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Home My WebLink AboutOAKRIDGE CROSSING (AFFORDABLE SENIOR HOUSING) - PDP - PDP160009 - REPORTS - (34)Final Drainage and Erosion Control Report for Oakridge Crossing Fort Collins, Colorado March 15, 2016 March 15, 2016 Mr. Glen Schleuter City of Fort Collins Storm Water Dept. 700 Wood Street Fort Collins, Colorado 80521 RE: Final Drainage and Erosion Control Report for Oakridge Crossing Dear Glen: We are pleased to submit to you, for your review and approval, this Final Drainage and Erosion Control Report for the Oakridge Crossing. All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. We appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. Respectfully, Aspen Engineering Prepared by: Reviewed by: Tony Willkomm, P.E. John Gooch, P.E. Senior Project Engineer Principal TABLE OF CONTENTS DESCRIPTION PAGE I. GENERAL LOCATION AND DESCRIPTION 5 A. LOCATION 5 B. DESCRIPTION OF PROPERTY 5 II. DRAINAGE BASINS 6 A. MAJOR BASIN DESCRIPTION 6 B. EXISTING SUB-BASIN DESCRIPTION 6 III. DRAINAGE DESIGN CRITERIA 7 A. REGULATIONS 7 B. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS 7 C. HYDROLOGIC CRITERIA 7 D. HYDRAULIC CRITERIA 7 E. VARIANCE 8 IV. DRAINAGE FACILITY DESIGN 8 A. GENERAL CONCEPT 8 B. SPECIFIC DETAILS 9 C. DETENTION PONDS 10 D. STREET CAPACITIES 10 V. STORM WATER QUALITY 10 A. GENERAL CONCEPT 10 B. SPECIFIC DETAILS 11 VI. EROSION CONTROL 12 A. GENERAL CONCEPT 12 VII. CONCLUSIONS 12 A. COMPLIANCE WITH STANDARDS 12 B. DRAINAGE CONCEPT 13 C. STORM WATER QUALITY 13 D. EROSION CONTROL CONCEPT 13 E. EROSION CONTROL ESCROW ESTIMATE 13 REFERENCES 14 APPENDIX PAGE VICINITY MAP A RATIONAL METHOD HYDROLOGY B POND AND RAIN GARDEN SIZING CALCULATIONS C CURB CUT, INLET, & SWALE SIZING D EROSION CONTROL, RIPRAP SIZING & EROSION ESCROW E PROPOSED DRAINAGE EXHIBIT & DRAINAGE REPORT EXCERPTS & EXISING BASIN EXHIBIT F 5 FINAL DRAINAGE AND EROSION CONTROL REPORT FOR THE OAKRIDGE CROSSING FORT COLLINS, COLORADO I. GENERAL LOCATION AND DESCRIPTION A. Location The Oakridge Crossing project is bounded to the north by Oakridge Business Park 11th Filing, to the east by Oakridge Business Park 23rd Filing, to the south by Oakridge Business Park 18th Filing, and to the west by McMurry Avenue. The project site can also be described as situated in the northeast quarter of Section 6, Township 6 North, Range 68 West of the 6th P.M., of the City of Fort Collins, County of Larimer, State of Colorado. The Oakridge Crossing building site is comprised of approximately 2.61 acres. The drainage analysis includes 2.61 acres of the onsite area which is a portion of the existing drainage basin 210 (7.51 acres) established with the Master Drainage Study For the Oakridge Business Park (Master Drainage Study). Please refer to the vicinity map in Appendix A for the site location. B. Description of Property The site is comprised of an approximate 32,746 +/-square foot building footprint along with associated parking lot, west entrance, northeast drive aisle access, private drive improvements and utility improvements. Previously, the Oakridge Crossing building site was an undeveloped lot, vegetated with sparse grass and weeds. Enhanced landscaping is established on adjoining lots to the east and south. At the northeast side the lot, an asphalt paved drive aisle and parking bay with one end-cap island is constructed. Two concrete curb and gutter islands are constructed straddling the north property boundary at the west end of the property and a concrete access drive is constructed at the approach from McMurry Avenue. The existing site topography of the Oakridge Crossing building site generally drains to the south and south east at 0.5% to 1% slope. The existing paved drive aisle and parking spaces to the north, drain to a concrete pan and flows east at a slope of 1%. 6 II. DRAINAGE BASINS A. Major Basin Description The site lies within the McClellands Drainage Basin, with site drainage previously accounted for in the Master Drainage Study for the Oakridge Business Park. The approved grading and drainage master plan and SWMM Model for the Master Drainage Study Oakridge Business Park (Master Plan) provided for the runoff from the entire basin being ultimately routed to the regional detention pond southeast of the project site. The proposed Oakridge Crossing building site will discharge runoff undetained and connect to existing storm sewer in McMurry Avenue as directed by the City of Fort Collins Stormwater Staff. The intended connection in the Master Plan was to storm sewer south of the site which would then discharge to an open swale. This connection point in no longer available with current development in place. The volume of site runoff will be in compliance with the Master Drainage Study for the Oakridge Business Park, September, 1990 by RBD Engineering Consultants. The proposed improvements meet the intent of approved Master Plan. The site runoff coefficient is 0.72 versus 0.80 for Basin 210 in the Master Plan. B. Existing Sub-Basin Description The existing Oakridge Crossing building site is contained within existing sub-basin 210 of the Master Plan. Existing basin 210 contains approximately 7.51 acres and was modeled with the entire 7.51 acres having a runoff coefficient of 0.80 in the developed condition. All flow from the basin being allowed to flow un-detained to the existing detention pond. No water quality was provided in the regional detention pond. Water quality will be provided for on site for the proposed improvements. The developed conditions for the Oakridge Crossing building site has been evaluated with the current IDF curve data for City of Fort Collins to determine if on site detention is needed for the property. It was determined that no addition detention will be necessary on site. The area south and east of the proposed building comprised of 0.47 acres will sheet flow off site as occurs historically. The existing 0.22 acres of paved drive aisle and parking lot at the north side of the site, will drain off site to the east as it historically has. The balance of the site will be directed to the proposed on site storm sewer and discharge to the existing storm sewer in McMurry Avenue. No offsite areas contribute overland flow to or through the Oakridge Crossing building project site. Please refer to Appendix F of this report for the existing and proposed drainage basin exhibits for the subject site. 7 III. DRAINAGE DESIGN CRITERIA A. Regulations Since the subject site has been previously modeled, the site is allowed to release un- detained to the existing regional detention pond in Master Plan basin 90, which has been sized to provide detention for the developed 100-year runoff from the subject site. LID improvements on site are required and have been provided for with this project. Please see the LID calculations in Appendix C, as well as the LID Table on sheet C-007, which provides the treatment methods and area calculations for LID treatment using a rain garden and grass buffer areas. B. Development Criteria Reference and Constraints The criteria and constraints from the City of Fort Collins will be met. The calculated detention pond sizing using the prorated allowable runoff from Basin 210, and the developed runoff coefficient for the proposed development results in no additional detention required. The site runoff will be released undetained to the regional detention pond. C. Hydrologic Criteria The Rational Method for determining surface runoff was used for the project site. The 2-year and 100-year storm event intensities were used in calculating runoff values. The City of Fort Collins intensity duration frequency curves were used to obtain rainfall data for each storm specified. Detention pond sizing was calculated using FAA methods and water quality volume was calculated using the rain garden sizing spreadsheets developed by Denver Urban Drainage. Detention will be provided for the subject site in the existing regional detention pond (Master Plan basin 90) from the previous infrastructure improvements of the Oakridge Business Park. BMP’s and LID measures are being incorporated into the proposed drainage development plan, with specific details and calculations shown in Appendices C and F of this report. D. Hydraulic Criteria All hydraulic calculations, including final calculations and sizing for curb cuts, swales, and erosion control and riprap measures have been provided in accordance with the City of Fort Collins Drainage Criteria and can be found in the Appendix D and E. 8 E. Variance No variances are being requested. IV. DRAINAGE FACILITY DESIGN A. General Concept A total of five drainage basins are delineated over the proposed Oakridge Crossing building site. One basin to the north, will drain 0.22 acres east, offsite as it historically occurs. Another basin south and east of the proposed building, will drain 0.47 acres through grass buffers to the south and east in the historic drainage pattern. Two drainage basins will convey drainage from 1.87 acres of the 2.61 acre site into a rain garden LID. A small basin will drain 0.06 acres to a proposed storm sewer inlet. The site drainage will be conveyed to the rain garden via curb and gutter, roof drains and proposed storm pipes. Site runoff will be intercepted by proposed storm sewer and flow through existing off site storm sewer and get routed to the existing regional detention pond south of the project site. The existing regional detention Pond (Basin 90) provides storage and detention and was sized to receive the 100-year developed flow from the Oakridge Crossing building site (from the Master Plan). The calculated composite 'C' value for Oakridge Crossing building site is 0.72. Please refer to the rational calculations in Appendix B, and the Drainage Basin Exhibit and Master Plan Drainage Exhibit in Appendix F for additional information. LID measures are provided for through the conveyance of approximately 89% (2.33 acres of the 2.61 acre site) of the proposed building, parking lot, and green areas of the site being routed through the rain garden and grass buffer area. Because the area being routed to and through the rain garden and grass buffer area exceeds the 75% requirement for LID treatment of the total site area, the project exceeds that normally required for water quality and LID treatment. Please refer to Appendix C for LID calculations, as well as sheet C-007, which provides an additional LID table, as required by the City of Fort Collins Stormwater Department. The rain garden, shown and called out in the plans, provides approximately 2,073 ft3 of storage volume with a maximum of 1’ of ponding depth, prior to the basin overflowing into proposed CDOT Type C inlets which discharge to proposed storm sewer then to existing storm sewer and ultimately entering the existing detention pond. It’s important to note that 0.47 acres of the site runoff along the south and east sides of the proposed building will be landscaped with grass to provide water quality 9 treatment by filtering through the grass before going off site. Please refer to Appendix C and sheets C-009 and C-011 of the civil utility plans for details on the rain garden. B. Specific Details Basin 1 Basin 1 consists primarily of grass/landscaped areas, located south and east of the proposed building. Runoff from basin 1 will sheet flow away from the building and flow off site as historically occurs. Since this basin will be established with grass, the ground cover is expected to be better than the existing grass cover on the undeveloped lot. The basin combines with offsite flow and will ultimately drain to the regional detention pond. Basin 2 Basins 2 consists of the proposed building, parking lot and rain garden. Runoff from the building roof enters roof downspouts and connect with underground roof drains which discharge runoff north and west onto riprap pads within the rain garden LID basin. Landscaped areas next the building will drain through sidewalk drains and discharge to curb and gutter. The parking lot will sheet flow north and west to curb and gutter and drain concentrated runoff to four, 3’ curb cuts with riprap pads draining to the rain garden. The rain garden is designed to provide a ponding depth of approximately 1.00’ and allow pollutants and sediment to settle out of the runoff, prior to overflowing into three CDOT Type C inlets to enter the proposed storm sewer. Eleven downspouts are consolidated to four underground roof drain pipes discharging to riprap pads in the rain garden. In the event of clogging, overflows for the downspouts will be provided and will drain to sidewalk drains. It should be noted that one drain basin is used between the building and sidewalk to drain the interior corner northwest of the building. This drain will discharge directly to the proposed storm sewer without rain garden treatment. This area could not drain to the surface due to grading constraints. A proposed storm sewer constructed in Basin 2 will receive flow from the 5’ Type R inlet in Basin 3, overflow from the rain garden in Basin 2 and drainage from the rain garden underdrain pipe. The storm sewer will drain south then west and connect to the existing storm sewer in McMurry Avenue which ultimately drains to the regional detention pond. Basin 3 Basins 3 conveys runoff from part of the existing north drive aisle and the proposed parking bay at the northwest corner of the site. The paved area drains southeast to 10 curb and gutter passes through a 1’ curb cut and riprap pad before entering the rain garden in basin 2. Basin 4 Basins 4 conveys runoff from the proposed parking bay at the northeast corner of the site. The paved area drains southwest to curb and gutter and enters a proposed 5’ Type R inlet which drains to a 12” RCP. Runoff from this basin was not able to drain to the rain garden due to grading constrains and be conveyed off site in the proposed storm sewer. Basin 5 Basins 5 conveys runoff from the existing paved drive aisle and parking bays. Sheet flow is concentrated in a central concrete drainage pan and flows east off the site to the neighboring parking lots which drain south and east. This area will not be disturbed and will drain as historically occurs. This basin area was develop in a prior phase of the Oakridge Business Park. The basin will ultimately drain to the regional detention pond. C. Detention Ponds No detention pond is required for the subject site, as detention is provided for in the existing regional detention pond (Basin 90), which was constructed as outlined in the Master Plan. D. Street Capacities The street