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Home My WebLink AboutMAVERIK AT I 25 AND HIGHWAY 392 - PDP200001 - SUBMITTAL DOCUMENTS - ROUND 4 - DRAINAGE REPORTDrainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 1 Preliminary Drainage Report for Maverik Inc. Store I-25 & North County Road 32 (Hwy 392) Fort Collins, Colorado 80528 # PERMIT NO. Prepared for: Maverik, Inc. 185 South State Street Suite 800 Salt Lake City, Utah 84111 Prepared by: DCI Engineers 1331 17th Street, Suite 605 Denver, Colorado (720) 464-7728 DCI Job No. 19-122-0006 March 11, 2020 Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 2 Engineer’s Certification: I hereby affirm that this report and plan for the preliminary drainage design for Maverick Fuel Station Fort Collins was prepared by me, or under my direct supervision, for the owners thereof, in accordance with the provision for City of Fort Collins Stormwater Criteria Manual (2017), and approved variances and exceptions thereto. I understand that they the City of Fort Collins does not and will not assume liability for drainage facilities designed by others. By: Manuel H. Nuño, P.E. Licensed Professional Engineer State of Colorado No. 52773 Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 3 Developer’s Certification: Maverik, Inc. hereby certifies that the drainage facilities for the Maverick Fuel Station Fort Collins shall be constructed according to the design presented in this report. I understand that the City of Fort Collins does not and will not assume liability for the drainage facilities designed and/or certified by my engineer and that the City of Fort Collins reviews drainage plans pursuant to Colorado Revised Statutes; but cannot, on behalf of Maverik, Inc. guarantee that final drainage design review will absolve Maverik, Inc. and/or their successors and/or assigns of future liability for improper design. I further understand that approval of the Preliminary Drainage Report does not constitute approval of my engineer’s final drainage design. Name Authorized Signature Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 4 SECTION 1. GENERAL LOCATION AND EXISTING SITE INFORMATION SITE LOCATION The proposed Maverick Fuel Station is located in the City of Fort Collins, within Larimer County in Colorado. The proposed 2.84 acre plot of land is comprised of one parcel #8615305702 with East County Road 32/Highway 392 to the South, Interstate 25 to the east, and SW Frontage Road, a federal right -of-way, to the North. Swede Lake is Northwest of the site. The proposal includes 9 standard fuel dispensers and 6 hi-flow commercial diesel dispensers. A total of 25 off-street parking spaces will be provided. Access is taken from SW Frontage Rd to the northwest. The property is within the I-25/State Highway 392 Corridor Activity Center in the General Commercial (CG) Zoning District and is subject to Planning and Zoning Board (Type 2) Review. East County Rd Fossil Creek Reservoir SW Frontage Rd DCI Engineers December 13, 2019 5 ___________________________ TOWNSHIP, RANGE SECTION AND ¼ SECTION The Colorado State Land Board maintains records of the Cadastral Survey of the state for purposes of establishing legal property boundaries in proposed land subdivisions. The proposed property is located in a portion of the SW ¼ of the Township 6N, Range 68W , Section 15 inside the 6 th Meridian in the State of Colorado. A survey was performed by Altura Land Consultants dated May 15, 2019, last revised June 3, 2019. The legal description, as identified on the Title Survey from Altura Land Consultants, is as follows: Lot 2, Interstate Land Holdings Minor Land Division File No. 12-S3124, County of Larimer, State of Colorado The proposed development is located within the boundary of the City of Fort Collins, within Larimer County in Colorado. The site is bordered by East County Road 32/Highway 392 to the South, Interstate Highway 25 to the East, and SW Frontage Road, a federal right-of-way, to the North.. Proposed driveway connections and improvements shall be subject to the review and approval of the Interstate Land Holdings Minor Land Division. The parcel is located in the General Commercial zoning district. Adjacent lots around the subject property consist of vacant lots and commercial uses. The Fossil Creek Reservoir is located northwest of the property. DESCRIPTION OF PROPERTY The proposed development consists of 2.841 acres of undeveloped property. The site consists of one parcel #8615305702. An analysis by DCI Engineers using a modified rational method indicates a weighted impervious percentage of 76% for the complete build out. Under the criteria of Table 4.1-2 and 3 from Chapter 5 of the Fort Collins Stormwater Criteria Manual, areas within the development were separated into categories. Roofs were assigned an impervious percentage of 90%, sidewalks and asphalt pavements received a 100% percent categorization, and lawn and landscaped areas were assigned a 2% weighted impervious percentage. The resulting calculations can be found in Appendix A _ Drainage Report: Maverick Fuel Station Fort Collins Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers December 13, 2019 6 At full build out, the proposed site includes approximately 2.17 acres of proposed impervious area, including rooftops, roadways, and paved sidewalk/courtyard areas. Approximately 6,662 cubic yards of soil will be removed and replaced or exported with the current proposed plan. The development will increase the impervious area by the full 75% (from the existing undeveloped land). The site currently consists of undeveloped property covered with low-lying vegetation. The land generally drains to the northwest with an approximate change in elevation of ten feet over a horizontal distance of 350 feet towards the interstate ramp road. Figure 1- Proposed project site facing north from Highway 392 Figure 2- Proposed project site facing west from Interstate 25 DCI consulted the Natural Resources Conservation Service’s (NRCS) Web Soil Survey for a description of local soil types in the area. The natural soils encountered at the site predominantly consisted of wiley silt loam and are classified as belonging to Hydrologic Soil Group C . Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers December 13, 2019 7 The site lies within the South Platte River Basin inside the Cache La Poudre River sub-basin. Inside the Cache La Poudre River sub-basin, the site is adjacent to the Fossil Creek drainage sub-basin. DCI Engineers consulted the latest FEMA Flood Insurance Rate Maps to analyze the potential floodplain delineations for the site. According to the FEMA Map 08069C1201F, the site is located in Zone X, which corresponds to an area outside of the boundary of the 500- year design storm floodplain. The DFIRM was last revised in April 2019. . SECTION 2. MASTER DRAINAGE BASIN DESCRIPTION MAJOR DRAINAGE BASINS The State of Colorado is comprised of seven major river basins that are governed by separate divisions within the Colorado Department of Water Resources. The City and County of Denver make up the largest metropolitan city within the South Platte River Basin. The River Basin covers approximately 22,000 square miles in northeastern Colorado and accounts for nearly two-thirds of the state’s gross municipal and industrial water demand. Estimates of the total demand for the South Platte River Basin fall between 324,000 and 467,000 acre-feet of water per year. Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers December 13, 2019 8 The South Platte Basin supports a wide range of water needs including municipal, industrial, agricultural as well as important water-dependent ecological and recreational attributes. Coloradoans and tourists regularly enjoy the recreational opportunities provided by the many environmental features of the basin. Within the South Platte River Basin, the site lies inside the Cache La Poudre River sub-basin. Inside the Cache La Poudre River sub-basin, the site is adjacent to the Fossil Creek drainage sub-basin. A Problem Identification Map was developed by the City of Fort Collins to identify the unique challenges associated within this basin. There were no problems located within the vicinity of the project site. Flood control is shown for the land in the sub-basin near the project site under the City of Fort Collins Selected Plan - Water Quality Improvements. The Fossil Creek drainage basin extends along the south end of Fort Collins, from the foothills across Interstate 25 past County Road 5. It encompasses 32 square miles in the city of Fort Collins and Larimer County. Historically, the basin consisted of agricultural land, but the basin has experienced significant development in the recent past. The original 1982 master plan mapped a floodplain and restricted developed from the floodplain; hence, fewer structures are damaged. An estimated 117 homes, 13 roads, and three railroads would be damaged during a 100-year storm with an estimated $10.6 million in damage. Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers December 13, 2019 9 The existing surface conditions were considered to be entirely pervious. In the fully developed condition, we propose a weighted impervious percentage of approximately 76% (per the land use calculations in Appendix A), well within the defined boundaries of the previous studies for the watershed. The basin drains to the Fossil Creek Reservoir outlet under Interstate-25. As a part of this proposal, we intend to capture the onsite stormwater within underground piped structures which shall be conveyed into water quality sand filters as part of the Low Impact Design requirements and ultimately into an engineered detention pond along the western boundary of the site. Stormwater detention shall consist of surface detention per the City of Fort Collins Stormwater Criteria with discharge being limited to the 2-year historic release rate for the Fossil Creek Basin (0.2 CFS/acre). Offsite flows shall continue their existing flow-path along CDOT maintained vegetated swales along the exterior of the proposed Maverik property. After mitigating for onsite flows and accounting for offsite stormwater flows in the existing swales around the site, there is no anticipated impact to the drainageway. MINOR DRAINAGE BASINS The City of Fort Collins contains various irrigation channels designed to carry flows to different regions within the city limits. At the time of the proposed development, there are no current irrigation channels within the proposed limits of the study. Flows from the surrounding interstate off-ramp improvements are carried via vegetated surface swales to an outlet in the northwest corner of this site. The off-site flow patterns and paths will not be impacted by the proposed development on the property. The proposed Maverik site plan has been designed to allow the un-obstructed capture and conveyance of the proposed off-site flows up to the 100 year recurrence interval and bypass them safely to the existing roadside vegetated swale that was installed as part of the CDOT interchange work. Flows along this swale are conveyed towards the north into an existing culvert that travels underneath Frontage Road and into Fossil Creek. In addition, the detention basin has been designed with emergency overflows capable of discharging the fully developed 100 year un-detained flow from the 2.841 acre property. The proposed site was split into five (5) separate sub-basins delineated by general flow patterns. Roofs and canopies were treated as single basins capturing flows in an internal piped system and discharging downstream via roof downspouts. Streets and patios were separated based on anticipated slopes and drainage conditions. Flows for the entire development have been designed to slow into LID sand filters prior to reaching the detention structure. Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 10 SECTION 3. FLOODPLAIN INFORMATION DCI Engineers consulted the latest FEMA Flood Insurance Rate Maps to analyze the potential floodplain delineations for the site. According to the FEMA Map 08069C1201F, the site is located in Zone X, which corresponds to an area outside of the boundary of the 500- year design storm floodplain. The DFIRM was last revised in April 2019. SECTION 4. PROJECT DESCRIPTION The subject property consists of 2.841 acres. A commercial gas station with supplementing paved parking is proposed for the subject property. The proposed 6,130 square foot convenience store facility will front SW Frontage Road and proposes approximately 1900 sf of landscaped areas . SECTION 5. PROPOSED DRAINAGE FACILITIES A 25,000 cubic foot detention facility designed to comply with the City of Fort Collins Criteria Manual is proposed on the western boundary of the site. Grading and surface runoff shall be utilized to minimize structural BMP devices in the proposed conditions. Landscaped areas shall be utilized to assist with water quality. SECTION 6. DRAINAGE DESIGN CRITERIA FOUR STEP PROCESS TO MINIMIZE ADVERSE IMPACTS OF URBANIZATION The Mile High Flood District and the City of Fort Collins employ a four step process to reduce the negative effects of urbanization on our existing waterways. The four steps include 1. Employing Runoff Reduction Practices 2. Implement BMPs that incorporate the water quality volume with slow release 3. Stabilizing streams 4. Implementing site specific and other source control BMPs In keeping with the requirements of the City of Fort Collins Storm Water Manual, the proposed Maverik site has been designed with ample open space that aids in the water quality treatment on the site. While large expanses of pavement are required for the standard operation of a fueling station, the proposed site plan has incorporated surface detention and surface treatment through sand filters in addition to decorative landscaping around the site. Water quality for the site is managed through a system of sand filters that have been designed to meet the criteria of the City of Fort Collins and the Mile High Flood District. Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 11 Each sand filter captures the proposed water quality control volume for its tributary basin and slowly releases the volume to the downstream detention as it filters through the sand and into the underdrain system below. Due to the nature of the proposed development, site source controls will be implemented to prevent the potential effects of urbanization to the Fossil Creek Watershed. In addition to implementing Low Impact Design practices, Maverik proposes the use of spill containment chambers or tanks underneath fueling canopies to prevent against the un-foreseen release of oil and fuel based contaminants into the downstream waterways. REGULATIONS The proposed development is located within the boundaries of the City of Fort Collins and is thus subject to the latest stormwater standards of the Fort Collins Stormwater Criteria Manual revised in December 2018. In accordance with the latest guideline, this project was analyzed with minimum and maximum release rate(s) for the developed condition 100-year recurrence interval storm. For developments smaller than 5 acres, the rational method is an accepted method for determining pre and post developed hydrology. The project’s contributing area, totaling 2.841 acres, falls into the five-acre threshold where the Modified FAA procedure is required for basin sizing. The project was analyzed using a modified FAA Rational Method in accordance with Table 6-3. The rational method is based on the direct relationship between rainfall and runoff and can be expressed by the equation. Q = CIA In which: Q = the peak rate of runoff (cubic feet per second [cfs]) C = the runoff coefficient that is the ratio between the runoff volume from an area and the average rainfall depth over a given duration for that area I = the average intensity of rainfall for a duration equal to the time of concentration (inches/hour) A = basin area (acres) Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 12 The runoff coefficients for each sub-watershed are available in the Appendix and based off of Table 3.2-2. DCI Engineers has prepared a Stormwater Site Plan for review by the City of Fort Collins. It is understood that prior to the acceptance of the project, this Preliminary Plan shall be made final and submitted for approval by the ruling jurisdiction. Included in the Plan Review is an existing conditions map, a map of proposed development, this Preliminary Drainage report, and an approved Soils report prepared by a geotechnical professional. Prior to the start of construction, a site Storm Water Pollution Prevention Plan (SWPPP) shall be prepared by DCI Engineers and submitted to the City of Fort Collins and the Colorado Department of Environmental Health. The Fort Collins Stormwater Criteria Manual calls for development and redevelopment projects that discharge stormwater directly, or indirectly through a conveyance system, into a surface waterbody to meet strict flow control criteria. Projects in which a total effective impervious surface is 1,000 square feet or more are required match developed discharge durations to pre-developed durations for the historic release rate of the individual drainage sub-basin. For the Fossil Creek Basin, the historic release rate is equivalent to 0.2 cfs per acre. DRAINAGE STUDIES, OUTFALL SYSTEMS PLANS, SITE CONSTRAINTS The project site has been the subject of various drainage studies and reports over the last 20 years. Maps of the Poudre River Floodplain were created for the first time in 1975. The city adopted floodplain regulations beginning in 1979. This particular site lies adjacent to the Fossil Creek drainage basin. The Master Plan for the Fort Collins drainage basins is underway at the time this report was written. A Problem Identification Map was developed by the city of Fort Collins to identify the unique challenges associated within this basin. There were no problems shown to be near the project site. Flood control is shown for the land in the sub-basin near the project site under Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 13 the Selected Plan - Water Quality Improvements. The nearest “problem area” is located approximately 12,000 feet to the west along the Fossil Creek river. The proposed development associated with Maverick Fuel Station Fort Collins includes a detention basin that has been sized to handle the stormwater runoff from the 2.841 acre development. The offsite flows into the property will not flow-through the basin, but rather will be carried through a separate swale that conveys flows around the property towards the Fossil Creek Reservoir Outlet. The swales were constructed and maintained by CDOT as part of the 2011 I-25 and Highway 392 Interchange Project. HYDROLOGY The project’s contributing area, totaling 2.84 acres, contains multiple sub-basins that are under the five-acre threshold for the use of the Rational Method: The rational method is based on the direct relationship between rainfall and runoff and can be expressed by the equation Q = CIA In which: Q = the maximum rate of runoff (cubic feet per second [cfs]) C = the runoff coefficient that is the ratio between the runoff volume from an area and the average rainfall depth over a given duration for that area I = the average intensity of rainfall for a duration equal to the time of concentration (inches/hour) A = basin area (acres) Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 14 Table 3.2-2. Surface Type - Runoff Coefficients Surface Type Runoff Coefficients Hardscape or Hard Surface Asphalt, Concrete 0.95 Rooftop 0.95 Recycled Asphalt 0.8 Gravel 0.5 Pavers 0.5 Landscape or Pervious Surface Lawns, Sandy Soil, Flat Slope < 2% 0.1 Lawns, Sandy Soil, Avg Slope 2-7% 0.15 Lawns, Sandy Soil, Steep Slope >7% 0.2 Lawns, Clayey Soil, Flat Slope < 2% 0.2 Lawns, Clayey Soil, Avg Slope 2-7% 0.25 Lawns, Clayey Soil, Steep Slope >7% 0.35 Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 15 IDF curves for Rational Method Duration (min) Intensity 2- year (in/hr) Intensity 100- year (in/hr) 5.00 2.85 9.95 10.00 2.21 7.72 15.00 1.87 6.52 20.00 1.61 5.60 25.00 1.43 4.98 30.00 1.30 4.52 35.00 1.17 4.08 40.00 1.07 3.74 45.00 0.99 3.46 50.00 0.92 3.23 55.00 0.87 3.03 60.00 0.82 2.86 65.00 0.78 2.71 70.00 0.73 2.59 75.00 0.70 2.48 80.00 0.66 2.38 85.00 0.64 2.29 90.00 0.61 2.21 95.00 0.58 2.13 100.00 0.56 2.06 105.00 0.54 2.00 110.00 0.52 1.94 115.00 0.51 1.88 120.00 0.49 1.84 Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 16 The basis of storm drainage and hydrologic design for the City of Fort Collins is found in Chapters 5 and 6 of the Fort Collins Stormwater Criteria Manual. An analysis of the Isopluvial Maps show that all areas within the Fort Collins area can be described within a single rainfall zone with minimal variation. The 1-hour duration rainfall depth for various recurrence intervals has historically been used for the calculation of runoff using the Rational method. For the purpose of small urban watersheds less than 20 acres in size, a rainfall intensity duration frequncy curve can be used in association with the Rational Method, to determine rainfall intensity distribution over the period of the 1 hour duration.quation 5.1 from the SDDTC decribes the intensity with the following equation: Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 17 DETENTION STORAGE CALCULATION New development and significant redevelopment in the City of Fort Collins is governed by the Fort Collins Stormwater Criteria Manual. Per the Fort Collins Stormwater Criteria Manual, the Modified FAA Procedure was utilized to size the detention volume. The peak control volume for the 100 year was determined, while maintaining release rates at the historic 2 year release for the Fossil Creek Basin. The City of Fort Collins utilizes the criteria described in the Storm Drainage Design and Technical Criteria as well as the District Manual to determine infiltration potential as it relates to soil types. In general, hydrologic soils group are classified into four categories based on ability to infiltrate stormwater. Hydrologic Group A has the highest capacity for infiltration, Hydrologic Group B is considered moderate, while Groups C and D are considered poor drainage and generally unsuitable for infiltration. An investigation of soils groups through the National Resource Conservation Service (NRCS) for our site indicates that the majority of soils within the project area can be classified as Hydrologic Group C based on the results of an NRCS Web Soil Survey analysis. Storm drainage runoff shall be determined by the Rational Method because the site is less than 5 acres. Table 2.0-1 below summarizes the acceptable methods along with an established criterion for the use of each method. Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 18 The drainage system shall account for runoff from both minor and major storm events as required in Section 1.4 of the FCSWCM. The design capacity for the development for the major and minor storm events does not include the effects of onsite detention on the peak flows. In all cases, the onsite system has been designed to minimize life hazards and health, damage to structures, and interruption to traffic and services associated with the 100-year storm event. The City of Fort Collins maintains a policy requirement for onsite detention of flood flows for all development and redevelopment projects as defined in the Fort Collins Stormwater Criteria Manual (FCSCM). Onsite detention is required or all projects proposing 1,000 sf of impervious coverage or more. Storage for the onsite detention of runoff shall be governed by the policies set forth in Chapter 6 of the Criteria Manual. The City of Fort Collins requires the Modified FAA Procedure for water quality detention design for sites less than 5 acres. The Modified FAA Procedure determines volumetric storage for peak flows. The FCSCM requires a peak release rate for the 100 year storm for the post developed condition to be no greater than the 2 year historic release rate of 0.2 cfs per acre. In order to detain the difference between the post-developed 100 year flow rate and the historic 2-year flows, the detention pond must hold approximately 25,000 CF of runoff with a metered outflow to Fossil Creek. Detention Pod calculations can be found in Appendix A. HYDRAULICS In accordance with the City of Fort Collins standards, drainage for the proposed Maverik Fuel Station has been designed to adequately capture and convey the runoff form the site for both the major and minor storm event. Pipes, swales, and catch basins have been designed to handle the 2-year developed flow rate as well as the 100-year major storm event based on a rational method analysis of each sub-drainage basin. We have assumed a frost depth of 30” from finished surface. HYDRAULIC GRADE LINE CALCULATION METHOD Private storm drainage for the property has been designed using the hydraulic grade line calculation and the methods outlined below. For the purposes of design, Manning’s equation was used to calculate the available pipe capacity at full flow for a stretch of pipe. Manning’s Equation is shown below: Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers March 11, 2020 19 Q = (1.49/n) AR 2/3 S ½ Where Q = available flow rate (cfs) n = Manning’s roughness factor A = cross sectional flow area (sf) R = hydraulic radius = D/4 (ft) S = friction slope (ft/ft) In order to analyze the hydraulic capacity of the onsite storm drain system, head losses were calculated through the pipe network to determine the Energy Grade Line. Head losses through pipe networks are defined by the following equation H = KoCD CdCQ CPCB (V2/2g) Where K = initial loss coefficient V = velocity in the outflow pipe g = gravitational acceleration (32.2 ft/sec2) C = correction factors for pipe size, bends, etc. WATER QUALITY ENHANCEMENT Per the current requirements of the Fort Collins Stormwater Manual, all new or redevelopment projects are required to implement Low Impact Development design as part of the initial site concept. The land Use Code allows for adherence to the L.I.D. requirements by one of the following options: 1. 50% of the newly added or modified impervious areas must be treated by LID techniques and 25% of new paved areas must be pervious 2. 75% of all newly added or modified impervious areas must be treated by LID techniques. Due to the soil conditions on this site, the use of pervious pavements is not recommended. As a result, Maverik proposed compliance with the Low Impact Development requirement using Option 2. The site proposes the use of L.I.D. sand filters to treat 100% of new impervious areas on the site. Sand Filters were designed in accordance with Chapter 7 of the FCSM as well as the Low Impact Development Implementation Manual (July 2017). Best Management Practices were designed to capture and treat the Water Quality Capture Volume as specified in the equation below Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers December 13, 2019 20 WQCV = a (0.91 3 – 1.19I 2 + 0.78I ) WQCV = Water Quality Control Volume (in watershed inches) A = Coefficient corresponding to WQCV drain time [Table 5.4.-1] I = Imperviousness (%/100) From FCSCM Table 5.4-1: Drain Time Coefficients for WQCV Calculations The required BMP Storage Volume, V is computed using Equation 7-2: V = (WQCV / 12 ) x A x 1.2 V = required volume, acre-ft A = tributary catchment area upstream, acres WQCV = Water Quality Capture Volume, watershed inches 1.2 = to account for the additional 20% of required storage for sedimentation accumulation DCI proposes the use of engineered sand filters to capture and remove pollutants from the asphalt and concrete roadways prior to conveyance into the detention pond. The sand filter consists of a surcharge zone underlain by a sand bed with a perforated pipe underdrain system. A forebay consisting of 1% of the WQCV shall be implemented at each sand filter. Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers December 13, 2019 21 Three sand filters are proposed on the site. Sand Filter A, which is designed to treat flows coming from the passenger vehicle fueling court treats 1.29 acres of tributary area for a total volume of 1,916 cubic feet. Sand Filter B corresponds to a tributary area of 0.49 acres which captures flows from a large portion of the commercial fueling court on the south side of the building. Lastly, flows from the building roofs, canopies, and the northern portion of the commercial fueling court are conveyed into a curb inlet to a designed sand filter located just west of the proposed structure. Sand Filter C has been designed to capture the water quality flows from 0.8 acres of tributary area for a total volume of 1,394 cubic feet. Immediately underneath the fueling canopies, Maverik proposes the use of an underground storage chamber system designed to capture potential spills or leaks of fuel or oil- contaminated water prior to entering the storm drain system. The sill containment chambers will capture potential contaminants and treat them through an oil/water separator prior to discharge into the downstream detention system. An LID Site Plan has been included in the appendices. EROSION CONTROL Maverik, Inc. is dedicated to the preservation of the natural environment throughout the life cycle of the project. The project shall maintain compliance with all requirements of the City of Fort Collins Erosion Control Criteria, including the provisions of Chapters 3 and 4 of the Stormwater Manual. All Erosion Control Materials will be provided with the Final Drainage Report. Drainage Report: Maverick Fuel Station Fort Collins DCI Engineers December 13, 2019 22 SECTION 7: CONCLUSIONS The Preliminary Drainage Report for Maverik Fort Collins has been designed to comply with the requirements of the City of Fort Collins Stormwater Criteria Manual. The drainage has been analyzed using the Rational Method for the minor and major storm events. Through the use of an engineered detention pond, the site shall detain the difference between the 100-year developed flow rate and the 2-year historic flow rate for the Fossil Creek Basin. In addition, 100% of the site impervious area shall be treated for water quality utilizing Low Impact Development in accordance with the LID Implementation Manual. SECTION 8: APPENDICES Please refer to the attached Appendices for additional information/ reference documents. SECTION A: HYDROLOGIC COMPUTATIONS SECTION B: WATER QUALITY /LID COMPUTATIONS SECTION C: REFERENCE INFORMATION SD SS SS W W W W W W W W W W W W W W W W W W SS SS SS SS SS SS SS SS 2.03 7.06 H-1 2.84 5 PROJECT NUMBER ISSUE DATE: REVISIONS: MAVERIK INC. STORE I-25 & E. COUNTY RD. 32 / HIGHWAY 392 FORT COLLINS, CO No. Date Description NOTE: Conflicting information or errors found in the construction documents should be brought to the attention of the architect immediatly. In the event of a conflict in the drawings, bidder should not assume the least expensive option will meet the project requirements. Bid documents should not be separated or issued as partial sets to subcontractors. Bidders are responsible for all portions of the documents that pertain to work covered by sub-bids. Bidder assumes full responsibility for error or misinterpretations resulting from partial sets of Bidding Documents by itself or any sub-bidder. Plot Date: 2020-09-29 File Location: O:\1200-Denver\DCI-Civil\Projects\2019\19-122-0006-MAVERIK-FORT COLLINS-CO\19-122-0006PDP.dwg OF 1331 17TH STREET SUITE 605 DENVER, COLORADO 80202 PHONE: (720) 439-4700 WEBSITE: www.dci-engineers.com CIVIL / STRUCTURAL © 09/2020 This document, and the ideas and designs may not be reused, in whole or in part, without written permission from D'Amato Conversano Inc. D'Amato Conversano Inc. disclaims any responsibility for its unauthorized use. DECEMBER 13, 2019 SD SS SS SS W W W W W W W W W W W W W W W W W W SS SS SS SS SS SS SS SS SS W VAN STOP STOP LOADING ZONE 0.87 1.00 E 1.28 5 0.82 1.00 B 0.32 2 0.95 1.00 A 0.14 3 0.73 0.91 D 0.48 4 0.91 1.00 C 0.26 6 0.29 0.36 F 0.37 1 Q2 = 0.53 CFS Q100= 2.1 CFS PROJECT NUMBER ISSUE DATE: REVISIONS: Appendix A Hydrologic Computations PROJECT: Maverik - Fort Collins SUBJECT: COMPOSITE RUNOFF FACTORS JOB #: 19-122-0006 DATE: 10/6/2020 BY: SDK Basin Square Landscaped Landscaped Gravel Gravel Asphalt Asphalt Roof Roof Name Footage Acres sf Acres sf Acres sf Acres sf Acres C 2 C 10 C 100 I % A 6269 0.14 0 0.00 0 0.00 6269 0.14 0.95 0.95 1.00 95.0 B 13748 0.32 2486 0.06 11262 0.26 0 0.00 0.82 0.82 1.00 78.2 C 11140 0.26 569 0.01 10571 0.24 0 0.00 0.91 0.91 1.00 90.2 D 20833 0.48 6693 0.15 14140 0.32 0.00 0.73 0.73 0.91 65.1 E 55558 1.28 6088 0.14 49470 1.14 0.87 0.87 1.00 84.8 F 16218 0.37 15291 0.35 927 0.02 0.29 0.29 0.36 7.3 Totals: 123766 2.84 31127.00 0.71 0.00 86370 1.98 6269 0.14 0.72 0.72 0.90 71.6 Land Use Imp., I % Landscaped 2% Gravel 50% Asphalt/Concrete 95% Rooftop 95% C = ∑ (CiXAi) At WHERE: C=COMPOSITE RUNOFF COEFFICIENT Ci=RUNOFF COEFFICIENT FOR SPECIFIC AREA (Ai) Ai=AREA OF SURFACE WITH RUNOFF COEFFICIENT OF Ci At=TOTAL AREA OVER WHICH C IS APPLICABLE Composite Runoff Factors Surface Type Hardscape Surface or Hard Surface Asphalt, Concrete Rooftop Recylced Asphalt Pavers Landscape or Pervious Surface Lawns, Sandy Soil, Flat Slope <2% Lawns, Sandy Soil, Avg Slope <2-7% Lawns, Sandy Soil, Steep Slope >7% Lawns, Clayey Soil, Flat Slope <2% Lawns, Clayey Soil, Avg Slope <2-7% Lawns, Clayey Soil, Steep Slope >7% Gravel Runoff Coefficients 0.95 0.95 0.80 0.50 0.20 0.25 0.35 0.50 0.10 0.15 0.20 25 1.10 50 1.20 100 1.25 Storm Return Period Frequency Adjustment PROJECT: Maverik - Fort Collins SUBJECT: TIME OF CONCENTRATION JOB #: 19-122-0006 DATE: BY: SDK TIME OF CONCENTRATION TRAVEL TIME Tc CHECK FINAL Time TIME (Ti) [Max. 500'] (Tt) (Urbanized Basins) Tc to Basin Area 2Yr. Elevations Dist. Slope Ti Elevations Dist. Slope Vel. Tt Length Tc Peak** Remarks No. (acres) C VALUE Upstream Downstream (ft) (%) (min) Upstream Downstream (ft) (%) * (fps) (min) Tc (ft) (min) (min) Flow A 0.14 0.95 4884.2 4884 10 2.0 0.7 4884 4878.25 231 2.5 6 3.0 1.3 2.0 241 11.3 2.0 5.0 Developed B 0.32 0.82 4886 4885.9 2 5.0 0.4 4885.9 4878.25 385 2.0 6 2.7 2.4 2.8 387 12.2 2.8 5.0 Developed C 0.26 0.91 4886 4885.9 1 10.0 0.2 4885.9 4878.25 180 4.2 5 3.4 0.9 1.0 181 11.0 1.0 5.0 Developed D 0.48 0.73 4886 4885.9 1 10.0 0.3 4885.9 4878.25 440 1.7 5 1.9 3.9 4.2 441 12.5 4.2 5.0 Developed E 1.28 0.87 4886 4885.9 1 10.0 0.2 4885.9 4878.25 550 1.4 6 2.0 4.6 4.8 551 13.1 4.8 5.0 Developed F 0.37 0.29 4882.72 4882.62 0.5 20.0 0.4 4882.62 4878.25 62 7.0 6 5.7 0.2 0.6 63 10.3 0.6 5.0 Developed **NOTE: FORT COLLINS REQUIRES MIN. Tc=5 MIN. IN ALL CASES. A MAX. Tc OF 5 MIN. IS TYP. 10/6/2020 TC 19-122-0006_Drainage Calcs.xlsx 10/6/202011:27 AM STANDARD FORM SF-3 STORM DRAINAGE SYSTEM DESIGN (RATIONAL METHOD PROCEDURE) CALCULATED BY: SDK DATE: 10/6/20 JOB NO: PROJECT: Maverik - Fort Collins DESIGN STORM: 2 Year DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME BASIN DESIGN POINT AREA DESIG. AREA (Acres) RUNOFF COEFF Tc (min) C A (Acres) I (in/hour) Q (cfs) Tc (min) (C A) (Acres) I (in/hour) Q (cfs) SLOPE (%) STREET FLOW (cfs) DESIGN FLOW (cfs) SLOPE (%) PIPE SIZE (in) LENGTH (ft) VELOCITY (fps) Tt (min) REMARKS A 1 A 0.14 0.95 5.00 0.14 2.85 0.4 5.0 0.14 2.85 0.4 COLLECTED IN NORTH ROOFTOP B 2 B 0.32 0.82 5.00 0.26 2.85 0.74 5.0 0.40 2.85 1.1 COLLECTED IN PARKING INLET C 3 C 0.26 0.91 5.00 0.23 2.85 0.67 5.0 0.23 2.85 0.67 COLLECTED IN PARKING CURB OPEN D 4 D 0.48 0.73 5.00 0.35 2.85 1.0 5.0 0.58 2.85 1.65 COLLECTED IN PARKING CURB OPEN E 5 E 1.28 0.87 5.00 1.11 2.85 3.2 5.0 1.11 2.85 3.2 COLLECTED IN PARKING CURB OPEN F 6 F 0.37 0.29 5.00 0.11 2.85 0.31 5.0 1.22 2.85 3.5 COLLECTED IN PARKING CURB OPEN 10.5 19-122-0006 2 YR 19-122-0006_Drainage Calcs.xlsx 10/6/202011:27 AM STANDARD FORM SF-3 STORM DRAINAGE SYSTEM DESIGN (RATIONAL METHOD PROCEDURE) CALCULATED BY: SDK DATE: 10/6/20 JOB NO: PROJECT: Maverik - Fort Collins DESIGN STORM: 100 Year DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME BASIN DESIGN POINT AREA DESIG. AREA (Acres) RUNOFF COEFF Tc (min) C A (Acres) I (in/hour) Q (cfs) Tc (min) (C A) (Acres) I (in/hour) Q (cfs) SLOPE (%) STREET FLOW (cfs) DESIGN FLOW (cfs) SLOPE (%) PIPE SIZE (in) LENGTH (ft) VELOCITY (fps) Tt (min) REMARKS A 1 A 0.14 1.00 5.00 0.14 9.95 1.4 5.0 0.14 9.95 1.4 COLLECTED IN NORTH ROOFTOP B 2 B 0.32 1.00 5.00 0.32 9.95 3.1 5.0 0.46 9.95 4.6 COLLECTED IN PARKING INLET C 3 C 0.26 1.00 5.00 0.26 9.95 2.5 5.0 0.26 9.95 2.5 COLLECTED IN PARKING CURB OPEN D 4 D 0.48 0.91 5.00 0.43 9.95 4.3 5.0 0.69 9.95 6.9 COLLECTED IN PARKING CURB OPEN E 5 E 1.28 1.00 5.00 1.28 9.95 12.7 5.0 1.28 9.95 12.7 COLLECTED IN PARKING CURB OPEN F 6 F 0.37 0.36 5.00 0.13 9.95 1.3 5.0 1.41 9.95 14.0 COLLECTED IN PARKING CURB OPEN 42.1 19-122-0006 100 YR 19-122-0006_Drainage Calcs.xlsx 10/6/202011:28 AM DP BASIN AREA C2 C100 Q2 Q100 (AC) (CFS) (CFS) (CFS) (CFS) 1 A 0.14 0.95 1.00 0.4 1.4 2 B 0.32 0.82 1.00 0.7 4.6 3 C 0.26 0.91 1.00 0.67 2.5 4 D 0.48 0.73 0.91 1.65 6.9 5 E 1.28 0.87 1.00 3.2 12.7 6 F 0.37 0.29 0.36 3.5 14.0 DRAINAGE BASIN SUMMARY BASIN Q2 Q100 Q2 Q100 (CFS) (CFS) (CFS) (CFS) 1 A 0.4 1.4 0.4 1.4 2 B 0.74 3.1 1.1 4.6 3 C 0.67 2.5 0.67 2.5 4 D 1.0 4.3 1.7 6.9 5 E 3.2 12.7 3.2 12.7 6 F 0.31 1.3 3.5 14.0 DEVELOPED RUNOFF DESIGN POINT DIRECT TOTAL IDF Table for Rational Method City of Fort Collins Duration Intensity Intensity (min) (in/hr) (in/hr) min 2-yr 100-yr 5 2.85 9.95 10 2.21 7.72 15 1.87 6.52 20 1.61 5.60 25 1.43 4.98 30 1.30 4.52 35 1.17 4.08 40 1.07 3.74 45 0.99 3.46 50 0.92 3.23 55 0.87 3.03 60 0.82 2.86 65 0.78 2.71 70 0.73 2.59 75 0.70 2.48 80 0.66 2.38 85 0.64 2.29 90 0.61 2.32 95 0.58 2.13 100 0.56 2.06 105 0.54 2.00 110 0.52 1.94 115 0.51 1.88 120 0.49 1.84 IDF Table 19-122-0006_Drainage Calcs.xlsx 10/6/202011:29 AM Project: Basin ID: Ia= 71.60 percent Ia= 71.60 percent A= 2.840 acres A= 2.840 acres Type C A,B,C, or D Type C A,B,C, or D T 2 years (2,5,10,) T 100 years(50,100,) Tc 5 minutes Tc 5.00 minutes q 0.20 cfs/acre q 0.20 cfs/acre P1 1.01 inches P1 348.00 inches C1 28.50 C1 28.50 C2 10 C2 10 Coefficient Three C3 0.786 C3 0.786 C= 0.72 C= 0.90 Qp-in= 5.83 cfs Qp-in= 25.43 cfs Qp-out= 0.57 cfs Qp-out= 0.57 cfs 5,151 cubic feet 31,732 cubic feet 0.118 acre-ft 0.728 acre-ft 5 <-Enter Rainfall Duration Increment Increase Value Here (e.g. 5 for 5-minutes) 5 <-Enter Rainfall Duration Increment Increase Value Here (e.g. 5 for 5-minutes) Rainfall Duration minutes Rainfall Intesity inches/hr Inflow Volume cubic feet Adjustment Factor "m" Average Outflow cfs Outflow Volume cubic feet Sorage Volume cubic feet Rainfall Duration minutes Rainfall Intesity inches/hr Inflow Volume cubic feet Adjustment Project: Basin ID: DETENTION VOLUME BY THE MODIFIED FAA METHOD Maverik Convinient Store and Fuel Station - Fort Collins 1 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 0 20 40 60 80 100 120 140 Volume (Cubic Feet) Duration (Minutes) Inflow and Outflow Volumes vs. Rainfall Duration Minor Storm Inflow Volume Minor Storm Outflow Volume Minor Storm Storage Volume Major Storm Inflow Volume Major Storm Outflow Volume Major Storm Storage Volume Elevation Area (sqft) Bottom 4878.25 4275 3,665.35 4879.00 5526 6,532.67 4880.00 7594 8,782.37 4881.00 10027 10,645.39 4882.00 11276 2,860.52 Top 4882.25 11609 V= 32486 cf V WHERE: V=Volume between contours, (cf) D=Depth between contours, (ft) A=Area of bottom contour, (sf) B=Area of top contour, (sf) Basin Characteristics AVAILABLE SITE DETENTION POND VOLUME = D/3(A+B+(A*B)^1/2 Appendix B Water Quality & LID Computations SD SS SS W W W W W W W W W W W W W W W W W SS SS SS SS SS SS SS W VAN STOP STOP LOADING ZONE PROJECT NUMBER ISSUE DATE: REVISIONS: MAVERIK INC. STORE I-25 & E. COUNTY RD. 32 / HIGHWAY 392 FORT COLLINS, CO No. Date Description NOTE: Conflicting information or errors found in the construction documents should be brought to the attention of the architect immediatly. In the event of a conflict in the drawings, bidder should not assume the least expensive option will meet the project requirements. Bid documents should not be separated or issued as partial sets to subcontractors. Bidders are responsible for all portions of the documents that pertain to work covered by sub-bids. Bidder assumes full responsibility for error or misinterpretations resulting from partial sets of Bidding Documents by itself or any sub-bidder. Plot Date: 2020-10-06 File Location: O:\1200-Denver\DCI-Civil\Projects\2019\19-122-0006-MAVERIK-FORT COLLINS-CO\19-122-0006PDP.dwg OF 1331 17TH STREET SUITE 605 DENVER, COLORADO 80202 PHONE: (720) 439-4700 WEBSITE: www.dci-engineers.com CIVIL / STRUCTURAL © 10/2020 This document, and the ideas and designs may not be reused, in whole or in part, without written permission from D'Amato Conversano Inc. D'Amato Conversano Inc. disclaims any responsibility for its unauthorized use. SEPTEMBER 30, 2020 19-122-0006 LID SITE PLAN 3 3 Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia = 84.8 % (100% if all paved and roofed areas upstream of sand filter) B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.848 C) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 0.29 watershed inches WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including sand filter area) Area = 55,558 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 1,336 cu ft VWQCV = WQCV / 12 * Area F) For Watersheds Outside of the Denver Region, Depth of d6 = in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER = cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth DWQCV = 1.0 ft B) Sand Filter Side Slopes (Horizontal distance per unit vertical, Z = 4.00 ft / ft 4:1 or flatter preferred). Use "0" if sand filter has vertical walls. C) Minimum Filter Area (Flat Surface Area) AMin = 589 sq ft D) Actual Filter Area AActual = 1687 sq ft E) Volume Provided VT = 2491 cu ft 3. Filter Material 4. Underdrain System A) Are underdrains provided? 1 B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y = ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 = cu ft iii) Orifice Diameter, 3/8" Minimum DO = in 19122-0006 Maverick Fort Collins, Colorado - Sand Filter "A" Design Procedure Form: Sand Filter (SF) Shawn Krieger DCI Engineers October 5, 2020 UD-BMP (Version 3.07, March 2018) Choose One Choose One 18" CDOT Class B or C Filter Material Other (Explain): YES NO UD-BMP_v3.07_SF-A.xlsm, SF 10/5/2020, 11:42 AM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? 