLORAQO Wets Ocunty Planning Dept APRIL, 1997 APR 1 5 1997 • ri ECOVED TOTAL ENGINEERING SERVICE, INC. © NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN 3310 State Street Evans, CO 80620 (970)339-5215 � � 971116 S Total Engineering Service, Inc. as 3310 State Street • Evans, CO 80620 • (970) 339-5215 April 9, 1997 Mr. Bill Jerke 23003 W.C.R. 39 La Salle, CO 80645 Re: Scotch Pines Estates Minor Subdivision La Salle, CO Dear Bill: We are pleased to submit this Geotechnical Investigation Report for the site investigation at the above referenced project, as you requested. Based upon our investigation of this site and the subsurface conditions encountered, it is our opinion the site is suitable for the proposed construction, providing the design criteria a n d recommendations set forth in this report are met. The enclosed report presents our findings of the subsurface conditions and our recommendations based upon these findings. Sincerely, TOTAL ENGINEERING SERVICE °t117"f/inn 4.e 4! // !?It95 Torn Cope, P.E. '°; y/17 f xc: File #97-120 GEOTECHNICAL INVESTIGATION REPORT BILL JERKE SCOTCH PINE ESTATES LA SALLE, COLORADO PROJECT NO. 97-120 Prepared by: Total Engineering Service, Inc. 3310 State Street Evans, CO 80620 April, 1997 TABLE OF CONTENTS Report Scope 1 Site Location and Description 1 Site Investigation _ 2 Laboratory Tests and Examinations 2 Subsoil and Groundwater Conditions 3 Recommendations and Discussion 3 Foundation _.._._._...._._.__._ _...__._._ 4 Concrete Slabs 5 General Recommendations 6 General Comments 7 Appendix A SitePlan ._...__._.............._,__._.___.__ 8 Key to Boring Logs 9 Boring Logs 10 Appendix B Summary of Test Results 13 Consolidation __..__.,... 1 5 Appendix C Suggested Specifications for Placement of Structural Fill 16 GEOTECHNICAL INVESTIGATION REPORT SCOPE This report presents the results of a geotechnical investigation on proposed home sites located on the east side of La Salle, Colorado. The investigation was performed for the developer of the site, Bill Jerke. The investigation included five test borings, one on each lot, and laboratory testing of samples obtained from these borings. The objectives of this study were to (1) evaluate the subsurface conditions at the site relative to the proposed construction, (2) make recommendations regarding the design of the substructures, and (3) recommend certain precautions which should be taken because of adverse soil and/or ground water conditions. The conclusions and recommendations presented in this report are based upon analysis of field and laboratory data and experience with similar subsurface conditions in the general vicinity. SITE LOCATION AND DESCRIPTION The site is located west of Weld County Road 41 and north of Weld County Road 50 1/2 in part of the Southeast Quarter (SE 1/4) of the Northeast Quarter (NE 1/4) of Section 32, Township 5 North (T. 5 N.), Range 65 West (R. 65 W.) of the Sixth Principal Meridian, Weld County, Colorado. The site is more particularly known as Scotch Pine Estates Minor Subdivision. The site consists of five existing vacant lot and one lot with a single family residence. Fields border the site to the south and east. The Union Ditch borders the site to the north. The site is essentially level. 1 SITE INVESTIGATION The field investigation was conducted on March 11, 1997 and consisted of five (5) borings at the approximate locations of proposed single family residences. The location of the test borings are approximated by field pacing from existing physical structures as shown on the Site Plan enclosed in Appendix A. The borings were advanced using a four inch (4") diameter, continuous flight auger powered by a truck mounted drilling rig. Samples of the subsoils were obtained to determine an index of the soils relative density and consistency by use of the standard penetration test, ASTM Standard Test D-1586. The penetration test result listed on the Summary of Test Results is the number of blows required to drive the 2 inch split-spoon sampler twelve inches, or increments as shown, into undisturbed soil by a 140 pound hammer dropped 30 inches. Undisturbed samples for use in the laboratory were taken in three inch (3") O.D. thin wall samplers (Shelby Tubes), pushed hydraulically into the soil. Undisturbed and disturbed samples were sealed in the field and preserved at natural moisture content until time of testing. Boring logs are provided in Appendix A and include visual classifications of each soil, location of subsurface changes, standard penetration test results, and subsurface water level measurements at the time of this investigation. LABORATORY TESTS AND EXAMINATIONS Samples obtained from the test boring were subjected to testing and inspection in the laboratory to provide a sound basis for determining the physical properties of the soils encountered. Moisture contents, dry unit weights, swelling potentials, consolidation data, and the Atterberg Limits were determined. A summary of the test results and laboratory analysis can be found in Appendix B. SUBSOIL AND GROUND WATER CONDITIONS The soil profile at the site consists of strata of materials arranged in different combinations. In order of increasing depths, they are as follows: 1 ) Topsoil: A one foot (1') layer of silty sand was encountered at the surface of the borings. The topsoil has been penetrated by root • growth and organic matter and should not be used as a bearing soil or as a fill/backfill material. 