capacity calculations are not required for the subject site, as no new public street construction will be built with this project. However, curb cut capacities have been analyzed and calculations provided in Appendix D of this report. V. STORM WATER QUALITY A. General Concept The water quality of stormwater runoff must be addressed on all final design utility plans. Therefore, Best Management Practices for the treatment of stormwater runoff for the subject site will include grass-lined swales, a rain garden LID basin, and the utilization of the grass buffers along the south and east side of the site. These water quality features will provide a mechanism for pollutants to settle out of the stormwater runoff before flows are directed to the regional detention pond. 11 B. Specific Details Best Management Practices (BMP) for the treatment of storm water runoff has been incorporated into the final design for this project. This will include continued utilization of extended detention in the existing, offsite detention pond. The existing detention facility has adequate capacity and will continue to provide detention for the developed condition of the subject site, prior to releasing flows downstream. LID measures are provided for through the conveyance of 1.87 acres over and through the rain garden LID basin and 0.47 acres over grass buffer area treating 2.34 acres of the 2.61acre site. The footprint of the rain garden is approximately 1,059 square feet, with a depth of approximately 1.0’, and provides approximately 2,073 cf of storage volume. It’s important to note that with 2.34 acres of the 2.61 acre site area (89% of site area) being conveyed over and through the rain garden and grass buffer the project exceeds that normally required for water quality and LID treatment. The rain garden, shown and called out in the civil utility plans, provides for approximately 1.0’ of ponding depth, prior to the basin overflowing to storm inlets and into the storm sewer and eventually into the existing detention pond. Approximately 1.0’ of ponding depth will occur over the proposed CDOT Type C inlets during the 100-yr storm event. Please refer to Appendices C and F, and sheets C-009 and C-011 of the civil utility plans, for details on the rain garden. Please also refer to the LID Table on sheet C-007 for area calculations and specific LID calculations, as required by the City of Fort Collins. 12 VI. EROSION CONTROL A. General Concept The subject site lies within the Moderate Rainfall Erodibility Zone and the Moderate Wind Erodibility Zone per the City of Fort Collins zone maps. The potential exists for erosion problems during construction, but should be minimal after completion of proposed development. Silt fence will be installed along the north, south, east, and west sides of the site to prevent sediment from leaving the site. A tracking pad will also be placed at west entrance/exit to the site. Gravel inlet filters will be placed at proposed curb cuts, and storm drain inlets. Riprap will also be utilized at concentration points (curb cuts and pipe outlets), as shown in the plans, to minimize erosion and increase soil stabilization. VII. CONCLUSIONS A. Compliance with Standards All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. The City of Fort Collins Storm water Utility will not maintain the on-site storm drainage facilities within the subject site. The owners of the subject site will maintain their on-site storm drainage facilities on a regular basis. The following shall be implemented for the private stormwater improvements’ operations/ maintenance procedures for the project on an annual or bi-annual basis: 1) Storm Sewer Inlets, pipes and flared-end-sections, curb cuts and concrete sidewalk culverts/chases, structures, manholes, and the water quality/ outlet control structures shall be cleaned through the removal of debris and sediment from the associated items to allow for adequate drainage through the site to the proposed detention facility 2) Sedimentation/ silting shall be removed to allow for adequate drainage along the bottom of the swales and LID/PLD basin. Grass scrubbing along the bottom of the LID/PLD basin may be required to remove sediment and promote grass growth. 3) Re-vegetation through the use of Natural Seeding/ Sod shall be provided for disturbed areas and other permanent erosion controls shall be provided for areas where erosion has taken place and requires remediation back to the proposed condition shown in the plans 13 The Stormwater Operating/ Maintenance Procedures listed above are guidelines to the minimum procedures that shall be implemented for the site, with these and additional measures being utilized on an as-needed basis. B. Drainage Concept The proposed drainage concepts presented in this study and shown on the utility plans adequately provide for the transmission of developed on-site runoff to the existing detention pond, located south of the subject site. The combination of the existing and proposed storm conveyances will provide for the 100-year developed flows to reach the existing detention pond. The existing release rate of the existing pond will be adhered to. If groundwater is encountered at the time of construction, a Colorado Department of Health Construction Dewatering Permit will be required. C. Storm Water Quality The final design has addressed the water quality aspect of stormwater runoff. The LID items presented in this report for the proposed site will provide an opportunity for stormwater pollutants to filter out of the stormwater runoff before flows are directed downstream. D. Erosion Control Concept Proposed erosion control concepts have been provided for and adequately provide for the control of wind and rainfall erosion from the proposed development. Through the construction of the proposed erosion control concepts, the City of Fort Collins performance standards will be met. The proposed erosion control concepts presented in this report and shown on the erosion control plan are in compliance with the City of Fort Collins Erosion Control Criteria. Erosion Control Escrow Estimate The Erosion Control Escrow Estimate for the subject property is approximately $17,648.00. Please refer to Appendix E for this calculation. 14 REFERENCES 1. Storm Drainage Design Criteria and Construction Standards by the City of Fort Collins, Colorado, May 1984, Revised January 1997. 2. Erosion Control Reference Manual for Construction Sites by the City of Fort Collins, Colorado, January 1991, Revised January 1997. 3. Master Drainage Study for the Oakridge Business Park, by RBD Engineering Consultants, Fort Collins, Colorado, September, 1990. 4. Overall Drainage Concept for The Overall Development Plan For Oakridge Business Park, by North Star Design , April, 2000. 15 APPENDIX 16 APPENDIX A VICINITY MAP 17 APPENDIX B RATIONAL METHOD HYDROLOGY 18 APPENDIX C POND AND RAIN GARDEN SIZING CALCULATIONS 19 APPENDIX D CURB CUT, INLET, & SWALE SIZING 20 APPENDIX E EROSION CONTROL & RIPRAP SIZING; EROSION ESCROW 21 APPENDIX F PROPOSED DRAINAGE EXHIBIT DRAINAGE REPORT EXCERPTS & EXISTING DRAINAGE EXHIBIT Geotechnical Engineering Report Oakridge Crossing Southeast of Oakridge Drive and McMurry Avenue Fort Collins, Colorado March 10, 2016 Terracon Project No. 20165021 Prepared for: McDermott Properties Centennial, Colorado Prepared by: Terracon Consultants, Inc. Fort Collins, Colorado TABLE OF CONTENTS Page EXECUTIVE SUMMARY ............................................................................................................ i 1.0 INTRODUCTION .............................................................................................................1 2.0 PROJECT INFORMATION .............................................................................................1 3.0 SUBSURFACE CONDITIONS ........................................................................................2 3.1 Typical Subsurface Profile ...................................................................................2 3.2 Laboratory Testing ...............................................................................................3 3.3 Corrosion Protection (Water-Soluble Sulfates) .....................................................3 3.4 Groundwater ........................................................................................................3 4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION ......................................4 4.1 Geotechnical Considerations ...............................................................................4 4.1.1 Potentially Unstable Clay Subgrade Soils .................................................4 4.1.2 Groundwater .............................................................................................4 4.1.3 Expansive Soils ........................................................................................4 4.1.4 Foundation Recommendations .................................................................5 4.2 Earthwork.............................................................................................................5 4.2.1 Site Preparation ........................................................................................5 4.2.2 Excavation ................................................................................................5 4.2.3 Subgrade Preparation ...............................................................................6 4.2.4 Fill Materials and Placement ......................................................................7 4.2.5 Compaction Requirements ........................................................................7 4.2.6 Utility Trench Backfill ................................................................................8 4.2.7 Grading and Drainage ...............................................................................8 4.2.8 Exterior Slab Design and Construction .....................................................9 4.3 Foundations .........................................................................................................9 4.3.3 Post-Tensioned Slabs – Construction Considerations ............................12 4.3.4 Spread Footings - Design Recommendations .........................................12 4.3.5 Spread Footings - Construction Considerations ......................................14 4.3.6 Overexcavation Beneath Footings ..........................................................14 4.4 Seismic Considerations......................................................................................15 4.5 Lateral Earth Pressures ...........................................................................................15 4.6 Pavements .........................................................................................................17 4.6.1 Pavements – Subgrade Preparation .......................................................17 4.6.2 Pavements – Design Recommendations ................................................17 4.6.3 Pavements – Construction Considerations .............................................20 4.6.4 Pavements – Maintenance .....................................................................20 5.0 GENERAL COMMENTS ...............................................................................................20 TABLE OF CONTENTS (continued) Appendix A – FIELD EXPLORATION Exhibit A-1 Site Location Map Exhibit A-2 Exploration Plan Exhibit A-3 Field Exploration Description Exhibits A-4 to A-11 Boring Logs Appendix B – LABORATORY TESTING Exhibit B-1 Laboratory Testing Description Exhibit B-2 Atterberg Limits Test Results Exhibits B-3 to B-7 Grain-size Distribution Test Results Exhibits B-8 to B-9 Swell-consolidation Test Results Exhibits B-10 to B-11 Unconfined Compression Test Results Exhibit B-12 Water-soluble Sulfate Test Results Appendix C – SUPPORTING DOCUMENTS Exhibit C-1 General Notes Exhibit C-2 Unified Soil Classification System Exhibit C-3 Description of Rock Properties Exhibit C-4 Laboratory Test Significance and Purpose Exhibits C-5 and C-6 Report Terminology Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable i EXECUTIVE SUMMARY A geotechnical investigation has been performed for the proposed Oakridge Crossing to be constructed southeast of Oakridge Drive and McMurry Avenue in Fort Collins, Colorado. A total of eight (8) exploratory borings, presented as Exhibits A-4 through A-11 were completed to depths of approximately 10 to 25 feet below existing site grades. This report specifically addresses the recommendations for the proposed structure. Borings performed in these areas are for informational purposes and will be utilized by others. Based on the information obtained from our subsurface exploration, the site can be developed for the proposed project. However, the following geotechnical considerations were identified and will need to be considered: n The proposed buildings may be supported on a post-tensioned slab foundation bearing on the stiff to very stiff native soil or on newly placed engineered fill. n The amount of movement of foundations, exterior concrete flatwork, pavements, etc. will be related to the wetting of underlying supporting soils. Therefore, it is imperative the recommendations discussed in the 4.2.7 Grading and Drainage section of this report be followed to reduce potential movement. n The 2012 International Building Code, Table 1613.5.2 IBC seismic site classification for this site is D. n Close monitoring of the construction operations discussed herein will be critical in achieving the design subgrade support. We therefore recommend that Terracon be retained to monitor this portion of the work. This summary should be used in conjunction with the entire report for design purposes. It should be recognized that details were not included or fully developed in this section, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. The section titled GENERAL COMMENTS should be read for an understanding of the report limitations. Responsive ■ Resourceful ■ Reliable 1 GEOTECHNICAL ENGINEERING REPORT Oakridge Crossing Southeast of Oakridge Drive and McMurry Avenue Fort Collins, Colorado Terracon Project No. 20165021 March 10, 2016 1.0 INTRODUCTION This report presents the results of our geotechnical engineering services performed for the proposed Oakridge Crossing Project to be located southeast of the intersection between Oakridge Drive and McMurry Avenue in Fort Collins, Colorado (Exhibit A-1). The purpose of these services is to provide information and geotechnical engineering recommendations relative to: n subsurface soil and bedrock conditions n foundation design and construction n groundwater conditions n floor system design and construction n grading and drainage n pavement construction n lateral earth pressures n earthwork n seismic considerations Our geotechnical engineering scope of work for this project included the advancement of eight test borings to depths ranging from approximately 10 to 25 feet below existing site grades, laboratory testing for soil engineering properties and engineering analyses to provide foundation, floor system and pavement design and construction recommendations. Logs of the borings along with an Exploration Plan (Exhibit A-2) are included in Appendix A. The results of the laboratory testing performed on soil and bedrock samples obtained from the site during the field exploration are included in Appendix B. 2.0 PROJECT INFORMATION 2.1 Site Location Item Description Location The site is located southeast of the intersection of Oakridge Drive and McMurry Avenue in Fort Collins, Colorado. Existing improvements Aerial photography suggests the site is currently vacant land surrounded by commercial and retail properties. Current ground cover The ground surface appears to be covered with native grasses and weeds. Existing topography The site appears to be relatively flat. Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 2 2.2 Project Description Item Description Proposed construction We understand the proposed project includes a new, 3-story, mixed-use senior apartments and approximately 5,000 square feet of ground floor commercial office space. The apartment building will consist of 110 units, a “great room”, fire place, library, game room, physical fitness center, community kitchen, storage units, and a computer area. The project will also include access drives and 103 parking spaces. Building construction We anticipate the apartment building will be constructed of steel, wood, and/or masonry. We understand the design team is considering post- tensioned slabs for the foundation system and wood exterior framing. Maximum loads Columns: 20 to 40 kips (assumed) Walls: 2 to 5 klf (assumed) Slabs: 150 psf max (assumed) Cut and fill slopes We anticipate minor cuts and fills on the order of 5 feet or less will be required for the construction at this site with deeper cuts and fills up to about 8 feet being required for the installation of new utilities. Below-grade areas No below-grade areas are planned for this site. 3.0 SUBSURFACE CONDITIONS 3.1 Typical Subsurface Profile Specific conditions encountered at each boring location are indicated on the individual boring logs included in Appendix A. Stratification boundaries on the boring logs represent the approximate location of changes in soil types; in-situ, the transition between materials may be gradual. Based on the results of the borings, subsurface conditions on the project site can be generalized as follows: Material Description Approximate Depth to Bottom of Stratum (feet) Consistency/Density/Hardness Lean clay with varying amounts of sand and gravel About 5 to 19 feet below existing site grades. Medium stiff to stiff Sand with varying amounts of clay and gravel About 10 to 24 feet below existing site grades. Loose to dense Interbedded Sandstone and Claystone bedrock To the maximum depth of exploration of about 25 feet. Weathered to very hard Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 3 3.2 Laboratory Testing Representative soil samples were selected for swell-consolidation testing and exhibited 0.8 swell to 2.4 percent compression when wetted. Two samples of clay soils exhibited unconfined compressive strengths of approximately 740 and 3,200 pounds per square foot (psf). Samples of site soils and bedrock selected for plasticity testing exhibited low to high plasticity with liquid limits ranging from non-plastic to 51 and plasticity indices ranging from 9 to 28. Laboratory test results are presented in Appendix B. 3.3 Corrosion Protection (Water-Soluble Sulfates) Results of water-soluble sulfate testing indicate that ASTM Type II, portland cement should be specified for all project concrete on and below grade. Foundation concrete should be designed for moderate sulfate exposure in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. 3.4 Groundwater The boreholes were observed while drilling and after completion for the presence and level of groundwater. In addition, delayed water levels were also obtained in some borings. The water levels observed in the boreholes are noted on the attached boring logs, and are summarized below. Boring Number Depth to groundwater while drilling, ft. Depth to groundwater 5 days after drilling, ft. Elevation of groundwater 8 days after drilling, ft. 1 9 9.9 90.3 2 11 8.9 89.9 3 12 9.9 89.6 4 11 10.4 89.6 5 Not encountered 11.0 90.0 P1 Not encountered Not encountered Not encountered P2 Not encountered Not encountered Not encountered P3 Not encountered Not encountered Not encountered These observations represent groundwater conditions at the time of the field exploration, and may not be indicative of other times or at other locations. Groundwater levels can be expected to fluctuate with varying seasonal and weather conditions, and other factors. Groundwater level fluctuations occur due to seasonal variations amount of rainfall, runoff and other factors not evident at the time the borings was/were performed. Therefore, groundwater levels during construction or at other times in the life of the structure(s) may be higher or lower Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 4 than 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. Fluctuations in groundwater levels can best be determined by implementation of a groundwater monitoring plan. Such a plan would include installation of groundwater piezometers, and periodic measurement of groundwater levels over a sufficient period of time. 4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION 4.1 Geotechnical Considerations Based on subsurface conditions encountered in the borings, the site appears suitable for the proposed construction from a geotechnical point of view provided certain precautions and design and construction recommendations described in this report are followed. We have identified geotechnical conditions that could impact design and construction of the proposed structures, pavements, and other site improvements. 4.1.1 Potentially Unstable Clay Subgrade Soils Based on our experience in the area, the data suggests that portions of the upper lean clay soils may be at moisture contents that could result in unstable conditions below the proposed foundations, exterior concrete flatwork, and pavements. Exposure to significant precipitation events, snowmelt, or repeated rubber tire traffic could also develop unstable conditions. We believe some subgrade areas below the site will require stabilization. It may be prudent to include a separate bid item for subgrade stabilization. 4.1.2 Groundwater As previously stated, groundwater was measured at depths ranging from about 8.9 to 11.0 feet below existing site grades. Terracon recommends maintaining a separation of at least 3 feet between the bottom of proposed below-grade foundations and measured groundwater levels. Groundwater levels below this site may fluctuate seasonally as well as during periods of drought and prolonged precipitation. 4.1.3 Expansive Soils Laboratory testing indicates the native clay soils exhibited low expansive potential at the samples in-situ moisture content. However, it is our opinion these materials will exhibit a higher expansive potential if the clays undergo a significant loss of moisture. This report provides recommendations to help mitigate the effects of soil shrinkage and expansion. However, even if these procedures are followed, some movement and cracking in the structures, pavements, and flatwork should be anticipated. The severity of cracking and other damage such as uneven floor slabs will probably increase if any modification of the site results in excessive wetting or drying of the expansive clays. Eliminating the risk of movement and distress Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 5 is generally not feasible, but it may be possible to further reduce the risk of movement if significantly more expensive measures are used during construction. It is imperative the recommendations described in section 4.2.7 Grading and Drainage of this report be followed to reduce movement. 4.1.4 Foundation Recommendations The proposed building may be supported on a post-tensioned slab system bearing on properly prepared on-site soils or properly placed imported fill. 4.2 Earthwork The following presents recommendations for site preparation, excavation, subgrade preparation and placement of engineered fills on the project. All earthwork on the project should be observed and evaluated by Terracon on a full-time basis. The evaluation of earthwork should include observation of over-excavation operations, testing of engineered fills, subgrade preparation, subgrade stabilization, and other geotechnical conditions exposed during the construction of the project. 4.2.1 Site Preparation Prior to placing any fill, strip and remove existing vegetation and any other deleterious materials from the proposed construction areas. Stripped organic materials should be wasted from the site or used to re-vegetate landscaped areas after completion of grading operations. Prior to the placement of fills, the site should be graded to create a relatively level surface to receive fill, and to provide for a relatively uniform thickness of fill beneath proposed structures. If fill is placed in areas of the site where existing slopes are steeper than 5:1 (horizontal:vertical), the area should be benched to reduce the potential for slippage between existing slopes and fills. Benches should be wide enough to accommodate compaction and earth moving equipment, and to allow placement of horizontal lifts of fill. 4.2.2 Excavation It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment. The excavated soils can vary significantly across the site as their classifications are based solely on the materials encountered in widely-spaced exploratory test borings. The contractor should verify that similar conditions exist throughout the proposed area of excavation. If different subsurface conditions are encountered at the time of construction, the actual conditions should be evaluated to determine any excavation modifications necessary to maintain safe conditions. Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 6 Although evidence of fills or underground facilities such as septic tanks, vaults, basements, and utilities was not observed during the site reconnaissance, such features could be encountered during construction. If unexpected fills or underground facilities are encountered, such features should be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction. Any over-excavation that extends below the bottom of foundation elevation should extend laterally beyond all edges of the foundations at least 8 inches per foot of over-excavation depth below the foundation base elevation. The over-excavation should be backfilled to the foundation base elevation in accordance with the recommendations presented in this report. Depending upon depth of excavation and seasonal conditions, surface water infiltration and/or groundwater may be encountered in excavations on the site. It is anticipated that pumping from sumps may be utilized to control water within excavations. The subgrade soil conditions should be evaluated during the excavation process and the stability of the soils determined at that time by the contractors’ Competent Person. Slope inclinations flatter than the OSHA maximum values may have to be used. The individual contractor(s) should be made responsible for designing and constructing stable, temporary excavations as required to maintain stability of both the excavation sides and bottom. All excavations should be sloped or shored in the interest of safety following local, and federal regulations, including current OSHA excavation and trench safety standards. As a safety measure, it is recommended that all vehicles and soil piles be kept a minimum lateral distance from the crest of the slope equal to the slope height. The exposed slope face should be protected against the elements 4.2.3 Subgrade Preparation After the deleterious materials have been removed from the construction areas, the top 8 inches of the exposed ground surface should be scarified, moisture conditioned, and recompacted to at least 95 percent of the maximum dry unit weight as determined by ASTM D698 before any new fill or foundation or pavement is placed. If pockets of soft, loose, or otherwise unsuitable materials are encountered at the bottom of the foundation excavations and it is inconvenient to lower the foundations, the proposed foundation elevations may be reestablished by over-excavating the unsuitable soils and backfilling with compacted engineered fill or lean concrete. After the bottom of the excavation has been compacted, engineered fill can be placed to bring the building pad and pavement subgrade to the desired grade. Engineered fill should be placed in accordance with the recommendations presented in subsequent sections of this report. The stability of the subgrade may be affected by precipitation, repetitive construction traffic or other factors. If unstable conditions develop, workability may be improved by scarifying and Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 7 drying. Alternatively, over-excavation of wet zones and replacement with granular materials may be used, or crushed gravel and/or rock can be tracked or “crowded” into the unstable surface soil until a stable working surface is attained. Lightweight excavation equipment may also be used to reduce subgrade pumping. 4.2.4 Fill Materials and Placement The on-site soils or approved granular and low plasticity cohesive imported materials may be used as fill material. The soil removed from this site that is free of organic or objectionable materials, as defined by a field technician who is qualified in soil material identification and compaction procedures, can be re-used as fill for the building pad and pavement subgrade. It should be noted that on-site clayey soils may require reworking to adjust the moisture content to meet the compaction criteria. Imported soils (if required) should meet the following material property requirements: Gradation Percent finer by weight (ASTM C136) 4” 100 3” 70-100 No. 4 Sieve 50-100 No. 200 Sieve 15-50 Soil Properties Values Liquid Limit 35 (max.) Plastic Limit 6 (max.) Maximum Expansive Potential (%) Non-expansive1 1. Measured on a sample compacted to approximately 95 percent of the maximum dry unit weight as determined by ASTM D698 at optimum moisture content. The sample is confined under a 100 psf surcharge and submerged. 