6. Inlet / Outlet Works A) Describe the type of energy dissipation at inlet points and means of conveying flows in excess of the WQCV through the outlet Notes: Design Procedure Form: Sand Filter (SF) Shawn Krieger DCI Engineers October 5, 2020 19122-0006 Maverick Fort Collins, Colorado - Sand Filter "A" Choose One YES NO UD-BMP_v3.07_SF-A.xlsm, SF 10/5/2020, 11:42 AM Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia = 65.1 % (100% if all paved and roofed areas upstream of sand filter) B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.651 C) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 0.20 watershed inches WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including sand filter area) Area = 20,833 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft VWQCV = WQCV / 12 * Area F) For Watersheds Outside of the Denver Region, Depth of d6 = in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER = cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = 566 cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth DWQCV = 1.0 ft B) Sand Filter Side Slopes (Horizontal distance per unit vertical, Z = 4.00 ft / ft 4:1 or flatter preferred). Use "0" if sand filter has vertical walls. C) Minimum Filter Area (Flat Surface Area) AMin = 170 sq ft D) Actual Filter Area AActual = 1140 sq ft E) Volume Provided VT = 1593 cu ft 3. Filter Material 4. Underdrain System A) Are underdrains provided? 1 B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y = ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 = cu ft iii) Orifice Diameter, 3/8" Minimum DO = in 19122-0006 Maverick Fort Collins, Colorado - Sand Filter "B" Design Procedure Form: Sand Filter (SF) Shawn Krieger DCI Engineers October 5, 2020 UD-BMP (Version 3.07, March 2018) Choose One Choose One 18" CDOT Class B or C Filter Material Other (Explain): YES NO UD-BMP_v3.07_SF-B.xlsm, SF 10/5/2020, 11:45 AM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? 6. Inlet / Outlet Works A) Describe the type of energy dissipation at inlet points and means of conveying flows in excess of the WQCV through the outlet Notes: Design Procedure Form: Sand Filter (SF) Shawn Krieger DCI Engineers October 5, 2020 19122-0006 Maverick Fort Collins, Colorado - Sand Filter "B" Choose One YES NO UD-BMP_v3.07_SF-B.xlsm, SF 10/5/2020, 11:45 AM Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia = 91.0 % (100% if all paved and roofed areas upstream of sand filter) B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.910 C) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 0.33 watershed inches WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including sand filter area) Area = 31,157 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft VWQCV = WQCV / 12 * Area F) For Watersheds Outside of the Denver Region, Depth of d6 = in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER = cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = 1,601 cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth DWQCV = 1.5 ft B) Sand Filter Side Slopes (Horizontal distance per unit vertical, Z = 4.00 ft / ft 4:1 or flatter preferred). Use "0" if sand filter has vertical walls. C) Minimum Filter Area (Flat Surface Area) AMin = 354 sq ft D) Actual Filter Area AActual = 651 sq ft E) Volume Provided VT = 1626 cu ft 3. Filter Material 4. Underdrain System A) Are underdrains provided? 1 B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y = ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 = cu ft iii) Orifice Diameter, 3/8" Minimum DO = in 19122-0006 Maverick Fort Collins, Colorado - Sand Filter "C" Design Procedure Form: Sand Filter (SF) Shawn Krieger DCI Engineers October 5, 2020 UD-BMP (Version 3.07, March 2018) Choose One Choose One 18" CDOT Class B or C Filter Material Other (Explain): YES NO UD-BMP_v3.07_SF-C.xlsm, SF 10/5/2020, 11:48 AM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? 6. Inlet / Outlet Works A) Describe the type of energy dissipation at inlet points and means of conveying flows in excess of the WQCV through the outlet Notes: Design Procedure Form: Sand Filter (SF) Shawn Krieger DCI Engineers October 5, 2020 19122-0006 Maverick Fort Collins, Colorado - Sand Filter "C" Choose One YES NO UD-BMP_v3.07_SF-C.xlsm, SF 10/5/2020, 11:48 AM 3.6 Sand Filter Sand Filters are a simple system that treat stormwater by passing it through a bed of clean sand. They rely on a single treatment process and do not provide as many of the multifunctional habitat and aesthetic benefits as bioretention areas. COST AND BENEFIT CONSIDERATIONS MAINTENANCE CONSIDERATIONS � Accept concentrated flow sources. � Can be designed for deeper ponding depth and larger tributary areas than bioretention. In some cases sand filters may be used to provide the flood control volume. � Easier to observe and access for maintenance than underground BMPs. � Simple design for installation. � Relies more heavily on mechanical cleaning and replacement of media to maintain filter rates vs bioretention which is aided by biological processes. � Vegetation will be more difficult to establish. � Remove plant debris frequently. � Smaller cells may require more frequent maintenance and sediment removal. � BMPs that are used for snow storage or receive flow from sanded areas require more frequent sediment removal. � Size forebays accordingly to maintenance frequency and context. � Consider using a pretreatment BMP such as vegetated buffer or vegetated conveyance swale upstream to capture sediment. Section Three: LID BMP Fact Sheet 3.7 City of Fort Collins | LID Implementation Manual � Plan and delineate sand filter areas prior to site disturbance to protect subgrade from construction related compaction � Protect finished BMPs from construction sediment including during landscape installation. � Provide adequately sized and armored overflow for high flow conditions. Precedent Projects � Foothills Mall (south side) � CSU Parking Structure DESIGN CONSIDERATIONS CONSTRUCTION CONSIDERATIONS � For concentrated flow applications, armor inlets against scour. � Scale the depth of drop from walking areas to the top of sand filter according to the site use and aesthetics, generally <18”. � For sites with infiltration limitations BMPS are drained by underdrains. � BMP is not applicable for right-of-way applications. Sand filter cross-section, per approved construction detail Notes and References � UDFCD Treatment BMP Fact Sheet T-06 * This is a graphic representation. For more technical guidance, refer to the construction detail. Appendix C Reference Documents GEOTECHNICAL ENGINEERING STUDY Proposed Maverik Store NWC of I-25 & North County Road 32 Fort Collins, Colorado CMT PROJECT NO. 12736 FOR: Cardno, Inc. 1142 West 2320 South, Suite A West Valley City, Utah 84119 May 24, 2019 ENGINEERING •GEOTECHNICAL •ENVIRONMENTAL (ESA I & II) • MATERIALS TESTING •SPECIAL INSPECTIONS • ORGANIC CHEMISTRY • PAVEMENT DESIGN •GEOLOGY ENGINEERING • GEOTECHNICAL • ENVIRONMENTAL (ESA I & II) • MATERIALS TESTING • SPECIAL INSPECTIONS ORGANIC CHEMISTRY • PAVEMENT DESIGN • GEOLOGY www.cmtlaboratories.com 5/24/19 May 24, 2019 Mr. Russ Hamblin Cardno, Inc. 1142 West 2320 South, Suite A West Valley City, Utah 84119 Subject: Geotechnical Engineering Study Proposed Maverik Store NWC of I-25 & East County Road 32 Fort Collins, Colorado CMT Project Number: 12736 Mr. Hamblin: Submitted herewith is the report of our supplemental geotechnical engineering study for the subject site. This report contains the results of our findings and an engineering interpretation of the results with respect to the available project characteristics. It also contains recommendations to aid in the design and construction of the earth related phases of this project. On April 30, 2019, a contracted driller and Cardno personnel were on the site and 6 bore holes were drilled to depths between about 5 to 25 feet below the existing ground surface. Soil samples were obtained in the bore holes during the field operations and subsequently transported to our laboratory for further testing and observation. Subsurface natural soils predominately consisted of CLAY (CL) with moderate to moderately high plasticity. Some of the near surface clay exhibited moisture sensitivity if the form of additional settlement (collapse) when wetted, but no indications of swell potential were noted. Based upon our findings the proposed Maverik Store may be supported on conventional foundations. A detailed discussion of design and construction criteria is presented in this report. We appreciate the opportunity to work with you at this stage of the project. CMT offers a full range of Geotechnical Engineering, Geological, Material Testing, Special Inspection services, and Phase I and II Environmental Site Assessments. With 8 offices throughout Utah, Idaho, and Arizona, our staff is capable of efficiently serving your project needs. If we can be of further assistance or if you have any questions regarding this project, please do not hesitate to contact us at (801) 492- 4132. Sincerely, CMT Engineering Laboratories Reviewed by: Jeffrey J. Egbert, P.E., LEED A.P., M. ASCE Andrew M. Harris, P.E. Senior Geotechnical Engineer Geotechnical Division Manager TABLE OF CONTENTS 1.0 INTRODUCTION .......................................................................................................................................................................... 1 1.1 General ...................................................................................................................................................................................1 1.2 Objectives, Scope and Authorization ......................................................................................................................................1 1.3 Description of Proposed Construction ....................................................................................................................................2 1.4 Executive Summary ................................................................................................................................................................2 2.0 FIELD EXPLORATION ................................................................................................................................................................... 3 2.1 General ...................................................................................................................................................................................3 2.2 Infiltration Testing ..................................................................................................................................................................3 3.0 LABORATORY TESTING ............................................................................................................................................................... 4 4.0 GEOLOGIC & SEISMIC CONDITIONS ............................................................................................................................................ 4 4.1 Geologic Setting ......................................................................................................................................................................4 4.2 Faulting ...................................................................................................................................................................................5 4.3 Seismicity ................................................................................................................................................................................6 4.3.1 Site Class ..........................................................................................................................................................................6 4.3.2 Ground Motions ...............................................................................................................................................................6 4.3.3 Liquefaction .....................................................................................................................................................................6 4.4 Other Geologic Hazards ..........................................................................................................................................................6 5.0 SITE CONDITIONS ........................................................................................................................................................................ 7 5.1 Surface Conditions ..................................................................................................................................................................7 5.2 Subsurface Soils ......................................................................................................................................................................7 5.3 Groundwater ..........................................................................................................................................................................7 5.4 Site Subsurface Variations ......................................................................................................................................................8 6.0 SITE PREPARATION AND GRADING ............................................................................................................................................. 8 6.1 General ...................................................................................................................................................................................8 6.2 Temporary Excavations ...........................................................................................................................................................8 6.3 Fill Material .............................................................................................................................................................................9 6.4 Fill Placement and Compaction ........................................................................................................................................... 10 6.5 Utility Trenches .................................................................................................................................................................... 