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HomeMy WebLinkAboutPlans1.0 INTRODUCTION To improve efficiency and safety, Garfield County is proposing to construct a new scale operation with dedicated inbound and outbound scales along with a new administration building. The scale house and administration building will be in an undeveloped area between the entrance road and a well pad access road approximately 1,000 feet southwest of the scale operation. The scale house and administration building will be modular structures designed specifically for this purpose. The proposed truck scales will be positioned to allow truck drivers to conduct business without having to exit their vehicles. The project also will include the following: • Installation of a 1,500 -gallon septic holding underground storage tank (UST); • Installation of a 1,787 -gallon potable UST; • Installation of a 500 -gallon propane above -ground storage tank (AST) that will service both new buildings; • Installation of the scale house will be equipped with red -green traffic signals at the scale house to control traffic using the scales; • Construction of a new bituminous access road; • Construction of a new bituminous parking area for both new buildings; and • Installation of stormwater management best management practices (BMPs). The site's address is 0075 Garfield County Road 246. The site is approximately 259.6 acres in size and is located within Public Land Survey System Section 6S 94W. The area to be disturbed is approximately 1.34 acres. Access to the facility is made from County Road 246 located to the southwest of the site. The facility entrance area is in the southwest corner of the property and the entrance road extends to the landfill located in the northeast portion of the property. A Vicinity Map is provided in Appendix A. Garfield County (Owner) is the owner for this project. Kuersten Construction (Contractor) is the general contractor for this project. 2.0 SOIL HANDLING The surficial soil including organic material (i.e., topsoil) varies in thickness and composition at the work area. During clearing and grubbing, the Contractor will salvage the surficial soil best suited for use as topsoil and place that soil in a stockpile that will be as near the work area as practicable. After reaching substantial completion of the main project work, the Contractor will place the stockpiled topsoil in the areas to be seeded. August 2019 Page 2 Vegetation + Reclamation Plan 4622.00 3.0 WEED MANAGEMENT PLAN This Weed Management Plan wholly follows the Garfield County Noxious Weed Management Plan, adopted by the Board of County Commissioners on February 16, 2016, and provides guidelines for managing designated noxious weeds that represent a threat to the continued economic, environmental, and agricultural value of lands in Garfield County. This Weed Management Plan provides for the implementation of the Colorado Noxious Weed Act by detailing integrated management options for designated noxious weeds. Options include education, preventive measures, good stewardship, and control techniques. This Weed Management Plan will incorporate those options that are the least environmentally damaging and are practical, timely, and economically feasible. Everyone is responsible for the use of integrated methods to manage noxious weeds. Garfield County is responsible for ensuring that these plants are managed on public and private lands. 3.1 Plan Details This Weed Management Plan wholly follows the Garfield County Noxious Weed Management Plan. Please refer to that document for the details of this Weed Management Plan. A list of noxious weed species of particular concern to Garfield County is included in the following table. Table 3.1-1- Noxious Weed List Scientific Name Common Name Artemesia absinthium Absinth wormwood Hyoscyamus niger Black henbane Saponaria officinalis Bouncingbet Cirsium vulgare Bull thistle Cirsium arvense Canada Thistle Cichorium intybus Chicory Clematis orientalis Chinese clematis Arctium minus Common Burdock Tanacetum vulgare Common tansy Dipsacus fullonum Common teasel Anthemis arvensis Corn chamomile Rumex crispus Curly Dock Dipsacus laciniatus Cutleaf teasel Euphorbia cyparissias Cypress spurge Dalmatian toadflax Linaria dalmatica Hesperis matronalis Dame's rocket Centaurea diffusa Diffuse Knapweed Cardaria draba Hoary Cress Cynoglossum officinale Houndstongue Aegilops cylindrica Jointed Goatgrass Euphorbia esula Leafy Spurge Anthemis cotula Mayweed chamomile Centaurea pratensis Meadow knapweed August 2019 Vegetation + Reclamation Plan Page 3 4622.00 Salvia aethiopsis Mediterranean sage Carduus nutans Musk Thistle Euphorbia myrsinites Myrtle spu ge Chrysanthemum leucantheum Oxeye Daisy Lepidium latifolium Perennial pepperweed Carduus acanthoides Plumeless Thistle Conium maculatum Poison hemlock Lythrum salicaria Purple Loosestrife Acroptilon repens Russian Knapweed Elaeagnus anqustifolia Russian Olive Tamarixparviflora, Tamarix ramosissima Salt Cedar Tripleurospermum perforatum Scentless chamomile Onopordum acanthium Scotch Thistle