Amendment 03 Soils Report Issued: November 7, 2017 For RFP 18-KG-0928(BF) Design/Build Services for New Synthetic Turf Field At Air Academy High School 6910 Carlton Drive Colorado Springs, CO 80840 Academy District 20 Proposals Due: November 13, 2017 by 2:00pm MST Issued by: Kris Garnhart Director for Building Fund Contracting and Procurement 1110 Chapel Hills Drive Colorado Springs, CO 80920 719.234.1564 (office) 719.493-3433 (cell) kris.garnhart@asd20.org
The following is information for Amendment 03 RFP 18-KG-0928(BF) Design/Build Services for New Synthetic Turf Field at Air Academy High School: 1. Soils Report is attached.
REPORT C OVER PAGE Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 Prepared for: Academy School District 20 Colorado Springs, Colorado Prepared by: Terracon Consultants, Inc. Colorado Springs, Colorado
REPORT C OVER L ETTER TO SIGN November 7, 2017 Academy School District 20 1295 Kelly Johnson Blvd. Colorado Springs, Colorado 80920 Attn: Re: Mr. Kris Garnhart P: (719) 234-1564 E: kris.garnhart@asd20.org Geotechnical Engineering Report Stadium Field at Air Academy High School 6910 Carlton Drive Colorado Springs, Colorado Terracon Project No. 23175090 Dear Mr. Garnhart: We have completed the Geotechnical Engineering services for the above referenced project. This study was performed in general accordance with our proposal number P23175090 dated October 6, 2017. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork for the proposed project. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report, or if we may be of further service, please contact us. Sincerely, Terracon Consultants, Inc. Tyler A. Compton, E.I. Staff Engineer Robert M. Hernandez, P.E. Geotechnical Services Manager Terracon Consultants, Inc. 4172 Center Park Drive Colorado Springs, Colorado 80916 P (719) 597 2116 F (719) 597 2117 terracon.com
REPORT T OPICS REPORT TOPICS REPORT SUMMARY... I INTRODUCTION... 1 SITE CONDITIONS... 1 PHOTOGRAPHY LOG... 2 PROJECT DESCRIPTION... 3 GEOTECHNICAL CHARACTERIZATION... 4 GEOTECHNICAL OVERVIEW... 5 EARTHWORK... 6 ATHLETIC FIELD SITE PREPARATION... 9 CORROSIVITY... 9 GENERAL COMMENTS... 10 Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section, and clicking on the logo in the top right corner will bring you back to this page. For more interactive features, please view your project online at client.terracon.com. ATTACHMENTS EXPLORATION AND TESTING PROCEDURES SITE LOCATION AND EXPLORATION PLAN EXPLORATION RESULTS (Boring Logs and Laboratory Data) SUPPORTING INFORMATION (General Notes, USCS, and Description of Rock Properties) Responsive Resourceful Reliable
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 REPORT SUMMARY Topic 1 Overview Statement 2 Project Description Geotechnical Characterization Earthwork General Comments Removal of an existing natural sod sports field and replacement with a synthetic turf sports field and sub-surface drainage system. Natural sod surfacing Sand soils to about 6 to 12 feet Sandstone underlying the sand soils Groundwater not encountered Remove existing sod and topsoil. Over-excavate or scarify top 12 inches of sports field subgrade and recompact. Provide drainage system to transport stormwater away from the sports field subgrade. This section contains important information about the limitations of this geotechnical engineering report. 1. If the reader is reviewing this report as a pdf, the topics above can be used to access the appropriate section of the report by simply clicking on the topic itself. 2. This summary is for convenience only. It should be used in conjunction with the entire report for design purposes. Responsive Resourceful Reliable i
INTRODUCTION Geotechnical Engineering Report Stadium Field at Air Academy High School 6910 Carlton Drive Colorado Springs, Colorado Terracon Project No. 23175090 November 7, 2017 INTRODUCTION This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed Stadium Field at Air Academy High School to be located at 6910 Carlton Drive in Colorado Springs, Colorado. The purpose of these services is to provide information and geotechnical engineering recommendations relative to: Subsurface soil and bedrock conditions Site preparation and earthwork Groundwater conditions Drainage The geotechnical engineering scope of services for this project included the advancement of four test borings to depths ranging from approximately 9.4 to 14.5 feet below existing site grades. Maps showing the site and boring locations are shown in the Site Location and Exploration Plan sections, respectively. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included on the boring logs and/or as separate graphs in the Exploration Results section of this report. SITE CONDITIONS The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps. Item Parcel Information Existing Improvements Description The project is located at 6910 Carlton Drive in Colorado Springs, Colorado. The site is at the northwest corner of the subject address. Latitude: 38.9680 Longitude: -104.8422 See Site Location The site is currently improved with an existing natural grass sports field. The site is also improved with bleachers and a press box on the west side of the field, and stadium lights. Responsive Resourceful Reliable 1
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 Item Current Ground Cover Existing Topography Geology Natural grass Description Less than about 1.5 feet elevation difference across the site as measured with a level and rod. Gravel in partially matrix-supported and partially clast-supported sandy, clayey material. We also collected photographs at the time of our field exploration program. Representative photos are provided in our Photography Log. PHOTOGRAPHY LOG Centerfield Facing North Responsive Resourceful Reliable 2
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 Centerfield Facing South PROJECT DESCRIPTION Our initial understanding of the project was provided in our proposal and was discussed in the project planning stage. A period of collaboration has transpired since the project was initiated, and our final understanding of the project conditions is as follows: Item Information Provided Project Description Grading/Slopes Description Our understanding of this project comes from the Client s Soils Report for Stadium Field at Air Academy High School document received on September 29, 2017, and the Client s RFP 18-KG-0928(BF). We understand that the existing natural grass sports field has been proposed to be replaced with a synthetic turf sports field. We understand the synthetic field will have a sub-surface drainage system under the field. The type and design of the proposed synthetic field has yet to be determined. In addition, we understand that the proposed sub-surface drainage system will be designed by others after the selection of the proposed synthetic field. The new field elevation is expected to be at or near the existing field elevation. Less than 1 foot of cut and/or fill is anticipated to develop final grades. Responsive Resourceful Reliable 3