10 6.6 Stabilization ......................................................................................................................................................................... 11 7.0 FOUNDATION RECOMMENDATIONS ........................................................................................................................................ 11 7.1 Foundation Recommendations ........................................................................................................................................... 11 7.2 Installation ........................................................................................................................................................................... 12 7.3 Estimated Settlement .......................................................................................................................................................... 12 7.4 Lateral Resistance ................................................................................................................................................................ 12 7.5 Uplift Loads .......................................................................................................................................................................... 13 8.0 LATERAL EARTH PRESSURES ..................................................................................................................................................... 13 9.0 FLOOR SLABS ............................................................................................................................................................................ 13 10.0 DRAINAGE RECOMMENDATIONS ........................................................................................................................................... 14 11.0 PAVEMENTS ............................................................................................................................................................................ 14 12.0 QUALITY CONTROL ................................................................................................................................................................. 15 12.1 Field Observations ............................................................................................................................................................. 15 12.2 Fill Compaction .................................................................................................................................................................. 15 12.3 Excavations ........................................................................................................................................................................ 16 13.0 LIMITATIONS ........................................................................................................................................................................... Supplemental Geotechnical Engineering Study Page 1 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 1.0 INTRODUCTION 1.1 General CMT Engineering Laboratories (CMT) was retained to conduct a geotechnical study for the proposed Maverik Store. The site is situated on the northwest corner of the intersection of Interstate 25 and East County Road 32 in Fort Collins, Colorado as shown in the Vicinity Map below. VICINITY MAP 1.2 Objectives, Scope and Authorization The objectives and scope of our study were planned in discussions between Mr. Russ Hamblin of Cardno, Inc., and Mr. Jeffrey Egbert of CMT Engineering Laboratories (CMT). In general, the objectives of this study were to define and evaluate the subsurface soil and groundwater conditions at the site, and provide appropriate foundation, earthwork, pavement and seismic recommendations to be utilized in the design and construction of the proposed development. In accomplishing these objectives, field explorations were performed on the site by others, which consisted of the drilling/logging/sampling of 5 bore holes, and the drilling of one bore hole (not logged or sampled) for an infiltration test. Our scope of work included performing laboratory testing on samples of the subsurface soils SITE N Geotechnical Engineering Study Page 2 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 collected in the bore holes as provided to us, and conducting an office program, correlating available data, performing engineering analyses, and preparing this summary report. 1.3 Description of Proposed Construction We understand that the proposed construction consists of a new Maverik convenience store and fuel station with accompanying fuel islands and canopies, and underground fuel storage tanks. We project that wall loads for the store building will not exceed 5,000 pounds per linear foot and column loads for the fuel island canopy will not exceed 50,000 pounds. Floor slab loads are anticipated to be relatively light, with an average uniform loading not exceeding 150 pounds per square foot. The fuel island canopies will be supported by steel frames and columns extending to the foundation system. It is projected that the maximum canopy downward column loads will be on the order of 60,000 pounds. In addition, uplift and lateral loads will be imposed upon these foundations. If the loading conditions are different than we have projected, please notify us so that any appropriate modifications to our conclusions and recommendations contained herein can be made. We also understand the parking/drive paved areas will utilize both asphalt and concrete pavement. Concrete pavement will likely be installed in front of the proposed store structure, as well as in the canopy fuel islands and the underground storage tank areas. In other areas, asphalt concrete sections will likely be used. Traffic is projected to consist of mostly automobiles and light trucks, a few daily medium-weight delivery trucks, multiple fuel delivery trucks, a weekly garbage truck, and an occasional fire truck. 1.4 Executive Summary The most significant geotechnical aspects regarding site development include the following: 1. Topsoil on the surface of the site to about 6 inches deep to be removed from building, exterior concrete flatwork, and pavement areas. 2. Extensive site grading appears to have occurred on the site in the past therefore there is a possibility of non-engineered fill soils to be present on the surface, but the depth and extent is unknown. Non- engineered fills should be completely removed from foundation and floor slab areas. 3. Groundwater was encountered at about 19 feet below the surface. 4. Subsurface soils predominately consist of medium stiff to hard CLAY (CL). 5. The potential for liquefaction to occur in the soils we encountered is low. 6. The proposed structures may be supported on conventional concrete foundations established on natural soils at least 4.5 feet below the existing site grade, or on a minimum of 18 inches of engineered fill extending to suitable natural soils. A qualified geotechnical engineer must assess that non-engineered fill, topsoil, debris, disturbed or unsuitable soils have been removed and that suitable soils have been encountered prior to placing site grading fills, footings, slabs, and pavements. Geotechnical Engineering Study Page 3 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 In the following sections, detailed discussions pertaining to the site and subsurface descriptions, geologic/seismic setting, earthwork, foundations, lateral resistance, lateral pressure, floor slabs, and pavements are provided. 2.0 FIELD EXPLORATION 2.1 General In order to define and evaluate the subsurface soil and groundwater conditions, 5 bore holes were drilled at the site to depths of approximately 10 to 25 feet below the existing ground surface. Locations of the bore holes are presented on Figure 1. Samples of the subsurface soils encountered in bore holes B-1 through B-5 were collected at varying depths through the hollow stem drill augers. Relatively undisturbed samples of the subsurface soils were obtained by driving a split-spoon sampler with 2.5-inch outside diameter rings/liners (Dames and Moore) into the undisturbed soils below the drill augers. Disturbed samples were collected utilizing a standard split spoon sampler. This standard split spoon sampler was driven 18 inches into the soils below the drill augers using a 140 pound hammer free-falling a distance of 30 inches. The number of hammer blows needed for each 6 inch interval was recorded. The sum of the hammer blows for the final 12 inches of penetration is known as a standard penetration test (SPT) and this ‘blow count’ was recorded on the bore hole logs. The blow count provides a reasonable approximation of the relative density of granular soils, but only a limited indication of the relative consistency of fine grained soils because the consistency of these soils is significantly influenced by the moisture content. The subsurface soils encountered in the bore holes were logged and described in general accordance with ASTM 1 D-2488. Soil samples were collected as described above, and were classified in the field based upon visual and textural examination. These field classifications were supplemented by subsequent examination and testing of select samples in our laboratory. Graphic logs of the bore holes, including a description of the soil strata encountered, are presented on the Bore Hole Logs, Figures 2 through 6, included in the Appendix. Sampling information and other pertinent data and observations are also included on the logs. In addition, a Key to Symbols defining the terms and symbols used on the log is provided as Figure 7 in the Appendix. 2.2 Infiltration Testing Infiltration testing was also performed in a bore hole drilled specifically for that purpose, but this bore hole (P- 6) was not logged or sampled. The testing consisted of removing the drill auger, filling the hole with water to soak for a few hours, then filling the hole again and measuring the rate of water drop over a certain time period (i.e. 60 minutes). The results of this test did not show any measurable drop in the water level in the test hole in 60 minutes. 1American Society for Testing and Materials Geotechnical Engineering Study Page 4 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 3.0 LABORATORY TESTING Selected samples of the subsurface soils were subjected to various laboratory tests to assess pertinent engineering properties, as follows: 1. Moisture Content, ASTM D-2216, Percent moisture representative of field conditions 2. Dry Density, ASTM D-2937, Dry unit weight representing field conditions 3. Atterberg Limits, ASTM D-4318, Plasticity and workability 4. Gradation Analysis, ASTM D-1140/C-117, Grain Size Analysis 5. One Dimension Consolidation, ASTM D-2435, Consolidation properties Based upon data obtained from the consolidation testing, the clay soils at this site are over-consolidated and moderately compressible under additional loading. Additionally, the near surface clay exhibited a potential to experience additional settlement (collapse) when wetted. Test results indicate collapse amounts of up to 2.5% in the upper 4 feet, diminishing to about 1% below 4 feet. Detailed results of the tests are maintained within our files and can be transmitted to you, upon your request. Laboratory test results are presented on the bore hole log (Figure 2) and in the following Lab Summary Table: LAB SUMMARY TABLE Bore Depth Soil Sample Moisture Dry Denstiy Collapse (-) or Hole (feet) Class Type Content (%) (pcf) Grav Sand Fines LL PL PI Expansion (+) B-1 5 CL Rings 15.3 105.0 40 16 24 -1.0% 18.5 CL SPT 23.4 38 18 20 B-2 8.5 CL SPT 16.6 34 15 19 B-3 8 CL SPT 16.2 35 15 20 B-4 1.5 CL Rings 10.2 101.3 37 16 21 -<0.5% B-5 2.5 CL Rings 12.9 110.1 39 17 22 -2.5% Gradation Atterberg Limits 4.0 GEOLOGIC & SEISMIC CONDITIONS 4.1 Geologic Setting The subject site is located near the eastern base of the Rocky Mountains in north-central Colorado. The site sits at an elevation of between approximately 4,880 and 4,930 feet above sea level. The subject site overlies the west-central portion of the Denver Basin. The Denver Basin is an extensive geologic structure extending from southeast Wyoming and southwest Nebraska southward to southeastern Colorado. The basin is comprised of a large, asymmetric syncline of the underlying bedrock which includes rocks of Paleozoic, Mesozoic, and Cenozoic age that dip down to the west toward the Rocky Mountains. The axis of the basin roughly parallels the eastern base of the Mountains and the deepest point of the basin is near the city of Denver where it reaches a depth of approximately 13,000 feet below the surface. The basin began forming approximately 300 million years ago during the Colorado orogenic event that formed the Ancestral Rocky Mountains. The basin remained Geotechnical Engineering Study Page 5 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 during the Cretaceous time period and was within the interior Cretaceous Seaway which deposited a thick sequence of sediment in the basin. The Denver Basin was deepened during Paleogene time (about 66 to 45 million years ago) during the Laramide Orogenic event that created the modern Rocky Mountains. During this event, the uplifting of the Rocky Mountains caused the crust east of the mountains in eastern Colorado to warp downward at the base of the mountain range. Younger Sediment eroded from the mountains subsequently filled in the basin. Geologic mapping for the location of the subject site is sparse. A geologic map of the entire State of Colorado has been completed by Tweto 2 . The geology at the site and adjacent areas is mapped to consist of “Eolian deposits” (Map Unit Qe) dated to be Holocene to upper Pleistocene. Unit Qe is described on the referenced map as “Includes dune sand and silt and Peoria Loess.” Refer to the Geologic Map., shown below. GEOLOGIC MAP 4.2 Faulting No surface fault traces are shown on the referenced geologic map crossing or projecting toward the subject site. The nearest mapped fault trace to the site appears to be part of the Williams Fork Mountains fault located about 72 miles southwest of the site. 2Tweto, O., 1979, Geologic Map of Colorado; U.S. Geological Survey, Scale 1:500,000. SITE Geotechnical Engineering Study Page 6 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 4.3 Seismicity 4.3.1 Site Class Most states have adopted the International Building Code (IBC) 2015. IBC 2015 determines the seismic hazard for a site based upon 2008 mapping of bedrock accelerations prepared by the United States Geologic Survey (USGS) and the soil site class. The USGS values are presented on maps incorporated into the IBC code and are also available based on latitude and longitude coordinates (grid points). For site class definitions, IBC 2015 (Section 1613.3.2) refers to Chapter 20, Site Classification Procedure for Seismic Design, of ASCE 3 7. Given the subsurface soils at the site encountered in the bore holes, and our projection of the soils to 100 feet, it is our opinion the site best fits Site Class D – Stiff Soil Profile, which we recommend for seismic structural design. 