4.2.5 Compaction Requirements Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift. Item Description Fill lift Thickness 9 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 or plate compactor) is used Minimum compaction requirements 95 percent of the maximum dry unit weight as determined by ASTM D698 Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 8 Item Description Moisture content cohesive soil (clay) -1 to +3 % of the optimum moisture content Moisture content cohesionless soil (sand) -3 to +3 % of the optimum moisture content 1. We recommend engineered fill be tested for moisture content and compaction during placement. Should the results of the in-place density tests indicate the specified moisture or compaction limits have not been met, the area represented by the test should be reworked and retested as required until the specified moisture and compaction requirements are achieved. 2. Specifically, moisture levels should be maintained low enough to allow for satisfactory compaction to be achieved without the fill material pumping when proofrolled. 3. Moisture conditioned clay materials should not be allowed to dry out. A loss of moisture within these materials could result in an increase in the material’s expansive potential. Subsequent wetting of these materials could result in undesirable movement. 4.2.6 Utility Trench Backfill All trench excavations should be made with sufficient working space to permit construction including backfill placement and compaction. All underground piping within or near the proposed structures should be designed with flexible couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts should be oversized to accommodate differential movements. It is imperative that utility trenches be properly backfilled with relatively clean materials. If utility trenches are backfilled with relatively clean granular material, they should be capped with at least 18 inches of cohesive fill in non- pavement areas to reduce the infiltration and conveyance of surface water through the trench backfill. Utility trenches are a common source of water infiltration and migration. All utility trenches that penetrate beneath the buildings should be effectively sealed to restrict water intrusion and flow through the trenches that could migrate below the buildings. We recommend constructing an effective clay “trench plug” that extends at least 5 feet out from the face of the building exteriors. The plug material should consist of clay compacted at a water content at or above the soil’s optimum water content. The clay fill should be placed to completely surround the utility line and be compacted in accordance with recommendations in this report. It is strongly recommended that a representative of Terracon provide full-time observation and compaction testing of trench backfill within building and pavement areas. 4.2.7 Grading and Drainage All grades must be adjusted to provide effective drainage away from the proposed buildings during construction and maintained throughout the life of the proposed project. Infiltration of water into foundation excavations must be prevented during construction. Landscape irrigation adjacent to foundations should be minimized or eliminated. Water permitted to pond near or adjacent to the perimeter of the structures (either during or post-construction) can result in significantly higher Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 9 soil movements than those discussed in this report. As a result, any estimations of potential movement described in this report cannot be relied upon if positive drainage is not obtained and maintained, and water is allowed to infiltrate the fill and/or subgrade. Exposed ground (if any) should be sloped at a minimum of 10 percent grade for at least 10 feet beyond the perimeter of the proposed buildings, where possible. The use of swales, chases and/or area drains may be required to facilitate drainage in unpaved areas around the perimeter of the buildings. Backfill against foundations and exterior walls should be properly compacted and free of all construction debris to reduce the possibility of moisture infiltration. After construction of the proposed buildings and prior to project completion, we recommend verification of final grading be performed to document positive drainage, as described above, has been achieved. Flatwork and pavements will be subject to post-construction movement. Maximum grades practical should be used for paving and flatwork to prevent areas where water can pond. In addition, allowances in final grades should take into consideration post-construction movement of flatwork, particularly if such movement would be critical. Where paving or flatwork abuts the structures, care should be taken that joints are properly sealed and maintained to prevent the infiltration of surface water. Planters located adjacent to structures should preferably be self-contained. Sprinkler mains and spray heads should be located a minimum of 5 feet away from the building line(s). Low-volume, drip style landscaped irrigation should not be used near the building. Roof drains should discharge on to pavements or be extended away from the structures a minimum of 10 feet through the use of splash blocks or downspout extensions. A preferred alternative is to have the roof drains discharge by solid pipe to storm sewers or to a detention pond or other appropriate outfall. 4.2.8 Exterior Slab Design and Construction Exterior slabs on-grade, exterior architectural features, and utilities founded on, or in backfill or the site soils will likely experience some movement due to the volume change of the material. Potential movement could be reduced by: n Minimizing moisture increases in the backfill; n Controlling moisture-density during placement of the backfill; n Using designs which allow vertical movement between the exterior features and adjoining structural elements; and n Placing control joints on relatively close centers. 4.3 Foundations The proposed building can be supported by a post-tensioned slab foundation system. Design recommendations for foundations for the proposed structure and related structural elements are presented in the following paragraphs. Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 10 4.3.1 Post-Tensioned Slab Design Recommendations Based on the soil conditions encountered, use of post-tensioned slabs is feasible for support of structures provided some potential for movement can be tolerated and: n The post-tensioned slab foundations are properly designed and constructed. n Approved materials underlying the foundation are properly placed and compacted. n Proper surface drainage is maintained throughout the life of the structures. n Managed landscaping measures are used. In our opinion, total foundation movements on the order of about 1 inch should be expected, provided our recommendations are followed. Proper drainage should be provided on the design and during construction to reduce potential movement. Provided foundations are properly designed, foundation movements could result in periodic, and possibly seasonal, cosmetic distress to drywall, window frames, door frames and other features. We would anticipate that the frequency of distress and amount of movement would generally diminish with time provided proper drainage is established and/or maintained. If the amount of movement and potential distress discussed cannot be tolerated, the use of drilled pier foundations and structural floor systems should be considered. It should be noted that the presences of 1 to 2-foot steps within long spans of post-tensioned slabs could create a situation where the slabs at different elevations perform independently of one another unless the steps are properly reinforced and designed to tie the slabs together to act as one rigid structure. We strongly recommend that joints be designed within the full height of the structure of the building over each step in order to help the structure be capable of withstanding movements on the order of 1 inch or more. Based on the subsurface conditions and the recommended modification of the on-site materials, post-tensioned slabs should be designed using criteria outlined by the Post-Tensioning Institute4 based on the following: Post-tensioned Slab Design Parameter PTI, Third Edition Edge moisture variation distance, em(feet) Center Lift Condition 9 Edge Lift Condition 5 Differential soil movement, ym (inches) Center Lift Condition 1-1/2 Edge Lift Condition 1-1/4 Description Value Foundation subgrade soils Native clay soils 1 (2004, Third Edition), Design (and Construction) of Post-Tensioned Slabs-on-Ground, Post- Tensioning Institute. Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 11 Maximum allowable bearing pressure (psf) 1,500 Slab-subgrade friction coefficient, m on polyethylene sheeting 0.75 on cohesionless soils 1.00 on cohesive soils 2.00 Post-tensioned slabs, thickened or turndown edges and/or interior beams should be designed and constructed in accordance with the requirements of the PTI and the American Concrete Institute (ACI). It should be noted that ym is the estimated vertical movement at the edges of a uniformly loaded slab. These are theoretical values that are used in the design of post-tensioned slabs-on-grade and do not represent the movements that would be expected from the actual loading conditions. As previously discussed, the use of post-tensioned slabs assumes that some potential movement and cosmetic distress is considered acceptable. If portions of the buildings floor slab will be unheated, such as patios and entryways, consideration should be given to structurally separating these areas of the slab from the remaining interior portion of the slab. Exterior slab areas may be cantilevered portions of the slab which are subject to uplift from frost heave and swelling of the expansive soils, sometimes beyond those used for design, due to over watering of adjacent landscaped areas. Such movement in the exterior slabs can result in change in slab grade to the point where negative grade results and water ponds adjacent to the interior areas of the slab. Repairs of such conditions are difficult and costly, particularly if the floor slabs are post-tensioned slabs. Exterior slabs in unheated areas are subject to frost heave beneath the slab. Therefore, in design of the exterior slabs, potential movement from frost heave should be considered in the design. As the slabs are subject to frost development beneath the slab, the perimeter beams around exterior post-tensioned slabs need not be 36 inches in depth as frost protection is not possible. Masonry walls should be detailed and reinforced as necessary to reduce the potential for distress caused by differential foundation movement. The use of joints at openings or other discontinuities in masonry walls is recommended. 4.3.2 Post-Tensioned Slab Construction Considerations The above outlined movement estimates should also be considered as the potential amount of tilting of the structure, which could be caused by non-uniform, significant wetting of the subsurface materials below the post-tensioned slab. Failure to maintain soil water content below the slab and to maintain proper drainage around the structure will nullify the movement estimates provided above. Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 12 4.3.3 Post-Tensioned Slabs – Construction Considerations Post-tensioned slabs, thickened or turndown edges and/or interior beams should be designed and constructed in accordance with the requirements of the PTI and the American Concrete Institute (ACI). As previously discussed, foundations should be protected from frost heave using insulation. If traditional post-tensioned slab foundations are selected, exterior slab edges should be placed a minimum of 30 inches below finished grade for frost protection. Finished grade is the lowest adjacent grade for perimeter beams. Extending exterior slab edges to depths of at least 30 inches will likely encroach upon soft to very loose and nearly saturated to wet soils requiring stabilization of subgrade prior to construction. If portions of the building floor slab will be unheated, such as patios and entryways, consideration should be given to structurally separating these areas of the slab from the remaining interior portion of the slab. Exterior slab areas may be cantilevered portions of the slab which are subject to uplift from frost heave and swelling of the expansive soils, sometimes beyond those used for design, due to over watering of adjacent to landscaped areas. Such movement in the exterior slabs can result in change in slab grade to the point where negative grade results and water ponds adjacent to the interior areas of the slab. Repairs of such conditions are difficult and costly, particularly if the floor slabs are post-tensioned slabs. Exterior slabs in unheated areas are subject to frost heave beneath the slab. Therefore, in design of the exterior slabs, potential movement from frost heave should be considered in the design. It should be noted that the presences of 1 to 2-foot steps within long spans of post-tensioned slabs could create a situation where the slabs at different elevations perform independently of one another unless the steps are properly reinforced and designed to tie the slabs together to act as one rigid structure. We strongly recommend that joints be designed within the full height of the structure of the building over each step in order to help the structure be capable of withstanding movements on the order of 1 inch. The estimated movement should also be considered as the potential amount of tilting of the structure, which could be caused by non-uniform, significant wetting of the subsurface materials below the post-tensioned slab, resulting in potential movement. Failure to maintain soil water content below the slab and to maintain proper drainage around the structure will nullify the movement estimates provided above. 