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 Item Below Grade Structures Ancillary Structures Free-Standing Retaining Walls Pavements Estimated Start of Construction Description Sub-surface drainage system. As we understand it, the type and design of the drainage system has yet to be determined and will be performed by others after selection of the proposed synthetic field. Recommendations for ancillary structures such as stadium lights and bleachers have not been requested. None anticipated Not reported as part of site development Summer 2018 GEOTECHNICAL CHARACTERIZATION Subsurface Profile Subsurface conditions at the boring locations can be generalized as follows: Stratum Approximate Depth to Bottom of Stratum (feet) 1 1 6 to 12 Material Description Sand with varying amounts of silt, clay, and gravel Consistency/Density Very loose to very dense 2 2 9.4 to 14.5 Sandstone Hard to very hard 1. Boring B-3 terminated in Stratum 1. 2. Borings B-1, B-2, and B-4 terminated in Stratum 2. Conditions encountered at each boring location are indicated on the individual boring logs shown in the Exploration Results section and are attached to this report. Stratification boundaries on the boring logs represent the approximate location of changes in native soil types; in situ, the transition between materials may be gradual. Groundwater Conditions The boreholes were observed while drilling and after completion for the presence and level of groundwater. Groundwater was not observed in the borings while drilling, or for the short duration that the borings could remain open. However, this does not necessarily mean these borings terminated above groundwater. Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels during construction or at other times in the life of the structure may be higher or lower than Responsive Resourceful Reliable 4
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project. GEOTECHNICAL OVERVIEW Based on the results of our field investigation, laboratory testing program and geotechnical analyses, development of the site is considered feasible from a geotechnical viewpoint provided the design takes into account the site specific geotechnical conditions. We understand the synthetic turf sports field and sub-surface drainage system will be designed and constructed by a contractor familiar with synthetic turf fields. We recommend the synthetic turf field and associated drainage systems be installed per the manufacturers and designer s recommendations. The following recommendations are based on our judgement and experience with similar projects and conditions, and are included to assist the designer. To provide a firm and stable base we recommend that the subgrade soils be either over-excavated or scarified a minimum depth of 12 inches, and then compacted back into place. Unsuitable areas should be identified by proof rolling. Our original proposal included an option to perform remolded permeability testing of the on-site soils to approximate the tested soils drainage characteristics. We were not requested to perform the additional testing as part of our base scope of services. During our field exploration we obtained bulk samples of the on-site soils from Boring B-1 at 1 to 10 feet, and Boring B-4 at 1 to 10 feet. We intend to hold these samples for up to 3 months after field exploration. Remolded permeability testing of the referenced bulk samples can be performed at a later date, for an additional fee, if requested. In our experience the subgrade soils should be considered to provide moderate to poor drainage based on our visual observations and classification. We recommend that appropriate drainage systems be designed and installed to drain water away from the field subgrade. We understand that typical drainage systems use either a crushed stone base layer or drainage mats to transport water away from the field. We recommend the drainage system be installed per the manufacturers and designer s specifications. Additionally, we understand that the synthetic field is typically placed on a cushion layer of either sand or fine gravel overlying the base. We recommend that a geotextile be used and wrapped around the drainage stone to separate the base and cushion layer to prevent migration of fines into the base drainage layer. The geotextile can consist of a Mirafi 140N filter fabric, or equivalent. Additional information can be found in the Earthwork section of this report. The General Comments section provides an understanding of the report limitations. Responsive Resourceful Reliable 5
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 EARTHWORK Earthwork will include clearing and grubbing, excavations and fill placement. The following sections provide recommendations for use in the preparation of specifications for the work. Recommendations include critical quality criteria as necessary to render the site in the state considered in our geotechnical engineering evaluation for the synthetic turf sports field. Site Preparation Prior to placing fill, existing vegetation and root mat should be removed. Complete stripping of the topsoil should be performed in the proposed field area. The subgrade should be proof-rolled with an adequately loaded vehicle such as a fully loaded tandem axle dump truck. The proof-rolling should be performed under the direction of the Geotechnical Engineer. Areas excessively deflecting under the proof-roll should be delineated and subsequently addressed by the Geotechnical Engineer. Such areas should either be removed or modified by stabilizing with geotextile. Excessively wet or dry material should either be removed or moisture conditioned and recompacted. Fill Material Types Fill required to achieve design grade should be classified as structural fill and general fill. Structural fill is material used below, or within 5 feet of the field. General fill is material used to achieve grade outside of these areas. Earthen materials used for structural and general fill should meet the following material property requirements: Soil Type 1 USCS Classification Acceptable Locations for Placement On-site soils Imported soils SC, SM Varies The on-site sand soils are considered acceptable for use as either structural and/or general fill. Imported soils meeting the gradation outlined herein can be considered suitable for use as structural and/or general fill. 1. Structural and general fill should consist of approved materials free of organic matter and debris. Frozen material should not be used, and fill should not be placed on a frozen subgrade. A sample of each material type should be submitted to the Geotechnical Engineer for evaluation prior to use on this site. Responsive Resourceful Reliable 6
