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HomeMy WebLinkAboutSoils ReportCONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING GEOTECHNICAL ENGINEERING STUDY FAITH FELLOWSHIP CHURCH: CHURCH, GYMNASIUM AND RESIDENTIAL STRUCTURES RIFLE, COLORADO Prepared for: FAITH FELLOWSHIP CHURCH PROJECT NUMBER: G08062GE JANUARY 29, 2009 "Copyright © Terra Firma Consultants, Inc. 2008" all rights reserved P. O. BOX 39" P. 0. BOX 0045 GRAND JUNCTION, CO 8.1502 MONTROSE, CO 81402 (970)245-6506 (970)249-2154 FAY- /97A1 9AAA7FA FAY! 19701 249-3262 I CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING Faith Fellowship Church 229 West Avenue Rifle, Colorado 81650 Attention: Pastor Mark Opstein January 29, 2009 PN: G08062GE Subject: Geotechnical Engineering Study for the Proposed Church, Gymnasium and Residential Structures Rifle, Colorado Mr. Opstein: Lambert and Associates is pleased to present our geotechnical engineering study for the subject project. The field study was completed on December 10, 2008. The laboratory study was completed on January 20, 2009. The analysis was performed and the report prepared from January 21 through 29, 2009. Our geotechnical engineering report is attached. We are available to provide material testing services for soil and concrete and provide foundation excavation observations during construction. We recommend that Lambert and Associates, the geotechnical engineer, for the project provide material testing services to maintain continuity between design and construction phases. If you have any questions concerning the engineering aspects of your project please for the opportunity to perform this study Respectfully submitted, LAMBERT AND ASSOCIATES Daniel R. Lambert, P.E. geotechnical contact us. Thank you for you. P. O. BOX 3986 R 0. BOX 0045 GRAND JUNCTION, CO 81502 MONTROSE, CO 81402 (970) 245-6506 (970) 249-2154 FAX: (970) 248-9758 FAX: (970) 249-3262 G08062GE TABLE OF CONTENTS 1.0 INTRODUCTION Page 1 1.1 Proposed Construction 1 1.2 Scope of Services 1 2.0 SITE CHARACTERISTICS 2 2.1 Site Location 2 2.2 Site Conditions 2 2.3 Subsurface Conditions 3 2.4 Site Geology 3 2.5 Seismicity 4 3.0 PLANNING AND DESIGN CONSIDERATIONS 4 4.0 ON -SITE DEVELOPMENT CONSIDERATIONS 6 5.0 FOUNDATION -RECOMMENDATIONS 8 5.1 Drilled Piers 9 5.2 Spread Footing Foundations 11 6.0 INTERIOR FLOOR SLAB DISCUSSION 19 7.0 COMPACTED STRUCTURAL FILL 22 8.0 LATERAL EARTH PRESSURES 24 9.0 DRAIN SYSTEM 26 10.0 CRAWL SPACE CONSIDERATIONS 27 11.0 BACKFILL 27 12.0 SURFACE DRAINAGE 28 13.0 LANDSCAPE IRRIGATION 29 14.0 SOIL CORROSIVITY TO CONCRETE 30 15.0 RADON CONSIDERATIONS 30 16.0 POST DESIGN CONSIDERATIONS 30 16.1 Structural Fill Quality 31 16.2 Concrete Quality 32 17.0 LIMITATIONS 33 MATERIALS TESTING CONCEPT ASFE PUBLICATION PROJECT VICINITY MAP Figure 1 TEST BORING LOCATION SKETCH 2 CONCEPTUAL SKETCH OF FOOTING SUBGRADE TREATMENT 3 EMBEDMENT CONCEPT 4 ZONE OF INFLUENCE CONCEPT 5 DRAIN SYSTEM CONCEPT 6 FIELD STUDY Appendix A KEY TO LOG OF TEST'BORING Figures Al LOG OF TEST BORINGS Figures A2 - A8 LABORATORY STUDY Appendix B SWELL -CONSOLIDATION TESTS Figures B1 - B4 GEOLOGY DISCUSSION SOUTHWEST COLORADO GEOLOGY Appendix C GENERAL GEOTECHNICAL ENGINEERING CONSIDERATIONS Appendix D RADON FLOW CONCEPT Figure D1 lambert atib rg;.sociate� CONSULTING GEOTECHNICAL ENGINEERS AND YATCRlAi TFC 1- G080'62GE 1.0 INTRODUCTION This report presents the results of the geotechnical engineering study we conducted for the three (3) proposed structures. The study was conducted at the request of Mr. Mark Opstein, Faith Fellowship Church, in accordance with our proposal for geotechnical engineering services dated November 20, 2008. The conclusions, suggestions and recommendations presented in this report are based on the data gathered during our site and laboratory study and on our experience with similar soil condi- tions. Factual data gathered during the field and laboratory work are summarized in Appendices A and B. 1.1 Proposed Construction It is our understanding the proposed construction is to include a pre -manufactured single family residential structure with basement type construction, a church building and a future gymnasium structure. 1.2 Scope of Services Our services included geotechnical engineering field and labora- L.ory studies, analysis of the acquired data and report preparation for the proposed site. The scope of our services is outlined below. - The field study consisted of describing and sampling the soil materials encountered in seven (7) small diameter continuous flight auger advanced test borings. Two (2) test borings were located in the general vicinity of the proposed residential structure, Two (2) test borings were located in the general vicinity of the proposed future gymnasium structure and Three (3) test borings were located in the general vicinity of the proposed church structure. - The materials encountered in the test borings were described and samples retrieved for the subsequent laboratory study. - The laboratory study included tests of select soil samples obtained during the field study to help assess: lambert anblfooriateg CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE the soil strength potential (internal friction angle and cohesion) of samples tested, . the swell and expansion potential of the samples tested, . the settlement/consolidation potential of the samples tested, . the moisture content and density of samples tested, . the soil sulfate concentration of soil samples tested. - This report presents our geotechnical engineering comments, suggestions and recommendations for planning and design of site development including: viable foundation types for the conditions encountered, allowable bearing pressures for the foundation types, . lateral earth pressure recommendations for design of laterally loaded walls, geotechnical engineering considerations and recommendations for concrete slab on grade floors, and . geotechnical engineering considerations and recommendations for compacted structural fill. - Our comments, suggestions and recommendations are based on the subsurface soil and ground water conditions encountered during our site and laboratory studies. - Our study did not include any environmental or geologic hazard issues. 2.0 SITE CHARACTERISTICS Site characteristics include observed existing and pre-existing site conditions that may influence the geotechnical engineering aspects of the proposed site development. 2.1 Site Location The site is located north of Rifle, Colorado, east of Highway 13. A project vicinity map is presented on Figure 1. 2.2 Site Conditions There is currently an existing single family residential structure on the western portion of the site. The remainder of the 2 lambert anb Zfggo cf arteg CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE site is vacant. Portions of the site have been used for ,agricultural purposes in the past. The site is vegetated with grasses, brush and trees and exhibits positive surface drainage toward Highway 13 to the west. An irrigation type ditch is located on the eastern portion of the site. North and south of the site are lots similar in terrain to the subject site. East of the site is a large, fairly steep hill and west of the site is Highway 13. 2.3 Subsurface Conditions The subsurface exploration consisted of observing, describing and sampling the soil materials encountered in seven (7) small diameter auger advanced test borings. The approximate locations of the test borings are shown on Figure 2. The logs describing the soil materials encountered in the test borings are presented in Appendix A. The soil materials encountered within the test borings generally consisted of silty clay to the depths explored and/or the formational shale material below. Formational shale material was encountered in Test Boring Nos. 1 and 2 at approximate depths of five and one-half (5-1/2) to six (6) feet below existing site grades and extended to the depths explored. Free subsurface water ,was not encountered, however, increased moisture contents were observed at approximate depths of five (5) to thirteen (13) feet in rest Boring Nos. 3 through 7. At the time of our field study the proposed development site was not irrigated. It has been our experience that after the site is developed and once landscape irrigation begins the free subsurface water level may tend to rise. In some cases the free subsurface water level rise, as a result of landscape irrigation and other development influences, can be fairly dramatic and the water level may become very shallow. It is difficult to predict if unexpected subsurface conditions will be encountered during construction. Since such conditions may be found, we suggest that the owner and the contractor make provi- sions in their budget and construction schedule to accommodate unexpected subsurface conditions. 2.4 Site Geology A brief discussion of the general geology of the area is presented in Appendix C. s 3 'Lambert anb 2 oriateg; CONSULTING G€OTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE _.� 2.5 Seismicity According to the International Building Code, 2006 Edition, based on the subsurface conditions encountered and the assumption that the soils described in the test borings are likely representative of the top 100 feet of the soil profile, we recommend that the site soil profile be "SD". 3.0 PLANNING AND DESIGN CONSIDERATIONS A geologic hazard study was not requested as part of the scope of this report, however there are some conditions which were observed at the site during the field study which may influence the develop- ment. All of the suggestions and design parameters presented in this report are based on high quality craftsmanship, care during con- struction and post construction cognizance of the potential for swell or settlement of the site support materials and appropriate post construction maintenance. All construction excavations should be sloped to prevent excavation wall collapse. We suggest that as a minimum the excavation walls should be sloped at an inclination of one -and -one-- half (1-1/2) to one (1) (horizontal to vertical) or flatter. The area above the foundation excavations should be observed at least daily for evidence of slope movement during construction. If evidence of slope movement is observed we should be contacted immediately. This report presents geotechnical engineering suggestions and recommendations for development on the portions of the site with slope inclinations of 3 to 1 or flatter. It is our understanding that your current plans do not include development at the proposed site in locations where the site slope is steeper than 3 to 1. If this is not the case, additional field and laboratory studies and subsequent analysis will be needed for geotechnical engineering suggestions and recommendations to address the slope considerations for development on the steeper site slopes. M lambert aub 2.aoriateo; CONSULTING GEOTECNNICAL ENGINEERS AND MATERIAL TESTING G08062GE Development in areas near slopes results in several factors that influence future slope stability. Typically, development changes surface drainage patterns and may also influence subsurface drain- age. Because water is usually the dominating factor influencing slope stability, drainage should be addressed at all stages of the development. Development that substantially changes the surface grades by excavating and filling not only changes drainage pat- terns, but also changes loads and stresses in the slopes. Base- ments and retaining walls do the same. The following precautionary measures should be included in the site development. The areas above the slopes should be kept as dry as possible. This may be aided by providing positive surface and subsurface drainage. A combination of drainage swales and subsur- face drains may be used to intercept surface runoff and subsurface water uphill and divert it so that it does not influence the site. Subsurface drains are discussed below. We anticipate that excavation and fill placement operations may be associated with the proposed site development. Excavations in the area which generate vertical or sloped exposures should be kept to a minimum. I Excavations which result in cut slopes with a vertical height greater than about four (4) feet or with a slope or structure above should be analyzed on a site specific basis. Temporary excavation cut slopes in competent material should not exceed a one -and -one- half to one (1-1/2 to 1) (horizontal to vertical) inclination. All construction excavations should conform to Occupational Safety and Health Administration (OSHA) standards or safer. All permanent slopes should have inclinations of three to one (3 to 1) or shallower. Excavation cut slopes steeper than one -and -one-half to one (1-1/2 to' 1) should be analyzed on a per site basis. Slope and excavation surfaces should be protected by vegetation and/or other means to prevent erosion. Surface runoff should not be allowed to cascade over the top of a slope or to pond at the toe of any slope. We anticipate that some embankment fill slopes will be construct- ed on the site. Fill slopes greater than about three (3) feet vertical height or fill slopes supporting structures will require additional analysis. We recommend that each proposed fill slope on the site be analyzed on a per site basis when the proposed site lambert aub Zlizoriato CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE configuration and fill material has been determined. If fill slopes swill be constructed on site we should be contacted to provide geotechnical engineering review and recommendations for the design and construction of the slopes. Generally, fill material placed on a sloping site surface which will be used to support structures or additional fill material should be placed so that the contact between the existing site surface and the added fill material will be strong enough to support the added load. This should be addressed on a site and fill area specific basis. The technique recommended will be based on the site configuration, the finished fill configuration the actual material to be used for the fill material and the size of the area thus constructed. Frequently the preparation of the site area to receive fill material will include keying and benching of the native material in the area to receive fill material, placing the material in thin horizontal lifts which are compacted at the appropriate moisture content and the installation of a subsurface drain system at the fill material/natural material contact. We are available to, and recommend that, we discuss this with you and provide site and fill specific recommendations when this portion of your development plan merits the additional study. 