4.3.2 Ground Motions The 2008 USGS mapping utilized by the IBC provides values of peak ground, short period and long period accelerations for the Site Class B boundary and the Maximum Considered Earthquake (MCE). This Site Class B boundary represents average bedrock values for the Western United States and must be corrected for local soil conditions. The following table summarizes the peak ground, short period and long period accelerations for the MCE event, and incorporates the appropriate soil correction factor for a Site Class D soil profile at site grid coordinates of 40.4802 degrees north latitude and -104.9933 degrees west longitude: Peak Ground Acceleration Fa = 1.658 Short Period Acceleration (0.2 Seconds) SS = 0.177 F a = 1.658 SMS = 0.294 SDS = 0.196 Short Period Acceleration (1.0 Second) S1 = 0.057 F v = 2.572 SM1 = 0.147 SD1 = 0.098 0.071 0.117 0.078 Spectral Acceleration Value, T Site Class B Boundary [Mapped Values] (g) Site Coefficient Site Class D [Adjusted for Site Class Effects] (g) Design Values (g) 4.3.3 Liquefaction Liquefaction is defined as the condition when saturated, loose, sandy soils lose their support capabilities because of excessive pore water pressure which develops during a seismic event. Clayey soils, even if saturated, will generally not liquefy during a major seismic event. Laboratory testing clearly indicates that the subsurface soils encountered in the bore holes are predominantly CLAY (CL), therefore we estimate a low liquefaction potential for the soils we encountered. 4.4 Other Geologic Hazards The site is not located within a known or mapped potential debris flow, stream flooding, or rock fall hazard area. 3American Society of Civil Engineers Geotechnical Engineering Study Page 7 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 5.0 SITE CONDITIONS 5.1 Surface Conditions The site is currently the gore area between the I-25 south bound off ramp and the Southwest Frontage Road, on the north side of East County Road 32. The site grade is approximately 25 to 30 feet lower than the grade of East County Road 32 and slopes downward to the north with an overall gradient of about 10 feet. The surface is vegetated with grass and weeds, with some trees around the perimeter which appear to have been planted when the Southwest Frontage Road intersection to East County Road 32 was reconfigured in 2012, based upon aerial photos dating back to 1999 that are readily available on the internet. The site is bordered on the north and west by the Southwest Frontage Road, on the south by East County Road 32, and on the east by the I-25 freeway off ramp (see Vicinity Map in Section 1.1 above). 5.2 Subsurface Soils At the locations of the bore holes clay soils with roots and organic material were encountered on the surface of the site which were estimated to be about 6 inches in thickness. Based upon aerial photos readily available on the internet, it appears that some extensive grading occurred on the site in 2012 when the south bound off ramp from I-25 to East County Road 32 was reconfigured, and the intersection of Southwest Frontage Road and East County Road 32 was moved about 300 feet west. As a result, there may be non-engineered fills on the site, but the depth and extent of any fill soils is not known. Below the topsoil, layers of gray-brown to brown CLAY (CL) were encountered, extending to the bottom of the bore holes B-2 through B-5. Near the bottom of borehole B-1, at a depth of about 23.5 feet, what appeared to be a very dense weathered claystone was encountered which extended to the bottom of B-1 at about 25 feet below the surface. For a more descriptive interpretation of subsurface conditions, please refer to the bore hole logs, Figures 2 through 6, which graphically represent the subsurface conditions encountered. The lines designating the interface between soil types on the log generally represent approximate boundaries; in situ, the transition between soil types may be gradual. 5.3 Groundwater Groundwater was noted in bore hole B-1 at about 19 feet below the surface, but not encountered in the other bore holes because they did not extend to this depth. This water could be perched on the claystone encountered near the bottom of B-1. Therefore, groundwater will not likely be encountered during construction, with the possible exception of the underground fuel storage tank excavation. Groundwater levels can fluctuate as much as 1.5 to 2 feet seasonally. Numerous other factors such as heavy precipitation, irrigation of neighboring land, and other unforeseen factors, may also influence ground water elevations at the site. The detailed evaluation of these and other factors, which may be responsible for ground water fluctuations, is beyond the scope of this study. Geotechnical Engineering Study Page 8 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 5.4 Site Subsurface Variations Based on the results of the subsurface explorations and our experience, variations in the continuity and nature of subsurface conditions should be anticipated. Due to the heterogeneous characteristics of natural soils, care should be taken in interpolating or extrapolating subsurface conditions between or beyond the exploratory locations. 6.0 SITE PREPARATION AND GRADING 6.1 General All deleterious materials should be stripped from the site prior to commencement of construction activities. This includes vegetation, topsoil, loose and disturbed soils, etc. Based upon the conditions observed in the bore holes there is topsoil on the surface of the site which we estimated to be about 6 inches in thickness. When stripping and grubbing, topsoil should be distinguished by the apparent organic content and not solely by color; thus we estimate that topsoil stripping will need to include the upper 4 inches. There is a potential for non-engineered fill to be present on the surface of the site, but the depth or extent is not known. Site grading activities and foundation excavations should be observed by a qualified geotechnical engineer to assess if suitable bearing soils have been encountered. If observed we recommend that all non- engineered fill be removed from beneath structures. Outside of building footprints, proper preparation of non- engineered fill and disturbed soils shall consist of removing the upper 12 inches, scarifying the exposed surface to a minimum depth of 8 inches, proper moisture conditioning, and compacting the scarified soils in place to the requirements for structural fill given in Section 6.4, below. The removed 12 inches of non-engineered fill, if free of organics, debris, or other unsuitable materials, can then be replaced in similarly compacted lifts. If the non-engineered fill depth is less than 18 inches, preparation shall consist of scarification to 8 inches and re- compaction as described above. The exposed subgrade must then be proofrolled by passing moderate-weight rubber tire-mounted construction equipment over the surface at least twice. If excessively soft or loose soils are encountered, they must be removed (up to a maximum depth of 2 feet) and replaced with structural fill. Fill placed over large areas to raise overall site grades can induce settlements in the underlying natural soils. If more than 3 feet of site grading fill is anticipated over the existing ground surface, we should be notified to assess potential settlements and provide additional recommendations as needed. These recommendations may include placement of the site grading fill far in advance to allow potential settlements to occur prior to construction. 6.2 Temporary Excavations Excavations up to 16 to feet deep are anticipated at the site. Groundwater was measured at a depth of about 19 feet below the existing ground surface. We anticipate that excavations extending below a depth of about 18 feet, if needed, will likely encounter groundwater, and dewatering of such excavations will likely be required. Geotechnical Engineering Study Page 9 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 The natural soils encountered at this site predominantly consisted of clay. In clayey (cohesive) soils, temporary construction excavations not exceeding 4 feet in depth may be constructed with near-vertical side slopes. Temporary excavations up to 16 feet deep, above or below groundwater, may be constructed with side slopes no steeper than one horizontal to one vertical (1H:1V). For sandy/gravelly (cohesionless) soils, temporary construction excavations not exceeding 4 feet in depth should be no steeper than one-half horizontal to one vertical (0.5H:1V). For excavations up to 8 feet and above groundwater, side slopes should be no steeper than one horizontal to one vertical (1H:1V). Excavations encountering saturated cohesionless soils will be very difficult to maintain, and will require very flat side slopes and/or shoring, bracing and dewatering. To reduce disturbance of the natural soils during excavation, we recommend that smooth edge buckets/blades be utilized. All excavations must be inspected periodically by qualified personnel. If any signs of instability or excessive sloughing are noted, immediate remedial action must be initiated. All excavations should be made following OSHA safety guidelines. 6.3 Fill Material The table on the following page contains our recommendations for the various fill types we anticipate will be used at this site: Fill Material Type Description | Recommended Specification Structural Fill Placed below structures, flatwork and pavement. Well-graded sand/gravel mixture, with maximum particle size of 4 inches, a minimum 70% passing 3/4-inch sieve, a maximum 20% passing the No. 200 sieve, and a maximum Plasticity Index of 10. Site Grading Fill Placed over larger areas to raise the site grade. Sandy to gravelly soil, with a maximum particle size of 6 inches, a minimum 70% passing 3/4-inch sieve, and a maximum 50% passing No. 200 sieve. Non-Structural Fill Placed below non-structural areas, such as landscaping. On-site soils or imported soils, with a maximum particle size of 8 inches, including silt/clay soils not containing excessive amounts of degradable/organic material (see discussion below). Stabilization Fill Placed to stabilize soft areas prior to placing structural fill and/or site grading fill. Coarse angular gravels and cobbles 1 inch to 8 inches in size. May also use 1.5- to 2.0-inch gravel placed on stabilization fabric, such as Mirafi RS280i or equivalent (see Section 6.6). Natural clay soils could be used as site grading fill and non-structural fill, but these soils will be inherently more difficult to work with in proper moisture conditioning (they are very sensitive to changes in moisture content), requiring very close moisture control during placement and compaction. This will be very difficult, if not impossible, during wet and cold periods of the year. We also recommend the site grading fill thickness using clay soils not exceed 3 feet below structures, to minimize potential settlements. All proposed fill material should be approved by a CMT geotechnical engineer prior to placement. Geotechnical Engineering Study Page 10 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 6.4 Fill Placement and Compaction The various types of compaction equipment available have their limitations as to the maximum lift thickness that can be compacted. For example, hand operated equipment is limited to lifts of about 4 inches and most “trench compactors” have a maximum, consistent compaction depth of about 6 inches. Large rollers, depending on soil and moisture conditions, can achieve compaction at 8 to 12 inches. The full thickness of each lift should be compacted to at least the following percentages of the maximum dry density as determined by ASTM D-1557 (or AASHTO 4 T-180) in accordance with the following recommendations: Location Total Fill Thickness (feet) Minimum Percentage Of Maximum Dry Density Beneath an area extending at least 4 feet beyond the perimeter of structures, and below flatwork and pavement (applies to structural fill and site grading fill) extending at least 2 feet beyond the perimeter 0 to 5 5 to 8 95 98 Site grading fill outside area defined above 0 to 5 5 to 8 92 95 Utility trenches within structural areas -- 96 Roadbase and subbase - 96 Non-structural fill 0 to 5 5 to 8 90 92 Pavement Subgrade --- 95* * Subgrade must be conditioned to 2% above optimum moisture content prior to compaction. Structural fills greater than 8 feet thick are not anticipated at the site. For best compaction results, we recommend that the moisture content for structural fill/backfill be within 2% of optimum. Field density tests should be performed on each lift as necessary to verify that proper compaction is being achieved. 6.5 Utility Trenches For the bedding zone around the utility, we recommend utilizing sand bedding fill material that meets current APWA 5 requirements. All utility trench backfill material below structurally loaded facilities (foundations, floor slabs, flatwork, parking lots/drive areas, etc.) should be placed at the same density requirements established for structural fill in the previous section. Most utility companies and local governments are requiring Type A-1a or A-1b (AASHTO Designation) soils (sand/gravel soils with limited fines) be used as backfill over utilities within public rights of way, and the backfill 4 American Association of State Highway and Transportation Officials 5 American Public Works Association Geotechnical Engineering Study Page 11 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 be compacted over the full depth above the bedding zone to at least 96% of the maximum dry density as determined by AASHTO T-180 (ASTM D-1557). 