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 Imported soils for use as structural and/or general fill should conform to the following: Gradation Percent finer by weight (ASTM C136) 3 100 No. 4 Sieve 50-100 No. 200 Sieve 35 (max) Liquid Limit...35 (max) Plastic Index..15 (max) Maximum Expansive Potential (%) 1.5* *Measured on a sample compacted to approximately 95 percent of the ASTM D698 maximum dry density at one percent below optimum water content. The sample is confined under a 150 psf surcharge and submerged. Fill Compaction Requirements Structural and general fill should meet the following compaction requirements. Item Maximum lift thickness Minimum compaction requirements Water content range 2 1, 2, 3 Structural Fill 8 inches or less in loose thickness when heavy, self-propelled compaction equipment is used 4 to 6 inches in loose thickness when hand-guided equipment (i.e. jumping jack, plate compactor) is used 95% of the materials maximum dry density for the upper 12 inches of field subgrade, fill within the field area, and the field base layer 90% of the materials maximum dry density for general fill outside of the field area Within three percent of optimum water content 1. We recommend that engineered fill be tested for water content and compaction during placement. Should the results of the in-place density tests indicate the specified water or compaction limits have not been met, the area represented by the test should be reworked and retested as required until the specified water and compaction requirements are achieved. 2. Maximum dry density and optimum water content as determined by ASTM D698. 3. If the granular material is a coarse sand or gravel, or of a uniform size, or has a low fines content, compaction comparison to relative density may be more appropriate. In this case, granular materials should be compacted to at least 70% relative density (ASTM D 4253 and D 4254). Grading and Drainage All grades must provide effective drainage away from the field during and after construction and should be maintained throughout the life of the field. Water retained on or next to the field can Responsive Resourceful Reliable 7
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 result in unacceptable soil movements beyond 1-inch (as measured over a span of 50 feet). Drainage systems should be designed to discharge water a minimum of 10 feet away from the field. Exposed ground around the field should be sloped and maintained to provide good positive drainage away from the field. Earthwork Construction Considerations Shallow excavations for the proposed structure are anticipated to be accomplished with conventional construction equipment. Upon completion of filling and grading, care should be taken to maintain the subgrade water content prior to construction of the field. Construction traffic over the completed subgrades should be avoided. The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. Water collecting over, or adjacent to, construction areas should be removed. If the subgrade freezes, desiccates, saturates, or is disturbed, the affected material should be removed, or the materials should be scarified, moisture conditioned, and recompacted, prior to construction of the base. As a minimum, excavations should be performed in accordance with OSHA 29 CFR, Part 1926, Subpart P, Excavations and its appendices, and in accordance with any applicable local, and/or state regulations. Construction site safety is the sole responsibility of the contractor who controls the means, methods, and sequencing of construction operations. Under no circumstances shall the information provided herein be interpreted to mean Terracon is assuming responsibility for construction site safety, or the contractor's activities; such responsibility shall neither be implied nor inferred. Construction Observation and Testing The earthwork efforts should be monitored under the direction of the Geotechnical Engineer. Monitoring should include documentation of adequate removal of vegetation and top soil, proofrolling and mitigation of areas delineated by the proof-roll to require mitigation. Each lift of compacted fill should be tested, evaluated, and reworked as necessary until approved by the Geotechnical Engineer prior to placement of additional lifts. Each lift of fill should be tested for density and water content at a frequency of at least one test for every 5,000 square feet in turf field areas. One density and water content test for every 50 linear feet of compacted utility trench backfill. In addition to the documentation of the essential parameters necessary for construction, the continuation of the Geotechnical Engineer into the construction phase of the project provides the continuity to maintain the Geotechnical Engineer s evaluation of subsurface conditions, including assessing variations and associated design changes. Responsive Resourceful Reliable 8
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 ATHLETIC FIELD SITE PREPARATION Depending upon the final planned field elevation, loose soils may be encountered at the subgrade elevation. These soils should be either over-excavated or scarified to a minimum depth of 12 inches below subgrade and then compacted back into place. Specific attention should be given to positive drainage away from the field during and after construction. Athletic Field Design Parameters Item Synthetic Field Support 1,2 Description Subgrade: At least 12 inches of moisture conditioned and compacted onsite granular soils. 1. Following the recommendations found in the Earthwork section of this report. Athletic Field Construction Considerations Finished subgrade within and for at least 5 feet beyond the field should be protected from traffic, rutting, or other disturbances until field base construction. If the subgrade should become damaged or desiccated prior to construction of the base, the affected material should be removed and structural fill should be added to replace the resulting excavation. Final conditioning of the finished subgrade should be performed immediately prior to placement of the base. If a cushion layer of sand or fine gravel are placed overlying the base layer, we recommend that a geotextile be used and wrapped around the drainage stone to separate the base and cushion layer to prevent the migration of fines into the base drainage layer. The geotextile can consist of a Mirafi 140N filter fabric, or equivalent. The Geotechnical Engineer should approve the condition of the subgrade immediately prior to placement of the base. Attention should be paid to high traffic areas that were rutted and disturbed earlier, and to areas where backfilled trenches are located. CORROSIVITY The table below lists the results of laboratory soluble sulfate, soluble chloride, electrical resistivity, and ph testing. The values may be used to estimate potential corrosive characteristics of the onsite soils with respect to contact with the various underground materials which will be used for project construction. Responsive Resourceful Reliable 9