4.3.4 Spread Footings - Design Recommendations Some structural elements or site features may be constructed on shallow spread footing foundations. However, there are certain precautions we recommend to reduce risk for significant foundation movements and to enhance performance Blow counts recorded during sampling of the upper soils within the borings suggest shallow footing foundations may settle without any ground modification. We recommend over-excavating Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 13 the soils below these shallow footing foundations to a depth of 2 feet and replacing with recompacted engineered fill. On-site soils or imported granular fill may be reused as over- excavation backfill (engineered fill). Subgrade soils at the base of the over-excavation should be properly scarified, moisture conditioned, and compacted as described in the 4.2 Earthwork section of our initial report. Design recommendations for spread footing foundations and related structural elements are presented in the following paragraphs. Description Values Bearing material Properly prepared on-site soil Maximum allowable bearing pressure 1 1,500 psf Lateral earth pressure coefficients 2 Active, Ka = 0.41 Passive, Kp = 2.46 At-rest, Ko = 0.58 Sliding coefficient 2 µ = 0.37 Moist soil unit weight ɣ = 125 pcf Minimum embedment depth below finished grade 3 30 inches Estimated total movement 4 About 1 inch Estimated differential movement 4 About ½ to ¾ of total movement 1. The recommended maximum allowable bearing pressure assumes any unsuitable fill or soft soils, if encountered, will be over-excavated and replaced with properly compacted engineered fill. The design bearing pressure applies to a dead load plus design live load condition. The design bearing pressure may be increased by one-third when considering total loads that include wind or seismic conditions. 2. The lateral earth pressure coefficients and sliding coefficients are ultimate values and do not include a factor of safety. The foundation designer should include the appropriate factors of safety. 3. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade soils. The minimum embedment depth is for perimeter footings beneath unheated areas and is relative to lowest adjacent finished grade, typically exterior grade. 4. The estimated movements presented above are based on the assumption that the maximum footing size is 4 feet for column footings and 1.5 feet for continuous footings. Footings should be proportioned to reduce differential foundation movement. As discussed, total movement resulting from the assumed structural loads is estimated to be on the order of about 1 inch. Additional foundation movements could occur if water from any source infiltrates the foundation soils; therefore, proper drainage should be provided in the final design and during construction and throughout the life of the structure. Failure to maintain the proper drainage as recommended in the 4.2.7 Grading and Drainage section of this report will nullify the movement estimates provided above. Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 14 4.3.5 Spread Footings - Construction Considerations Spread footing construction should only be considered if the estimated foundation movement can be tolerated. Subgrade soils beneath footings should be moisture conditioned and compacted as described in the 4.2 Earthwork section of this report. The moisture content and compaction of subgrade soils should be maintained until foundation construction. Footings and foundation walls should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement. Unstable surfaces will need to be stabilized prior to backfilling excavations and/or constructing the building foundation, floor slab and/or project pavements. The use of angular rock, recycled concrete and/or gravel pushed or “crowded” into the yielding subgrade is considered suitable means of stabilizing the subgrade. The use of geogrid materials in conjunction with gravel could also be considered and could be more cost effective. Unstable subgrade conditions should be observed by Terracon to assess the subgrade and provide suitable alternatives for stabilization. Stabilized areas should be proof-rolled prior to continuing construction to assess the stability of the subgrade. Foundation excavations should be observed by Terracon. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required. 4.3.6 Overexcavation Beneath Footings If unsuitable bearing soils are encountered in footing excavations, the excavations could be extended deeper to suitable soils and the footings could bear directly on these soils at the lower level or on lean concrete backfill placed in the excavations. As an alternative, the footings could also bear on properly compacted backfill extending down to the suitable soils. Over-excavation for compacted backfill placement below footings should extend laterally beyond all edges of the footings at least 8 inches per foot of over-excavation depth below footing base elevation. The over-excavation should then be backfilled up to the footing base elevation with approved granular materials placed in lifts of 9 inches or less in loose thickness (6 inches or less if using hand-guided compaction equipment) and compacted to at least 98 percent of the maximum dry unit weight as determined by ASTM D698. The over-excavation and backfill procedure is described in the following figure. Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 15 4.4 Seismic Considerations Code Used Site Classification 2012 International Building Code (IBC) 1 D 2 1. In general accordance with the 2012 International Building Code, Table 1613.5.2. 2. The 2012 International Building Code (IBC) requires a site soil profile determination extending a depth of 100 feet for seismic site classification. The current scope requested does not include the required 100 foot soil profile determination. The borings completed for this project extended to a maximum depth of about 25½ feet and this seismic site class definition considers that similar soil and bedrock conditions exist below the maximum depth of the subsurface exploration. Additional exploration to deeper depths could be performed to confirm the conditions below the current depth of exploration. Alternatively, a geophysical exploration could be utilized in order to attempt to justify a more favorable seismic site class. However, we believe a higher seismic site class for this site is unlikely. 4.5 Lateral Earth Pressures Reinforced concrete walls with unbalanced backfill levels on opposite sides should be designed for earth pressures at least equal to those indicated in the following table. Earth pressures will be influenced by structural design of the walls, conditions of wall restraint, methods of construction and/or compaction and the strength of the materials being restrained. Two wall restraint conditions are shown. Active earth pressure is commonly used for design of free-standing cantilever retaining walls and assumes wall movement. The "at-rest" condition assumes no wall movement. The recommended design lateral earth pressures do not include a factor of safety and do not provide for possible hydrostatic pressure on the walls. Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 16 EARTH PRESSURE COEFFICIENTS Earth Pressure Conditions Coefficient for Backfill Type Equivalent Fluid Density (pcf) Surcharge Pressure, p1 (psf) Earth Pressure, p2 (psf) Active (Ka) Imported Fill - 0.27 Lean Clay - 0.41 34 51 (0.27)S (0.41)S (34)H (51)H At-Rest (Ko) Imported Fill - 0.43 Lean Clay - 0.58 54 72 (0.43)S (0.58)S (54)H (72)H Passive (Kp) Imported Fill - 3.69 Lean Clay - 2.46 460 300 --- --- --- --- Applicable conditions to the above include: n For active earth pressure, wall must rotate about base, with top lateral movements of about 0.002 H to 0.004 H, where H is wall height; n For passive earth pressure to develop, wall must move horizontally to mobilize resistance; n Uniform surcharge, where S is surcharge pressure; n In-situ soil backfill weight a maximum of 125 pcf; n Horizontal backfill, compacted between 95 and 98 percent of maximum dry unit weight as determined by ASTM D698; n Loading from heavy compaction equipment not included; n No hydrostatic pressures acting on wall; n No dynamic loading; n No safety factor included in soil parameters; and n Ignore passive pressure in frost zone. Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 17 To control hydrostatic pressure behind the wall we recommend that a drain be installed at the foundation wall with a collection pipe leading to a reliable discharge. If this is not possible, then combined hydrostatic and lateral earth pressures should be calculated for lean clay backfill using an equivalent fluid weighing 90 and 100 pcf for active and at-rest conditions, respectively. For granular backfill, an equivalent fluid weighing 85 and 90 pcf should be used for active and at-rest, respectively. These pressures do not include the influence of surcharge, equipment or floor loading, which should be added. Heavy equipment should not operate within a distance closer than the exposed height of retaining walls to prevent lateral pressures more than those provided. 4.6 Pavements 4.6.1 Pavements – Subgrade Preparation On most project sites, the site grading is accomplished relatively early in the construction phase. Fills are typically placed and compacted in a uniform manner. However as construction proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, or rainfall/snow melt. As a result, the pavement subgrade may not be suitable for pavement construction and corrective action will be required. Additionally, existing undocumented fill was encountered on this site that may not provide adequate support for new pavements. The subgrade should be carefully evaluated at the time of pavement construction for signs of disturbance or instability. We recommend the pavement subgrade be thoroughly proofrolled with a loaded tandem-axle dump truck prior to final grading and paving. All pavement areas should be moisture conditioned and properly compacted to the recommendations in this report immediately prior to paving. 4.6.2 Pavements – Design Recommendations Design of new privately-maintained pavements for the project has been based on the procedures described by the National Asphalt Pavement Associations (NAPA) and the American Concrete Institute (ACI). We assumed the following design parameters for NAPA flexible pavement thickness design: n Automobile Parking Areas · Class I - Parking stalls and parking lots for cars and pick-up trucks, with Equivalent Single Axle Load (ESAL) up to 7,000 over 20 years n Main Traffic Corridors · Class II – Parking lots with a maximum of 10 trucks per day with Equivalent Single Axle Load (ESAL) up to 27,000 over 20 years (Including trash trucks) n Heavy Traffic Areas · Class III – Collector streets with a maximum of 10 trucks per day with Equivalent Single Axle Load (ESAL) up to 110,000 over 20 years n Subgrade Soil Characteristics · USCS Classification – CL, classified by NAPA as poor Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 18 We assumed the following design parameters for ACI rigid pavement thickness design based upon the average daily truck traffic (ADTT): n Automobile Parking Areas (Light Duty) · ACI Category A: Automobile parking with an ADTT of 1 over 20 years n Main Traffic Corridors (Medium Duty) · ACI Category B: Entrance and service lanes with an ADTT of up to 300 over 20 years (Including trash trucks) n Truck Entrance and Exterior Lanes (Heavy Duty) · ACI Category C: Entrance and exterior lanes with an ADTT of up to 700 over 20 years n Subgrade Soil Characteristics · USCS Classification – CL n Concrete modulus of rupture value of 600 psi We should be contacted to confirm and/or modify the recommendations contained herein if actual traffic volumes differ from the assumed values shown above. Recommended alternatives for flexible and rigid pavements are summarized for each traffic area as follows: Traffic Area Alternative Recommended Pavement Thickness (Inches) Asphaltic Concrete Surface Aggregate Base Course Portland Cement Concrete Total Automobile Parking (light duty) A 3 6 -- 9 B -- -- 5½ 5½ Main Traffic Corridors (medium duty) A 4½ 6 -- 10½ B -- -- 6 6 Truck Entrance and Exterior Lanes (heavy duty) A 6 6 -- 12 B -- -- 7 7 Aggregate base course (if used on the site) should consist of a blend of sand and gravel which meets strict specifications for quality and gradation. Use of materials meeting Colorado Department of Transportation (CDOT) Class 5 or 6 specifications is recommended for aggregate base course. Aggregate base course should be placed in lifts not exceeding 6 inches and compacted to a minimum of 95 percent of the maximum dry unit weight as determined by ASTM D698. Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 19 Asphaltic concrete should be composed of a mixture of aggregate, filler and additives (if required) and approved bituminous material. The asphalt concrete should conform to approved mix designs stating the Superpave properties, optimum asphalt content, job mix formula and recommended mixing and placing temperatures. Aggregate used in asphalt concrete should meet particular gradations. Material meeting CDOT Grading S or SX specifications or equivalent is recommended for asphalt concrete. Mix designs should be submitted prior to construction to verify their adequacy. Asphalt material should be placed in maximum 3-inch lifts and compacted within a range of 92 to 96 percent of the theoretical maximum (Rice) density (ASTM D2041). Where rigid pavements are used, the concrete should be produced from an approved mix design with the following minimum properties: Properties Value Compressive strength 4,000 psi Cement type Type I or II portland cement Entrained air content (%) 5 to 8 Concrete aggregate ASTM C33 and CDOT Section 703 Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes from the time the water is added to the mix. Longitudinal and transverse joints should be provided as needed in concrete pavements for expansion/contraction and isolation per ACI 325. The location and extent of joints should be based upon the final pavement geometry. Joints should be sealed to prevent entry of foreign material and doweled where necessary for load transfer. For areas subject to concentrated and repetitive loading conditions such as dumpster pads, truck delivery docks and ingress/egress aprons, we recommend using a portland cement concrete pavement with a thickness of at least 6 inches underlain by at least 4 inches of granular base. Prior to placement of the granular base, the areas should be thoroughly proofrolled. For dumpster pads, the concrete pavement area should be large enough to support the container and tipping axle of the refuse truck. Pavement performance is affected by its surroundings. In addition to providing preventive maintenance, the civil engineer should consider the following recommendations in the design and layout of pavements: n Site grades should slope a minimum of 2 percent away from the pavements; n The subgrade and the pavement surface have a minimum 2 percent slope to promote proper surface drainage; n Consider appropriate edge drainage and pavement under drain systems; n Install pavement drainage surrounding areas anticipated for frequent wetting; n Install joint sealant and seal cracks immediately; Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 20 n Seal all landscaped areas in, or adjacent to pavements to reduce moisture migration to subgrade soils; and n Placing compacted, low permeability backfill against the exterior side of curb and gutter. 