Centaurea maculosa Spotted Knapweed Potentilla recta Sulfur cinquefoil Centaurea solstitalis Yellow Starthistle Linaria vulgaris Yellow Toadflax 4.0 SITE REVEGETATON AND RESTORATION Approximately 0.52 acres of the 1.34 acres proposed to be disturbed will require seeding. The balance will include buildings, truck scales, tanks, and impervious surfaces such as roads, parking areas, rip rap and other BMPs, and the like. When site conditions are suitable for seeding (likely in Spring 2020), the Contractor will seed using mechanical (e.g., drill -seeding, hydro -seeding, etc.), manual means, or both, depending on size and location. The Contractor will use the Low -Grow Mix, a mixture of low -growing (8 to 12 inches) grasses that is drought tolerant, is suitable for areas where mowing is difficult or not desirable, and is very compatible with wildflowers. The Contractor will seed at the dryland rate of 0.5 pound per 1,000 square feet, or 21.780 pounds per acre, because the Owner will not irrigate the seeded area. A summary of the native seed mix is shown in following table. Table 4.0-1- Summary of Low -Grow Mix Scientific Name Common Name Weight (Pounds of Pure Live Seed per Acre) Percent Agropyron cristatum Ephraim Crested Wheatgrass 6.534 30 Festuca ovina Sheeps Fescue 5.445 25 Lolium Perenne Vibrant Perennial Ryegrass 4.356 20 Festuca rubra supsp. commutata Chewings Fescue 3.267 15 Poa compressa Canada Bluegrass 2.178 10 Totals 21.780 100 August 2019 Vegetation + Reclamation Plan Page 4 4622.00 Unless seeding is via hydro -seeding (including mulch), after finishing seeding, the Contractor will place and crimp weed -free mulch, the Contractor will place the mulch by hand or via equipment (depending on size and area) over the seeded areas, and the Contractor will crimp the mulch using an appropriate tractor pulling an appropriate mulch crimper. The Contractor will install erosion control and other stormwater management BMPs as needed and in accordance with the Stormwater Management Plan for this project. 5.0 COST ESTIMATE Sanborn Head has prepared an opinion of cost (i.e., a cost estimate) relative to vegetation and reclamation and to establish the amount of financial security. Our cost opinion is included in the following table. Table 5.0-1- Engineer's Opinion of Cost (i.e , Cost Estimate) Activity Quantity Unit Unit Cost Activity Cost Mobilization / Demobilization 1 Lump Sum $ 2,500 $ 2 500 Earthmoving (1.34 Acres Averaging 2 Feet Thick) 360 Cubic Yard $ 2.50 $ 1,000 Seed and Planting 0.52 Acre $ 1,000 $ 550 Weed -Free Mulch, Erosion Control, Dust Suppression 1.34 Acre $ 2,000 $ 2,700 Irrigation 0 Lump Sum $ 0 $ 0 Weed Management 1 Lump Sum $ 1,000 $ 1,000 Total $ 7,750 6.0 FINANCIAL SECURITY The Owner will provide financial security for this portion of the project. The Owner will provide cash, bonds, or a letter of credit (valid for at least two years) in the amount noted in the Cost Estimate section above. 7.0 COUNTY INSPECTION AND RELEASE OF FINANCIAL SECURITY When grading is finished and vegetation is re-established, the Owner will contact the County Vegetation Manager and request an inspection. When the County Vegetation Manager has determined that restoration is adequate, the County will inform the Owner and release the financial security noted in the Financial Security section above. P:\4600s\4622.00\Source Files\Veg+Reclamation Plan\Vegetation + Reclamation Plan.docx APPENDIX A VICINITY MAP SANBORN 1111 HEAD Rifle SITE „,.E. Mesa Anvil Points PROJECT AREA Inughenbm,,J MK Vws.re ;cm. mom NOTES: BASE MAP WAS PREPARED FROM USGS 7.5 -MINUTE QUADRANGLE MAPS FOR ANVIL POINTS, RULISON, RIFLE, AND NORTH MAMM PEAK, COLORADO. 1-- 5,000 0 Feet 10,000 GARFIELD COUNTY LANDFILL RIFLE, COLORADO SCALE HOUSE PROJECT VICINITY PLAN SCALE: AS NOTED DATE: AUG 19 DRAWN BY: TWR CHECKED BY: MBK FILE NO. 4622.00 FIGURE NO. 1 SCALE: AS NOTED' Anvil Points PROJECT AREA SITE Rifle NOTES: BASE MAP WAS PREPARED FROM USGS 7.5 -MINUTE QUADRANGLE MAPS FOR ANVIL POINTS, RULISON, RIFLE, AND NORTH MAMM PEAK, COLORADO. Webs c Mew Llutf "WRY. Feet 5,000 0 10,000 GARFIELD COUNTY LANDFILL RIFLE, COLORADO SCALE HOUSE PROJECT VICINITY PLAN DATE: AUG 19 DRAWN BY: TWR CHECKED BY: MBK FILE NO. 4622.00 FIGURE NO. 1 Y 1 - C.O.D. BOUNDARY BASED ON NWCC, INC. GENERAL FACILITY MAP UNDERGROUND GAS LINE OVERHEAD ELECTRICAL .37'/ TEST PTT 1 f/ � f f POTABLE WATER UST 500 -GALLON PROPANE AST l /4 - rr � 6 _ O EXTEND EXISTING 24'0 CMP CULVERT 10_WET STING 24'0 CMP CULVERT EXISTING 18.0 CMP CULVERT EMERGENCY SPILLWAY DISCHARGE STRUCTURE RIPRAP OUTLET PROTECTION APRON I CONCRETE WASHOUT LOCATION SANBORN 1111 HEAD Building Trust. Engineering Success. REVEGETATION AND RECLAMATION PLAN LANDFILL SCALE HOUSE PROJECT Garfield County Rifle, Colorado • 1 A I T.TERSTEN • ■� ;.0Iis auction 1E -Garfield County Prepared for Kuersten Construction, Inc and Garfield County, Colorado File No. 4622.00 August 2019 SANBORN, STEAD & ASSOCIATES, INC. www.sanbornhead.com TABLE OF CONTENTS 1.0 INTRODUCTION 1 2.0 SOIL HANDLING 1 3.0 WEED MANAGEMENT PLAN 2 3.1 Plan Details 2 4.0 SITE REVEGETATON