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 Boring Sample Depth (feet) Corrosivity Test Results Summary Soluble Sulfate (percent) Soluble Chloride (percent) Electrical Resistivity (Ωcm) B-2 1-9.4 0.007 0.0014 4203 7.8 ph Results of soluble sulfate testing indicate samples of the on-site soils tested possess negligible sulfate concentrations when classified in accordance with Table 4.3.1 of the ACI Design Manual. Concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. GENERAL COMMENTS Our services are conducted with the understanding of the project as described in the proposal, and will incorporate collaboration with the design team as we complete our services to verify assumptions. Revision of our understanding to reflect actual conditions important to our services will be based on these verifications and will be reflected in the final report. The design team should collaborate with Terracon to confirm these assumptions and to prepare the final design plans and specifications. This facilitates the incorporation of our opinions related to implementation of our geotechnical recommendations. Any information conveyed prior to the final report is for informational purposes only and should not be considered or used for decision-making purposes. Our analysis and opinions are based upon our understanding of the geotechnical conditions in the area, the data obtained from our site exploration and from our understanding of the project. Variations will occur between exploration point locations, across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. Terracon should be retained as the Geotechnical Engineer, where noted in the final report, to provide observation and testing services during grading, excavation, foundation construction and other earth-related construction phases of the project. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations. Our scope of services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) 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 undertaken. Our services and any correspondence are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third party beneficiaries intended. Responsive Resourceful Reliable 10
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 Any third party access to services or correspondence is solely for information purposes only. Reliance upon the services and any work product is limited to our client, and is not intended for third parties. Any use or reliance of the provided information by third parties is done solely at their own risk. No warranties, either express or implied, are intended or made. Site characteristics as provided are for design purposes and not to estimate excavation cost. Any use of our report in that regard is done at the sole risk of the excavating cost estimator as there may be variations on the site that are not apparent in the data that could significantly impact excavation cost. Any parties charged with estimating excavation costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing. Site safety, and cost estimating including, excavation support, and dewatering requirements/design are the responsibility of others. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing. Responsive Resourceful Reliable 11
ATT ACHM ENTS ATTACHMENTS
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 EXPLORATION AND TESTING PROCEDURES Field Exploration Number of Borings Boring Depth (feet) Planned Location 1. Below ground surface 4 10 to 15 Sports field Boring Layout and Elevations: We use handheld GPS equipment to locate borings with an estimated horizontal accuracy of +/-20 feet. Field measurements from existing site features may be utilized. Approximate elevations are measured from a temporary benchmark using a rod and level. Subsurface Exploration Procedures: We advance the borings with a track-mounted drill rig using continuous flight augers (solid stem and/or hollow stem as necessary depending on soil conditions). Four samples are obtained in the upper 10 feet of each boring and at intervals of 5 feet thereafter. In the split-barrel sampling procedure, a standard 2-inch outer diameter split-barrel sampling spoon is driven into the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration is recorded as the Standard Penetration Test (SPT) resistance value. The SPT resistance values, also referred to as N-values, are indicated on the boring logs at the test depths. A 3-inch O.D. split-barrel sampling spoon with 2.5-inch I.D. ring lined sampler was used for sampling in the upper 14 feet. Ring-lined, split-barrel sampling procedures are similar to standard split spoon sampling procedure; however, blow counts are typically recorded for 6-inch intervals for a total of 12 inches of penetration. We observe and record groundwater levels during drilling and sampling. Our exploration team prepares field boring logs as part of standard drilling operations including sampling depths, penetration distances, and other relevant sampling information. Field logs include visual classifications of materials encountered during drilling, and our interpretation of subsurface conditions between samples. Final boring logs, prepared from field logs, represent the geotechnical engineer's interpretation, and include modifications based on observations and laboratory tests. Laboratory Testing The project engineer reviews field data and assigns various laboratory tests to better understand the engineering properties of various soil and rock strata. Exact types and number of tests cannot be defined until completion of field work. Procedural standards noted below are for reference to methodology in general. In some cases, local practices and professional judgement require Responsive Resourceful Reliable
Geotechnical Engineering Report Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 method variations. Standards noted below include reference to other related standards. Such references are not necessarily applicable to describe the specific test performed. ASTM D2216 Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass ASTM D4318 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils ASTM D422 Standard Test Method for Particle-Size Analysis of Soils ASTM D2435/D2435M Standard Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading ASTM D4327 Standard Test Methods for Water Soluble Chloride and Sulfate Content AASHTO T289-91 Standard Test Methods for Determination of ph and Resistivity Our laboratory testing program often includes examination of soil samples by an engineer. Based on the material s texture and plasticity, we describe and classify soil samples in accordance with the Unified Soil Classification System (USCS). If bedrock samples are obtained, rock classification is conducted using locally accepted practices for engineering purposes. Boring log rock classification is determined using the Description of Rock Properties. Responsive Resourceful Reliable
SIT E LOC ATION AND EXPLOR AT ION PL AN S SITE LOCATION AND EXPLORATION PLANS
SITE LOCATION Stadium Field at Air Academy High School Colorado Springs, Colorado October 6, 2017 Terracon Project No. P23175090 DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY QUADRANGLES INCLUDE: CASCADE, CO (1/1/1994) and PIKEVIEW, CO (1/1/1994).