4.6.3 Pavements – Construction Considerations Openings in pavement, such as landscape islands, are sources for water infiltration into surrounding pavements. Water collects in the islands and migrates into the surrounding subgrade soils thereby degrading support of the pavement. This is especially applicable for islands with raised concrete curbs, irrigated foliage, and low permeability near-surface soils. The civil design for the pavements with these conditions should include features to restrict or to collect and discharge excess water from the islands. Examples of features are edge drains connected to the storm water collection system or other suitable outlet and impermeable barriers preventing lateral migration of water such as a cutoff wall installed to a depth below the pavement structure. 4.6.4 Pavements – Maintenance Preventative maintenance should be planned and provided for an ongoing pavement management program in order to enhance future pavement performance. Preventive maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first priority when implementing a planned pavement maintenance program and provides the highest return on investment for pavements. 5.0 GENERAL COMMENTS Terracon’s Scope of Services has been provided under the belief that this site will be used as apartments. As such, Terracon would like to inform the Client that if this apartment project is converted at any time to another purpose such as condominiums, the Client understands the services Terracon is providing is not applicable for a condominium project and that a separate consultant will need to be retained for such services. Terracon will have no liability for any such unintended use of our services and Client agrees to defend, indemnify, and hold harmless Terracon for any such unintended usage. Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide observation and testing services during grading, excavation, foundation construction and other earth-related construction phases of the project. The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, 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. If variations appear, we should be Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable 21 immediately notified so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, and 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. This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as described in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing. APPENDIX A FIELD EXPLORATION SITE LOCATION MAP Oakridge Crossing Southeast of Oakridge Drive and McMurry Avenue Fort Collins, CO TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY QUADRANGLES INCLUDE: FORT COLLINS, CO (1984) and LOVELAND, CO (1984). 1901 Sharp Point Dr Ste C Fort Collins, CO 80525-4429 20165021 Project Manager: Drawn by: Checked by: Approved by: KFS EDB EDB 1”=2,000’ 3/4/16 Project No. Scale: File Name: Date: A-1 EDB Exhibit SITE 0’ 20’ 40’ APPROXIMATE SCALE Scale: EDB KFS EDB EDB Project Manager: Drawn by: Checked by: Approved by: EXPLORATION PLAN Oakridge Crossing Southeast of Oakridge Drive and McMurry Avenue Fort Collins, Colorado A-2 20165021 Exhibit 3/10/16 1=40’ Project No. File Name: DIAGRAM IS FOR GENERAL LOCATION ONLY, AND Date: IS NOT INTENDED FOR CONSTRUCTION PURPOSES 1 APPROXIMATE BORING LOCATION LEGEND B-1 B-4 B-5 1901 Sharp Point Drive, Suite C Fort Collins, Colorado 80525 PH. (970) 484-0359 FAX. (970) 484-0454 P-1 P-2 P-3 B-2 B-3 TBM TBM APPROXIMATE LOCATION OF TEMPORARY BENCHMARK (CONCRETE CURB-ASSUMED ELEVATION 100.0) Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable Exhibit A-3 Field Exploration Description The locations of borings were based upon the proposed development shown on the provided site plan. The borings were located in the field by measuring from property lines and existing site features. The ground surface elevation was surveyed at each boring location referencing the temporary benchmark shown on Exhibit A-2 using an engineer’s level. The borings were drilled with a CME-75 truck-mounted rotary drill rig with solid-stem augers. During the drilling operations, lithologic logs of the borings were recorded by the field engineer. Disturbed samples were obtained at selected intervals utilizing a 2-inch outside diameter split- spoon sampler and a 3-inch outside diameter ring-barrel sampler. Penetration resistance values were recorded in a manner similar to the standard penetration test (SPT). This test consists of driving the sampler into the ground with a 140-pound hammer free-falling through a distance of 30 inches. The number of blows required to advance the ring-barrel sampler 12 inches (18 inches for standard split-spoon samplers, final 12 inches are recorded) or the interval indicated, is recorded as a standard penetration resistance value (N-value). The blow count values are indicated on the boring logs at the respective sample depths. Ring-barrel sample blow counts are not considered N-values. A CME automatic SPT hammer was used to advance the samplers in the borings performed on this site. A greater efficiency is typically achieved with the automatic hammer compared to the conventional safety hammer operated with a cathead and rope. Published correlations between the SPT values and soil properties are based on the lower efficiency cathead and rope method. This higher efficiency affects the standard penetration resistance blow count value by increasing the penetration per hammer blow over what would be obtained using the cathead and rope method. The effect of the automatic hammer's efficiency has been considered in the interpretation and analysis of the subsurface information for this report. The standard penetration test provides a reasonable indication of the in-place density of sandy type materials, but only provides an indication of the relative stiffness of cohesive materials since the blow count in these soils may be affected by the moisture content of the soil. In addition, considerable care should be exercised in interpreting the N-values in gravelly soils, particularly where the size of the gravel particle exceeds the inside diameter of the sampler. Groundwater measurements were obtained in the borings at the time of site exploration and several days after drilling. After subsequent groundwater measurements were obtained, the borings were backfilled with auger cuttings. Some settlement of the backfill may occur and should be repaired as soon as possible. 13 14 14 20 16 91 90 76 4-4-5 N=9 7-11 5-13-27 N=40 50/2" 50/6" 50/5" 9.0 10.0 24.4 SANDY LEAN CLAY, fine to coarse grained, brown to reddish-brown, stiff WEATHERED BEDROCK, CLAYEY SAND, light brown, dense INTERBEDDED SANDSTONE AND CLAYSTONE, light brown to olive, very hard Boring Terminated at 24.4 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic GRAPHIC LOG THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165021.GPJ TERRACON2015.GDT 3/10/16 Oakridge Drive and McMurry Avenue Fort Collins, CO SITE: Page 1 of 1 Advancement Method: 4-inch continuous flight auger Abandonment Method: Borings backfilled with soil cuttings upon completion. 1901 Sharp Point Drive, Suite C Fort Collins, Colorado Notes: Project No.: 20165021 Drill Rig: CME-75 Boring Started: 2/25/2016 BORING LOG NO. 1 CLIENT: McDermott Properties Centennial, Colorado Driller: ROB Boring Completed: 2/25/2016 Exhibit: A-4 See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. PROJECT: Oakridge Crossing UNCONFINED COMPRESSIVE STRENGTH (psf) PERCENT FINES WATER 31 11 16 18 26 19 27-13-14 NP 90 86 84 73.5 9-10 10-17 3-5-4 N=9 4-4-7 N=11 50/6" 50/3" 9.0 13.0 15.0 25.3 SANDY LEAN CLAY, fine to coarse grained, brown to reddish-brown, stiff CLAYEY SAND (SC), light brown, loose INTERBEDDED SANDSTONE AND CLAYSTONE, light brown to olive, medium dense, highly weathered INTERBEDDED SANDSTONE AND CLAYSTONE, light brown to olive, very hard very hard lense from 24 to 24.7 Boring Terminated at 25.3 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic GRAPHIC LOG THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165021.GPJ TERRACON2015.GDT 3/10/16 Oakridge Drive and McMurry Avenue Fort Collins, CO SITE: Page 1 of 1 Advancement Method: 4-inch continuous flight auger Abandonment Method: Borings backfilled with soil cuttings upon completion. 1901 Sharp Point Drive, Suite C Fort Collins, Colorado Notes: Project No.: 20165021 Drill Rig: CME-75 Boring Started: 2/25/2016 BORING LOG NO. 2 CLIENT: McDermott Properties Centennial, Colorado Driller: ROB Boring Completed: 2/25/2016 Exhibit: A-5 See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and 743 67 96 20 23 21 22 19 17 86 27-18-9 51-23-28 92.5 85.5 82.5 75 4-6-5 N=11 5-7 2-3-3 N=6 5-8-8 N=16 19-21-36 N=57 50/6" 7.0 14.0 17.0 24.5 SANDY LEAN CLAY WITH GRAVEL (CL), light brown to reddish-brown, stiff SANDY LEAN CLAY, light brown, medium stiff, trace of crystalline precipitate, moist WEATHERED BEDROCK, CLAYEY SAND, fine to coarse grained, brown, medium dense, trace of iron oxides INTERBEDDED SANDSTONE AND CLAYSTONE (CH), brown to olive, hard Boring Terminated at 24.5 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic GRAPHIC LOG THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165021.GPJ TERRACON2015.GDT 3/10/16 Oakridge Drive and McMurry Avenue Fort Collins, CO SITE: Page 1 of 1 Advancement Method: 4-inch continuous flight auger Abandonment Method: Borings backfilled with soil cuttings upon completion. 1901 Sharp Point Drive, Suite C Fort Collins, Colorado Notes: Project No.: 20165021 Drill Rig: CME-75 Boring Started: 2/25/2016 BORING LOG NO. 3 CLIENT: McDermott Properties Centennial, Colorado Driller: ROB Boring Completed: 2/25/2016 19 44 23 5 31-13-18 89.5 88 85 82 75.5 11-17 5-8 1-1-2 N=3 3-3-4 N=7 8-17-19 N=36 50/3" 10.5 12.0 15.0 18.0 24.3 SANDY LEAN CLAY WITH GRAVEL, brown to reddish-brown, soft to very stiff WELL GRADED SAND WITH GRAVEL, brown, loose SANDY LEAN CLAY WITH GRAVEL, brown POORLY GRADED SAND, brown, loose SEDIMENTARY BEDROCK - SANDSTONE, fine to coarse grained, brown to gray, firm to very hard Boring Terminated at 24.3 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic GRAPHIC LOG THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165021.GPJ TERRACON2015.GDT 3/10/16 Oakridge Drive and McMurry Avenue Fort Collins, CO SITE: Page 1 of 1 Advancement Method: 4-inch continuous flight auger Abandonment Method: Borings backfilled with soil cuttings upon completion. 1901 Sharp Point Drive, Suite C Fort Collins, Colorado Notes: Project No.: 20165021 Drill Rig: CME-75 Boring Started: 2/25/2016 BORING LOG NO. 4 CLIENT: McDermott Properties Centennial, Colorado Driller: ROB Boring Completed: 2/25/2016 Exhibit: A-7 See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. PROJECT: Oakridge Crossing 3241 59 70 12 12 14 22 23 12 10 97 39-17-22 30-15-15 NP 82 77 76 9-14-15 N=29 5-18 2-3-2 N=5 3-4-2 N=6 10-12-14 N=26 17 50/4" 19.0 24.0 24.8 SANDY LEAN CLAY (CL), fine to coarse grained, dark brown to light brown, medium stiff to very stiff, trace sulfate WELL GRADED SAND WITH CLAY AND GRAVEL, brown, medium dense SEDIMENTARY BEDROCK - SANDSTONE, brown, hard, trace iron oxide Boring Terminated at 24.8 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic GRAPHIC LOG THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165021.GPJ TERRACON2015.GDT 3/10/16 Oakridge Drive and McMurry Avenue Fort Collins, CO SITE: Page 1 of 1 Advancement Method: 4-inch continuous flight auger Abandonment Method: Borings backfilled with soil cuttings upon completion. 1901 Sharp Point Drive, Suite C Fort Collins, Colorado Notes: Project No.: 20165021 Drill Rig: CME-75 Boring Started: 2/25/2016 BORING LOG NO. 5 CLIENT: McDermott Properties Centennial, Colorado Driller: ROB Boring Completed: 2/25/2016 Exhibit: A-8 4 16 20 19 13 103 25-13-12 95.5 90 -2.38/500 3-3-3 N=6 4-7 2-3-3 N=6 3-3-3 N=6 5.0 10.5 SANDY LEAN CLAY, reddish-brown to brown, medium stiff to stiff WELL GRADED SAND WITH CLAY AND GRAVEL (SW), reddish-brown to brown, loose Boring Terminated at 10.5 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic GRAPHIC LOG THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165021.GPJ TERRACON2015.GDT 3/10/16 Oakridge Drive and McMurry Avenue Fort Collins, CO SITE: Page 1 of 1 Advancement Method: 4-inch continuous flight auger Abandonment Method: Borings backfilled with soil cuttings upon completion. 1901 Sharp Point Drive, Suite C Fort Collins, Colorado Notes: Project No.: 20165021 Drill Rig: CME-75 Boring Started: 2/25/2016 BORING LOG NO. P1 CLIENT: McDermott Properties Centennial, Colorado Driller: ROB Boring Completed: 2/25/2016 Exhibit: A-9 See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. PROJECT: Oakridge Crossing UNCONFINED COMPRESSIVE STRENGTH (psf) PERCENT FINES WATER CONTENT (%) DRY UNIT 17 14 113 92.5 91.5 89.5 8-8-9 1.4/250 26-23 6-6-4 10-6 7.0 8.0 10.0 SANDY LEAN CLAY, light brown, very stiff POORLY GRADED SAND, light brown, medium dense SANDY LEAN CLAY, light brown, stiff Boring Terminated at 10 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic GRAPHIC LOG THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165021.GPJ TERRACON2015.GDT 3/10/16 Oakridge Drive and McMurry Avenue Fort Collins, CO SITE: Page 1 of 1 Advancement Method: 4-inch continuous flight auger Abandonment Method: Borings backfilled with soil cuttings upon completion. 