AND RESTORATION 3 5.0 COST ESTIMATE 4 6.0 FINANCIAL SECURITY 4 7.0 COUNTY INSPECTION AND RELEASE OF FINANCIAL SECURITY 4 APPENDICES Appendix A - Vicinity Map ■SANAM API NorthWest Colorado Consultants, Inca ■ V WkiiMisil Geotechnical / Environmental Engineering • Materials Testing August 21, 2019 Garfield County Landfill Attn: Deb Fiscus — Landfill Manager 0075 County Road 246A Rifle, Colorado 81650 Job Number: 02-5136 Subject: Subsoil and Foundation Investigation, Scale House and Administration Building, Garfield County Landfill (GCLF), Rifle, Colorado Ms. Fiscus: NWCC is pleased to provide this report presenting results of a Subsoil and Foundation Investigation completed for the proposed scale house and administration building to be constructed at Garfield County Landfill (GCLF). The new scale house facility is to be constructed on Garfield County Road (GCR) 246A and to the west of the current landfill access gate. The proposed build -out is on GCR 246A and along the south side of the road. NWCC previously completed a Preliminary Geotechnical Investigation and Geologic Hazard Evaluation to the northeast and in the general vicinity during 2018 (NWCC; June 19, 2018). The approximate location of the GCLF is shown in Figure 1. NWCC, Inc's (NWCC) scope of work included obtaining data from cursory observations made at the proposed scale house location, logging of two test pits, sampling of probable foundation soils, laboratory testing of samples obtained, and review of the previously completed geotechnical investigation (NWCC, 2018). This report presents recommendations for an economically feasible and safe type foundation, as well as allowable soil pressures and other design and construction considerations that are advisable, but not necessarily routine to quality design and building practices. This report also provides recommendations regarding site grading and pavement design. Proposed Construction NWCC understands that a new scale house, including uncovered double scales, administration building, and relatively small parking area will be constructed on and south of County Road 246A. The buildings will be wood framed structures constructed over concrete foundations. NWCC assumes the lower levels of the buildings will be constructed using concrete slab -on - grade or structural floor systems constructed at or above the existing ground surface. Fill placement, re -grading, and paving of roadways and parking areas will also be conducted. The proposed facility layout is shown on Figure 2. (970) 879-7888 • Fax (970) 879-7891 "con on 0/1A 0'7 Subsoil and Foundation Investigation Proposed Scale House and Administration Building Garfield County Landfill, Garfield County, Colorado August 21, 2019 Page 2 of 9 Site Conditions NWCC conducted field activities on July 24, 2019, including cursory observation data collection, excavation and logging of two test pits, soil sampling, and subsequent analysis. NWCC understands that GCLF ascertained the site location based on surveyor information and provided utility clearances before excavation activities. GCLF provided excavation services during the field assessment. Collected soil samples were transported to the NWCC Geotechnical Laboratory located in Steamboat Springs, Colorado for soil classification and materials properties testing. Field activities and findings are summarized below. The proposed building area appeared undeveloped and vacant during site activities. The existing landfill access road, GCR 246A, runs through the northern portion of the proposed building site. The south side of the road is vegetated with mainly sage brush, weeds, and grasses. The topography is variable and generally slopes moderately down to the south-southwest. A natural gas pipeline is located along the north side of the access road and a natural gas well and tank facility is located to the southwest and in the vicinity. Subsurface Conditions To investigate subsurface conditions, two test pits were excavated; Test Pit 1 to approximately 6 '/z feet and Test Pit 2 to approximately to 5 feet below the existing ground surface (bgs), using a CASE 580 backhoe provided and operated by GCLF. The approximate test pit locations are shown on Figure 2 and graphic logs of the exploratory test pits, including associated legend and notes, are provided in Figure 3. Variable subsurface conditions were encountered, generally consisting of a layer of natural topsoil and organic materials or fill materials overlying sands and gravels to the maximum excavation depths. A 1 1/2 foot thick layer of fill materials composed of clayey sands and gravels with roots was encountered at the ground surface in Test Pit 1 and a 9 -inch thick layer of natural topsoil and organic materials was encountered at the ground surface in Test Pit 2. Sands and gravels were encountered beneath the fill materials in Test Pit 1 and beneath the topsoil and organic materials in Test Pit 2, extending to 6 1/2 feet bgs in Test Pit 1 and to 5 feet bgs in Test Pit 2. The sands and gravels were clayey to silty, fine to coarse grained with cobble to