EXPLORATION PLAN Stadium Field at Air Academy High School Colorado Springs, Colorado November 3, 2017 Terracon Project No. 23175090 Temporary benchmark at base of west goal post. Assumed elevation 100.0 feet. DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES AERIAL PHOTOGRAPHY PROVIDED BY MICROSOFT BING MAPS
EXPLOR AT ION RESULTS EXPLORATION RESULTS
PROJECT: Stadium Field at Air Academy High School BORING LOG NO. B-1 CLIENT: Academy District 20 Colorado Springs, CO Page 1 of 1 SITE: GRAPHIC LOG LOCATION 6910 Carlton Drive USAFA, CO See Exploration Plan Latitude: 38.9684 Longitude: -104.8424 DEPTH CLAYEY SAND (SC), fine to medium grained, light brown to gray-brown, loose Surface Elev.: 99.2 (Ft.) ELEVATION (Ft.) DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE FIELD TEST RESULTS WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI PERCENT FINES THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 23175090 STADIUM FIELD AT.GPJ TERRACON_DATATEMPLATE.GDT 11/6/17 3.5 6.0 SILTY SAND WITH GRAVEL (SM), fine to medium grained, light brown to gray-brown, medium dense SANDSTONE, fine to medium grained, brown-red, hard to very hard fine to coarse grained from 6 to 12 feet color change to brown-yellow and fine to medium grained below 12 feet 14.5 Boring Terminated at 14.5 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: 4-inch solid stem auger Abandonment Method: Boring backfilled with auger cuttings and a near surface cement plug. WATER LEVEL OBSERVATIONS None Encountered 95.5 93 84.5 5 10 See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. See Exploration Plan for temporary benchmark location 4172 Center Park Dr Colorado Springs, CO 5-8 15-25 50/5'' 50/6'' 50/5'' Hammer Type: Automatic Notes: 16 7 3 2 3 107 114 97 116 129 NP Elevation referenced from temporary benchmark 100.0'. See Exploration Plan for temporary benchmark location. Boring Started: 10-23-2017 Drill Rig: CME-45 Project No.: 23175090 Driller: Vine Laboratories 19 Boring Completed: 10-23-2017
PROJECT: Stadium Field at Air Academy High School BORING LOG NO. B-2 CLIENT: Academy District 20 Colorado Springs, CO Page 1 of 1 SITE: GRAPHIC LOG LOCATION 6910 Carlton Drive USAFA, CO See Exploration Plan Latitude: 38.9681 Longitude: -104.8417 DEPTH CLAYEY SAND (SC), fine to medium grained, brown, medium dense, trace gravel to 3.5 feet Surface Elev.: 98.7 (Ft.) ELEVATION (Ft.) DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE FIELD TEST RESULTS WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI PERCENT FINES THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 23175090 STADIUM FIELD AT.GPJ TERRACON_DATATEMPLATE.GDT 11/6/17 3.5 6.0 9.4 SILTY SAND WITH GRAVEL (SM), fine to medium grained, brown, medium dense SANDSTONE, fine to medium grained, brown, hard to very hard with gravel and color change to brown-red below 8 feet Boring Terminated at 9.4 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: 4-inch solid stem auger Abandonment Method: Boring backfilled with auger cuttings and a near surface cement plug. WATER LEVEL OBSERVATIONS None Encountered 95 92.5 89.5 See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. See Exploration Plan for temporary benchmark location 4172 Center Park Dr Colorado Springs, CO 5 11-10 2-20 50/6'' 50/5'' Hammer Type: Automatic Notes: 7 11 3 3 116 117 110 104 Elevation referenced from temporary benchmark 100.0'. See Exploration Plan for temporary benchmark location. Boring Started: 10-23-2017 Drill Rig: CME-45 Project No.: 23175090 Boring Completed: 10-23-2017 Driller: Vine Laboratories
PROJECT: Stadium Field at Air Academy High School BORING LOG NO. B-3 CLIENT: Academy District 20 Colorado Springs, CO Page 1 of 1 SITE: GRAPHIC LOG LOCATION 6910 Carlton Drive USAFA, CO See Exploration Plan Latitude: 38.9678 Longitude: -104.8425 Surface Elev.: 98.9 (Ft.) DEPTH ELEVATION (Ft.) SILTY SAND WITH GRAVEL (SM), fine to medium grained, dark brown DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE FIELD TEST RESULTS WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI PERCENT FINES THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 23175090 STADIUM FIELD AT.GPJ TERRACON_DATATEMPLATE.GDT 11/6/17 2.0 CLAYEY SAND (SC), fine to medium grained, brown, loose trace gravel and mottled gray below 9 feet 10.0 Boring Terminated at 10 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: 4-inch solid stem auger Abandonment Method: Boring backfilled with auger cuttings and a near surface cement plug. WATER LEVEL OBSERVATIONS None Encountered 97 89 5 10 See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. See Exploration Plan for temporary benchmark location 4172 Center Park Dr Colorado Springs, CO 8-9 3-4 2-2 3-5 Hammer Type: Automatic Notes: 8 17 11 15 115 104 102 100 Elevation referenced from temporary benchmark 100.0'. See Exploration Plan for temporary benchmark location. Boring Started: 10-23-2017 Drill Rig: CME-45 Project No.: 23175090 Boring Completed: 10-23-2017 Driller: Vine Laboratories