4.0 ON -SITE DEVELOPMENT CONSIDERATIONS We anticipate that the subsurface water elevation may fluctuate with seasonal and other varying conditions. Excavations may encounter subsurface water and soils that tend to cave or yield. If water is encountered it may be necessary to dewater construction excavations to provide more suitable working conditions. Excavations should be well braced or sloped to prevent wall col- lapse. Federal, state and local safety codes should be observed. All construction excavations should conform to Occupational Safety and Health Administration (OSHA) standards or safer. The site construction surface should be graded to drain surface water away from the site excavations. Surface water should not be allowed to accumulate in excavations during construction. Accumul- ated water could negatively influence the site soil conditions. Construction surface drainage should include swales, if necessary to divert surface water away from the construction excavations. 0 lainbert aub !aaotiatefs CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE Organic soil materials were encountered in the test borings. The organic soil materials are not suitable for support of the struc- ture or structural components. The organic soil materials should be removed prior to foundation construction. The formational material encountered in Test Boring Nos. 1 and 2 had very hard, cemented lenses. We anticipate that it may be possible to excavate this material; however, additional effort may be necessary. We do not recommend blasting to aid in excavation of the material. Blasting may fracture the formational material which will reduce the support characteristic integrity of the formational material. It has been our experience that sites in developed areas may con- tain -existing subterranean structures or poor quality man placed fill. If subterranean structures or poor quality man placed fill are suspected or encountered, they should be removed and replaced with compacted structural fill as discussed under COMPACTED STRUC- TURAL FILL below. The proposed building site has been used in the recent past for agricultural purposes. We anticipate that the near surface site soils may have been tilled to a depth of about twelve (12) to eighteen (18) inches. Tilling typically results in a loose low density soil with low support characteristics and high settlement characteristics. The foundations or any concrete flat work should not be supported by tilled soils. The near surface tilled soils should be removed and replaced with compacted structural fill in areas supporting structures, structural components or concrete flat work. The soil materials exposed in the bottom of the excavation may be very moist and may become yielding under construction traffic during construction. It may be necessary to use techniques for placement of fill material or foundation concrete which limits construction traffic in the vicinity of the very moist soil material. If yielding should occur during -construction it may be necessary to construct a subgrade stabilization fill blanket or similar to provide construction traffic access. The subgrade stabilization blanket may include over excavating the subgrade soils one (1) to several feet and replacing with aggregate subbase course type material. The stabilization blanket may also include geotextile stabilization fabric at the bottom of the excavation prior to placement of aggregate subbase course stabilization fill. Lambert anb 2,90ociateg CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G09062GE Other subgrade stabilization techniques may be available. We are available to discuss this with you. Free subsurface water was not encountered in our test borings, however, increased moisture levels were observed in Test Boring Nos. 3 through 7 at depths ranging from about five (5) to thirteen (13) feet. We anticipate that the free subsurface water may be much shallower during wetter seasons. We do not recommend con- struction of basements below the highest anticipated free subsurface water elevation. It may be necessary to.install stand- pipe piezometers in areas where basements will be planned and the free subsurface water elevation monitored for a significant period of time to help identify the anticipated highest elevation of the free subsurface water. 5.0 FOUNDATION RECOMMENDATIONS Geotechnical engineering considerations which influence the foundation design and construction recommendations presented below are discussed in Appendix D. We have analyzed drilled piers and spread footing foundations as 'potential foundation systems for the proposed structure. These are discussed below. Due to the number of possible foundation types available and design and construction techniques there may be design alternatives which we have not presented in this report. We are available to discuss other foundation types. We recommend that the entire structure be supported on only one foundation type. Combining foundation types will result in differ- ential and unpredictable foundation performance between the varying foundation types. We recommend that the structure footprint not be traversed by the cut/fill contact which would result in a portion of the structure underlain by fill material and part of the structure underlain by materials exposed by excavated cut. If this condition will exist please contact us so that we can revise our recommendations to accommodate the cut/fill contact scenario. All of the design parameters presented below are based on tech- niques performed by an experienced competent contractor and high quality craftsmanship and care during construction. We recommend post construction cognizance of the volume change potential of the near surface soil materials and the need for appropriate post -onstruction maintenance. lambert anb !L2;.!oc1ate2; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE The spread footing recommendations include recommended design and construction techniques to reduce the influence of movement of the soil materials supporting the foundation but should not be interpreted as solutions for completely mitigating the potential for movement from the support soil material volume change. Exterior column supports should be supported by foundations incorporated into the foundation system of the structure not supported on flatwork. Column supports placed on exterior concrete flatwork may move if the support soils below the concrete slab on grade become wetted and swell or freeze and raise or settle. Differential movement of the exterior columns may cause stress to accumulate in the supported structure and translate into other portions of the structure. 5.1 Drilled Piers Drilled piers or caissons that are drilled into the unweathered formational material may be used to support the proposed pre - manufactured residential structure. The piers should have a minimum length of twenty (20) feet and be drilled into the formational material a minimum of five (5) feet. The piers should `be designed as end bearing piers using a formational material bearing capacity of 9,000 pounds per square foot and a side friction of 900 pounds per square foot for the portion of the pier in the unweathered formational material. The drilled piers should be designed with a minimum dead load of 2,000 pounds per square foot. Varying weathering and formational competence may result in a shorter required penetration of the drilled piers into the formational material to provide the end bearing capacity discussed above. We should be contacted to observe the pier drilling operations and provide additional geotechnical engineering suggestions and recommendations for design bearing capacity and minimum penetration into the formational material as needed. There are differing theories on the use of side shear as part of the load carrying assessment of drilled pier foundation systems. The differences are related to the strain compatibility between end bearing and side shear. One theory is that mobilization of the drilled pier is required to generate the side shear soil strength values. This mobilization would require the movement of the bottom of the pier which may not be a desirable characteristic. Another 17 Lunbert aub Ztioctatef� CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING GO.8062GE theory is that the support materials will develop static frictional ,forces in contact with the materials along the surface of the pier. It is our opinion that sufficient movement of the piers to mobi- lize skin friction for bearing support may result in undesirable performance of the pier in the form of settlement. We suggest consideration to the amount of settlement tolerable to the struc- ture be included in your assessment if skin friction is used in your design as part of the bearing support of the drilled pier. We suggest that piers be designed using end bearing capacity only. The side shear in the formational material may be used for the design to resist uplift forces. When using skin friction for resisting uplift we suggest that you discount the upper portion of the pier embedment in the formational material to a depth of at least one and one-half (1-1/2) pier diameters into the formational material. The bottom of the pier holes should be thoroughly cleaned to insure that all loose and disturbed materials are removed prior to placing pier concrete. It is very important to thoroughly clean the bottom of the pier holes prior to placement of the pier concrete. Loose disturbed material left in the bottom of the pier hole will likely result in long term settlement of the piers as the Disturbed material consolidated under the pier loads. The pier holes should be observed during the excavation and cleaning operation and again immediately prior to placement of pier concrete after steel reinforcement and any casing materials have been installed to verify that material was not dislodge into the pier hole during steel reinforcement or casing placement. Because of the rebounding potential in the formational materials when unloaded by excavation and because of the possibility of desiccation of the newly exposed material we suggest that concrete be placed in the pier holes immediately after excavation and cleaning. If the piers are designed and constructed as discussed above we anticipate that the post construction settlement potential of each pier may be less than about one half (1/2) inch. The portion of the pier above the formational surface and in the weathered formational material should be cased with a sono tube or similar casing to help prevent flaring on the top of the pier holes 10 lambert aub !amwriateg; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE and help provide a positive separation of the pier concrete and the .. `adjacent soils. Construction of the piers should include extreme care to prevent flaring of the top of the piers. Enlarged portions of the drilled pier excavation near the surface may perform similar to the top flaring. Preventing flaring may be aided by casing the drilled pier excavation with a sono tube or similar casing. Reducing flaring is to help reduce the potential of swelling soils to impose uplift forces which will put the pier in tension. The drilled piers should be vertically reinforced to provide tensile strength in the piers should swelling on site soils apply tensile forces on the piers. The structural engineer should be consulted to provide structural design recommendations. If ground water is encountered during pier drilling, the pier holes should be dewatered prior to placing pier concrete and no pier concrete should be placed when more than six (6) inches of water exists in the bottom of the pier holes. The piers should be filled with a tremie placed concrete immediately after the drilling and cleaning operation is complete. It may be necessary to case the pier holes with temporary casing to prevent caving during pier construction. The contact between the weathered formational material and the unweathered formational material may be gradual and difficult to identify. The minimum penetration of the drilled pier into the unweathered formational material as discussed above is important for the long term performance of the pier foundation. We should be contacted to observe the pier drilling operation to verify the construction techniques used, the material encountered during the drilling operation and condition of the bottom of the drilled pier hole prior to placement of pier concrete. The structural engineer should be consulted to provide structural design recommendations for the drilled piers and grade beam founda- tion system. 5.2 Spread Footing Foundation In our analysis it was necessary to assume that the material encountered in the test borings extended throughout the building site and to a depth below the maximum depth of the influence of the foundations. We should be contacted to observe the soil materials 11 'Lambert ato Zl!oaciateq; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING GO8062GE exposed in the foundation excavations prior to placement of foundations to verify the assumptions made during our analysis. We anticipate that the surface of the formational material in the general vicinity of the proposed residential structure, Test Boring Nos. 1 and 2, may undulate which may result in a portion of the footings supported on the overlying soils and a portion of the foundation members supported on the formational material. If this happens the foundations will perform differently between the areas supported on formational material and the areas supported on the non -formational material. For this reason we suggest that if formational material is encountered only in portions of the foundation excavations at footing depth the foundation in all areas should be extended to support all foundation members on the' formational material. The bottom of the foundation excavations should be thoroughly cleaned and observed when excavated. Any loose or disturbed material exposed in the foundation excavation should be removed prior to placing foundation concrete. The bottom of the foundation excavations should be compacted prior to placing compacted structural fill or foundation concrete. le suggest the materials exposed be compacted to at least ninety (90) percent of the materials moisture content -dry density rela- tionship (Proctor) test, ASTM D1557. Excavation compaction is to help reduce the influence of any disturbance that may occur during the excavation operations. Any areas of loose, low density or yielding soils evidenced during the excavation compaction operation should be removed and replaced with compacted structural fill. Caution should be exercised during the excavation compaction operations. Excess rolling or compacting may increase pore pres- sure of the subgrade soil material and degrade the integrity of the support soils. Loose or disturbed material in the bottom of the foundation excavations which are intended to support structural members will.likely result in large and unpredictable amounts of settlement, if the loose or disturbed material is not compacted The bottom of any footings exposed to freezing temperatures should be placed below the maximum depth of frost penetration for the area. Refer to the local building code for details. All footings should be appropriately proportioned to reduce the post construction differential -settlement. Footings for large 12 Lambert anb 21.aotiatei� CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE localized loads should be designed for bearing