boulder -sized bedrock fragments, low plastic, medium dense, dry and brown in color. In Test Pit 1, sands and gravels were clayey from 9 inches to 4 feet bgs and silty from 4 to 5 feet bgs. Samples of the sands and gravels classified as GM and SC soils in accordance with the Unified Soil Classification System. The sands and gravels encountered in Test Pit 2 were similar to those encountered in Test Pit 1. Groundwater was not encountered in the test pits during the field investigation; however, groundwater levels in monitoring wells at the adjacent landfill increase and decrease with seasonal changes. Shallow groundwater is typically perched atop impervious bedrock and believed to be recharged through precipitation and seasonal runoff. Bedrock was not encountered in any of the test pits encountered at this site or at the site located to the northeast and along the north side of County Road 246A. NWCC, Inc. Subsoil and Foundation Investigation Proposed Scale House and Administration Building Garfield County Landfill August 21, 2019 Page 3 of 9 Laboratory Results Samples obtained from the test pits were examined and classified by the principal engineer, prior to conducting laboratory testing. Laboratory testing included natural moisture content, grain size analysis, and liquid and plastic limits. Laboratory testing was conducted in general accordance with applicable ASTM/AASHTO specifications. Results of the laboratory tests are summarized in Table 1. Foundation Recommendations Based upon the investigation, NWCC believes a feasible foundation system for the proposed administration building and scale house buildings would consist of spread footings or reinforced mats placed on the natural sands and gravels or on properly compacted structural fill materials placed over the natural sands and gravels. NWCC suggests that the recommendations outlined below be followed during building design and construction. 1) Footings and/or mat placement on the sands and gravels or properly compacted structural backfill materials should be designed using an allowable soil bearing pressure of 3,000 psf. 2) Footings or pad sizes computed using the above soil pressures and placed on undisturbed natural sands and gravels found below existing topsoil and organic materials and/or existing fill materials, or on properly compacted structural fill materials placed over the natural sands and gravels. 3) Site Class C designation be used in structural design calculations in accordance with Table 20.3-1 in Chapter 20 of ASCE 7-10. 4) Any topsoil and organic materials, existing fill materials or loose and soft natural soils encountered within the foundation excavations should be removed and excavations extended to competent natural sands and gravels. If structural fill materials are placed beneath the foundations, we recommend they consist of non -expansive granular soils placed in 6 to 9 inch loose lifts and be compacted to at least 100 percent of the maximum standard Proctor density and within 2 percent of the optimum moisture content determined in accordance with ASTM D698. 5) Foundation walls designed and reinforced to span an unsupported distance of 10 feet or the length between pads, whichever is greater. 6) Based on experience, NWCC estimates that total settlement for footings and pads designed and constructed, as discussed in this section, will be approximately 1 inch. Additional bearing capacity values along with associated settlements, are presented in Figure 4. 7) Care should be taken when excavating to avoid disturbing supporting materials. Disturbing bearing materials may increase settlements. 8) Footings and mats should be placed far enough below final backfill grades to protect them from frost heave. Thirty-six (36) inches is recognized by the local building authority. NWCC, Inc. Subsoil and Foundation Investigation Proposed Scale House and Administration Building Garfield Countv landfill. Garfield County. Colorado August 21, 2019 Paee 4 of 9 9) NWCC must observe foundation excavations when they are near completion to identify bearing soils and confirm recommendations provided in this report, as well as test the structural fill materials placed beneath the foundations for compaction. Floor Slab Recommendations NWCC has assumed concrete slab -on -grade floor systems and/or structural floors constructed over crawl spaces will be used for the scale house and administration building. On-site soils, apart from topsoil and organic materials, are capable of supporting slab -on -grade construction. Floor slabs should be provided with control joints placed a maximum of 10 to 12 feet on center (depending on the slab configurations) in each direction to help control shrinkage cracking. Location of the joints should be carefully checked to assure that the natural, unavoidable cracking will be controlled. Depth of the control joints should be a minimum 1/4 thickness of the slab. NWCC recommends that any topsoil and organic materials encountered within the excavations be removed from beneath floor slabs, prior to concrete or fill placement. Any fill