2 ) Silty Sand & Gravel: A stratum of silty sand & gravel was encountered beneath the topsoil in all bores. The amount of silt varies thoughout the stratum. The sand exhibits a slight to moderate bearing capacity with a very slight potential for swell. 3 ) Ground Water: At the time of the investigation, free ground water was not encountered in any of the five bores. Water levels in this area are subject to change due to seasonal variations and irrigation demands on and/or adjacent to the property. RECOMMENDATIONS AND DISCUSSION It is our understanding that future homes will be constructed with a full depth basement foundation, if possible. Construction materials, most likely, will consist of wood framed walls. We do not anticipate foundation loading to be unusual for this type of construction. 3 FOUNDATION In view of the loads transmitted by a single family house and the soil conditions encountered at the site, it is recommended the structure be supported by a continuous spread footing foundation system. The following design criteria should be observed: a) All exterior footings should be placed a minimum of thirty inches (30") below finished grade for frost protection. b ) Footings may be designed for a maximum allowable bearing capacity (dead load plus maximum live load) of one thousand five hundred pounds per square foot (1500 psf). The predicted settlement under the above maximum loading is anticipated a t approximately one inch (1"), generally considered to be within acceptable tolerances. c) Footings should be proportioned as much as practicable to minimize differential movement. Spread footings should be a minimum of sixteen inches (16") in width. Pad footings should be a minimum width of twenty-four inches (24"). d ) Continuous concrete foundation walls should be well reinforced top and bottom. e) The base for structural fill should include all areas within a 1:1 horizontal to vertical slope from the edge of the footings. f) All footings should be placed on undisturbed natural soil o r compacted fill and should be verified by the geotechnical engineer prior to placement of any foundation concrete. 4 CONCRETE SLABS The concrete slab construction and design should take into account the following recommendations: a) Slabs should be designed for the imposed loading. b) To minimize and control shrinkage cracks which may develop in slabs, we suggest control joints be place every fifteen feet (15') and areas of potential cracking. The total area contained within these joints should be no greater than two hundred and twenty- five square feet (225 sf). c) The slabs should be continuous reinforced with wire mesh or equivalent. d ) Positive drainage should be provided for the excavation subgrade to prevent pooling of water beneath the slab. e) Exterior slabs exposed to de-icing chemicals or extreme weathering should be constructed using Type II cement with higher air contents and higher compressive strengths. 5 • GENERAL RECOMMENDATIONS The following recommendations should be followed during construction and maintained at all times after the structure has been completed: 1 ) Finished grade should be sloped away from the structures on all sides to give positive drainage. A minimum slope of six inches (6") for the first ten feet (10') is suggested. 2 ) Backfill around the exterior foundation walls in non-structural areas should be moistened and compacted to at least ninety percent (90%) of Standard Proctor density according to ASTM D698. 3 ) It is recommended compaction requirements in the project specifications be verified in the field with density test performed under the direction of the geotechnical engineer. 4) It is recommended a registered professional structural engineer design the substructures, and they should take into account the findings and recommendations of this report. 5) Backfill material should be free of frozen soil, large dried clods a n d organic matter. Backfilling should only be accomplished when concrete strength and adequate support to foundation walls are applied and acceptable to the Foundation Engineer. 