pressures and `,footing dimensions in the range of adjacent footings to reduce the potential for differential settlement. We are available to discuss this with you. Foundation walls should be reinforced for geotechnical engineering purposes. The structural engineer should be consulted for foundation design. The structural engineering reinforcing design tailored for this project will be more appropriate than the suggestions presented above. The structures may be founded on spread footings. We recommend the use of a blanket of structure fill material beneath the spread footing foundation members. Spread footings may be placed either on the natural undisturbed soils or on a blanket of compacted structural fill. The blanket of compacted structural fill is to help provide uniform support for the footings and to help reduce the theoretical calculated post construction settlement. The theoretical calculated post construction settlement and associated fill thickness supporting the footings are presented below. We suggest that you consider the foundation be supported on a blanket of compacted structural fill at least as thick as the width ,,of the footing that will bear upon the fill to help mask the influence of volume change of the soil materials supporting the footings. The blanket of compacted structural fill will not prevent movement of the footings from volume change in the support soil materials but will mask the influence of volume changes of the soils supporting the footings. If the footings are supported on a blanket of compacted structural fill the blanket of compacted structural fill should extend beyond each edge of each footing a distance at least equal to the fill thickness. This concept is shown on Figure 3. Geotechnical engineering recommendations for constructing compacted structural fill are presented below. All footings should have a minimum depth of embedment of at least one (1) foot below the lowest adjacent grade when placed either on the natural undisturbed soils or a blanket of compacted structural fill. Deeper embedment will be needed for footings exposed to exterior climate. The bearing capacity will depend on the minimum depth of embedm- ent of the bottom of the footings below the lowest adjacent grade 13 lambert aub 22; ouateg� CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE and the support characteristics of the soils supporting the founda- -,,tion. Other characteristics may influence embedment. The embed- ment concept is shown on Figure 4. Bearing capacity and associated minimum depth of embedment of the bottom of the footing below the lowest adjacent grade are presented below. SPREAD FOOTING SOIL BEARING CAPACITY CONTINUOUS ISOLATED A* (POUNDS PER SQUARE FOOT) feet 1,900 2,500 0 2,300 3,100 1 2,800 3,700 2 A* Minimum depth of embedment for footings adjacent to level areas. If deeper embedment is considered for increased bearing capacity greater than presented above, we should be contacted to provide additional analysis and recommendations as needed. The bearing capacity design value"is based on several considerations and these may change with depth. The bearing capacity may be increased by about twenty (20) percent for transient loads such as wind and seismic loads. It is our opinion that footings exposed to frost or freezing ground influences and all exterior footings should be embedded to frost depth or deeper. Interior footings should have a minimum depth of embedment of at least one (1) foot on all sides to provide a more predictable long term performance of the footing. We understand that construction techniques typically used in the area may result in some of the footings in the crawl space constructed without significant embedment of the bottom of the footing below the lowest adjacent grade. For this reason we have provided design values for footings constructed with little or no embedment. It is our opinion that the performance of footing constructed without embedment may be influenced by erosion, temperature changes, moisture content changes, swell potential of the soil supporting the footings and weathering of the soils supporting the footings and will have a less predictable settlement response than footings with embedment. 14 Xambert arib Rmgociate4 CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING C08062GE Exterior footings and footings with uneven backfill may result in 'movement of the footings. Embedment of the footings on all sides will help reduce the potential for movement of footings with uneven backfill. We do not recommend exterior footings or footings with uneven backfill be constructed without a minimum depth of embedment of the bottom of the footing below the lowest adjacent grade of at least one (1) foot on all sides of the footings. The minimum depth of embedment is sufficient only to develop the bearing capacity for design purposes and does not account for frost influences. Actual design and construction should result in interior footings with one (1) foot or more embedment and exterior footings with frost depth or more embedment. Typically deeper embedment will increase bearing capacity and decrease post construction settlement and decrease the influence of expansive soils. The calculated theoretical estimated post construction settlement and swell potential may be reduced by placing the footings on a blanket of compacted structural fill. The calculated theoretical estimated post construction settlement and associated thickness of compacted structural fill are presented below. PROPOSED RESIDENTIAL STRUCTURE CALCULATED THEORETICAL ESTIMATED POST THICKNESS OF CONSTRUCTION SETTLEMENT FOR COMPACTED STRUCTURAL FILL CONTINUOUS SPREAD FOOTINGS SUPPORTING FOOTINGS INCHES 0 *B/2 B 3B/2 2B 15 'Lambert atib Rm oriateg; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING GO.8062GE CALCULATED THEORETICAL ESTIMATED POST THICKNESS OF CONSTRUCTION SETTLEMENT FOR COMPACTED STRUCTURAL FILL ISOLATED SPREAD FOOTINGS SUPPORTING FOOTINGS t INCHES 0 2-1/4 *B/2 1-1/8 B 3/4 3B/2 1/2 2B 1/4 *B is equal to the footing width The calculated theoretical settlement estimated values above are appropriate for continuous spread footings with a width of about two (2) feet or less and isolated spread footings with a width of about four (4) feet or less. Larger footings should be analyzed on a footing, load and width specific basis. PROPOSED CHURCH AND GYMNASIUM STRUCTURE CALCULATED THEORETICAL ESTIMATED POST THICKNESS OF CONSTRUCTION SETTLEMENT FOR ,-COMPACTED STRUCTURAL FILL CONTINUOUS SPREAD FOOTINGS SUPPORTING FOOTINGS INCHES 0 3-1/8 *B/2 2 B 1-1/4 3B/2 3/4 2B 1/2 CALCULATED THEORETICAL ESTIMATED POST THICKNESS OF CONSTRUCTION SETTLEMENT FOR COMPACTED STRUCTURAL FILL ISOLATED SPREAD FOOTINGS SUPPORTING FOOTINGS INCHES 0 *B/2 B 3B/2 2B *B is equal to the footing width 16 lamrbert anb P01goriateg; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE The calculated theoretical settlement estimated values above are appropriate for continuous spread footings with a width of about four (4) feet or less and isolated spread footings with a width of about six (6) feet or less. Larger footings should be analyzed on a footing, load and width specific basis. Footings should be sized so that each footing is in a similar size and load range as nearby footings to encourage similar performance. Very large footings or heavily loaded footings will influence the support soil materials to a deeper depth than small or lightly loaded footings and therefore will have different post construction performance. The calculated settlement estimates are theoretical only. Actual settlement could vary throughout the site and with time. If the footings are supported on a blanket of compacted structur- al fill, the blanket of compacted structural fill should extend beyond each edge of each footing a distance at least equal to the fill thickness. This concept is shown on Figure 3. Compacted Structural Fill is discussed in Section 7.0 below. The soil samples tested had measured swell pressures of approximately 400 to 3,800 pounds per square foot and the actual swell pressure of the support materials could be greater. When wetted the site soil materials have the ability to raise supported foundation members with loads less than the swell pressure. The foundation design should be as rigid as possible with as high of a dead load as can be available. The greater the dead load on the footings the less the potential for movement from the foundation soils should they become wetted. If the soils become wetted they will swell and will raise the foundation portions supported on the wetted soils. If the lightly loaded structures are supported on spread footings the owner must realize that post construction movement of the footings is likely. We are available to discuss the implications of supporting foundations on swelling soils. 17 lambert atib Imli-wWortato CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE PROPOSED PRE -MANUFACTURED RESIDENTIAL STRUCTURE SPREAD FOOTINGS WITH APPROXIMATELY 700 PSF MINIMUM DEAD LOAD THICKNESS OF COMPACTED CALCULATED THEORETICAL ESTIMATED POST STRUCTURAL FILL CONSTRUCTION HEAVE (INCHES) FOR SUPPORTING FOOTINGS CONTINUOUS SPREAD FOOTINGS 0 4-3/4 to 7 *B/2 4 to 6 B 3-1/4 to 5 3B/2 2-1/2 to 3-3/4 2B 1-3/4 to 2-3/4 THICKNESS OF COMPACTED CALCULATED THEORETICAL ESTIMATED POST STRUCTURAL FILL CONSTRUCTION HEAVE (INCHES) FOR SUPPORTING FOOTINGS ISOLATED SPREAD FOOTINGS 0 7-1/4 to 11 *B/2 6 to 9 B 4-1/2 to 7 3B/2 3-1/2 to 5-1/4 2B 2-1/2 to 3-3/4 PROPOSED CHURCH AND GYMNASIUM STRUCTURES SPREAD FOOTINGS WITH APPROXIMATELY 700 PSF MINIMUM DEAD LOAD THICKNESS OF COMPACTED CALCULATED THEORETICAL ESTIMATED POST STRUCTURAL FILL CONSTRUCTION HEAVE (INCHES) FOR SUPPORTING FOOTINGS CONTINUOUS SPREAD FOOTINGS 0 3-3/4 to 5-3/4 *B/2 3-1/8 to 4-3/4 B 2-1/2 to 3-3/4 3B/2 1-3/4 to 2-3/4 2B 1-1/2 to 2 lambert aub Roaciate; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE THICKNESS OF COMPACTED STRUCTURAL FILL SUPPORTING FOOTINGS CALCULATED THEORETICAL ESTIMATED POST CONSTRUCTION HEAVE (INCHES) FOR ISOLATED SPREAD FOOTINGS 0 4-3/4 to 7 *B/2 3-3/4 to 5-1/2 B 2-3/4 to 4 3B/2 1-3/4 to 2-3/4 2B 1-1/4 to 1-3/4 *B is equal to the footing width If the footings are supported on a blanket of compacted structur- al fill, the blanket of compacted structural fill should extend beyond each edge of each footing a distance at least equal to the fill thickness. This concept is shown on Figure 3. Compacted Structural Fill is discussed in Section 7.0 below. - The bottom of the foundation excavations should be thoroughly clearied and observed by the project Geotechnical Engineer or his representative when excavated. Any loose or disturbed material exposed in the foundation excavation should be removed or remedied prior to additional construction. We recommend that we be contacted to observe the foundation excavations and backfill operations during construction to verify the soil support conditions and our assumptions upon which our recommendations are based. If necessary we may revise our recom- mendations based on our observations. We are available to provide material testing services during the construction phase of the project. 6.0 INTERIOR FLOOR SLAB DISCUSSION It is our understanding that concrete slab on grade floors may be included in the construction. The geotechnical engineering suggestions and recommendations for interior floor slabs presented below are appropriate for garage floor slabs. The natural soils that will support interior floor slabs are stable at their natural moisture content. However, the owner should realize that when wetted, the site soils may experience volume changes. The site soil samples tested had measured swell pressures up to 3,800 pounds per square foot with an associated magnitude of 11.6 percent of the wetted soil volume at a surcharge load of 100 pounds per square /oot. 19 Imbed aiib Roaciateg CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE The recommendations in this report do not address a monolithic floor slab/footing combination. The design and construction characteristics of the monolithic floor slab need geotechnical engineering design parameters tailored specifically for a monolithic slab and integral footing. Generally this type foundation/floor combination in this area with these site conditions does not perform as well as other choices. Conditions which vary from those encountered during our field study may become apparent during excavation. We should be contact- ed to observe the conditions exposed at concrete slab on grade subgrade elevation to verify the assumptions made during the preparation of this report and to provide additional geotechnical engineering suggestions and recommendations as needed. Engineering design dealing with swelling soils is an art which is still developing. The owner is cautioned that the soils on this site may have swelling potential and concrete slab on grade floors and other lightly loaded members may experience movement when the supporting soils become wetted. We suggest you consider floors suspended from the foundation systems as structural floors or a similar design that will not be influenced by subgrade volume '.hanges. If the owner is willing to accept the risk of possible damage from swelling soils supporting concrete slab on grade floors, the following recommendations to help reduce the damage from swelling soils should be,followed. These recommendations are based on generally accepted design and construction procedures for construction on soils that tend to experience volume changes when wetted and are intended to help reduce the damage caused by swell- ing soil materials. Lambert and Associates does not intend that the owner, or the owner's consultants should interpret these recommendations as a solution to the problems of swelling soils, but as measures to reduce the influence of swelling soils. The shallow soil materials tested have a moderate volume change potential under light loading conditions. Concrete slab on grade floors may experience significant movement when supported by the natural onsite soils. Concrete slab on grade floors will perform best if designed to tolerate movement introduced by the subgrade soil materials. Concrete flatwork, such as concrete slab on grade floors, should be underlain by compacted structural fill. The layer of compacted 20 'Lambert anb eft-00ottatefg CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE fill should be at least one (1) foot thick or thicker and con- --.,structed as discussed under COMPACTED STRUCTURAL FILL below. A one (1) foot thick or thicker blanket of structural fill material beneath the concrete flatwork is not sufficient to entirely mask the settlement or swell potential of the subgrade soil material but will only provide better subgrade conditions for construction. The concrete slab on grade should be designed by a structural engineer to be compatible with the site soil conditions. The natural soil materials exposed in the areas supporting concrete slab on grade floors should be kept very moist during construction prior to placement of concrete slab on grade floors. This is to help increase the