materials placed beneath floor slabs should be a non -expansive granular soil approved by NWCC, prior to placement. Fill should be placed in 6 to 9 -inch loose lifts and be compacted to at least 95% of the maximum standard Proctor density and within 2% of the optimum moisture content. Perimeter Drainage System Recommendations To enhance site drainage and improve foundation and slab -on -grade performance, NWCC recommends a perimeter drainage system be installed around the building perimeters. However, this recommendation can be waived if the finished floor level is situated above the final ground surface and the surface drainage is directed away from the buildings. The drainage system should be located around the building perimeter and placed at least 12 inches below interior building grades and a minimum of 24 inches below final grades to provide frost protection. Ideally, the drainage system should be centered along roof drip -line locations. In locations where roof driplines are not present, the drainage systems may be located within 24 inches of foundation walls. Drains should be insulated using 2 -inches of rigid polystyrene insulation board in locations higher than 48 inches below final grade to provide protection against freezing. Perimeter drainage system piping should be constructed using perforated PVC pipe that meets or exceeds ASTM D-3034/SDR 35 requirements to provide satisfactory long-term function and rapid runoff of water. The drainpipes should be installed at a minimum slope of 1% and be daylighted at positive outfalls that are protected from freezing. The drainpipe holes should be oriented down, between 4 and 8 o'clock, to promote rapid runoff of water and protected from contamination using a geotextile filter fabric covering of Mirafi 140N subsurface drainage fabric or an equivalent product. Following geotextile fabric installation, the pipes should be covered with at least 12 inches of free draining gravel. Caution should be taken when backfilling so as not to damage or disturb the installed drain. NWCC recommends that drainage piping include cleanouts provided at minimum 100 -foot intervals, protected against intrusion by animals at the outfalls and tested prior to backfilling. NWCC, Inc. Subsoil and Foundation Investigation Proposed Scale House and Administration Building Garfield County Landfill August 21, 2019 Page 5 of 9 NWCC should be retained to provide periodic observations of underdrain construction to verify that installation was conducted in general accordance with recommendations provided herein. Flow testing of the system is also recommended. A typical shallow perimeter drain detail is shown in Figure 5. Foundation Wall and Retaining Structure Recommendations Foundation walls and retaining structures, which are laterally supported and can be expected to undergo only a moderate degree of deflection, may be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of 45 pcf for imported, free draining granular backfill and 50 pcf for the on-site soils. Cantilevered retaining structures on the site can be expected to deflect sufficiently to mobilize the full active earth pressure condition. Therefore, cantilevered structures may be designed for a lateral earth pressure computed based on an equivalent fluid unit weight of 35 pcf for imported, free draining granular backfill and 40 pcf for the on-site soils. Foundation walls and retaining structures should be designed for appropriate hydrostatic and surcharge pressures such as adjacent buildings, traffic and construction materials. An upward sloping backfill and/or natural slope will also significantly increase earth pressures on foundation walls and retaining structures and the structural engineer should carefully evaluate these additional lateral loads when designing foundation and retaining walls. The lateral resistance of retaining wall foundations placed on undisturbed natural sands and gravels or properly compacted structural fill materials will be a combination of the sliding resistance of footings on foundation materials and passive pressure against sides of the footings. Sliding friction can be taken as 0.4 times the vertical dead load. Passive pressure against the sides of the footing can be calculated using an equivalent fluid pressure of 250 pcf. Fill placed against sides of footings to resist lateral loads should be compacted to at least 100% of the maximum standard Proctor density and near the optimum moisture content. NWCC recommends importing granular soils for backfilling foundation walls and retaining structures because their use results in lower lateral earth pressures. Imported granular materials should be placed to within 2 to 3 feet of ground surface. Imported granular soils should be free draining and less than 5% passing the No. 200 sieve. Granular soils behind foundation and retaining walls should be sloped away from the base of the wall at an angle of at least 45 degrees from vertical. The upper 2 to 3 feet of fill should be a relatively impervious soil or pavement structure to help inhibit surface water infiltration