PROJECT: Stadium Field at Air Academy High School BORING LOG NO. B-4 CLIENT: Academy District 20 Colorado Springs, CO Page 1 of 1 SITE: GRAPHIC LOG LOCATION 6910 Carlton Drive USAFA, CO See Exploration Plan Latitude: 38.9674 Longitude: -104.8419 DEPTH CLAYEY SAND WITH GRAVEL (SC), fine to medium grained, brown, loose to medium dense Surface Elev.: 99.0 (Ft.) ELEVATION (Ft.) DEPTH (Ft.) WATER LEVEL OBSERVATIONS SAMPLE TYPE FIELD TEST RESULTS WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI PERCENT FINES THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 23175090 STADIUM FIELD AT.GPJ TERRACON_DATATEMPLATE.GDT 11/6/17 8.5 12.0 POORLY GRADED SAND WITH SILT (SP-SM), fine to medium grained, brown, very dense, with gravel to 12 feet SANDSTONE, fine to coarse grained, brown-red, very hard, with gravel to total depth 14.4 Boring Terminated at 14.4 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Advancement Method: 4-inch solid stem auger Abandonment Method: Boring backfilled with auger cuttings and a near surface cement plug. WATER LEVEL OBSERVATIONS None Encountered 90.5 87 84.5 5 10 See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. See Exploration Plan for temporary benchmark location 4172 Center Park Dr Colorado Springs, CO 15-17 3-5 10-4 11-43 50/5'' Hammer Type: Automatic Notes: 7 11 11 5 2 114 98 103 115 104 NP Elevation referenced from temporary benchmark 100.0'. See Exploration Plan for temporary benchmark location. Boring Started: 10-23-2017 Drill Rig: CME-45 Project No.: 23175090 Driller: Vine Laboratories 10 Boring Completed: 10-23-2017
ATTERBERG LIMITS RESULTS ASTM D4318 60 LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 23175090 STADIUM FIELD AT.GPJ TERRACON_DATATEMPLATE.GDT 11/2/17 P L A S T I C I T Y I N D E X 50 40 30 20 10 Boring ID B-1 B-4 "U" Line CL or OL CH or OH "A" Line MH or OH CL-ML ML or OL 0 0 20 40 60 80 100 PROJECT: Stadium Field at Air Academy High School SITE: 6910 Carlton Drive USAFA, CO Depth 4-5 9-10 LL NP NP PL NP NP PI NP NP Fines 19 10 LIQUID LIMIT USCS SM SP-SM 4172 Center Park Dr Colorado Springs, CO Description SILTY SAND with GRAVEL POORLY GRADED SAND with SILT and GRAVEL PROJECT NUMBER: 23175090 CLIENT: Academy District 20 Colorado Springs, CO
100 95 90 85 80 75 70 GRAIN SIZE DISTRIBUTION ASTM D422 / ASTM C136 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 4 2 1 1/2 6 30 50 200 1.5 4 8 10 3/4 3/8 3 16 6 3 14 40 60 100 20 140 HYDROMETER LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 23175090 STADIUM FIELD AT.GPJ TERRACON_DATATEMPLATE.GDT 11/2/17 PERCENT FINER BY WEIGHT 65 60 55 50 45 40 35 30 25 20 15 10 5 0 100 PROJECT: Stadium Field at Air Academy High School SITE: 6910 Carlton Drive USAFA, CO 10 1 GRAIN SIZE IN MILLIMETERS Boring ID Depth USCS Classification WC (%) LL PL PI Cc Cu B-1 4-5 SILTY SAND with GRAVEL (SM) B-4 9-10 POORLY GRADED SAND with SILT and GRAVEL (SP-SM) 5 NP NP NP 0.84 49.53 Boring ID Depth D 100 D 60 D 30 D 10 %Gravel %Sand %Silt %Fines %Clay B-1 B-4 COBBLES 4-5 9-10 coarse GRAVEL 25 37.5 fine coarse 1.367 3.762 medium SAND 0.121 0.49 4172 Center Park Dr Colorado Springs, CO fine 0.076 0.1 7 28.1 34.8 NP 52.9 55.4 0.01 SILT OR CLAY NP NP PROJECT NUMBER: 23175090 CLIENT: Academy District 20 Colorado Springs, CO 19.0 9.8 0.001
Analytical Results TASK NO: 171027035 Report To: Tyler Compton Company: Terracon, Inc. - Colo Springs 4172 Center Park Drive Colo. Springs CO 80916 Bill To: Tyler Compton Company: Terracon, Inc. - Accounts Payable 18001 W. 106th St Suite 300 Olathe KS 66061 Task No.: 171027035 Client PO: Client Project: Stadium Field at Air Academy High School 23175090 Date Received: 10/27/17 Date Reported: 11/3/17 Matrix: Soil - Geotech Customer Sample ID Lab Number: B-2 @ 1-9.4ft 171027035-01 Test Result Method Chloride - Water Soluble 0.0014 % AASHTO T291-91/ ASTM D4327 ph 7.8 units AASHTO T289-91 Resistivity 4203 ohm.cm AASHTO T288-91 Sulfate - Water Soluble 0.007 % AASHTO T290-91/ ASTM D4327 Abbreviations/ References: AASHTO - American Association of State Highway and Transportation Officials. ASTM - American Society for Testing and Materials. ASA - American Society of Agronomy. DIPRA - Ductile Iron Pipe Research Association Handbook of Ductile Iron Pipe. DATA APPROVED FOR RELEASE BY 240 South Main Street / Brighton, CO 80601-0507 / 303-659-2313 Mailing Address: P.O. Box 507 / Brighton, CO 80601-0507 / Fax: 303-659-2315 171027035
SUPPORT ING INFORM AT ION SUPPORTING INFORMATION