moisture regime of the potentially expansive soils supporting floor slabs and help reduce the expan- sion potential of the soils. We are available to discuss this concept with you. Concrete slab on grade floors should be provided with a positive separation, such as a slip joint, from all bearing members and utility lines to allow their independent movements and to help reduce possible damage that could be caused by movement of soils supporting interior slabs. The floor slab should be constructed as a floating slab. All water and sewer pipe lines should be isolated ,from the slab. Any equipment placed on the floating floor slab should be constructed with flexible joints to accommodate future movement of the floor slab with respect to the structure. We suggest partitions constructed on the concrete slab on grade floors be provided with a void space above or below the partitions to relieve stresses induced by elevation changes in the floor slab. Floor slabs should not extend over foundations or foundation members. Floor slabs which extend over foundations or foundation members will likely experience post construction movement as a result of foundation movements. We are available to discuss this with you. The concrete slabs should be scored or jointed to help define the locations of any cracking. We recommend that joint spacing be designed as outlined in ACI 224R. In addition joints should be scored in the floors a distance of about three (3) feet from, and parallel to, the walls. It should be noted that when curing fresh concrete experiences shrinkage. This shrinkage almost always results in some cracks in 21 lainbert aub Zfm odateg CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING C08062GE the finished concrete. The actual shrinkage depends on the config- �`uration and strength of the concrete and placing and finishing techniques. The recommended joints discussed above are intended to help define the location of the cracks but should not be interpreted as a solution to shrinkage cracks. The owner must understand that concrete flatwork will contain shrinkage cracks after curing and that all of the shrinkage cracks may not be located in control joints. Some cracking at random locations may occur. If moisture migration through the concrete slab on grade floors will adversely influence the performance of the floor or floor coverings we suggest that a moisture barrier may be installed beneath the floor slab to help discourage capillary and vapor moisture rise through the floor slab. The moisture barrier may consist of a heavy plastic membrane, six (6) mil or greater, protected on the top and bottom by clean sand. The clean sand will help to protect the plastic from puncture. The layer of clean sand on the top of the plastic membrane will help the overlying concrete slab cure properly. According to the American Concrete Institute, proper curing requires at least three (3) to six (6) inches of clean sand between the plastic membrane and the bottom of the concrete. The plastic membrane should be lapped and taped or glued ind protected from punctures during construction. The Portland Cement Association suggests that welded wire rein- forcing mesh is not necessary in concrete slab on grade floors when properly jointed. It is our opinion that welded wire mesh may help improve the integrity of the slab on grade floors. We suggest that concrete slab on grade floors should be reinforced, for geotechni- cal purposes, with at least 6 x 6 - W2.9 x W2.9 (6 x 6 - 6 x 6) welded wire mesh positioned midway in the slab. The structural engineer should be contacted for structural design of floor slabs. 7.0 COMPACTED STRUCTURAL FILL Material characteristics desirable for compacted structural fill are discussed in Appendix D. Areas that are over excavated or slightly below grade should be backfilled to grade with properly compacted structural fill or concrete, not loose fill material. If backfilled with other than compacted structural fill material or concrete there will be significant post construction settlement proportional to, the amount of loose material. 22 Imbed aiib ZWfwdatef� CONSULTING GEOTECHNICAL ENGINEERS AND UATswar TrVrWr. G08062GE The natural on site soils are not suitable for use as 'compacted y structural fill material supporting building or structure members because of their clay content and swell potential. The natural on - site soils may be used as compacted fill in areas that will not influence the structure such as to establish general site grade. We are available to discuss this with you. All areas to receive compacted structural fill should be properly prepared prior to fill placement. The preparation should include removal of all organic or deleterious material. The areas to receive fill material should be compacted after the organic delete- rious material has been removed prior to placing the fill material. The area may need to be moisture conditioned for compaction. Any areas of soft, yielding, or low density soil, evidenced during the excavation compaction operation should be removed. The area excavated to receive fill should be moisture conditioned to wet of optimum moisture content as part of the preparation to receive .Gill. Fill should be moisture conditioned, placed in thin lifts riot exceeding six (6) inches in compacted thickness and compacted to at least ninety (90) percent of maximum dry density as defined by ASTM D1557, modified moisture content -dry density (Proctor) test. After placement of the structural fill the surface should not be allowed to dry prior to placing concrete or additional fill materi- al. This may be achieved by periodically moistening the surface of the compacted structural fill as needed to prevent drying of the structural fill. We are available to discuss this with you. The soil materials exposed in the bottom of the excavation may be very moist and may become yielding under construction traffic during construction. It may be necessary to use techniques for placement of fill materials or foundation concrete which limit construction traffic in the very moist soil materials. If yielding should occur during construction it may be necessary to construct a subgrade stabilization fill blanket or similar to provide con- struction traffic access. We are available to discuss this with you. We recommend that the geotechnical engineer or his representative be present during the excavation compaction and fill placement operations to observe and test the material. 23 latubert attb Z oociate4 CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE 8.0 LATERAL EARTH PRESSURES Laterally loaded walls supporting soil, such as basement walls, will act as retaining walls and should be designed as such. Walls that are designed to deflect and mobilize the internal soil strength should be designed for active earth pressures. Walls that are restrained so that they are not able to deflect to mobilize internal soil strength should be designed for at -rest earth pres- sures. The values for the lateral earth pressures will depend on the type of soil retained by the wall, backfill configuration and construction technique. If the backfill is not compacted the lateral earth pressures will be very different from those noted below. Lateral earth pressure (L.E.P.) values are presented below: Level Backfill with on -site soils (pounds per cubic foot Tper foot of depth) Active L.E.P. 50 At -rest L.E.P. 70 Passive L.E.P. 320 •1 The soil samples tested have measured swell pressure of approximately 400 to 3,800 pounds per square foot and the actual swell pressure of the backfill material could be greater. Our experience has shown that the actual swell pressure may be much higher. If the retained soils should become moistened after construction the soil may swell against retaining walls. The walls should be designed to resist the swell pressure of the soil materials if these are used as part of the backfill within the zone of influence. The zone of influence concept is presented on Figure 5. The above lateral earth pressures may be reduced by overexcavat- irg the wall backfill area beyond the zone of influence and back - filling with crushed rock type_ material. The zone of influence concept is presented on Figure 5. The lateral earth pressure design parameters may change signifi- cantly if the area near the wall is loaded or surcharged or is sloped. If any of these conditions occur we should be contacted for 24 lambert anb A.!ooctate2� CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING GO8062GE additional design parameters tailored to the specific site and --_�5tructure conditions. Suggested lateral earth pressure (L.E.P.) values if the backfill is overexcavated beyond the zone of influence and backfilled with crushed rock are presented below. Level Backfill with crushed rock material ounds er cubic foot 3per foot of depth) Active L.E.P. 30 At -rest L.E.P. 50 If the area behind a wall retaining soil material is sloped we should be contacted to provide lateral earth pressure design values tailored for the site specific sloped conditions. Resistant forces used in the design of the walls will depend on the type of soil that tends to resist movement. We suggest that you consider a coefficient of friction of 0.25 for the on site soil. The lateral earth pressure values provided above, for design purposes, should be treated as equivalent fluid pressures. The _lateral earth pressures provided above are for level well drained backfill and do not include surcharge loads or additional loading as a result of compaction of the backfill. Unlevel or non-horizon- L-al backfill either in front of or behind walls retaining soils will significantly influence the lateral earth pressure values. Care should be taken during construction to prevent construction and backfill techniques from overstressing the walls retaining soils. Backfill should be placed in thin lifts and compacted, as discussed in this report to realize the lateral earth pressure values. Walls retaining soil should be designed and constructed so that hydrostatic pressure will not accumulate or will not affect the integrity of the walls. Drainage plans should include a subdrain behind the wall at the bottom of the backfill to provide positive drainage. Exterior retaining walls should be provided with perime- ter drain or weep holes to help provide an outlet for collected water behind the wall. The ground surface adjacent to the wall should be sloped to permit rapid drainage of rain, snow melt and 25 lambert anb 3m oriatin; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE irrigation water away from the wall backfill. Sprinkler systems should not be installed directly adjacent to retaining or basement walls. 9.0 DRAIN SYSTEM A drain system should be provided around building spaces below the finished grade and behind any walls retaining soil. The drain systems are to help reduce the potential for hydrostatic pressure to develop behind retaining walls. A sketch of the drain system is shown on Figure 6. Subdrains should consist of a three (3) or four (4) inch diameter perforated rigid pipe surrounded by a filter. The filter should consist of a filter fabric or a graded material such as washed concrete sand or pea gravel. If sand or gravel is chosen the pipe should be placed in the middle of about four (4) cubic feet of aggregate per linear foot of pipe. The drain system should be sloped to positive gravity outlets. If the drains are daylighted the drains should be provided with all weather outlets and the outlets should be maintained to prevent them from being plugged or frozen. We do not recommend that the drains be discharged to dry well type structures. Dry well structures may tend to fail if the surrounding soil -material becomes wetted and swells or if the ground water rises to a elevation of or above the discharge eleva- tion in the dry well. We should be called to observe the soil exposed in the excavations and to verify the details of the drain system. A drain blanket may be constructed beneath the basement concrete slab on grade floor slab to intercept water that may tend to rise into the basement area. The drain blanket should be at least one foot thick and consist of a free draining sand or gravel material which is compacted as discussed under Compacted Structural Fill above, Section 7.0 The subgrade below the drain blanket should be sloped ,to collection points prior to constructing the drain blan- ket. A perforated pipe should be installed at the collection points and graded to discharge similar to the foundation drain discussed above.. The drain blanket concept is shown on Figure 6. The under slab drain blanket may be considered as part of the structural fill intended to support the floor slab as discussed under Interior Floor Slabs, Section 6.0 above. We are available tc discuss this concept with you. 26 lambert aub am ociateg; CONSULTING GEOTECHNICAL ENGINEERS ANO MATERIAL TESTING G08062GE 10.0 CRAWL SPACE CONSIDERATIONS We suggest that if it is desired to reduce the influence of water in the crawl space area a foundation drain should be installed as discussed above. - The surface of the crawl space may be provided with a layer of about six (6) inches of clean washed .gravel or an impervious geotextile fabric to reduce the inconvenience of very moist or muddy crawl space conditions if these should occur. The crawl space should be adequately vented to reduce the potential for humidity to accumulate in the crawl space area. 11.0 BACKFILL Backfill areas and utility trench backfill should be constructed such that the backfill will not settle after completion of con- struction, and that the backfill is relatively impervious for the upper few feet. The backfill material should be free of trash and other deleterious material. It should be moisture conditioned and compacted to at least ninety (90) percent relative compaction using a modified moisture content -dry density (Proctor) relationship test '(ASTM D1557). Only enough water should be added to the backfill ' , material to allow proper compaction. Do not pond, puddle, float or jet backfill soil materials. Improperly placed backfill material will allow water migration more easily than properly recompacted fill. Improperly compacted fill is likely to settle, creating a low surface area which further enhances water accumulation and subsequent migration to the founda- tion soils. Improperly placed backfill will allow water to migrate along the utility trench or backfill areas to gain access to the subgrade support soils with subsequent mobilization of the swell or settle - merit mechanism resulting in movement of the supported structure. Moisture migration could also result in the inconvenience of free water in the crawl space. Backfill placement techniques should not jeopardize the integrity of existing structural members. We recommend recently constructed 27 lambert attb R!oariateq CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G00062GE concrete structural members be appropriately cured prior to adja- cent backfilling. 