into the backfill. Wall backfill should be carefully placed in uniform lifts and compacted to at least 95% of the maximum standard Proctor density and near the optimum moisture content. Care should be taken not to overcompact the backfill since this could cause excessive lateral pressure on the walls. It should be noted that a certain degree of settlement of foundation wall backfill materials will occur even if the material is placed correctly. Surface Drainage Recommendations Proper surface drainage at this site is of paramount importance for minimizing infiltration of surface drainage into wall backfill and bearing soils, that could result in increased wall pressures, differential foundation, and slab movement. The following drainage construction precautions NWCC, Inc. Subsoil and Foundation Investigation Proposed Scale House and Administration Building Garfield County Landfill Garfield County. Colorado August 21, 2019 Page 6 of 9 should be followed. These activities should be observed at all times by an engineer, during construction and until completion, to ascertain that the recommended precautions were followed. 1) The ground surface surrounding the structures should be sloped (minimum of 1.0 inch per foot) to drain away from the structures in all directions a minimum of 10 feet. Ponding water must be avoided. If necessary, raising the top of foundation walls to achieve a better surface grade is advisable. 2) Non-structural backfill placed around the structures should be compacted to at least 95% of the maximum standard Proctor density at or near the optimum moisture content in order to minimize future settlement of the fill. The backfill should be placed immediately after the braced foundation walls are able to structurally support the fill. Puddling or sluicing of water must be avoided. 3) The top 2 to 3 feet of soil placed within 10 feet of the foundations should be impervious in nature, to minimize infiltration of surface water into the wall backfill. 4) Roof downspouts and drains should discharge well beyond the limits of all backfill. Roof overhangs that project two to three feet beyond the foundations should be considered if gutters are not used. 5) Landscaping, which requires excessive watering and lawn sprinkler heads, should be located a minimum of 10 feet from the structure foundation walls. 6) Plastic membranes should not be used to cover the ground surface adjacent to foundation walls. Site Grading Recommendations Based upon review of the proposed site grading plan draft prepared by Sanborn Head, it appears that site grading will likely include cuts and fills up to approximately 6 feet in depth. NWCC suggests that the following recommendations be used during preliminary site grading design and construction. 1) Temporary cuts for foundation construction should meet OSHA safety standards associated with trenching and temporary excavations. Permanent, unretained cuts should not exceed a 2(H):1(V) configuration. Permanent cut slopes should be limited to 15 feet in height or less. The risk of slope instability will be significantly increased if groundwater seepage is encountered in the cuts. NWCC should be notified immediately to evaluate the site if seepage is encountered or if cuts deeper than 15 feet are planned. Additional investigations and/or stabilization measures may be warranted at that time. 2) Contractor must provide a construction sequencing plan for excavation, wall construction and bracing and backfilling for steeper and more sensitive portions of the site, prior to starting excavations or construction. 3) Fills up to 10 feet in height can be constructed to a 2(H):1(V) or flatter configuration. Fill areas should be prepared by stripping topsoil and organics, scarification and compaction of exposed subgrade to at least 95% of the maximum standard Proctor density and within 2% of optimum moisture content as detennined by ASTM D698. Fills should be benched/keyed into natural hillsides after the topsoil and organic materials have been stripped using minimum 6 -foot wide benches. Fill materials may consist of the on-site soils (exclusive of topsoil, organics or silts) and should be uniformly placed NWCC, Inc. Subsoil and Foundation Investigation Proposed Scale House and Administration Building Garfield County Landfill August 21, 2019 Page 7 of 9 and compacted in 6 to 8 -inch loose Lifts to the minimum density value and moisture content range indicated above. 4) Where unstable fill surfaces cannot be stabilized by scarification and recompaction, additional stabilization measures will likely be required. These measures may include additional subexcavation and backfill with imported granular materials and/or placement of stabilization fabric (Mirafi 500X or equivalent) and/or geogrid. Stabilization requirements are likely to be variable based on subsoils, groundwater levels and surface runoff conditions at the time of construction and should be evaluated by NWCC at the time of construction. 