6.6 Stabilization The natural clay soils at this site will likely be susceptible to rutting and pumping. The likelihood of disturbance or rutting and/or pumping of the existing natural soils is a function of the load applied to the surface, as well as the frequency of the load. Consequently, rutting and pumping can be minimized by avoiding concentrated traffic, minimizing the load applied to the surface by using lighter equipment and/or partial loads, by working in drier times of the year, or by providing a working surface for the equipment. Rubber-tired equipment particularly, because of high pressures, promotes instability in moist/wet, soft soils. If rutting or pumping occurs, traffic should be stopped and the disturbed soils should be removed and replaced with stabilization material. Typically, a minimum of 18 inches of the disturbed soils must be removed to be effective. However, deeper removal is sometimes required. To stabilize soft subgrade conditions (if encountered), a mixture of coarse, clean, angular gravels and cobbles and/or 1.5- to 2.0-inch clean gravel should be utilized. Often the amount of gravelly material can be reduced with the use of a geotextile fabric such as Mirafi RS280i, or equivalent. Its use will also help avoid mixing of the subgrade soils with the gravelly material. After excavating the soft/disturbed soils, the fabric should be spread across the bottom of the excavation and up the sides a minimum of 18 inches. Otherwise, it should be placed in accordance with the manufacturer’s recommendation, including proper overlaps. The gravel material can then be placed over the fabric in compacted lifts as described above. 7.0 FOUNDATION RECOMMENDATIONS The following recommendations have been developed on the basis of the previously described project characteristics, the subsurface conditions observed in the field and the laboratory test data, as well as common geotechnical engineering practice. 7.1 Foundation Recommendations Based on our geotechnical engineering analyses, the proposed structures may be supported upon conventional spread and/or continuous wall foundations placed on suitable, undisturbed, uniform natural soils at least 4.5 feet below the existing surface, or on a minimum of 18 inches of structural fill extending to suitable natural soils. Footings may be designed using a net bearing pressure of 2,000 psf if placed on suitable, undisturbed, uniform natural soils at least 4.5 feet below the existing surface, or 2,500 psf if placed on a minimum 18 inches of structural fill extending to suitable natural soils. The term “net bearing pressure” refers to the pressure imposed by the portion of the structure located above lowest adjacent final grade, thus the weight of the footing and backfill to lowest adjacent final grade need not be considered. The allowable bearing pressure may be increased by 1/3 for temporary loads such as wind and seismic forces. Geotechnical Engineering Study Page 12 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 We also recommend the following: 1. Exterior footings subject to frost should be placed at least 30 inches below final grade. 2. Interior footings not subject to frost should be placed at least 16 inches below grade. 3. Continuous footing widths should be maintained at a minimum of 18 inches. 4. Spot footings should be a minimum of 24 inches wide. 7.2 Installation Under no circumstances shall foundations be placed on non-engineered fill, topsoil with organics, sod, rubbish, construction debris, other deleterious materials, frozen soils, or within ponded water. If unsuitable soils are encountered, they must be completely removed and replaced with properly compacted structural fill. Excavation bottoms should be examined by a geotechnical engineer to confirm that suitable bearing materials soils have been exposed. All structural fill should meet the requirements for such, and should be placed and compacted in accordance with Section 6 above. The width of structural replacement fill below footings should be equal to the width of the footing plus 1 foot for each foot of fill thickness. For instance, if the footing width is 2 feet and the structural fill depth beneath the footing is 2 feet, the fill replacement width should be 4 feet, centered beneath the footing. The minimum thickness of structural fill below footings should be equivalent to one-third the thickness of structural fill below any other portion of the foundations. For example, if the maximum depth of structural fill is 6 feet, all footings for the new structure should be underlain by a minimum 2 feet of structural fill. 7.3 Estimated Settlement Foundations designed and constructed in accordance with our recommendations could experience some settlement, but we anticipate that total settlements of footings founded as recommended above will not exceed 1 inch, with differential settlements on the order of 0.5 inches over a distance of 25 feet. We expect approximately 50% of the total settlement to initially take place during construction. 7.4 Lateral Resistance Lateral loads imposed upon foundations due to wind or seismic forces may be resisted by the development of passive earth pressures and friction between the base of the footings and the supporting soils. In determining frictional resistance, a coefficient of 0.30 for natural clay soils or 0.40 for natural sand/gravel and structural fill, may be utilized for design. Passive resistance provided by properly placed and compacted structural fill above the water table may be considered equivalent to a fluid with a density of 350 pcf. A combination of passive earth resistance and friction may be utilized if the friction component of the total is divided by 1.5. Geotechnical Engineering Study Page 13 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 7.5 Uplift Loads Uplift loads may be resisted by the weight of the foundation and the backfill wedge above the top of the foundation within the area defined by an imaginary line extending outward from the outside top edge of the footing 10 degrees from vertical, up to final grade. A unit weight of 120 pounds per square foot can be used for sand and gravel backfill over the footings. 8.0 LATERAL EARTH PRESSURES We anticipate that below-grade walls up to 4 feet high will be constructed at this site. The lateral earth pressure values given in the table on the following page are for a backfill material that will consist of drained sand/gravel soils (less than 10% passing No. 200 sieve) placed and compacted in accordance with the recommendations presented herein. If other soil types will be used as backfill, we should be notified so that appropriate modifications to these values can be provided, as needed. The lateral pressures imposed upon subgrade facilities will depend upon the relative rigidity and movement of the backfilled structure. Following are the recommended lateral pressure values, which also assume that the soil surface behind the wall is horizontal and that the backfill within 3 feet of the wall will be compacted with hand-operated compacting equipment. Condition Equivalent Fluid Pressure (psf/ft) Static Seismic Active Pressure (wall is allowed to yield, i.e. move away from the soil, with a minimum 0.001H movement/rotation at the top of the wall, where “H” is the total height of the wall) 35 55 At-Rest Pressure (wall is not allowed to yield) 55 --- Passive Pressure (wall moves into the soil) 350 550 9.0 FLOOR SLABS Floor slabs should be established upon a minimum of 12 inches of structural fill extending to suitable natural soils. Under no circumstances shall floor slabs be established directly on any topsoil, non-engineered fills, loose or disturbed soils, sod, rubbish, construction debris, other deleterious materials, frozen soils, or within ponded water. In order to facilitate curing of the concrete, we recommend that floor slabs be directly underlain by at least 4 inches of “free-draining” fill, such as “pea” gravel or 3/4-inch quarters to 1-inch minus, clean, gap-graded gravel. To help control normal shrinkage and stress cracking, the floor slabs should have the following features: 1. Adequate reinforcement for the anticipated floor loads with the reinforcement continuous through interior floor joints; 2. Frequent crack control joints; and Geotechnical Engineering Study Page 14 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 3. Non-rigid attachment of the slabs to foundation walls and bearing slabs. 10.0 DRAINAGE RECOMMENDATIONS It is important to the long-term performance of foundations and floor slabs that water not be allowed to collect near the foundation walls and infiltrate into the underlying soils. We recommend the following: 1. All areas around the structure should be sloped to provide drainage away from the foundations. We recommend a minimum slope of 6 inches in the first 10 feet away from the structure. This slope should be maintained throughout the lifetime of the structure. 2. All roof drainage should be collected in rain gutters with downspouts designed to discharge at least 10 feet from the foundation walls or well beyond the backfill limits, whichever is greater. 3. Adequate compaction of the foundation backfill should be provided. We suggest a minimum of 90% of the maximum laboratory density as determined by ASTM D-1557. Water consolidation methods should not be used under any circumstances. 4. Landscape sprinklers should be aimed away from the foundation walls. The sprinkling systems should be designed with proper drainage and be well-maintained. Over watering should be avoided. 5. Other precautions that may become evident during construction 11.0 PAVEMENTS All pavement areas must be prepared as discussed above in Section 6.1, including moisture conditioning and compaction of the upper 8 inches of subgrade soils. Under no circumstances shall pavements be established over topsoil, unprepared non-engineered fill, loose or disturbed soils, sod, rubbish, construction debris, other deleterious materials, frozen soils, or within ponded water. In pavement areas, subsequent to stripping and prior to the placement of pavement materials, the exposed subgrade must be proof rolled by passing moderate- weight rubber tire-mounted construction equipment over the surface at least twice. If excessively soft or otherwise unsuitable soils are encountered, we recommend they be removed to a minimum of 18 inches below the subgrade level and replaced with structural fill. We anticipate that natural clay soils will exhibit poor pavement support characteristics when saturated or nearly saturated. Based on our laboratory testing experience with similar soils, our pavement design is based upon a California Bearing Ratio (CBR) of 3. Given the projected traffic as discussed above in Section 1.3, the following pavement sections are recommended for the given ESAL's (18-kip equivalent single-axle loads) per day: Geotechnical Engineering Study Page 15 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 Material Pavement Section Thickness (inches) Parking Areas (3 ESAL'S Per Day) Drive Areas (8 ESAL’S Per Day) Asphalt 3 3 --- 3 3 --- Concrete --- -- 5 --- --- 6 Road-Base 8 4 5 11 5 5 Subbase 0 6 0 0 8 0 Total Thickness 11 13 10 14 16 11 Untreated base course (UTBC) should conform to city specifications, or DOT specifications for A–1-a/NP, and have a minimum CBR value of 70%. Material meeting our specification for structural fill can be used for subbase, as long as the fines content (percent passing No. 200 sieve) does not exceed 15%. Roadbase and subbase material should be compacted as recommended above in Section 6.4. Asphalt material generally should conform to APWA requirements, having a ½-inch maximum aggregate size, a 75-gyration Superpave mix containing no more than 15% of recycled asphalt (RAP) and a PG58-28 binder. Concrete pavement should be designed in accordance with the American Concrete Institute (ACI) and joint details should conform to the Portland Cement Association (PCA) guidelines. The concrete should have a minimum 28-day unconfined compressive strength of 4,000 pounds per square inch and contain 6 percent ±1 percent air-entrainment. 12.0 QUALITY CONTROL We recommend that a comprehensive quality control testing and observation program be implemented. Without such a program CMT cannot be responsible for application of our recommendations to subsurface conditions which may vary from those described herein. This program may include, but not necessarily be limited to, the following: 12.1 Field Observations Observations should be completed during all phases of construction such as site preparation, foundation excavation, structural fill placement and concrete placement. 12.2 Fill Compaction Compaction testing is required for all structural supporting fill materials. Maximum Dry Density (Modified Proctor, ASTM D-1557) tests should be requested by the contractor immediately after delivery of any fill materials. The maximum density information should then be used for field density tests on each lift as necessary to ensure that the required compaction is being achieved. Geotechnical Engineering Study Page 16 Proposed Maverik Store, Fort Collins, Colorado CMT Project No. 12736 12.3 Excavations All excavation procedures and processes should be observed by a geotechnical engineer. In addition, for the recommendations in this report to be valid, all backfill and structural fill placed in trenches and all pavements should be density tested. We recommend that freshly mixed concrete be tested in accordance with ASTM designations. 