12.0 SURFACE DRAINAGE The foundation soil materials should be prevented from becoming wetted after construction. Post construction wetting of the soil support soil materials can initiate swell potential or settlement potential as well as decrease the bearing capacity of the support soil materials. Protecting the foundation from wetting can be aided by providing positive and rapid drainage of surface water away from the structure. The final grade of the ground surface adjacent to the structure should have a well defined slope away from the foundation walls on all sides. The ability to establish proper site surface drainage away from the structure foundation system may be influenced by the existing topography, existing structure elevations and the grades and elevations of the ground surface adjacent to the proposed structure. We suggest where possible a minimum fall of the surface grade away from the structure be that which will accommodate other project grading constraints and provide rapid drainage of surface ,Hater away from the structure. If there are no other project onstraints"we suggest a fall of about one (1) foot in the first ten (10) feet away from the structure foundation. Appropriate surface drainage should be maintained for the life of the project. Future landscaping plans should include care and attention to the potential influence on the long term performance of the foundation and/or crawl space if improper surface drainage is not maintained. Roof runoff should be collected in appropriate roof drainage collection devices, such as eve gutters or similar, and directed to discharge in appropriate roof drainage systems. Roof runoff should not be allowed to fall on or near foundations, backfill areas, flatwork, paved areas or other structural members. Downspouts and faucets should discharge onto splash blocks that extend beyond the limits of the backfill areas. Splash blocks should be sloped away from the foundation walls. Snow storage areas should not be located next to the structure. Proper surface drainage should be maintained from the onset of construction through the proposed project life. '.a mbert atib Aff*Voartateo CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE If significant water concentration and velocity occurs erosion may occur. Erosion protection may be considered to reduce soil erosion potential. A landscape specialist or civil engineer should be consulted for surface drainage design, erosion protection and landscaping considerations. 13.0 LANDSCAPE IRRIGATION An irrigation system should not be installed next to foundations, concrete flatwork or paved areas. If an irrigation system is in- stalled, the system should be placed so that the irrigation water does not fall or flow near foundations, flatwork or pavements. The amount of irrigation water should be controlled. We recommend that wherever possible xeriscaping concepts be used. Generally, the xeriscape includes planning and design concepts which will reduce irrigation water. The reason we suggest xeri- scape concepts for landscaping is because the reduced landscape water will decrease the potential for water to influence the long term performance of the structure foundations and flatwork. Many publications are available which discuss xeriscape. Colorado State University Cooperative Extension has several useful publications and most landscape architects are familiar with the subject. 'Montrose Botanical Society has a Botanical Garden, 1800 Pavilion Drive, south of Niagara Drive, Montrose, Colorado, that has a very good exhibit with examples and information regarding successful xeriscape concepts. Due to the expansive nature of the soils tested we suggest that the owner consider landscaping with only native vegetation which requires only natural precipitation to survive. Additional irriga- tion water will greatly increase the likelihood of damage to the structure as a result of volume changes of the material supporting the structure. Impervious geotextile material may be incorporated into the project landscape design to reduce the potential for irrigation water to influence the foundation soils. 29 lambert imb Zfo ociateq CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE 14.0 SOIL CORROSIVITY TO CONCRETE The chemical tests to help identify the potential for soil corrosivity to concrete were not complete at the time of this report. The chemical tests will be presented when available. It has been our experience that much of the soils in the area contain sufficient water soluble sulfate content to be corrosive to concrete. We suggest sulfate resistant cement be used in concrete which will be in contact with the on -site soils. American Concrete Institute recommendations for sulfate resistant cement based on the water soluble sulfate content should be used. 15.0 RADON CONSIDERATIONS Our experience indicates that many of the soils in western Colorado produce small quantities of radon gas. Radon gas may tend to collect in closed poorly ventilated structures. Radon consider- ations are presented in Appendix D. 16.0 POST DESIGN CONSIDERATIONS The project geotechnical engineer should be consulted during construction of the project to observe site conditions and open excavations during construction and to provide materials testing of soil and concrete. This subsurface soil and foundation condition study is based on limited sampling; therefore, it is necessary to assume that the subsurface conditions do not vary greatly from those encountered in the field study. Our experience has shown that significant varia- tions are likely to exist and can become apparent only during additional on site excavation. For this reason, and because of our familiarity with the project, Lambert and Associates should be retained to observe foundation excavations prior to foundation construction, to observe the geotechnical engineering aspects of the construction and to be available in the event any unusual or unexpected conditions are encountered. The cost of the geotech- nical engineering observations and material testing during con- struction or additional engineering consultation is not included in the fee for this report. We recommend that your construction budget include site visits early during construction schedule for A 30 Imbed a nb Ztoodatef� CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE the project geotechnical engineer to observe foundation excavations -� and for additional site visits to test compacted soil. We recommend that the observation and material testing services during construction be retained by the owner or the owner's engi- neer or architect, not the contractor, to maintain third party credibility. We are experienced and available to provide material testing services. We have included a copy of a report prepared by Van Gilder Insurance which discusses testing services during con- struction. It is our opinion that the owner, architect and engi- neer be familiar with the information. If you have any questions regarding this concept please contact us. We suggest that your construction plans and schedule include provisions for geotechnical engineering observations and material testing during construction and your budget reflect these provi- sions. It is difficult to predict if unexpected subsurface conditions will be encountered during construction. Since such conditions may be found, we suggest that the owner and the contractor make provi- sions in their budget and construction schedule to accommodate unexpected subsurface conditions. ti 16.1 Structural Fill Quality It is our understanding that the proposed development may include compacted structural fill. The quality of compacted structural fill will depend on the type of material used as structural fill, fill lift thickness, fill moisture condition and compactive effort used during construction of the structural fill. Engineering observation and testing of structural fill is essential as an aid to safeguard the quality and performance of the structural fill. Fill materials placed on sloped areas require special placement techniques that key the fill materials unto the underlying support materials. These techniques include a toe key at the toe contact of the slope fill and benching the fill/natural contact up the slope into the competent natural material. The placing technique will also include subdrains at several locations to intercept subsurface water and route it away from the fill materials. We are available to discuss these techniques with you and your earthwork contractor. 31 Lambert attb Zaociate2; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE Testing of the structural fill normally includes tests to deter- mine the grain size distribution, swell potential and moisture - density relationship of the fill material to verify the material suitability for use as structural fill. As the material is placed the in -place moisture content and dry density are tested to indi- cate the relative compaction of the placed structural fill. We recommend that your budget include provisions for observation and testing of structural fill during construction. Testing of the compacted fill material should include tests of the moisture content and density of the fill material placed and compacted prior to placement of additional fill material. We suggest that a reasonable number of density tests of the fill material can best be determined on a site, material and constructi- on basis although as a guideline we suggest one test per about each 300 to 500 square feet of each lift of fill material. Utility trench backfill may need to be tested about every 100 linear feet of lift of backfill. 16.2 Concrete Quality It is our understanding current plans include reinforced struc- tural concrete for foundations and walls and may include concrete slabs on grade and pavement. To insure concrete members perform as intended, the structural engineer should be consulted and should address factors such as design loadings, anticipated movement and deformations. The quality of concrete is influenced by proportioning of the corcrete mix, placement, consolidation and curing. Desirable qualities of concrete include compressive strength, water tightness and resistance to weathering. Engineering observations and testing of concrete during construction is essential as an aid to safeguard the quality of the completed concrete. Testing of the concrete is normally performed to determine com- pressive strength, entrained air content, slump and temperature. I.,,e recommend that your budget include provisions for testing of concrete during construction. We suggest that a reasonable frequen- cy of concrete tests can best be determined on a site, materials and construction specific basis although as a guideline American Concrete Institute, ACI, suggests one test per about each fifty (50) cubic yards or portion thereof per day of concrete material placed. 32 Rambert anb Zf2;.qociate.5 CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE 17.0 LIMITATIONS It is the owner's and the owner's representatives' responsibility to read this report and become familiar with the recommendations and suggestions presented. We should be contacted if any questions arise concerning the geotechnical engineering aspects of this project as a result of the information presented in this report. The scope of services for this study does not include either specifically or by implication any environmental or biological (such as mold, fungi, bacteria, etc.) Assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be performed. The proposed building site contains soil materials with significant swell potential. For this reason we suggest that you consult, as suggested by Senate Bill 13, a copy of Colorado Geological Survey Special Publication 11, "Home Construction on Shrinking and Swelling Soils", and a copy of CGS Special Publication 14, "Home Landscaping and Maintenance on Swelling Soils". We are available to discuss this with you. The recommendations outlined above are based on our understanding of the currently proposed construction. We are available to discuss the details of our recommendations with you and revise them where necessary. This geotechnical engineering report is based on the proposed site development and scope of services as discussed with Mr. Mark Opstein, Faith Fellowship Church, on the type of construction planned, existing site conditions at the time of the field study, and on our findings. Should the planned, proposed use of the site be altered, Lambert and Associates must be contacted, since any such changes may make our suggestions and recommendations inappropriate. This report should be used ONLY for the planned development for which this report was tailored and prepared, and ONLY to meet information needs of the owner and the owner's representatives. In the event that any changes in the future design or location of the building are planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or verified in writing. It is recommended that the geotechnical engineer be provided the opportunity for a general review of the final project design and specifications in order that the earthwork and foundation recommendations may be properly interpreted and implemented in the design and specifications. .J 33 Imbed anb A(ffsemwdateq; CONSULTING GEOTECNNICAL ENGINEERS AND MATERIAL TESTING G08062GE This report does not provide earthwork specifications. We can provide guidelines for your use in preparing project specific earthwork specifications. Please contact us if you need these for your project. This report presents both suggestions and recommendations. The suggestions are presented so that the owner and the owner's representatives may compare the cost to the potential risk or benefit for the suggested procedures. This report contains suggestions and recommendations which are intended to work in concert with recommendations provided by the other design team members to provide somewhat predictable founda- tion performance. If any of the recommendations are not included in -the design and construction of the project it may result in unpredictable foundation performance or performance different than anticipated. We recommend that we be requested to provide geotech- nical engineering observation and materials testing during the construction phase of the project as discussed in this report. The purpose for on site observation and testing by us during construc- tion is to help provide continuity of service from the planning of the project through the construction of the project. This service will also allow us to revise our recommendations if conditions iccur or are discovered during construction that were not evidenced during the initial study. We suggest that the owner and the contractor make provisions in their construction budget and con- struction schedule to accommodate unexpected subsurface conditions. We represent that our services were performed within the limits prescribed by you and with the usual thoroughness and competence of the current accepted practice of the geotechnical engineering pro- fession in the area. No warranty or representation either ex- pressed or implied is included or intended in this report or our contract. We are available to discuss our findings with you. If you have any questions please contact us. The supporting data for this report is included in the accompanying figures and appendices. This report is a product of Lambert and Associates. Excerpts from this report used in other documents may not convey the intent or proper concepts when taken out of context, or they may be misinterpreted or used incorrectly. Reproduction, in part or whole, of this document without prior written consent of Lambert and Associates is prohibited. 