5) Surface drainage features should be provided around all permanent cuts and fills and steep natural slopes to direct surface runoff away from these areas. Cuts, fills and other stripped areas should be protected against erosion by revegetation or other methods. Areas of concentrated drainage should be avoided and may require the use of riprap for erosion control. NWCC recommends that a maximum of 4 inches of topsoil be placed over the new cut and fill slopes. It should be noted that the newly placed topsoil materials may slough/slide off the slopes during the spring runoff seasons until the root zone in the vegetated cover establishes. 6) A registered professional engineer experienced in site plan preparation in this arid to semi -arid geographic area is recommended for site grading and drainage plan preparation. 7) Subgrade preparation and placement of materials should be observed and tested by NWCC in the field and laboratory for compliance with the contract documents. Pavement Recommendations Pavement section alternatives presented below are based on field and laboratory investigations, assumed traffic loadings indicated below, pavement design procedures presented in the AASHTO Guide for Design of Pavement Structures, and NWCC's experience at similar sites and conditions. AASHTO pavement design procedures have been adopted and are used by the Colorado Department of Transportation (CDOT). Based on the results of field and laboratory investigations and our understanding of the proposed construction, it appears that materials to be encountered at proposed pavement subgrade elevations will most likely consist of natural sands and gravels or sand and gravel fill materials. The sands and gravels were variable and generally classified as GM and SC soils in accordance with the USCS and as A-2 and A-4 soils in accordance with the AASHTO classification system. These materials are generally considered to provide fair to good support for pavement structures. NWCC recommends the pavement areas subjected to both automobile and truck traffic be constructed with a composite pavement section consisting of at least 6 inches of hot mix asphalt (HMA) placed over 4 inches of CDOT Class 6 aggregate base course (ABC) and 8 inches of subbase materials consisting of CDOT Class 2 aggregates. Areas subjected to automobile traffic only, such as in automobile parking stalls, can be paved with composite section consisting of 3 inches of HMA, 4 inches of ABC and 8 inches of Class 2 aggregates. NWCC recommends the areas subjected to heavy truck traffic turning movements be paved with a rigid pavement section consisting of at least 8 inches of Portland cement concrete (PCC). NWCC, Inc. Subsoil and Foundation Investigation Proposed Scale House and Administration Building Garfield County Landfill, Garfield County, Colorado August 21, 2019 Paac 8 of 9 Prior to placement of subbase materials, the upper 1 foot of subgrade soils should be removed, uniformly mixed and moisture conditioned and placed back in the excavation in 6 to 8 -inch loose lifts. Subgrade soils should be moisture conditioned to within 2% of the optimum moisture content and recompacted to at least 95% of the maximum standard Proctor density. Depending on the time of year when subgrade preparation is considered, moisture conditioning including drying and/or moistening of subgrade materials will most likely be required in order to attain uniform compaction. NWCC also recommends that the properly moisture conditioned and recompacted subgrade soils be proof -rolled using a loaded tandem dump truck or water truck, prior to placing subbase gravels. Areas exhibiting deflection and rutting will most likely require deeper stabilization. The depth and type of stabilization should be determined during construction. NWCC recommends the HMA materials consist of an approved "Superpave" mix designed by a qualified, registered engineer. The mix should be designed using the SX gradation and mixed with PG 58-28 oil or higher performance graded asphaltic materials. The mix should be produced and placed by a qualified contractor and compacted to between 92 and 96% of the maximum theoretical (Rice) density. Quality control activities should be conducted on paving materials during placement. ABC materials should consist of well -graded aggregate base course materials that meet CDOT Class 6 ABC grading and durability requirements. Base course and subbase materials (Class 2 Subbase) should be uniformly placed and compacted in 4 to 6 -inch loose lifts to at least 95 % of the maximum modified Proctor density and within +/- 2 % of the optimum moisture content as determined by ASTM D1557. Concrete pavement materials should be based on a mix design developed by a qualified engineer. Concrete properties should include a minimum 28 -day compressive strength of 4,500 psi, be air entrained with approximately 6% air, and consist of a maximum water/cement ratio of 0.42. The maximum slump allowable is 4 inches. Control joints should be a depth of at least '/4 of the slab thickness and not greater than 12 feet on centers. The collection and diversion of surface and subsurface drainage away from the paved areas is extremely