GENERAL NOTES DESCRIPTION OF SYMBOLS AND ABBREVIATIONS Stadium Field at Air Academy High School Colorado Springs, CO 11/7/2017 23175090 Modified Dames & Moore Ring Sampler SAMPLING WATER LEVEL FIELD TESTS Grab Sample Water Initially Encountered Water Level After a Specified Period of Time Water Level After a Specified Period of Time Water levels indicated on the soil boring logs are the levels measured in the borehole at the times indicated. Groundwater level variations will occur over time. In low permeability soils, accurate determination of groundwater levels is not possible with short term water level observations. N (HP) (T) (DCP) UC (PID) Standard Penetration Test Resistance (Blows/Ft.) Hand Penetrometer Torvane Dynamic Cone Penetrometer Unconfined Compressive Strength Photo-Ionization Detector (OVA) Organic Vapor Analyzer DESCRIPTIVE SOIL CLASSIFICATION Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency. LOCATION AND ELEVATION NOTES Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy of such devices is variable. Surface elevation data annotated with +/- indicates that no ctual topographical survey was conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic maps of the area. RELATIVE DENSITY OF COARSE-GRAINED SOILS (More than 50% retained on No. 200 sieve.) Density determined by Standard Penetration Resistance Descriptive Term (Density) Very Loose Loose Medium Dense Dense Very Dense Standard Penetration or N-Value Blows/Ft. 0-3 4-9 10-29 30-50 > 50 Ring Sampler Blows/Ft. 0-6 7-18 19-58 59-98 _ > 99 STRENGTH TERMS CONSISTENCY OF FINE-GRAINED SOILS (50% or more passing the No. 200 sieve.) Consistency determined by laboratory shear strength testing, field visual-manual procedures or standard penetration resistance Descriptive Term (Consistency) Very Soft Soft Medium Stiff Stiff Very Stiff Hard Unconfined Compressive Strength Qu, (tsf) less than 0.25 0.25 to 0.50 0.50 to 1.00 1.00 to 2.00 2.00 to 4.00 > 4.00 Standard Penetration or N-Value Blows/Ft. 2-4 8-15 15-30 > 30 Ring Sampler Blows/Ft. < 3 3-4 5-9 10-18 19-42 > 42 Ring Sampler Blows/Ft. < 30 30-49 50-89 90-119 > 119 BEDROCK Standard Penetration or N-Value Blows/Ft. 30-49 50-79 >79 Descriptive Term (Consistency) < 20 Weathered 20-29 Firm Medium Hard Hard Very Hard RELATIVE PROPORTIONS OF SAND AND GRAVEL Descriptive Term(s) of other constituents Trace Modifier Major Component of Sample Boulders Percent of Dry Weight <15 With 15-29 Cobbles Gravel Sand Silt or Clay GRAIN SIZE TERMINOLOGY >30 Particle Size Over 12 in. (300 mm) 12 in. to 3 in. (300mm to 75mm) 3 in. to #4 sieve (75mm to 4.75 mm) #4 to #200 sieve (4.75mm to 0.075mm Passing #200 sieve (0.075mm) RELATIVE PROPORTIONS OF FINES Descriptive Term(s) of other constituents Trace With Modifier Term Non-plastic Low Medium High PLASTICITY DESCRIPTION Percent of Dry Weight <5 5-12 >12 Plasticity Index 0 1-10 11-30 > 30
UNIFIED SOIL C L ASSIFIC AT ION SYST EM UNIFIED SOIL CLASSIFICATION SYSTEM Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Coarse-Grained Soils: More than 50% retained on No. 200 sieve Fine-Grained Soils: 50% or more passes the No. 200 sieve Gravels: More than 50% of coarse fraction retained on No. 4 sieve Sands: 50% or more of coarse fraction passes No. 4 sieve Silts and Clays: Liquid limit less than 50 Silts and Clays: Liquid limit 50 or more Clean Gravels: Less than 5% fines C Gravels with Fines: More than 12% fines C Clean Sands: Less than 5% fines D Sands with Fines: More than 12% fines D Inorganic: Organic: Inorganic: Soil Classification Group Group Name Symbol B Cu 4 and 1 Cc 3 E GW Well-graded gravel F Cu 4 and/or 1 Cc 3 E GP Poorly graded gravel F Fines classify as ML or MH GM Silty gravel F,G,H Fines classify as CL or CH GC Clayey gravel F,G,H Cu 6 and 1 Cc 3 E SW Well-graded sand I Cu 6 and/or 1 Cc 3 E SP Poorly graded sand I Fines classify as ML or MH SM Silty sand G,H,I Fines classify as CL or CH SC Clayey sand G,H,I PI 7 and plots on or above A CL Lean clay K,L,M line PI J 4 or plots below A line J ML Silt K,L,M Liquid limit - oven dried Organic clay 0.75 OL Liquid limit - not dried Organic silt K,L,M,O PI plots on or above A line CH Fat clay K,L,M PI plots below A line MH Elastic Silt K,L,M Liquid limit - oven dried Organic clay Organic: 0.75 OH K,L,M,P Liquid limit - not dried Organic silt K,L,M,Q Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat A Based on the material passing the 3-inch (75-mm) sieve H If fines are organic, add with organic fines to group name. B If field sample contained cobbles or boulders, or both, add with cobbles or boulders, or both to group name. C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay. D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay E Cu = D 60/D 10 Cc = D (D 10 30 ) 2 x D F If soil contains 15% sand, add with sand to group name. G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM. 60 I If soil contains 15% gravel, add with gravel to group name. J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. K If soil contains 15 to 29% plus No. 200, add with sand or with gravel, whichever is predominant. L If soil contains 30% plus No. 200 predominantly sand, add sandy to group name. M If soil contains 30% plus No. 200, predominantly gravel, add gravelly to group name. N PI 4 and plots on or above A line. O PI 4 or plots below A line. P PI plots on or above A line. Q PI plots below A line.