34 Imbed anb Z[9;2;otiates� CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING 1 G08062GE This report and information presented can be used only for this —,site, for this proposed development, and only for the client for whom our work was performed. Any other circumstances are not appropriate applications of this information. Other development plans will require project specific review by us. We have enclosed a copy of a brief discussion about geotechnical engineering reports published by Association of Soil and Foundation Engineers for your reference. Please call when further consultation or observations and tests are required. If you have any questions concerning this report or if we'may be of further assistance, please contact us. Respectfully submitted; LAMBERT AND ASSOCIATES D( e R . Larrjhert, P.E. Geotechnic l� Engineer i DRL/nr 35 Revi Des II� Lambert. P.E. Geotechnical Engineer Ra mbert a nb ZNgoriateg; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING ,t,>"�Van cidder NEWSLETTER WV** Insurance Corporation Brokers Since 1905 - 700 Broadway, Suite 1035, Denver, CO 80203 - 303/837-8500 THE PROFESSIONAL LIABILITY PERSPECTIVE Vol. 8, No. 8 Copyright 1988 August 1988 WHO HIRES THE TESTING LABORATORY? It is one of those relatively small details in the overall scheme of things. Independent testing may be required by local building codes, or it may be insisted upon by lenders. Additional testing can usually be ordered by the design team during construction. What- ever the source of the requirement, many owners perceive it to be an unnecessary burden —an additional cost imposed principal - for someone else's benefit. What does this have may be the only o n Resist this inclination where you can. It is not in your client's best interests, and it is certainly not in yours. There are important issues of quality and even more important issues of life safety at stake. In the complex environment of today's construction arena, it makes very Little sense for either of you to give up your control of quality control. Yet it happens altogether too often. What's Behind this Misadventure? The culprit seems to be the Federal Govern- ment. In the 19601s, someone came up with the idea that millions could be saved by eliminating the jobs of Federal workers en- gaged in construction inspection. The pro- curement model used to support ' this stroke of genius was the manufacturing segment of the economy, where producers of goods pur- chased by the Government had been required for years to conduct their own quality assur- ance programs. The result was a trendy new concept in Federal construction known as Contractor Quality Control (CQC). It was a dumb idea. Costs were simply shifted from the Federal payroll to capital improvement budgets. Government contrac- tors, selected on the basis of the lowest bid, were handed resources to assure the quality of their own performance. Some did so; many did not. All found themselves caught up in an impossible conflict between the demands of time and cost, on one hand, and the dictates of quality, on the other. CQC was opposed by the Associated General Contractors of America, by independent testing laboratories, by the design profes- sions, and by those charged with front-line responsibility for quality control in the Federal Agencies. Eventually, even the General Accounting Office came to the con- clusion that it aught to be abandoned. But, once set in motion and fueled by the per- vasive influence of the Federal Government, the idea spread —first to state and local governments; finally, to the private sector. Why would the private sector embrace such an ill-conceived notion? Because so many Binder Hey: Professional Practices VoL S. No. 8 page 2 August 1988' ,wners view testing and inspection as an .ndertaking which simply duplicates some- thing they are entitled to in any event. They are confident they will be protected by contract documents which cover every detail and contingency. They look to local building inspectors to assure compliance with codes. And they fully expect the design team to fulfill its obligation to safeguard the quality of the work. A Fog in the Henhouse If testing is perceived as little more than an 'unnecessary, but unavoidable expense, Why not make the general contractor respon- sible for controlling the cost? It may pro- duce a savings, and it certainly eliminates an adminstrative headache. If contractual obligations dealing with the project schedule and budget can be enforced, surely those governing quality can be enforced, as well. Possibly so, but who is going to do it? Some testing consultants will not accept C work. The reasons they give come Lrom firsthand experience. They include: 1) inadequate to barely adequate scope, 2) selection based on the lowest bid; 3) non- negotiable contract terms inappropriate to the delivery of a professional service; 4) intimidation of inspectors by field super- visors; and 5) suppression of low or failing test results. This ought to be fair warning to any owner. Keeping Both Hands on the Wheel The largest part of the problem, from your point of view, is one of artful persuasion. If you cannot convince your client of the value of independent testing and inspection, no one can. Yet, if you do not, you are likely to find yourself responsible for an assurance of quality you are in no position to deliver. How can you keep quality control where it belongs and, in the process, prevent the owner from compromising his or her interests in the project as well as yours? (''-eider these suggestions: I. Put the issue on an early agenda. It needs your attention. Anticipate the owner's inclination to avoid dealing with testing and inspection, and explain its importance to the success of the project. Persist, if you can, until your client agrees to hire the testing laboratory independently and to establish an adequate budget to meet the anticipated costs. A testing consultant hired by the owner cannot be fired by the general con- tractor for producing less than favorable results. 2. Tailor the testing requirements carefuuu. Scissors and paste can be your very worst enemies. Specify what the job requires, retain control of selection and hiring, make certain the contractor's responsibilities for notification for scheduling purposes 'are clear, and require that copies of all reports be distributed by the laboratory directly to you. 3. Insist on a econstruction testin con- ference. It can be an essential element of effective coordination. Include the owner, the general contractor, major subcontrac- tors, the testing consultant, and the design team. Review your requirements, the pro- cedures to be followed, and the responsibili- ties of each of the parties. Have the testing consultant prepare a conference memoran- dum for distribution to all participants. 4. Monitor tests and inspections closet . Make certain your ield representative is present during tests and inspections, so that deficiencies in procedures or results can be reported and acted upon quickly. Scale back testing if it becomes clear it is appropiate to do so under the circumstances; do not hesitate to order additional tests if they are required. 5. Finally, keep your client informed. With- out your help, he or she is not likely to understand what the test results mean, nor will your actions in response to them make much sense. If additional testing is called for, explain why. Remember, it is an unex- pected and, possibly, unbudgeted additional cost for which you will need to pave the way. In this sense, independent testing and inspection can serve an important, secondary purpose. You might view it as a communica- tions resource. Use it in this way, and it just may yield unexpected dividends. THE PROFESSIONAL LIABILITY PERSPECTIVE IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL ENGINEERING REPORT More construction problems are caused by site subsur- face conditions than any other factor. As troublesome as subsurface problems can be. their frequency and extent have been lessened considerably in recent years, due in large measure to programs and publications of ASFE/ The Association of Engineering Firms Practicing in the Geosciences. The following suggestions and observations are offered to help you reduce the geotechnical-related delays. cost -overruns and other costly headaches that can occur during a construction project. A GEOTECHNICAL ENGINEERING REPORT IS BASED ON A UNIQUE SET OF PROJECT SPECIFIC FACTORS A geotechnical engineering report is based on a subsur- face exploration plan designed to incorporate a unique set of protect -specific factors. These typically include. - the general nature of the structure involved, its size and configuration; the location of the structure on the site and its orientation; physical concomitants such as access roads, parking lots, and underground utilities. the level of additional risk which the client assumed virtue of limitations imposed upon the exploratory program. To help avoid costly problems, consult the geotechnical engineer to determine how any factors which change subsequent to the date of the report may affect its recommendations. Unless your consulting geotechnical engineer indicates otherwise, your geotechnical oigfnceriml replyt should not he used: • When the nature of the proposed structure is changed. for example, if an office building will be eructed instead of a parking garage, or if a refriger- ated warehouse will be built instead of an u n re- frigerated one; • when the size or configuration of the proposed structure is altered; • when the location or orientation of the proposed structure is modified; • when there is a change of ownership, or • for application to an adjacent site. Geolechnic al ettyinerrs cannot accept re sportsibdity for prohfrms which pray de't'elop if troy are not consulted sifter factors consid- ered in their reporf's development have rharnged. MOST GEOTECHNICAL "FINDINGS" F PROFESSIONAL ESTIMATES Site exploration identifies actual subsurface conditions only at those points where samples are taken. when they are taken. Data derived through sampling and sub- sequent laboratory testing are extrapolated by gco- technical engineers who then render an opinion about overall subsurface conditions, their likely reaction to proposed construction activity, and appropriate founda- tion design. Even under optimal circumstances actual conditions may differ from those inferred to exist. because no geotechnical engineer. no matter how qualified, and no subsurface exploration program, no matter how comprehensive. can reveal what is hidden by earth. rock and time. The actual interface between mate- rials may be far more gradual or abrupt than a report indicates. Actual conditions in areas not sampled may differ from predictions. Nottiing can be done to prevent the unanticipated. but steps cur: he taken to help minimize their impact. For this reason. most experienced owners retain their grolechrtical consuffanls through the construction stage. to iden- tify variances. conduct additional tests which may be needed, and to recommend solutions to problems encountered on site. SUBSURFACE CONDITIONS CAN CHANGE Subsurface conditions may be modified by constantly - changing natural forces. Because a geotechnical engi- neering report is based on conditions which existed at the time of subsurface exploration. construction decisions should avi be 5atsed on at anTI micaI rnroineering report whose adequaactl may have Bern arffecfetl by Iime. Speak with the geo- technical consultant to learn if additional tests are advisable before construction starts. Construction operations at or adjacent to the site and natural events such as floods, earthqua!-es or ground- water fluctuations may also affect subsurface conditions and, thus. the continuing adequacy of a geotechnical retort. The geotechnical engineer should be kept apprised of any such events, and should be consulted to determine if additional tests are necessary. GEOTECHNICAL SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES AND PERSONS GootechnicaI engineers reports are prepared to meet the specific needs of specific individuals. A report pre- pared for a consulting civil engineer may not be ade- quate for a construction contractor, or even some other consulting civil engineer. Unless indicated otherwise. this report was prepared expressly for the client involved and expressly for purposes indicated by the client. Use by any other persons for any purpose. or by the client for a different purpose. may result in problems. No indi- vidual other Man the client should apply lhtis report for its intended purpose withoatt first (onferrfng print (fie geaalechnicaf enafneer. No person should apply Ili is report for ony purpose olfrer 1haan than origfnarlly carn[ctltplatte'rf without first conferring with the oe'trle'i fr+tfc art artalnver, A GEOTECHNICAL ENGINEERING REPORT IS SUBJECT TO TSINTERPRETATION Costly problems can occur when other design profes- sionals develop their plans based on misinterpretations of a geotechnical engineering report. Th help avoid these problems, the geotechnical engineer should be retained to work with other appropriate design profes- sionals to explain relevant geotechnical findings and to review the adequacy of their plans and specifications relative to geotechnical issues. BORING LOGS SHOULD NOT BE SEPARATED FROM THE ENGINEERING REPORT Final boring logs are developed by geotechnical engi- neers based upon their interpretation of field logs (assembled by site personnel) and laboratory evaluation of Field samples. Only final boring logs customarily are included in geotechnical engineering reports. These fogs should not under any circumstances be redrawn for inclusion in architectural or other design drawings, because drafters may commit errors or omissions in the transfer process. Although photographic reproduction eliminates this pri-hlem, it does nothing to minimize the possibility of actors misinterpreting the logs during bid prepara- Uon. When this occurs, delays, disputes and unantici- pated costs are the all -too -frequent result. To minimize the likelihood of boring log misinterpreta- tion, give contractors ready access to the complete geotechnical engineering report prepared or authorized for their use. Those who do not provide such access may proceed un- der the mistaken impression that simply disclaiming re- sponsibility for the accuracy of subsurface information always insulates them from attendant liability. Providing the best available information to contractors helps pre- vent costly construction problems and the adversarial attitudes which aggravate them to disproportionate scale. READ RESPONSIBILITY CLAUSES CLOSELY Because geotechnical engineering is based extensively on ludgment and opinion, it is far less exact than other design disciplines. This situation has resulted in wholly unwarranted claims being lodged against geotechnical consultants. To help prevent this problem. geotechnical engineers have developed model clauses for use in writ- ten transmittals. These are not exculpatory clauses designed to foist geotechnical engineers liabilities onto someone else. Rather, they are definitive clauses which identify where geotechnical engineers responsibilities begin and end. Their use helps all parties involved rec- ognize their individual responsibilities and take appro- pr€ate action. Some of these definitive clauses are likely to appear In your geotechnical engineering report, and you are encouraged to read them closely. Your geo- technical engineer will be pleased to give full and Frank answers to your questions. OTHER STEPS YOU CAN TAKE TO REDUCE RISK Your consulting geotechnical engineer will be pleased to discuss other techniques which can be employed to mit- igate risk. fn addition, ASFE has developed a variety of materials which may be beneficial. Contact ASFE for a complimentary copy of its publications directory. Published by THE ASSOCIATION OF ENGINEERING FIRMS PRACTICING IN THE GEOSCIENCES 8811 Colesville Road/Suite G 106/Silver Spring, Maryland 20910/(301) 565-2733 Q� Indicates approximate pro'e'ct location This map is intended to present geotechnical engineering data only NO SCALE PROJECT VICINITY MAP W r 3 L 6 5 �3 �4 2 07 01 7 (iP Indicates approximate test boring locations This map was reproduced from notes taken in the field and is intended to present geotechnical engineering data only TEST BORING LOCATION SKETCH amb anb Rosociate i Noy 1080629E ■ 2 0 w N J _ Q O V) '0 V) N o I— u (.0 rp L I— n. 0 C) E +- z O ro r.J s" J I , 1 L I L,� N V) 4-J u M (u L Q 7 E 4J O ro U Z ,..) a� u N ro N m -0 c -0¢ w u 4-) 0) N +-J O O J O - LL- 3 u O c N ro O m 7 N 4J +-J m c u N c L E L L L/ -0 +-r 4-J 0 N U V) •- 3 -0 Ld N — rn 4 rn C U •— C rp LL .