1901 Sharp Point Drive, Suite C Fort Collins, Colorado Notes: Project No.: 20165021 Drill Rig: CME-75 Boring Started: 2/25/2016 BORING LOG NO. P2 CLIENT: McDermott Properties Centennial, Colorado Driller: ROB Boring Completed: 2/25/2016 Exhibit: A-10 See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. PROJECT: Oakridge Crossing UNCONFINED COMPRESSIVE STRENGTH (psf) PERCENT FINES WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI Surface Elev.: 99.49 (Ft.) ELEVATION (Ft.) SAMPLE TYPE 68 24 21 21 25 105 36-15-21 90.5 2-4-4 N=8 3-5-7 N=12 8-7 4-4-4 10.5 N=8 SANDY LEAN CLAY (CL), dark brown to reddish-brown, stiff Boring Terminated at 10.5 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic GRAPHIC LOG THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20165021.GPJ TERRACON2015.GDT 3/10/16 Oakridge Drive and McMurry Avenue Fort Collins, CO SITE: Page 1 of 1 Advancement Method: 4-inch continuous flight auger Abandonment Method: Borings backfilled with soil cuttings upon completion. 1901 Sharp Point Drive, Suite C Fort Collins, Colorado Notes: Project No.: 20165021 Drill Rig: CME-75 Boring Started: 2/25/2016 BORING LOG NO. P3 CLIENT: McDermott Properties Centennial, Colorado Driller: ROB Boring Completed: 2/25/2016 Exhibit: A-11 See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. PROJECT: Oakridge Crossing UNCONFINED COMPRESSIVE STRENGTH (psf) PERCENT FINES WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI Surface Elev.: 101.16 (Ft.) ELEVATION (Ft.) APPENDIX B LABORATORY TESTING Geotechnical Engineering Report Oakridge Crossing ■ Fort Collins, Colorado March 10, 2016 ■ Terracon Project No. 20165021 Responsive ■ Resourceful ■ Reliable Exhibit B-1 Laboratory Testing Description The soil and bedrock samples retrieved during the field exploration were returned to the laboratory for observation by the project geotechnical engineer. At that time, the field descriptions were reviewed and an applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials. Laboratory tests were conducted on selected soil and bedrock samples. The results of these tests are presented on the boring logs and in this appendix. The test results were used for the geotechnical engineering analyses, and the development of foundation and earthwork recommendations. The laboratory tests were performed in general accordance with applicable locally accepted standards. Soil samples were classified in general accordance with the Unified Soil Classification System described in Appendix C. Rock samples were visually classified in general accordance with the description of rock properties presented in Appendix C. Procedural standards noted in this report are for reference to methodology in general. In some cases variations to methods are applied as a result of local practice or professional judgment. n Water content n Plasticity index n Grain-size distribution n Consolidation/swell n Unconfined compressive strength n Dry density n Water-soluble sulfate content 0 10 20 30 40 50 60 0 20 40 60 80 100 CL or OL CH or OH ML or OL MH or OH Boring ID Depth PL PI Description CLAYEY SAND SANDY LEAN CLAY FAT CLAY CLAYEY SAND SANDY LEAN CLAY LEAN CLAY with SAND SILTY SAND with GRAVEL WELL-GRADED SAND with GRAVEL SANDY LEAN CLAY SC CL CH SC CL CL SM SW CL Fines P L A S T I C I T Y I N D E X LIQUID LIMIT "U" Line "A" Line 27 27 51 31 39 30 NP 25 36 13 18 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS PERCENT FINER 3/4 1/2 3/8 SIEVE (size) D60 30 40 3 60 U.HYDROMETERS. SIEVE OPENING IN INCHES % FINES % CLAY USCS 1 2 2 0.0 0.0 0.0 0.0 4.5 0.0 43.1 64.0 89.1 31.0 () CLAYEY SAND (SC) POORLY GRADED SAND with SILT (SP-SM) 0.004 0.125 0.088 0.28 0.186 1.15 26.0 DEPTH GRAIN SIZE 16 20 100 90 80 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS PERCENT FINER 3/4 1/2 3/8 SIEVE (size) D60 30 40 3 60 U.HYDROMETERS. SIEVE OPENING IN INCHES % FINES % CLAY USCS 3 3 4 0.0 0.0 1.7 0.0 31.6 4.2 35.2 34.9 SANDY LEAN CLAY (CL) FAT CLAY (CH) () 0.002 0.054 29.9 DEPTH GRAIN SIZE 16 20 100 90 80 70 60 50 40 30 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS PERCENT FINER 3/4 1/2 3/8 SIEVE (size) D60 30 40 3 60 U.HYDROMETERS. SIEVE OPENING IN INCHES % FINES % CLAY USCS 4 5 5 0.0 0.0 2.2 6.7 0.3 46.9 34.2 29.4 CLAYEY SAND (SC) SANDY LEAN CLAY (CL) LEAN CLAY with SAND (CLCL) 0.257 0.079 DEPTH GRAIN SIZE 16 20 100 90 80 70 60 50 40 30 20 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 100 10 1 0.1 0.01 0.001 0.102 GRAIN SIZE IN MILLIMETERS PERCENT FINER 3/4 1/2 3/8 SIEVE (size) D60 30 40 3 60 U.HYDROMETERS. SIEVE OPENING IN INCHES % FINES % CLAY USCS 5 P1 P2 0.0 0.0 0.0 15.5 24.3 0.0 72.5 71.2 54.9 26.4 SILTY SAND with GRAVEL (SM) WELL-GRADED SAND with GRAVEL (SW) () 0.178 0.527 0.009 1.55 2.276 0.203 0.30 1.19 18.7 DEPTH GRAIN SIZE 16 20 100 90 80 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS PERCENT FINER 3/4 1/2 3/8 SIEVE (size) D60 30 40 3 60 U.HYDROMETERS. SIEVE OPENING IN INCHES % FINES % CLAY USCS P3 0.0 0.0 32.3 SANDY LEAN CLAY (CL) DEPTH GRAIN SIZE 16 20 100 90 80 70 60 50 40 30 20 10 0 REMARKS COBBLES SILT OR CLAY GRAVEL SAND medium 67.7 U.S. SIEVE NUMBERS 4 4 6 100 3 2 fine coarse SOIL DESCRIPTION CU -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 100 1,000 10,000 AXIAL STRAIN, % PRESSURE, psf SWELL CONSOLIDATION TEST ASTM D2435 NOTES: Sample exhibited 1.4% swell at an applied load of 250 psf. 1901 Sharp Point Drive, Suite C Fort Collins, Colorado PROJECT: Oakridge Crossing PROJECT NUMBER: 20165021 SITE: Oakridge Drive and McMurry Avenue Fort Collins, CO CLIENT: McDermott Properties Centennial, Colorado EXHIBIT: B-9 Specimen Identification Classification , pcf 113 17 WC, % P2 2 - 3.5 ft SANDY LEAN CLAY LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. 65155045-SWELL/CONSOL 20165021.GPJ TERRACON2012.GDT 3/10/16 -10 -8 -6 -4 -2 0 2 4 100 1,000 AXIAL STRAIN, % PRESSURE, psf SWELL CONSOLIDATION TEST ASTM D4546 NOTES: Sample exhibited 2.4% compression at an applied load of 500 psf. 1901 Sharp Point Drive, Suite C Fort Collins, Colorado PROJECT: Oakridge Crossing PROJECT NUMBER: 20165021 SITE: Oakridge Drive and McMurry Avenue Fort Collins, CO CLIENT: McDermott Properties Centennial, Colorado EXHIBIT: B-8 Specimen Identification Classification , pcf 103 20 WC, % P1 4 - 5 ft SANDY LEAN CLAY LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. 65155045-SWELL/CONSOL 20165021.GPJ TERRACON2012.GDT 3/10/16 0 100 200 300 400 500 600 700 800 0 1.0 2.0 3.0 4.0 2.40 5.35 743 Assumed Specific Gravity: 27 18 9 Unconfined Compressive Strength (psf) Undrained Shear Strength: (psf) Calculated Void Ratio: Height / Diameter Ratio: SPECIMEN FAILURE MODE SPECIMEN TEST DATA 2.23 2.99 Moisture Content: % Dry Density: pcf COMPRESSIVE STRESS - psf DESCRIPTION: SANDY LEAN CLAY(CL) 23 371 LL PL PI Percent < #200 Sieve 67 AXIAL STRAIN - % Remarks: ASTM D2166 UNCONFINED COMPRESSION TEST Failure Mode: Shear (dashed) Diameter: in. Height: in. Calculated Saturation: % Failure Strain: % Strain Rate: in/min 86 SAMPLE TYPE: D&M RING SAMPLE LOCATION: 3 @ 4 - 5 feet PROJECT NUMBER: 20165021 PROJECT: Oakridge Crossing SITE: Oakridge Drive and McMurry Avenue Fort Collins, CO CLIENT: McDermott Properties Centennial, Colorado EXHIBIT: B-10 1901 Sharp Point Drive, Suite C Fort Collins, Colorado LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. UNCONFINED 20165021.GPJ TERRACON2012.GDT 3/10/16 0 500 1,000 1,500 2,000 2,500 3,000 3,500 0 1 2 3 4 5 6 7 8 2.40 5.96 3241 Assumed Specific Gravity: 39 17 22 Unconfined Compressive Strength (psf) Undrained Shear Strength: (psf) Calculated Void Ratio: Height / Diameter Ratio: SPECIMEN FAILURE MODE SPECIMEN TEST DATA 2.48 5.04 Moisture Content: % Dry Density: pcf COMPRESSIVE STRESS - psf DESCRIPTION: SANDY LEAN CLAY(CL) 14 1620 LL PL PI Percent < #200 Sieve 59 AXIAL STRAIN - % Remarks: ASTM D2166 UNCONFINED COMPRESSION TEST Failure Mode: Bulge (dashed) Diameter: in. Height: in. Calculated Saturation: % Failure Strain: % Strain Rate: in/min 97 SAMPLE TYPE: D&M RING SAMPLE LOCATION: 5 @ 4 - 5 feet PROJECT NUMBER: 20165021 PROJECT: Oakridge Crossing SITE: Oakridge Drive and McMurry Avenue Fort Collins, CO CLIENT: McDermott Properties Centennial, Colorado EXHIBIT: B-11 1901 Sharp Point Drive, Suite C Fort Collins, Colorado LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. UNCONFINED 20165021.GPJ TERRACON2012.GDT 3/10/16 TASK NO: 160302082 Analytical Results Terracon, Inc. - Fort Collins Eric D. Bernhardt Company: Report To: Company: Bill To: 1901 Sharp Point Drive Suite C Fort Collins CO 80525 Accounts Payable Terracon, Inc. - Lenexa 13910 W. 96th Terrace Lenexa KS 66215 Date Reported: 3/9/16 Task No.: 160302082 Matrix: Soil - Geotech Date Received: 3/2/16 Client Project: Client PO: Customer Sample ID 20165019 B2 4-6 Test Method Lab Number: 160302082-01 Result Sulfate - Water Soluble 0.010 % AASHTO T290-91/ ASTM D4327 Customer Sample ID 20165021 1 @ 2 Test Method Lab Number: 160302082-02 Result Sulfate - Water Soluble 0.064 % AASHTO T290-91/ ASTM D4327 Customer19 Sample ID 20165021 4 @ Test Method Lab Number: 160302082-03 Result Sulfate - Water Soluble 0.005 % AASHTO T290-91/ ASTM D4327 Customer Sample ID 20165021 3 @ 4 Test Method Lab Number: 160302082-04 Result Sulfate - Water Soluble 0.107 % AASHTO T290-91/ ASTM D4327 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 DATA APPROVED FOR RELEASE BY Abbreviations/ References: 160302082 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. APPENDIX C SUPPORTING DOCUMENTS Exhibit: C-1 Unconfined Compressive Strength Qu, (psf) 500 to 1,000 2,000 to 4,000 4,000 to 8,000 1,000 to 2,000 less than 500 > 8,000 Non-plastic Low Medium High DESCRIPTION OF SYMBOLS AND ABBREVIATIONS SAMPLING WATER LEVEL FIELD TESTS GENERAL NOTES 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) Particle Size < 5 5 - 12 > 12 Percent of Dry Weight Descriptive Term(s) of other constituents RELATIVE PROPORTIONS OF FINES 0 1 - 10 11 - 30 > 30 Plasticity Index 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 Percent of Dry Weight Major Component of Sample Trace With Modifier RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY Trace With Modifier DESCRIPTIVE SOIL CLASSIFICATION Boulders Cobbles Gravel Sand UNIFIED SOIL CLASSIFICATION SYSTEM Exhibit C-2 Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Soil Classification Group Symbol Group Name B Coarse Grained Soils: More than 50% retained on No. 200 sieve Gravels: More than 50% of coarse fraction retained on No. 4 sieve Clean Gravels: Less than 5% fines C 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 Gravels with Fines: More than 12% fines C Fines classify as ML or MH GM Silty gravel F,G,H Fines classify as CL or CH GC Clayey gravel F,G,H Sands: 50% or more of coarse fraction passes No. 4 sieve Clean Sands: Less than 5% fines D 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 Sands with Fines: More than 12% fines D Fines classify as ML or MH SM Silty sand G,H,I Fines classify as CL or CH SC Clayey sand G,H,I Fine-Grained Soils: 50% or more passes the No. 200 sieve Silts and Clays: Liquid limit less than 50 Inorganic: PI  7 and plots on or above “A” line J CL Lean clay K,L,M PI  4 or plots below “A” line J ML Silt K,L,M Organic: Liquid limit - oven dried  0.75 OL Organic clay K,L,M,N Liquid limit - not dried Organic silt K,L,M,O Silts and Clays: Liquid limit 50 or more Inorganic: PI plots on or above “A” line CH Fat clay K,L,M PI plots below “A” line MH Elastic Silt K,L,M Organic: Liquid limit - oven dried  0.75 OH Organic clay 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 B If field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name. DESCRIPTION OF ROCK PROPERTIES Exhibit C-3 WEATHERING Fresh Rock fresh, crystals bright, few joints may show slight staining. Rock rings under hammer if crystalline. Very slight Rock generally fresh, joints stained, some joints may show thin clay coatings, crystals in broken face show bright. Rock rings under hammer if crystalline. Slight 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. Moderate 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. Moderately severe 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. Severe 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. Very severe All rock except quartz discolored or stained. Rock “fabric” discernible, but mass effectively reduced to “soil” with only fragments of strong rock remaining. Complete Rock reduced to ”soil”. Rock “fabric” not 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) Very hard Cannot be scratched with knife or sharp pick. Breaking of hand specimens requires several hard blows of geologist’s pick. Hard Can be scratched with knife or pick only with difficulty. Hard blow of hammer required to detach hand specimen. Moderately hard 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. Medium 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. Soft 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. Very soft 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 a 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 a. 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) a 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 a. RQD (given as a percentage) = length of core in pieces Greater than 0.1 ft. Wide 4 in. and longer/length of run. 