6 GENERAL COMMENTS This report has been prepared to aid in the evaluation of the property and to assist the architect and/or engineer in the design of this project. In the event any changes in the design of the structures or their locations are planned, the conclusions and recommendations contained in this report will not be considered valid unless said changes are reviewed and conclusions of this report modified or approved in writing by Total Engineering Service, Inc., the geotechnical engineer of record. The professional judgments expressed in this report meet the standard care of our profession. Every effort was made to provide comprehensive site coverage through careful locations of the test borings, while keeping the site investigation economically viable. Variations in soil and ground water conditions between test borings may be encountered during construction. In order to permit correlation between the reported subsurface conditions and the actual conditions encountered during construction and to aid in carrying out the plans and specifications as originally contemplated, it is recommended Total Engineering Service, Inc. be retained to perform continuous construction review during the excavation and foundation phases of the work. Total Engineering Service, Inc. assumes no responsibility for compliance with the recommendations included in this report unless they have been retained to perform adequate on-site construction review during the course of construction. 7 APPENDIX A Site Plan Key to Boring Logs Boring Logs APPROXIMATE CENTERLINE OF THE UNION DITCH O TB #1 O TB #2 tY OTB #5 1 TB #3 O O TB #4 a U GRAPHIC SCALE W.C.R. 50 1 /2 (111.12.) O BORE LOCATION lin°°-•°°9 71zosP BORE LOCATION MAP SCOTCH PINE ESTATES SUBDIVISION LA SALLE, COLORADO DATE: 4/1 1 /97 SCALE: ©Total En ineering Service, Inc. PROD. No: 97-120 1" = 200' EVANS, COLORADO 3310 STATE STREET 1I\\ L e0620 DRAWN BY: K.B.B. SHEET 1 (970) 339-5215 CHECKED BY: T.M.C. OF 1 KEY TO BORING LOGS \ .. . ROAD BASE fy�44 SANDY SILTY CLAY TOP SOIL I:1 GRAVEL ✓r MAG FILL ..:. SAND& GRAVEL SILT : :.' SILTY SAND & GRAVEL • i • iq CLAYEY SILT •• • COBBLES `t •'• SANDY SILT ' SAND, GRAVEL & COBBLES FI'// CLAY • WEATHERED BEDROCK YY / ,M SILTY CLAY M SILTSTONE BEDROCK ra SANDY CLAY CLAYSTONE BEDROCK SAND S SANDSTONE BEDROCK COARSE SAND ® LIMESTONE SILTY SAND 5 GRANITE ri CLAYEY SAND STANARD PENETRATION 5/121 DRIVE SAMPLER SHELBY TUBE SAMPLE 5 blows of a 140#hammer falling 30"was required to penetrate 12" v _C _ WATER TABLE CAVED TOTAL ENGINEERING SERVICE, INC. 1 LOG OF BORINGS Boring#1 Boring#2 Sit 0' ' ' P '"""" P 11111 Topsoil 'If 1 f 1 f Topsoil !nitrite: VVVVV y ''' / 8,12R / / / /L 8/1211 /.J.J v !/ '/ .......... VVVVV """" «« Silty Sand& Gravel ' /'' '•' Silt Sand _ ' ' ' ' ' •'•'•'•' Y E.E.�i i!i .......' Gravel C /'/V V V ✓'i'/'/y :j•••'/'i ---J /;y '/'/'/'/ •••••• Sand & Gravel ••••••t• Sand & Gravel 15' — ..{ TOTAL ENGINEERING SERVICE, INC. mod LOG OF BORINGS Boring#3 Boring#4 Depth 0' . Topsoil Topsoil Ill '7,lII/ VVVVV YYY'/Y 1•• 4 2VVVV i I r Silt Sand & Gravel .t; YYYY '/t/ 13/12" • 5. • • _Silty Sand & C ;; Gravel ,.•,{.4.{- Sand & Gravel /v vv •t.t•t 8/12" t f-t 12/12" 10' :.,.... -•••••••• Sand & Gravel • 15' TOTAL ENGINEERING SERVICE, INC. J LOG OF BORINGS Boring#5 o '' '"' Topsoil .:...:> ;f:;f:;f:;:':;:' Silty Gravely Sand '''v v v 8/12" «...«.« 5 . •yyyyy 7 'i .y.«,«i.2. Silty Sand & Gravel (✓ i7'vtiti .......... 10' :.:.:.t .: .. .: t•t•t-t•t Sand& Gravel t.t.t.t.t :.:.:.:.:. t.:.t•tL 15' :.:.:.:L TOTAL ENGINEERING SERVICE, INC. si APPENDIX B Summary of Test Results Consolidation / C i 3 CV CM CM O O O CO O m a c 0 u = U < 0. N N di 0 Q 7 R N m Q U V/ all o o e o F 0 c J u K .• Cl) -O0 O V� cow C .-" W a CC 9 r m I'm c E at - Cl) = W a F— von r m # IL N 0 ... N O _ O TO 'jai /' ° a CO ` a Y. a)a) a >To t p 2 r tl p LL N i C co W a ;! a a) C O N d O D o U N Cl) a O .; T w o _ CO CO r-CO o a, 0 m 3 • .. tl 2e in c` i0 N. CM ? In co co 0. 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J CC CC w O a a c • ▪ o a N o Z `m f sTotal Ensineering Service, Inc. ©© 3310 STATE STREET I EVANS, COLORADO 80620 (970) 339-5215 I SWELL — CONSOLIDATION TEST I .725 Project No.: 97-120 Boring No.: 5 I .700 Depth: 3.0' Dry Density: 106.54 pcf Moisture: 9.41% ' .675 .------'..