— N 4- a +-J -0 O E o O ro O O c O L L U rp LL C7 II II II m ¢ in CONCEPTUAL SKETCH OF FOOTING SUBGRADE TREATMENT v;- mm,r r r 4:: z Concrete Floor Slab or Finished Interior Grade Foundation Wall Foot i ng Concrete Floor Slab or Finished Interior Grade Minimum Embedment Footing Minimum Embedment Existing Exterior Grade Foundation Wall Wall Backfill EMBEDMENT CONCEPT G08062GE l s m(IM f anh %glgotfiltra to - No.:1 /29/09 - Foundation/Retaining Wall Concrete slab=on-grad: or finished elevation Zone of Influence 580 Footing BACKFILL ZONE OF INFLUENCE CONCEPT i Ali r GO 062GE i� of*Mdanx'.7 29/0 A S Foundation/Retaining Wall Concrete Slab -on -Grade -Free Draining Sand or Gravel Material Moisture Barrier This sketch is to show concept only. The text of our report should be consulted for additional information. ! Low ! permeability ! Backfill f Material ! Comnacted Backfill I Drainage I Blanket ! Geotechnical �al Filter Fabric Q�- a o•n ! Free Drain . no• ! Fi 1 ter Material ! Perforated Drain ' Pipe Sloped to — ---� Outlet Perforated Drain Pipe Installed at Collection Points and Graded to Drain - CONCEPTUAL SKETCH OF FOUNDATION DRAIN SYSTEM t F,Iw�wrw 1 G08062GE APPENDIX A The field study was performed December 10, 2008. The field study consisted of logging and sampling the soils encountered in seven (7) test borings. The approximate locations of the test borings are shown on Figure 2. The log of the soils encountered in the test borings are presented on Figures A2 through A8. The test borings were logged by Lambert and Associates and samples of significant soil types were obtained. The samples were obtained from the borings using a Modified California Barrel sampler and bulk disturbed samples were obtained. Penetration blow counts were determined using a 140 pound hammer free falling 30 inches. The blow counts are presented on the logs of the test borings such as 23/6 where 23 blows with the hammer were required to drive the sampler 6 inches. The engineering field description and major soil classification are based on our interpretation of the materials encountered and are prepared according to the Unified Soil Classification System, ASTM D2488. The description and classification which appear on the test boring log is intended to be that which most accurately describes a given interval of the test boring (frequently an interval of several feet). Occasionally discrepancies occur in the Unified Soil Classification System nomenclature between an interval of the soil log and a particular sample in the interval. For example, an interval on the test boring log may be identified as a silty sand (SM) while one sample taken within the interval may have individually been identified as a sandy silt (ML). This discrepancy is frequently allowed to remain to emphasize the occurrence of local textural variations in the interval. The stratification lines presented on the logs are intended to present our interpretation of the subsurface conditions encountered in the test borings. The stratification lines represent the approximate boundary between soil types and the transition may be gradual. Al lambert aub 'ARQ;attat0 CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING Date Drilled: Location: Sample Type I N b B C 5 41 10 15 20 25 KEY TO LOG OF TEST BORING Field Engineer: Boring Number: Elevation: Total Depth: Depth to Water at Time of Drilling: Soil Description Sand, silty, medium dense, moist, tan (SM) L Unified Soil Classification Indicates Bulk Bag Sample Indicates Drive Sample Incicates Sampler Type: C - Modified California St - Standard Split Spoon H - Hand Sampler 7/12 Indicates seven blows required to drive the sampler twelve inches with a hammer that weighs one hundred forty pounds and is dropped thirty inches. BOUNCE: Indicates no further penetration occurred with additional blows with the hammer NR: Indicates no sample recovered CAVED: Indicates depth the test boring caved after drilling ♦ Indicates the location of free subsurface water when measured CLAY Note: Symbols are often used only to help visually SILT identify the described information presented on SAND the log. GRAVEL CLAYSTONE SANDSTONE Laboratory Test Results Notes in this column indicate tests performed and test results if not plotted. DD: Indicates dry density in pounds per cubic foot MC: Indicates moisture content as percent of dry unit weight LL: Indicates Liquid Limit PL: Indicates Plastic Limit PI: Indicates Plasticity Index Pr ;Name: Faith Fellowship-3 Structures project Number: G08062G E X4'M&Mter Aolwrimtvo CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING Figure: Al LOG OF TEST BORING Date Drilled: 12/10/2008 Field Engineer: DRL Boring Number: 1 'ocation: Southern portion of proposed modular structure Elevation: Diameter: 4 inches Total Depth: 14 feet Depth to Water at Time of Drilling: None Encountered 0 Sample E C Soil Description Laboratory Test Results cn 0 Type N 0 •rr.�.� rrr: �r!r J ;� C 23/6 r:,, 5 I 2516 NUM Clay, sandy, stiff, moist, brown, tan (CL) Intermittent Cobbles Formational Shale Material 15 �1 I I Bottom of Test Boring at 14 feet B Direct Shear Test: DID: 122.0 pcf MC: 6.1 % Swell -Consolidation Tests: DID: 114.0 pcf MC: 8.2% - I i I i i i 25 roject Name: Faith Fellowship - 3 Structures Project Number: G08062GE X=,&Jerf mtbAsojarinfro CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING Figure: A2 LOG OF TEST BORING Date Drilled: 12/10/2008 Field Engineer: DRL Boring Number: 2 ocation: Northern portion of proposed modular structure Elevation: -Aameter: 4 inches Total Depth: 14 feet Depth to Water at Time of Drilling: None Encountered n s Sample 1-1 E Soil Description Laboratory Test Results ❑ Type N 0 ",`f,, , Clay, sandy, stiff, moist, brown, ff�r tan (CL) 5 Intermittent Cobbles Formational Shale Material 10 1� I + Intermittent Cemented Lenses 15 I Bottom of Test Borinq at 14 feet 20 f 25 Jject Name: Faith Fellowship - 3 Structures Project Number: G08062GE' Figure: A3 TMI&M m1ar �1 Jadaf ez CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING LOG OF TEST GORING 11 Date Drilled: 12/10/2008 Field Engineer: DRL Boring Number: 3 ocation: Northeastern portion of proposed gymnasium Elevation: ,+ameter: 4 inches Total Depth: 24 feet Depth to Water at Time of Drilling: None Encountered r Sample E C Soil Description Laboratory Test Results o Type N # 0I Clay, sandy, stiff to soft, moist, brown, tan (CL) 22/6 C 50/6 F•.•rr �r1t} rr 10 I ' Increased Moisture Content I Observed =err/.• � r�r}lf f/Jl! I1J/ 'f'1trs 20 'tJ.'tJ 25 !1 ' � Bottom of Test Borinq at 24 feet Swell -Consolidation Test: DD: 119.0 pcf MC: 5.6% Ject Name: Faith Fellowship - 3 Structures Project Number: G08062GE Figure: A4 TMT&M ttxx1-1 pv"vidateo CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING LOG OF TEST BORING Date Drilled: 12/10/2008 Field Engineer: DRL Boring Number: 4 { ocation: Southwestern portion of proposed gymnasium Elevation: ameter: 4 inches Total Depth: 14 feet Depth to -Water at Time of Drilling: None Encountered y Sample E Soil Description Laborato Test Results N o Type N ry 0 Clay, to /'Wz sandy, stiff soft, moist, brown, frfil + tan (CL) 5 f���•. C 14/6 Swell -Consolidation Test: "''r.• 10 ' 21/6 DID: 127.0 pcf MC: 7.5% ffr * Increased Moisture Content Observed .. rr rrrr. rr� 15 Bottom of Test Boring at 14 feet T I J—t Name: Faith Fellowship - 3 Structures Project Number: G08062GE Figure: A5 xamilm mtb C��vrf&m CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING LOG OF TEST BORING Date Drilled: 12/10/2008 Field Engineer: DRL Boring Number: 5 ' ocation: Northeast portion of proposed Church Building Elevation: -iameter: 4 inches Total Depth: 14 feet Depth to Water at Time of Drilling: None Encountered _a Sample E d Soil Description Laboratory Test Results rn ❑ Type N 101 A .frrr C 19/6 44/6 err 5 Clay, sandy, stiff to soft, moist, brown, tan (CL) Increased Moisture Content Observed - �rr1 f//A AIVA �V/ o lry 15 11 1 ' Bottom of Test Boring at 14 feet 20 25 Direct Shear Test: DD: 122.0 pcf MC: 7.4% ,ject Name: Faith Fellowship - 3 Structures Project Number: G08062GE Figure: A6 TMIthm Mtb Asolarfafleg CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING LOG OF TEST BORING Date Drilled: 12/10/2008 Field Engineer: DRL Boring Number: 6 1-ocation: Northwest portion of proposed Church Building Elevation: iameter: 4 inches Total Depth: 14 feet Depth to Water at Time of Drilling: None Encountered °Q Sample CL E Soil Description Laboratory Test Results a) TYPe N � Q frr Clay, silty, stiff to soft, moist, brown, rrrr :rrsr1 it I 1 tan (CL) •rrrr 5 err * Increased Moisture Content Observed ff.�rr rrlri rrrr "r!!l •fr rrrr rrfr, �$ ! Bottom of Test Borinq at 14 feet I 20 I i I 25 ,_ ject Name: Faith Fellowship - 3 Structures Project Number: G08062GE Figure: A7 XMx&.erf mtb Awarinfi-m CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING LOG OF TEST BORING 11 Date Drilled: 12/10/2008 Field Engineer: DRL Boring Number: 7 zcation: Southwest portion of proposed Church Building Elevation: .ameter: 4 inches Total Depth: 14 feet Depth to Water at Time of Drilling: None Encountered s Sample E C Soil Description Laboratory Test Results U o TYpe N 0 'ri"4 1 1 rr}r 14/6 ''rrrr C 14/6 r.�rr r✓rr :f�rr �.rrf •rrrr arrr /J Clay, silty, sandy, stiff to soft, moist, brown, tan (CL) Increased Moisture Content Observed Bottom of Test Boring at 14 feet Swell -Consolidation Test: DID: 123.0 pcf MC: 7.2% j\ect Name: Faith Fellowship - 3 Structures Project Number: G08062GE Figure: A8 Tumdnrf mTb &Azoax ides CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE APPENDIX B The laboratory study consisted of performing: Moisture content and dry density tests, Swell -consolidation tests, Direct Shear Strength tests, and Chemical tests. It should be noted that samples obtained using a drive type sleeve sampler may experience some disturbance during the sampling operations. The test results obtained using these samples are used only as indicators of the in situ soil characteristics. TESTING Moisture Content and Dry Density Moisture content and dry density were determined for each sample tested of the samples obtained. The moisture content was determined according to ASTM Test Method D2216 by obtaining the moisture sample from the drive sleeve. The dry density of the_ sample was determined by using the wet weight of the entire sample tested. The results of the moisture and dry density determinations are presented on the logs of borings, Figures A2 through A8. Swell Tests Loaded swell tests were performed on drive samples obtained during the field study. These tests are performed in general accordance with ASTM Test Method D2435 to the extent that the same equipment and sample dimensions used for consolidation testing are used for the determination of expansion. A sample is subjected to static surcharge, water is introduced to produce saturation, and volume change is measured as in ASTM Test Method D2435. Results are reported as percent change in sample height. m Kambert aub 3*4aociateq CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE APPENDIX C GEOLOGY DISCUSSION SOUTHWEST COLORADO GEOLOGY Southwest Colorado exhibits many geologic features formed by a multitude of geologic processes. Regional inundation, uplift, volcanism and glaciation are responsible for some of the complex geology of the region. Many theories and speculations concerning the mode of occurrence of the regions's geology have been presented over the years. This cursory discussion of the geology of southwest Colorado presents some theories accepted by the geologic community, but is only intended to introduce the basic concepts and restraints that arise due to geologic activity. Prior to the formation of the Rocky Mountains southwest Colorado was a primarily a flat lying region with little topographic expression. The North American continent was experiencing many episodes of deposition. The Transcontinental Sea was transgressing and regressing across the continent, these transgressions and regressions are the cause for such diverse rock types. The stratigraphic column in southwestern Colorado expresses rock types from variable depositional environments. Limestones are formed in deeper water, sandstones are formed in beach and tidal flat environments, while arkosic sandstone and conglomerates are formed in alluvial plains and fans. Particle size and mineralogic content in rock units are related to the depositional environment. A sandstone or conglomerate would not be likely to form in a deep sea environment because there would not be enough energy to carry such large particles a great distance from the source lands. As one observes the stratigraphic column of southwest Colorado a siltstone may be overlain by a sandstone which is in turn overlain by a siltstone. This represents a regressional then transgressional sequence. Many such sequences or combinations of other rock units are exhibited throughout southwest Colorado. The final regression of the sea may have been caused by orogenic activity and uplift. This