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. Exhibit C-4 LABORATORY TEST SIGNIFICANCE AND PURPOSE Test Significance Purpose California Bearing Ratio Used to evaluate the potential strength of subgrade soil, subbase, and base course material, including recycled materials for use in road and airfield pavements. Pavement Thickness Design Consolidation Used to develop an estimate of both the rate and amount of both differential and total settlement of a structure. Foundation Design Direct Shear Used to determine the consolidated drained shear strength of soil or rock. Bearing Capacity, Foundation Design, and Slope Stability Dry Density Used to determine the in-place density of natural, inorganic, fine-grained soils. Index Property Soil Behavior Expansion Used to measure the expansive potential of fine-grained soil and to provide a basis for swell potential classification. Foundation and Slab Design Gradation Used for the quantitative determination of the distribution of particle sizes in soil. Soil Classification Liquid & Plastic Limit, Plasticity Index Used as an integral part of engineering classification systems to characterize the fine-grained fraction of soils, and to specify the fine-grained fraction of construction materials. Soil Classification Permeability Used to determine the capacity of soil or rock to conduct a liquid or gas. Groundwater Flow Analysis pH Used to determine the degree of acidity or alkalinity of a soil. Corrosion Potential Resistivity Used to indicate the relative ability of a soil medium to carry electrical currents. Corrosion Potential R-Value Used to evaluate the potential strength of subgrade soil, subbase, and base course material, including recycled materials for use in road and airfield pavements. Pavement Thickness Design Soluble Sulfate Used to determine the quantitative amount of soluble sulfates within a soil mass. Corrosion Potential Unconfined Compression To obtain the approximate compressive strength of soils that Exhibit C-5 REPORT TERMINOLOGY (Based on ASTM D653) Allowable Soil Bearing Capacity The recommended maximum contact stress developed at the interface of the foundation element and the supporting material. Alluvium Soil, the constituents of which have been transported in suspension by flowing water and subsequently deposited by sedimentation. Aggregate Base Course A layer of specified material placed on a subgrade or subbase usually beneath slabs or pavements. Backfill A specified material placed and compacted in a confined area. Bedrock A natural aggregate of mineral grains connected by strong and permanent cohesive forces. Usually requires drilling, wedging, blasting or other methods of extraordinary force for excavation. Bench A horizontal surface in a sloped deposit. Caisson (Drilled Pier or Shaft) A concrete foundation element cast in a circular excavation which may have an enlarged base. Sometimes referred to as a cast-in-place pier or drilled shaft. Coefficient of Friction A constant proportionality factor relating normal stress and the corresponding shear stress at which sliding starts between the two surfaces. Colluvium Soil, the constituents of which have been deposited chiefly by gravity such as at the foot of a slope or cliff. Compaction The densification of a soil by means of mechanical manipulation Concrete Slab-on- Grade A concrete surface layer cast directly upon a base, subbase or subgrade, and typically used as a floor system. Differential Movement Unequal settlement or heave between, or within foundation elements of structure. Earth Pressure The pressure exerted by soil on any boundary such as a foundation wall. ESAL Equivalent Single Axle Load, a criteria used to convert traffic to a uniform standard, (18,000 pound axle loads). Engineered Fill Specified material placed and compacted to specified density and/or moisture conditions under observations of a representative of a geotechnical engineer. Equivalent Fluid A hypothetical fluid having a unit weight such that it will produce a pressure against a lateral support presumed to be equivalent to that produced by the actual soil. This simplified approach is valid only when deformation conditions are such that the pressure increases linearly with depth and the wall friction is neglected. Existing Fill (or Man-Made Fill) Materials deposited throughout the action of man prior to exploration of the site. Existing Grade The ground surface at the time of field exploration. Exhibit C-6 REPORT TERMINOLOGY (Based on ASTM D653) Expansive Potential The potential of a soil to expand (increase in volume) due to absorption of moisture. Finished Grade The final grade created as a part of the project. Footing A portion of the foundation of a structure that transmits loads directly to the soil. Foundation The lower part of a structure that transmits the loads to the soil or bedrock. Frost Depth The depth at which the ground becomes frozen during the winter season. Grade Beam A foundation element or wall, typically constructed of reinforced concrete, used to span between other foundation elements such as drilled piers. Groundwater Subsurface water found in the zone of saturation of soils or within fractures in bedrock. Heave Upward movement. Lithologic The characteristics which describe the composition and texture of soil and rock by observation. Native Grade The naturally occurring ground surface. Native Soil Naturally occurring on-site soil, sometimes referred to as natural soil. Optimum Moisture Content The water content at which a soil can be compacted to a maximum dry unit weight by a given compactive effort. Perched Water Groundwater, usually of limited area maintained above a normal water elevation by the presence of an intervening relatively impervious continuous stratum. Scarify To mechanically loosen soil or break down existing soil structure. Settlement Downward movement. Skin Friction (Side Shear) The frictional resistance developed between soil and an element of the structure such as a drilled pier. Soil (Earth) Sediments or other unconsolidated accumulations of solid particles produced by the physical and chemical disintegration of rocks, and which may or may not contain organic matter. Strain The change in length per unit of length in a given direction. Stress The force per unit area acting within a soil mass. Strip To remove from present location. Subbase A layer of specified material in a pavement system between the subgrade and base course. Subgrade The soil prepared and compacted to support a structure, slab or pavement system. Oakridge Crossing Recreational Areas Date: May 20, 2016 ON SITE OPEN SPACE Plazas/ seating areas 945 sf Open Turf (park) areas 1,735 sf Patio/ Bar B Que areas 645 sf TOTAL 3,325 sf INTERNAL COMMON AREAS Community Room 893 sf Arts-n-Crafts Room 378 sf Library 286 sf Billiards Room 269 sf Workout Room 178 sf Computer Lab 150 sf TOTAL 2,154 sf TOTAL SITE/ BUILDING COMMON SPACES 5,479 SF FIRST FLOOR SPACES Ofﬁce/ Commercial Space 5,168 sf Community Room 893 sf Mail / Restrooms / Bike Storage 498 sf SECOND FLOOR SPACES Arts-n-Crafts Room 378 sf Library 286 sf Billiards Room 269 sf Workout Room 178 sf Computer Lab 150 sf PO Box 1889 · Fort Collins, CO 80522-1889 970.472.9125 possess sufficient cohesion to permit testing in the unconfined state. Bearing Capacity Analysis for Foundations Water Content Used to determine the quantitative amount of water in a soil mass. Index Property Soil Behavior 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 = D60/D10 Cc = 10 60 2 30 D x D (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. H If fines are organic, add “with organic fines” to group name. 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. Silt or Clay Descriptive Term(s) of other constituents N (HP) (T) (DCP) (PID) (OVA) < 15 15 - 29 > 30 Term PLASTICITY DESCRIPTION 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. Water Level After a Specified Period of Time Water Level After a Specified Period of Time Water Initially Encountered Modified Dames & Moore Ring Sampler Standard Penetration Test 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 actual topographical survey was conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic maps of the area. Standard Penetration Test Resistance (Blows/Ft.) Hand Penetrometer Torvane Dynamic Cone Penetrometer Photo-Ionization Detector Organic Vapor Analyzer STRENGTH TERMS Standard Penetration or N-Value Blows/Ft. Descriptive Term (Consistency) Descriptive Term (Density) 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 Standard Penetration or N-Value Blows/Ft. (More than 50% retained on No. 200 sieve.) Density determined by Standard Penetration Resistance RELATIVE DENSITY OF COARSE-GRAINED SOILS Hard > 30 > 50 Very Stiff 15 - 30 Stiff Medium Stiff Very Soft 0 - 1 Medium Dense Loose Soft Very Dense Dense 30 - 50 8 - 15 10 - 29 4 - 8 4 - 9 2 - 4 Very Loose 0 - 3 BORING ID 10 14 6 50 1.5 8 200 1 140 coarse fine COEFFICIENTS % COBBLES % GRAVEL % SAND D30 D10 CC PERCENT FINER BY WEIGHT PERCENT COARSER BY WEIGHT % SILT 100.0 99.31 97.71 95.21 91.66 85.55 67.7 GRAIN SIZE DISTRIBUTION ASTM D422 CL 1 1/2" 1" 3/4" 1/2" 3/8" #4 #10 #20 #40 #60 #100 #200 9 - 10.5 PROJECT NUMBER: 20165021 PROJECT: Oakridge Crossing SITE: Oakridge Drive and McMurry Avenue Fort Collins, CO CLIENT: McDermott Properties Centennial, Colorado EXHIBIT: B-7 1901 Sharp Point Drive, Suite C Fort Collins, Colorado LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS 1 20165021.GPJ 35159097 - ATTERBERG ISSUE.GPJ 3/10/16 70 60 50 40 30 20 10 0 REMARKS COBBLES SILT OR CLAY GRAVEL SAND medium 12.0 4.5 U.S. SIEVE NUMBERS 4 4 6 100 3 2 fine coarse SOIL DESCRIPTION CU 22.73 22.23 BORING ID 10 14 6 50 1.5 8 200 1 140 coarse fine COEFFICIENTS % COBBLES % GRAVEL % SAND D30 D10 CC PERCENT FINER BY WEIGHT PERCENT COARSER BY WEIGHT % SILT GRAIN SIZE DISTRIBUTION ASTM D422 SM SW 24 - 24.8 9 - 10.5 9 - 10 PROJECT NUMBER: 20165021 PROJECT: Oakridge Crossing SITE: Oakridge Drive and McMurry Avenue Fort Collins, CO CLIENT: McDermott Properties Centennial, Colorado EXHIBIT: B-6 1901 Sharp Point Drive, Suite C Fort Collins, Colorado LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS 1 20165021.GPJ 35159097 - ATTERBERG ISSUE.GPJ 3/10/16 10 0 REMARKS COBBLES SILT OR CLAY GRAVEL SAND medium 43.5 59.1 70.2 U.S. SIEVE NUMBERS 4 4 6 100 3 2 fine coarse SOIL DESCRIPTION CU BORING ID 10 14 6 50 1.5 8 200 1 140 coarse fine COEFFICIENTS % COBBLES % GRAVEL % SAND D30 D10 CC PERCENT FINER BY WEIGHT PERCENT COARSER BY WEIGHT % SILT 92.55 92.55 92.55 90.39 85.82 76.86 67.63 59.57 52.6 43.5 100.0 95.79 95.11 93.29 90.89 86.27 81.46 76.48 69.86 59.12 100.0 99.66 99.39 98.84 97.75 95.37 89.11 70.25 GRAIN SIZE DISTRIBUTION ASTM D422 SC CL CL 1 1/2" 1" 3/4" 1/2" 3/8" #4 #10 #20 #40 #60 #100 #200 9 - 10.5 4 - 5 14 - 15.5 PROJECT NUMBER: 20165021 PROJECT: Oakridge Crossing SITE: Oakridge Drive and McMurry Avenue Fort Collins, CO CLIENT: McDermott Properties Centennial, Colorado EXHIBIT: B-5 1901 Sharp Point Drive, Suite C Fort Collins, Colorado LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS 1 20165021.GPJ 35159097 - ATTERBERG ISSUE.GPJ 3/10/16 20 10 0 REMARKS COBBLES SILT OR CLAY GRAVEL SAND medium 66.7 95.7 U.S. SIEVE NUMBERS 4 4 6 100 3 2 fine coarse SOIL DESCRIPTION CU BORING ID 10 14 6 50 1.5 8 200 1 140 coarse fine COEFFICIENTS % COBBLES % GRAVEL % SAND D30 D10 CC PERCENT FINER BY WEIGHT PERCENT COARSER BY WEIGHT % SILT GRAIN SIZE DISTRIBUTION ASTM D422 CL CH 4 - 5 19 - 20.5 4 - 5 PROJECT NUMBER: 20165021 PROJECT: Oakridge Crossing SITE: Oakridge Drive and McMurry Avenue Fort Collins, CO CLIENT: McDermott Properties Centennial, Colorado EXHIBIT: B-4 1901 Sharp Point Drive, Suite C Fort Collins, Colorado LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS 1 20165021.GPJ 35159097 - ATTERBERG ISSUE.GPJ 3/10/16 70 60 50 40 30 20 10 0 REMARKS COBBLES SILT OR CLAY GRAVEL SAND medium 31.5 10.9 U.S. SIEVE NUMBERS 4 4 6 100 3 2 fine coarse SOIL DESCRIPTION CU 2.54 BORING ID 10 14 6 50 1.5 8 200 1 140 coarse fine COEFFICIENTS % COBBLES % GRAVEL % SAND D30 D10 CC PERCENT FINER BY WEIGHT PERCENT COARSER BY WEIGHT % SILT 100.0 99.45 80.7 70.0 56.93 100.0 99.05 95.46 90.53 81.46 70.22 57.27 45.7 31.47 100.0 99.76 98.44 96.88 92.2 36.78 10.86 GRAIN SIZE DISTRIBUTION ASTM D422 SC SP-SM 1 1/2" 1" 3/4" 1/2" 3/8" #4 #10 #20 #40 #60 #100 #200 2 - 3.5 9 - 10.5 19 - 19.5 PROJECT NUMBER: 20165021 PROJECT: Oakridge Crossing SITE: Oakridge Drive and McMurry Avenue Fort Collins, CO CLIENT: McDermott Properties Centennial, Colorado EXHIBIT: B-3 1901 Sharp Point Drive, Suite C Fort Collins, Colorado LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS 1 20165021.GPJ 35159097 - ATTERBERG ISSUE.GPJ 3/10/16 23 13 17 15 NP 13 15 14 9 28 18 22 15 NP 12 21 31 67 96 44 59 70 12 4 68 LL USCS 2 3 3 4 5 5 5 P1 P3 ATTERBERG LIMITS RESULTS ASTM D4318 9 - 10.5 4 - 5 19 - 20.5 9 - 10.5 4 - 5 14 - 15.5 24 - 24.8 9 - 10.5 9 - 10.5 PROJECT NUMBER: 20165021 PROJECT: Oakridge Crossing SITE: Oakridge Drive and McMurry Avenue Fort Collins, CO CLIENT: McDermott Properties Centennial, Colorado EXHIBIT: B-2 1901 Sharp Point Drive, Suite C Fort Collins, Colorado LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20165021.GPJ TERRACON2015.GDT 3/4/16 CL-ML SAMPLE TYPE WATER LEVEL OBSERVATIONS DEPTH (Ft.) 5 10 SWELL-CONSOL / LOAD (%/psf) FIELD TEST RESULTS DEPTH LOCATION See Exhibit A-2 Latitude: 40.52133196° Longitude: -105.047601° No free water observed during drilling No free water measured 3/1/16 WATER LEVEL OBSERVATIONS WATER LEVEL OBSERVATIONS DEPTH (Ft.) 5 10 SWELL-CONSOL / LOAD (%/psf) FIELD TEST RESULTS DEPTH LOCATION See Exhibit A-2 Latitude: 40.52070198° Longitude: -105.047747° No free water observed during drilling No free water measured 3/1/16 WATER LEVEL OBSERVATIONS WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI Surface Elev.: 100.69 (Ft.) ELEVATION (Ft.) SAMPLE TYPE WATER LEVEL OBSERVATIONS DEPTH (Ft.) 5 10 SWELL-CONSOL / LOAD (%/psf) FIELD TEST RESULTS DEPTH LOCATION See Exhibit A-2 Latitude: 40.52077901° Longitude: -105.048449° No free water observed during drilling No free water measured 3/1/16 WATER LEVEL OBSERVATIONS See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. PROJECT: Oakridge Crossing UNCONFINED COMPRESSIVE STRENGTH (psf) PERCENT FINES WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI Surface Elev.: 100.96 (Ft.) ELEVATION (Ft.) SAMPLE TYPE WATER LEVEL OBSERVATIONS DEPTH (Ft.) 5 10 15 20 SWELL-CONSOL / LOAD (%/psf) FIELD TEST RESULTS DEPTH LOCATION See Exhibit A-2 Latitude: 40.52117698° Longitude: -105.047385° No free water observed during drilling Water level on 3/1/16 WATER LEVEL OBSERVATIONS UNCONFINED COMPRESSIVE STRENGTH (psf) PERCENT FINES WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI Surface Elev.: 100.02 (Ft.) ELEVATION (Ft.) SAMPLE TYPE WATER LEVEL OBSERVATIONS DEPTH (Ft.) 5 10 15 20 SWELL-CONSOL / LOAD (%/psf) FIELD TEST RESULTS DEPTH LOCATION See Exhibit A-2 Latitude: 40.52084598° Longitude: -105.04755° While drilling Water level on 3/1/16 WATER LEVEL OBSERVATIONS Exhibit: A-6 See Exhibit A-3 for description of field procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and abbreviations. PROJECT: Oakridge Crossing UNCONFINED COMPRESSIVE STRENGTH (psf) PERCENT FINES WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI Surface Elev.: 99.55 (Ft.) ELEVATION (Ft.) SAMPLE TYPE WATER LEVEL OBSERVATIONS DEPTH (Ft.) 5 10 15 20 SWELL-CONSOL / LOAD (%/psf) FIELD TEST RESULTS DEPTH LOCATION See Exhibit A-2 Latitude: 40.520433° Longitude: -105.047213° While drilling Water level on 3/1/16 WATER LEVEL OBSERVATIONS abbreviations. PROJECT: Oakridge Crossing UNCONFINED COMPRESSIVE STRENGTH (psf) PERCENT FINES WATER CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI Surface Elev.: 98.82 (Ft.) ELEVATION (Ft.) SAMPLE TYPE WATER LEVEL OBSERVATIONS DEPTH (Ft.) 5 10 15 20 25 SWELL-CONSOL / LOAD (%/psf) FIELD TEST RESULTS DEPTH LOCATION See Exhibit A-2 Latitude: 40.52054901° Longitude: -105.047874° While drilling Water level on 3/1/16 WATER LEVEL OBSERVATIONS CONTENT (%) DRY UNIT WEIGHT (pcf) ATTERBERG LIMITS LL-PL-PI Surface Elev.: 100.21 (Ft.) ELEVATION (Ft.) SAMPLE TYPE WATER LEVEL OBSERVATIONS DEPTH (Ft.) 5 10 15 20 SWELL-CONSOL / LOAD (%/psf) FIELD TEST RESULTS DEPTH LOCATION See Exhibit A-2 Latitude: 40.52041498° Longitude: -105.048557° While drilling Water level on 3/1/16 WATER LEVEL OBSERVATIONS