\\ sso WATER O ADDED I • .625 v 600 , 550 i • I .550 .525 I l .500 0.1 0.25 0.5 1.0 5 10 IApplied Pressure — TSF I 5.0 ul 0.0 I WADED IK —/,� ADDED so I I 10.0 0 o 15.0 in 20.0 I 25.0 0.1 0.25 0.5 1.0 5 10 Applied Pressure — TSF I ■97120con TES MT-006 APPENDIX C Suggested Specifications for Placement of Structural Fill APPENDIX C Suggested Specifications for Placement of Structural Fill General A geotechnical engineer shall be on-site to provide continuous observation during filling and grading operations and shall be the owner's representative to inspect placement of all compacted fill and/or backfill on the project. The geotechnical engineer shall approve all earth materials prior to their use, the methods of placing, and the degree of compaction obtained. Materials Soils used for all compacted fill and backfill shall be approved by the geotechnical engineer prior to their use. The upper two (2) feet of compacted earth backfill placed adjacent to exterior foundation walls shall be an impervious, nonexpansive material. No material, including rock, having a maximum dimension greater than six (6) inches shall be placed in any fill. Any fill containing rock should be carefully mixed to avoid nesting and creation of voids. In no case shall frozen material be used as a fill and/or backfill material. Preparation of Subgrade All topsoil, vegetation (including trees and brush), timber, debris, rubbish, and other unsuitable material shall be removed to a depth satisfactory to the geotechnical engineer and disposed of by suitable means before beginning preparation of the subgrade. The subgrade surface of the area to be filled shall be scarified a minimum depth of six (6) inches, moistened as necessary, and compacted in a manner specified below for the subsequent layers of fill. Fill shall not be placed on frozen or muddy ground. Placing Fill No sod, brush, frozen or thawing material, or other unsuitable material shall be placed in the fill, and no fill shall be placed during unfavorable weather conditions. All clods shall be broken into small pieces, and distribution of material in the fill shall be such as to preclude the formation of lenses of material differing from the surrounding material. The materials shall be delivered to and spread on the fill surface in a manner which will result in a uniformly compacted fill. Each layer shall be thoroughly blade mixed during spreading to ensure uniformity of material and moisture in each layer. Prior to compacting, each layer shall have a maximum thickness of eight (8) inches, and its upper surface shall be approximately horizontal. Each successive 6" to 8" lift of fill being placed on slopes or hillsides should be benched into the existing slopes, providing good bond between the fill and existing ground. Moisture Control While being compacted, the fill material in each layer shall as nearly as practical contain the amount of moisture required for optimum compaction or as specified, and the moisture shall be uniform throughout the fill. The contractor may be required to add necessary moisture to the fill material and to uniformly mix the water with the fill material if, in the opinion of the geotechnical engineer, it is not possible to obtain uniform moisture content by adding water on the fill surface. If, in the opinion of the geotechnical engineer, the material proposed for use in the compacted fill is too wet to permit adequate compaction, it shall be dried in an acceptable manner prior to placement and compaction. Compaction When an acceptable, uniform moisture content is obtained, each layer shall be compacted by a method acceptable to the geotechnical engineer and as specified in the foregoing report as determined by applicable standards. Compaction shall be performed by rolling with approved tamping rollers, pneumatic-tired rollers, three-wheel power rollers, vibrator compactors, or other approved equipment well suited to the soil being compacted. If a sheepfoot roller is used, it shall be provided with cleaner bars attached in a manner which will prevent the accumulation of material between the tamper feet. The rollers should be designed so that effective weight can be increased. Moisture-Density Determination Samples of representative fill materials to be placed shall be furnished by the contractor to the geotechnical engineer for determination of maximum density and optimum moisture or percent of Relative Density for these materials. Tests for this determination will be made using methods conforming to requirements of ASTM D 698, ASTM D 1557, or ASTM D 2049. Copies of the results of these tests will be furnished to the owner, the project engineer, and the contractor. These test results shall be the basis of control for all compaction effort. Density Tests The density and moisture content of each layer of compacted fill will be determined by the geotechnical engineer in accordance with ASTM D 1556, ASTM D 2167, or ASTM D 2922. Any material found not to comply with the minimum specified density shall be recompacted until the required density is obtained. Sufficient density tests shall be made and submitted to support the geotechnical engineer's recommendations. The results of density tests will also be furnished to the owner, the project engineer, and the contractor by the geotechnical engineer. Hello