uplift was not confined to Colorado, it was a regional uplift that occurred in many stages. The uplift is what caused the formation of the ancestral rockies. The Larimide Orogenic episode is responsible for the formation of the San Juan dome. (Note: The San Juan dome theory is not accepted by the entire geologic community. It is used here, for descriptive purposes). The San Juan dome was essentially an upwarp of the stratigraphy formed by sedimentation during the Transcontinental Sea. An actual dome probably never existed due to erosion during the uplift. The idea being that a dome of sediments and rock units C1 lambert aub !am ociateg; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE Consolidation Tests One dimensional consolidation properties of drive samples were evaluated according to the provisions of ASTM Test Method D2435. Water was added in all cases during the test. Exclusive of special readings during consolidation rate tests, readings during an increment of load were taken regularly until the change in sample height was less than 0.001 inch over a two hour period. The results of the swell -consolidation load tests are summarized on Figures B1 through B4, swell -consolidation tests. It should be noted that the graphic presentation of consolidation data is a presentation of volume change with change in axial load._ As a result, both expansion and consolidation can be illustrated. Direct Shear Strength Tests Direct shear strength properties of sleeve samples were evaluated in general accordance with testing procedures defined by ASTM Test Method D3080. Direct shear strength tests were performed on samples obtained from Test Boring Nos. 1 and 5 at approximate depths of four (4) feet. An internal angle of friction of 26 degrees and a cohesion of 186 pounds per square foot were used in our analysis. Chemical Tests The chemical tests to help identify the potential for soil corrosivity to concrete were not complete at the time of this report. The chemical tests will be presented when available. M. Imbed atib 202;aciatet; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING PRESSURE (POUNDS PER SQUARE FOOT) 10 100 1000 10 000 Swell Under Constant Pressure 11 Due To Wetting 10 9 8 7 6 5 4 0 co 3 a 2 0 0Ll a 1 '^ c Wafer added ti 0 to sample 0 1 1 - 2 Boring No. 1 SUMMARY OF TEST RESULTS Moisture ensity Height Diameter Swell Pressure Depth 9-10 f t . ontent 2ZC�F in, in. P. S. F. Initial 7.2 114.0 1 •0 1' 9 3800 ± 15.0 .990 4.94 Soil Descei Lion Forma i ona i Shale Material SWELL -CONSOLIDATION TEST Pt ioct No.: G08062GE lambert ani) 20 oclatea Date : 1 /29/09 Figure: B1 PRESSURE (POUNDS PER SQUARE FOOT) Le we, we -we 10 000 Swell Under Constant Pressure Due To Wetting 2 1 0 1 2 3 1 Nil 4 5 6 *Water added to sample 4 I Boring No. 3 Depth 4-5 feet SUMMARY OF on tent P.C.F, Moisture Dr DensityM1,1 TEST RESULTS Diameter Swell Pressure in. P. S. F.Initial .6 11 .01. 4400Final 4 T4. 12 01. Soil Descri lion C 1 a sand brown tan SWELL - CONSOLIDATION TEST jEambert anb A000ciate's Reject No.: G08062GE Date: 1 /29/09 Figure B2 PRESSURE (POUNDS PER SQUARE FOOT) 2 M i C :, IN 100 us 9=8 10,000 Swell Under Constant Pressure Due To Wetting SWELL —CONSOLIDATION TEST Project No.: G08062GE XaMbC41 ani) 3000f filtCO Date - 1 /29/09 Figure: B 4 G08062GE The orientation of bedding planes forms a radial pattern around the San Juan region which seems to vindicate this theory. The stresses need to "upwarp" this large area were obviously tremendous. Locally occurring stresses may not be sufficient to move this quantity of material, global tectonics, directly or indirectly, may have been involved. Compression of the entire North American plate could have occurred. The magnitude of the stresses and the deep seated origin of these stresses also have caused extensive volcanism. Colorado has many large remnants of Calderas that were active during the orogenic activity. The Silverton and Lake City Calderas are the largest in the San Juan region. Activity in the Silverton Caldera has been estimated (radiometrically) to have occurred 22 million years ago. Calderas of this magnitude are believed to have formed by the collapse of epierogenic magma chambers. Volcanic and metamorphic rock bodies are common in the San Juan region, many of these units are related to the orogenic activity in the region. Faults associated with local orogenic activity are another common geologic feature found in southwestern Colorado. As stated previously, extreme stresses were probably associated with the formation of the San Juan Mountains and may be responsible for deep-seated volcanic and metamorphic processes. These stresses had to be released, the geologic mode for stress release is faulting. Diastrophic activity in the area today is quite low, the lack of seismic activity indicates that stresses are not currently being released. An explanation for the loss of stresses is through faulting. The last episode of regional geologic activity in the area was glaciation. The most recent period of glacial activity ended approximately 10,000 years ago. Glacial activity is responsible for much of the topographic expression in the area. "U-Shaped" valleys, moraine deposits, tarns, (glacial formed lakes), and rock glaciers are the most prominent features which are found in southwestern Colorado as a result of glacial activity. The valley configurations are a result of the erosional activity of the glaciers. Moraine deposits developed during the glacial activity. Rock glaciers are moving masses of rock which are thought to have an ice core which may be the last remnant of glacial ice. As the subsurface ice core moves and melts, the overlying mass of rock also moves. C2 lambert anb !ggortato CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062CE APPENDIX D GENERAL GEOTECHNICAL ENGINEERING CONSIDERATIONS D1.0 INTRODUCTION Appendix D presents general geotechnical engineering considerations for design and construction of structures which will be in contact with soils. The discussion presented in this appendix are referred to in the text of the report and are intended as tutorial and supplemental information to the appropriate sections of the text of the report. D2.0 FOUNDATION RECOMMENDATIONS Two criteria for any foundation which must be satisfied for satisfactory foundation performance are: contact stresses must be low enough to preclude shear failure,of the foundation soils which would result in lateral movement of the soils from beneath the foundation, and settlement or heave of the foundation must be within amounts tolerable to the superstructure. The soils encountered during our field study have varying engineering characteristics that may influence the design and construction considerations of the foundations. The characteristics include swell potential, settlement potential, bearing capacity and the bearing conditions of the soils supporting the foundations. The general discussion below is intended to increase the readers familiarity with characteristics that can influence any structure. D2.1 Swell Potential Some of the materials encountered during our field study at the anticipated foundation depth may have swell potential. Swell potential is the tendency of the soil to increase in volume when it becomes wetted. The volume change occurs as moisture is absorbed into the soil and water molecules become attached to or adsorbed by the individual clay platlets. Associated with the process of volume change is swell pressure. The swell pressure is the force the soil applies on its surroundings when moisture is absorbed into the soil. Foundation design considerations concerning swelling soils include structure tolerance to movement and dead load pressures to help D1 Imbed aub ZW OCiatee; CONSULTING GEOTECNNICAL ENGINEERS AND MATERIAL TESTING G08062GE restrict uplift. The structure's tolerance to movement should be addressed by the structural engineer and is dependent upon many facets of the design including the overall structural concept and the building material. The uplift forces or pressure due to wetted clay soils can be addressed by designing the foundations with a minimum dead load and/or placing the foundations on a blanket of compacted structural fill. The compacted structural fill blanket will increase the dead load on the swelling foundations soils and will increase the separation of the foundation from the swelling soils. Suggestions and recommendations for design dead load and compacted structural fill blanket are presented below. Compacted structural fill recommendations are presented under COMPACTED STRUCTURAL FILL below. D2.2 Settlement Potential Settlement potential of a soil is the tendency for the soil to experience volume change when subjected to a load. Settlement is characterized by downward movement of all or a portion of the supported structure as the soil particles move closer together resulting in decreased soil volume. Settlement potential is a function of; foundation loads, depth of footing embedment, the width of the footing, and the settlement potential or compressibility of the influenced soil. Foundation design considerations concerning settlement potential include the amount of movement tolerable to the structure and the design and construction concepts to help reduce the potential movement. The settlement potential of the foundation can be reduced by reducing foundation pressures and/or by placing the foundations on a blanket of compacted structural fill. The anticipated post construction settlement potential and suggested compacted fill thickness recommendations are based on site specific soil conditions and are presented in the text of the report. D2.3 Soil Support Characteristics The soil bearing capacity is a function of; the engineering properties of the soil material supporting the foundations, . the foundation width, the depth of embedment of the bottom of the foundation below the lowest adjacent grade, . the influence of the ground water, and the amount of settlement tolerable to the structure. FIX Rambert anb Zf!oociateg CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE Soil bearing capacity and associated minimum depth of embedment are presented in the text of the report. The foundation for the structure should be placed on relatively uniform bearing conditions. Varying support characteristics of the soils supporting the foundation may result in nonuniform or differential performance of the foundation. Soils encountered at foundation depths may contain cobbles and boulders. The cobbles and boulders encountered at foundation depths may apply point loads on the foundation resulting in nonuniform bearing conditions. The surface of the formational material may undulate throughout the building site. If this is the case it may result in a portion of the foundation for the structure being placed on the formational material and a'portion of the foundation being placed on the overlying soils. Varying support material will result in nonuniform bearing conditions. The influence of nonuniform bearing conditions may be reduced by placing the foundation members on a blanket of compacted structural fill. Suggestions and recommendations for constructing compacted structural fill are presented under COMPACTED STRUCTURAL FILL below and in the text of the report. _D3.0 COMPACTED STRUCTURAL FILL Compacted structural fill is typically a material which is constructed for direct support of structures or structural components. There are several material characteristics which should be examined before choosing a material for potential use as compacted structural fill. These characteristics include; the size of the larger particles, the engineering characteristics of the fine grained portion of material matrix, . the moisture content that the material will need to be for compaction with respect to the existing initial moisture content, the organic content of the material, and the items that influence the cost to use the material. Compacted fill should be a non -expansive material with the maximum aggregate size less than about two (2) inches and less than about twenty five (25) percent coarser than three quarter (3/4) inch size. The reason for the maximum size is that larger sizes may have too great an influence on the compaction characteristics of the material and may also impose point loads on the footings or floor slabs that are in contact with the material. Frequently pit -run material or crushed aggregate material is used for structural fill material. Pit- -un material may be satisfactory, however crushed aggregate material . J D3 Imbed aub Raociateq; CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING G08062GE with angular grains is preferable. Angular particles tend to interlock with each other better than rounded particles. The fine grained portion of the fill material will have a significant influence on the performance of the fill. Material which has a fine grained matrix composed of silt and/or clay which exhibits expansive characteristics should be avoided for use as structural fill. The moisture content of the material should be monitored during construction and maintained near optimum moisture. content for compaction of the material. Soil with an appreciable organic content may not perform adequately for use as structural fill material due to the compressibility of the material and ultimately due to the decay of the organic portion of the material. D4.0 RADON CONSIDERATIONS Information presented in "Radon Reduction in New Construction, An Interim Guide: OPA-87-009 by the Environmental Protection Agency dated August 1987 indicates that currently there are no standard soil tests or specific standards for correlating the results of soil tests at a building site with subsequent indoor radon levels. Actual indoor levels can be affected by construction techniques and may vary greatly from soil radon test results. Therefore it is recommended that radon tests be conducted in the structure after construction is complete to verify the actual radon levels in the home. We suggest that you consider incorporating construction techniques into the development to reduce radon levels in the residential structures and provide for retrofitting equipment for radon gas removal if it becomes necessary. Measures to reduce radon levels in structures include vented crawl spaces with vapor barrier at the surface of the crawl space to restrict radon gas flow into the structure or a vented gravel layer with a vapor barrier beneath a concrete slab -on -grade floor to allow venting of radon gas collected beneath the floor and to restrict radon gas flow through the slab -on -grade floor into the structure. These concepts are shown on Figure D1. If you have any questions or would like more information about radon, please contact us or the State Health Department at 303-692- 3030. FBIA! Lambert aub Zmmoriateg CONSULTING GEOTECHNICAL ENGINEERS AND MATERIAL TESTING This figure was excerpted from an EPA manual "Radon- resistant Construction Techniques for New Residential Construction" and reproduced here for reference only RADON FLOW CONCEPT itambert- anb 2000riates. t NA= G08062GE 1729709