13.0 LIMITATIONS The recommendations provided herein were developed by evaluating the information obtained from the subsurface explorations and soils encountered therein. The exploration logs reflect the subsurface conditions only at the specific location at the particular time designated on the logs. Soil and ground water conditions may differ from conditions encountered at the actual exploration locations. The nature and extent of any variation in the explorations may not become evident until during the course of construction. If variations do appear, it may become necessary to re-evaluate the recommendations of this report after we have observed the variation. Our professional services have been performed, our findings obtained, and our recommendations prepared in accordance with generally accepted geotechnical engineering principles and practices. This warranty is in lieu of all other warranties, either expressed or implied. We appreciate the opportunity to be of service to you on this project. If we can be of further assistance or if you have any questions regarding this project, please do not hesitate to contact us at (801) 492-4132. To schedule materials testing, please call (801) 381-5141. SUPPORTING DOCUMENTATION APPENDIX Date: Job # Maverik Store Figure: NWC of I-25 & N. County Rd 32, Ft. Collins, CO Bore Hole Location 1 23-Apr-19 12736 N. County Raod 32 N P-1 B-2 Taylor Road B-5 B-3 B-4 B-1 TOPSOIL: Clay, roots, organics, moist, brown 5 CLAY (CL), moist, gray-brown stiff 1 5 14 9 6 2 11 23 12 5 3 7 14 7 grades brown 6 4 12 27 15.3 105 40 16 24 15 grades sandy 3 medium stiff 5 3 7 4 6 4 wet 7 4 10 23.4 38 18 20 6 Claystone, weathered, moist, gray-brown 15 very dense 8 31 65 34 END AT 25 FEET Remarks: Drilled By: Logged By: Page: Drilling Engineers J. Grippa 1 of 1 Blows (N) Surface Elev. (approx): 12736 Gradation Atterberg Groundwater encountered during drilling at depth of 19 feet. Water Depth: Soil Description Total Depth: Date: NWC of I-25 & N, County Rd 32, Ft. Collins, CO Boring Type: Hollow-Stem Auger Job #: 25' 19' 4/30/19 Maverik Store 2 Bore Hole Log B-1 Figure: 0 4 8 12 16 20 24 28 Depth (ft) GRAPHIC LOG Sample Type Sample # TOPSOIL: Clay, roots, organics, moist, brown 6 CLAY (CL), moist, gray-brown very stiff 9 6 17 11 4 stiff 10 7 19 12 6 very stiff 11 7 17 10 grades dark brown 4 stiff 12 4 11 7 grades sandy, brown 7 very stiff 13 10 24 16.6 34 15 19 14 END AT 10 FEET Remarks: Drilled By: Logged By: Page: Groundwater not encountered during drilling. Figure: Drilling Engineers 3 J. Grippa 1 of 1 Soil Description Blows (N) Gradation Atterberg Water Depth: (see Remarks) Job #: 12736 NWC of I-25 & N, County Rd 32, Ft. Collins, CO Boring Type: Hollow-Stem Auger Total Depth: 10' Date: 4/30/19 Surface Elev. (approx): Maverik Store Bore Hole Log B-2 0 4 8 12 16 20 24 28 Depth (ft) GRAPHIC LOG Sample Type Sample # Total Moisture (%) Dry Density(pcf) Gravel % Sand % Fines % LL PL PI TOPSOIL: Clay, roots, organics, moist, brown 11 CLAY (CL), moist, gray-brown stiff 14 11 25 14 grades brown 5 15 7 15 8 6 16 10 24 14 3 17 5 13 16.2 35 15 20 8 END AT 10 FEET Remarks: Drilled By: Logged By: Page: Maverik Store Bore Hole Log B-3 4/30/19 Surface Elev. (approx): NWC of I-25 & N, County Rd 32, Ft. Collins, CO Boring Type: Hollow-Stem Auger Total Depth: 10' Date: Soil Description Blows (N) Gradation Atterberg Water Depth: (see Remarks) Job #: 12736 Groundwater not encountered during drilling. Figure: Drilling Engineers 4 J. Grippa 1 of 1 0 4 8 12 16 20 24 28 Depth (ft) GRAPHIC LOG Sample Type Sample # Total Moisture (%) Dry Density(pcf) Gravel % Sand % Fines % LL PL PI TOPSOIL: Clay, roots, organics, moist, brown 3 CLAY (CL), some fine sand, moist, brown stiff 18 3 10 7 17 very stiff 19 18 41 10.2 101 37 16 21 23 gardes dark brown 8 20 12 25 13 11 21 15 34 19 12 hard 22 15 35 20 4 stiff 23 6 13 7 END AT 15 FEET Remarks: Drilled By: Logged By: Page: Maverik Store Bore Hole Log B-4 4/30/19 Surface Elev. (approx): NWC of I-25 & N, County Rd 32, Ft. Collins, CO Boring Type: Hollow-Stem Auger Total Depth: 15' Date: Soil Description Blows (N) Gradation Atterberg Water Depth: (see Remarks) Job #: 12736 Groundwater not encountered during drilling. Figure: Drilling Engineers 5 J. Grippa 1 of 1 0 4 8 12 16 20 24 28 Depth (ft) GRAPHIC LOG Sample Type Sample # Total Moisture (%) Dry Density(pcf) Gravel % Sand % Fines % LL PL PI TOPSOIL: Clay, roots, organics, moist, brown 10 CLAY (CL), moist, gray-brown very stiff 24 10 20 10 8 stiff 25 10 21 12.9 110 39 17 22 11 4 26 5 11 6 5 27 7 15 8 END AT 10 FEET Remarks: Drilled By: Logged By: Page: Maverik Store Bore Hole Log B-5 4/30/19 Surface Elev. (approx): NWC of I-25 & N, County Rd 32, Ft. Collins, CO Boring Type: Hollow-Stem Auger Total Depth: 10' Date: Soil Description Blows (N) Gradation Atterberg Water Depth: (see Remarks) Job #: 12736 Groundwater not encountered during drilling. Figure: Drilling Engineers 6 J. Grippa 1 of 1 0 4 8 12 16 20 24 28 Depth (ft) GRAPHIC LOG Sample Type Sample # Total Moisture (%) Dry Density(pcf) Gravel % Sand % Fines % LL PL PI Key to Symbols Date: Job #: Gradation ⑩ ① ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ MODIFIERS Description Thickness Trace Seam Up to ½ inch <5% Lense Up to 12 inches Some Layer Greater than 12 in. 5-12% Occasional 1 or less per foot With Frequent More than 1 per foot > 12% Note: Dual Symbols are used to indicate borderline soil classifications (i.e. GP-GM, SC-SM, etc.). Silty Sands, Sand-Silt Mixtures TYPICAL DESCRIPTIONS COLUMN DESCRIPTIONS USCS SYMBOLS Blows(N) Atterberg Clayey Gravels, Gravel-Sand-Clay Mixtures Well-Graded Sands, Gravelly Sands, Little or No Fines MAJOR DIVISIONS 1. The results of laboratory tests on the samples collected are shown on the logs at the respective sample depths. 2. The subsurface conditions represented on the logs are for the locations specified. Caution should be exercised if interpolating between or extrapolating beyond the exploration locations. 3. The information presented on each log is subject to the limitations, conclusions, and recommendations presented in this report. Dry: Absence of moisture, dusty, dry to the touch. Moist: Damp / moist to the touch, but no visible water. Well-Graded Gravels, Gravel-Sand Mixtures, Little or No Fines Poorly-Graded Gravels, Gravel-Sand Mixtures, Little or No Fines Silty Gravels, Gravel-Sand-Silt Mixtures Figure: 7 Poorly-Graded Sands, Gravelly Sands, Little or No Fines COARSE- GRAINED SOILS More than 50% of material is larger than No. 200 sieve size. GRAVELS The coarse fraction retained on No. 4 sieve. CLEAN GRAVELS GW (< 5% fines) GRAVELS WITH FINES GC ( ≥ 12% fines) GP CLEAN SANDS Maverik Store NWC of I-25 & N, County Rd 32, Ft. Collins, CO Soil Description 4/30/19 12736 Soil Description: Description of soils encountered, including Unified Soil Classification Symbol (see below). PI = Plasticity Index (%): Range of water content at which a soil exhibits plastic properties (= Liquid Limit - Plastic Limit). Gradation: Percentages of Gravel, Sand and Fines (Silt/Clay), obtained from lab test results of soil passing the No. 4 and No. 200 sieves. Graphic Log: Graphic depicting type of soil encountered (see ② below). PL = Plastic Limit (%): Water content at which a soil changes from liquid to plastic behavior. Moisture (%): Water content of soil sample measured in laboratory (percentage of dry weight of sample). (< 5% fines) GM ( ≥ 12% fines) Sample #: Consecutive numbering of soil samples collected during field exploration. Blows: Number of blows to advance sampler in 6" increments, using a 140-lb hammer with 30" drop. Inorganic Silts, Micacious or Diatomacious Fine Sand or Silty Soils Clayey Sands, Sand-Clay Mixtures Inorganic Clays of Low to Medium Plasticity, Gravelly Clays, Sandy Clays, Silty Clays, Lean Organic Silts and Organic Silty Clays o f Low Plasticity Organic Silts and Organic Clays of Medium to High Plasticity Sample Type: Type of soil sample collected at depth interval shown; sampler symbols are explained below-right. Total Blows: Number of blows to advance sampler the 2nd and 3rd 6" increments. SILTS AND CLAYS Liquid Limit greater than 50% SANDS WITH FINES SM SW (see Remarks on Logs) Inorganic Clays of High Plasticity, Fat Clays ML CL Rock Core MH 3.5" OD, 2.42" ID D&M Sampler Block Sample MOISTURE CONTENT OH Inorganic Silts and Very Fine Sands, Rock Flour, Silty or Clayey Fine Sands or Clayey Silts with WATER SYMBOL SAMPLER OL SC SP Bulk/Bag Sample Measured Water Level HIGHLY ORGANIC SOILS Encountered Water Level FINE- GRAINED SOILS More than 50% of material is smaller than No. 200 sieve size. Standard Penetration Split Spoon Sampler Thin Wall (Shelby Tube) SANDS The coarse fraction passing through No. 4 sieve. SILTS AND CLAYS Liquid Limit less than 50% Peat, Humus, Swamp Soils with High Organic Contents Saturated: Visible water, usually soil below groundwater. UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) SYMBOLS CH PT Atterberg: Individual descriptions of Atterberg Tests are as follows: Modified California Sampler STRATIFICATION Dry Density (pcf): The dry density of a soil measured in laboratory (pounds per cubic foot). Depth (ft.): Depth (feet) below the ground surface (including groundwater depth - see water symbol below). LL = Liquid Limit (%): Water content at which a soil changes from plastic to liquid behavior. Depth (ft) GRAPHIC LOG Sample Type Sample # Total Moisture (%) Dry Density(pcf) Gravel % Sand % Fines % LL PL PI Total Moisture (%) Dry Density(pcf) Gravel % Sand % Fines % LL PL PI 16 APPENDIX Figure 1: Bore Hole Location Figures 2 through 6: Bore Hole Log Figure 7: Key to Symbols Factor "m" Average Outflow cfs Outflow Volume cubic feet Sorage Volume cubic feet 5 2.85 1,748 1.00 0.57 170 1,578 5 9.95 7,630 1.00 0.57 170 7,459 10 2.21 2,711 0.75 0.43 256 2,456 10 7.72 11,839 0.75 0.43 256 11,584 15 1.87 3,441 0.67 0.38 341 3,101 15 6.52 14,999 0.67 0.38 341 14,658 20 1.61 3,951 0.63 0.36 426 3,525 20 5.60 17,176 0.63 0.36 426 16,750 25 1.43 4,386 0.60 0.34 511 3,875 25 4.98 19,093 0.60 0.34 511 18,582 30 1.30 4,785 0.58 0.33 596 4,188 30 4.52 20,796 0.58 0.33 596 20,199 35 1.17 5,024 0.57 0.32 682 4,342 35 4.08 21,900 0.57 0.32 682 21,218 40 1.07 5,251 0.56 0.32 767 4,484 40 3.74 22,943 0.56 0.32 767 22,176 45 0.99 5,466 0.56 0.32 852 4,614 45 3.46 23,878 0.56 0.32 852 23,026 50 0.92 5,644 0.55 0.31 937 4,706 50 3.23 24,768 0.55 0.31 937 23,830 55 0.87 5,871 0.55 0.31 1,022 4,848 55 3.03 25,557 0.55 0.31 1,022 24,535 60 0.82 6,036 0.54 0.31 1,108 4,929 60 2.86 26,317 0.54 0.31 1,108 25,209 65 0.78 6,220 0.54 0.31 1,193 5,027 65 2.71 27,014 0.54 0.31 1,193 25,822 70 0.73 6,269 0.54 0.30 1,278 4,991 70 2.59 27,804 0.54 0.30 1,278 26,526 75 0.70 6,441 0.53 0.30 1,363 5,078 75 2.48 28,525 0.53 0.30 1,363 27,162 80 0.66 6,478 0.53 0.30 1,448 5,030 80 2.38 29,200 0.53 0.30 1,448 27,751 85 0.64 6,674 0.53 0.30 1,534 5,141 85 2.29 29,852 0.53 0.30 1,534 28,318 90 0.61 6,736 0.53 0.30 1,619 5,117 90 2.21 30,503 0.53 0.30 1,619 28,885 95 0.58 6,760 0.53 0.30 1,704 5,056 95 2.13 31,032 0.53 0.30 1,704 29,328 100 0.56 6,871 0.53 0.30 1,789 5,081 100 2.06 31,592 0.53 0.30 1,789 29,803 105 0.54 6,956 0.52 0.30 1,874 5,082 105 2.00 32,206 0.52 0.30 1,874 30,331 110 0.52 7,018 0.52 0.30 1,960 5,058 110 1.94 32,727 0.52 0.30 1,960 30,767 115 0.51 7,196 0.52 0.30 2,045 5,151 115 1.88 33,156 0.52 0.30 2,045 31,112 120 0.49 7,214 0.52 0.30 2,130 5,084 120 1.84 33,862 0.52 0.30 2,130 31,732 5,151 31,732 0.1182 0.7285 Allowable Unit Release Rate Two-hour Precipitation Mod. FAA Minor Storage Volume (cubic-ft.)= Mod. FAA Minor Storage Volume (acre-ft.)= Mod. FAA Major Storage Volume (cubic-ft.)= Mod. FAA Major Storage Volume (acre-ft.)= Mod. FAA Minor Storage Volume= Mod. FAA Minor Storage Volume= Determination of Average Outflow from the Basin (Calculated): Runoff Coefficient Inflow Peak Runoff Allowable Peak Outflow Rate Runoff Coefficient Inflow Peak Runoff Allowable Peak Outflow Rate Mod. FAA Minor Storage Volume= DETENTION VOLUME BY THE MODIFIED FAA METHOD Maverik Convinient Store and Fuel Station - Fort Collins 1 Return Period for Detention Control Time of Concentration of Watershed Return Period for Detention Control Time of Concentration of Watershed (Reference: IDF Values used from Fort Collins Stormwater Criteria Manual, Table 3.4-1. IDF Table for Rational Method) Mod. FAA Minor Storage Volume= Determination of Major Detention Volume Using Modified FAA Method Design Information (Input): Catchment Drainage Imperviousness Catchment Drainage Area Predevelopment NRCS Soil Group Design Rainfall IDF Formula i=C1*P1/(C2+TC)^C3 Coefficient Two Determination of Average Outflow from the Basin (Calculated): Determination of Minor Detention Volume Using Modified FAA Method Design Information (Input): Catchment Drainage Imperviousness Catchment Drainage Area Predevelopment NRCS Soil Group Allowable Unit Release Rate Two-hour Precipitation Coefficient Three Coefficient Two Coefficient One Coefficient One Design Rainfall IDF Formula i=C1*P1/(C2+TC)^C3 (years) Factor (Ct) 2, 5, 10 1.00 IMP Copy of 19-122-0006_Drainage Calcs.xlsx 10/6/202011:13 AM MAVERIK INC. STORE I-25 & E. COUNTY RD. 32 / HIGHWAY 392 FORT COLLINS, CO No. Date Description NOTE: Conflicting information or errors found in the construction documents should be brought to the attention of the architect immediatly. In the event of a conflict in the drawings, bidder should not assume the least expensive option will meet the project requirements. Bid documents should not be separated or issued as partial sets to subcontractors. Bidders are responsible for all portions of the documents that pertain to work covered by sub-bids. Bidder assumes full responsibility for error or misinterpretations resulting from partial sets of Bidding Documents by itself or any sub-bidder. Plot Date: 2020-10-06 File Location: O:\1200-Denver\DCI-Civil\Projects\2019\19-122-0006-MAVERIK-FORT COLLINS-CO\19-122-0006PDP.dwg OF 1331 17TH STREET SUITE 605 DENVER, COLORADO 80202 PHONE: (720) 439-4700 WEBSITE: www.dci-engineers.com CIVIL / STRUCTURAL © 10/2020 This document, and the ideas and designs may not be reused, in whole or in part, without written permission from D'Amato Conversano Inc. D'Amato Conversano Inc. disclaims any responsibility for its unauthorized use. SEPTEMBER 30, 2020 19-122-0006 POST-DEVELOPED DRAINAGE CONDITIONS 2 3 1 0.14 0.79 A 0.88 A 19-122-0006 PRE-DEVELOPED DRAINAGE CONDITIONS 1 3 A 1.41 A 0.14 0.40 1