ROCK VER SION 2 DESCRIPTION OF ROCK PROPERTIES Stadium Field at Air Academy High School Colorado Springs, Colorado November 7, 2017 Terracon Project No. 23175090 Fresh Very Slight Slight Moderate Moderately Severe Severe Very Severe Complete Very Hard Hard Moderately Hard Medium Soft Very Soft WEATHERING Rock fresh, crystals bright, few joints may show slight staining. Rock rings under hammer if crystalline. Rock generally fresh, joints stained, some joints may show thin clay coatings, crystals in broken face show bright. Rock rings under hammer if crystalline. Rock generally fresh, joints stained, and discoloration extends into rock up to 1 in. Joints may contain clay. In granitoid rocks some occasional feldspar crystals are dull and discolored. Crystalline rocks ring under hammer. Significant portions of rock show discoloration and weathering effects. In granitoid rocks, most feldspars are dull and discolored; some show clayey. Rock has dull sound under hammer and shows significant loss of strength as compared with fresh rock. All rock except quartz discolored or stained. In granitoid rocks, all feldspars dull and discolored and majority show kaolinization. Rock shows severe loss of strength and can be excavated with geologist s pick. All rock except quartz discolored or stained. Rock fabric clear and evident, but reduced in strength to strong soil. In granitoid rocks, all feldspars kaolinized to some extent. Some fragments of strong rock usually left. All rock except quartz discolored or stained. Rock fabric discernible, but mass effectively reduced to soil with only fragments of strong rock remaining. Rock reduced to soil. Rock fabric no discernible or discernible only in small, scattered locations. Quartz may be present as dikes or stringers. HARDNESS (for engineering description of rock not to be confused with Moh s scale for minerals) Cannot be scratched with knife or sharp pick. Breaking of hand specimens requires several hard blows of geologist s pick. Can be scratched with knife or pick only with difficulty. Hard blow of hammer required to detach hand specimen. Can be scratched with knife or pick. Gouges or grooves to ¼ in. deep can be excavated by hard blow of point of a geologist s pick. Hand specimens can be detached by moderate blow. Can be grooved or gouged 1/16 in. deep by firm pressure on knife or pick point. Can be excavated in small chips to pieces about 1-in. maximum size by hard blows of the point of a geologist s pick. Can be gouged or grooved readily with knife or pick point. Can be excavated in chips to pieces several inches in size by moderate blows of a pick point. Small thin pieces can be broken by finger pressure. Can be carved with knife. Can be excavated readily with point of pick. Pieces 1-in. or more in thickness can be broken with finger pressure. Can be scratched readily by fingernail. Joint, Bedding, and Foliation Spacing in Rock 1 Spacing Joints Bedding/Foliation Less than 2 in. Very close Very thin 2 in. 1 ft. Close Thin 1 ft. 3 ft. Moderately close Medium 3 ft. 10 ft. Wide Thick More than 10 ft. Very wide Very thick 1. Spacing refers to the distance normal to the planes, of the described feature, which are parallel to each other or nearly so. Rock Quality Designator (RQD) 1 Joint Openness Descriptors RQD, as a percentage Diagnostic description Openness Descriptor Exceeding 90 Excellent No Visible Separation Tight 90 75 Good Less than 1/32 in. Slightly Open 75 50 Fair 1/32 to 1/8 in. Moderately Open 50 25 Poor 1/8 to 3/8 in. Open Less than 25 Very poor 3/8 in. to 0.1 ft. Moderately Wide 1. RQD (given as a percentage) = length of core in pieces 4 inches and longer / length of run Greater than 0.1 ft. Wide References: American Society of Civil Engineers. Manuals and Reports on Engineering Practice - No. 56. Subsurface Investigation for Design and Construction of Foundations of Buildings. New York: American Society of Civil Engineers, 1976. U.S. Department of the Interior, Bureau of Reclamation, Engineering Geology Field Manual.