important to satisfactory performance of the pavement. The design of the surface and subsurface drainage features should be carefully considered to remove all water from paved areas and to prevent ponding of water on and adjacent to paved areas. NWCC recommends subgrade areas be graded to drain if feasible, so that surface runoff is not allowed to pond on the subgrade surface. Limitations The recommendations provided in this report are based on the soils encountered at this site and our understanding of the proposed construction. NWCC believes that this information provides a high degree of reliability to anticipate the behavior of the proposed structures; however, our recommendations are professional opinions and cannot control nature, nor can they assure the soils profiles beneath those or adjacent to those observed. No warranties expressed or implied are given on the content of this report. This report is based on the investigation at the described site and specific anticipated construction stated herein. If either of these conditions is changed, the results would also most likely change. Therefore, NWCC strongly recommends that our firth be contacted prior to finalizing the NWCC, Inc. Subsoil and Foundation Investigation Proposed Scale House and Administration Building (iarliiI.d County Landfill August 21, 2019 Page 9 01'9 construction plans so that we can verify that our recommendations are being properly incorporated into the construction plans. Man-made or natural changes in the conditions of a property can also occur over time. In addition, changes in requirements due to state-of-the-art knowledge and/or legislation do from time to time occur. As a result, the findings of this report may become invalid due to these changes. Therefore, this report is subject to review and not considered valid after a period of 3 years or if conditions stated above are altered. It is the responsibility of the owner or his representative to ensure that the information in this report is incorporated into the plans and/or specifications and construction of the project. If you have any questions regarding this report or if we may be of further service, please do not hesitate to contact us. Sincerely, n NWC Eri Prnq Reviewed by Bri Principal Enginee Attachments Z:\Jobs102-5136 Garfield County Landfill\Engineering\Scale l louse\Soils Rport\GCLF Scale I -louse SFLdocx NWCC, Inc. z 0 0 In 0 rn 17, 7 0 0 0 7 0 0 O 0 D.26.000' N 106`07.000' W 108°05.000' Vl 108`03.000' w 106' 01.000 w 07'59.000' w J.! TO?0: map printed on 11/17/11 from "COLORADO.TFO" and "Untitled.tpg" 107'57;080' W 107°55.000' W 107'5'.000' F"•1 107'51.000' V! • }G&f• ;ls?1 i SHALE 107'49.000' W t Prdvel NOT TO SCALE I \ I. I+ I -sem 1 1 - 1 a 15N 19'a. GTNTRPI 1 'I I ' I e I P, ■ a • rvi!F `efr5TFa i1:'L•}_re t•LY'r...�•�RS J � 1-XLIT23:1 aro �• - FEN=. unnnJ.,csnc >]FI}iI4G r,t1L P.ti. -- e•S�� Test Pit 2 Title: SITE PLAN—LOCATION OF TEST PITS Date: 6/12/2018 411111 . 14.11 . Job Name: Garfield County Landfill Scale House LO°ati°n: Garfield County, Colorado Job No. 02-5136 Figure 2 re.e<e, r , ae���.,I&4 r,n�,.nro•v,�wa rne^ 19781879-7881• Fox 1978878-7891 2580 Copper Rletle Olive Sieemboal Spittle, C01=8o88187 Depth (ft) 0 - - 1 5 10 LEGEND: i,i1 ►'+'i r+ p Test Pit 1 FILL: Clayey sands and gravels with roots. TOPSOIL AND ORGANICS. SANDS AND GRAVELS: Clayey to silty, fine to coarse grained with cobble to boulder sized bedrock fragments, low plastic, medium dense, dry and brown. Small Disturbed Bag Sample. Test Pit 2 NOTES: 1) 2) 3) 4) 0 1 5 10 Test pita were excavated on July 24, 2019 with a CASE 580 backhoe provided by client. Test pit locations were determined using a site plan of proposed features provided by client. The elevations of the test pits were not measured and the logs are drawn to the depths investigated. The lines between materials shown on the teat pit logs represent the approximate boundaries between material types and transitions may be gradual. Title: LOGS, LEGEND AND NOTES Date: 8/13/19 .sr ,i1fdt.,riraTr mrtrin limn. grill Job Name: Garfield County Landfill Scale House Location` Garfield County, Colorado Job No. 02-5136 Figure 3 wsn.N • RnNner—nl+r Fry'N.•s.p• UM..w. Meq (9701079-7000• Fay (970079-7091 2580 Copper Ridge Olive Sleamboel Springs. Colorado 88487 6000 4500 3000 1500 0 0 0.5 1.0 1.5 Estimated Settlement (inches) 20 Note: These values are based on footing widths of 1 to 4 feet. If the footing width is to be greater than 4 feet in width, then we should be notified to re—evaluate these recommendations. Title: BEARING CAPACITY CHART Job Name: Garfield County Landfill Scale House Location: Garfield County, Colorado Date: 8/12/2019 Job No. 02-5136 Figure 4 • (970)879-7888• Fav 1970879-7891 7580 Capper Podge Dave Steamboat Sennas, Cdaredo 80487 / / / / I / // / / / / / // / / / / / / / 0 0.5 1.0 1.5 Estimated Settlement (inches) 20 Note: These values are based on footing widths of 1 to 4 feet. If the footing width is to be greater than 4 feet in width, then we should be notified to re—evaluate these recommendations. Title: BEARING CAPACITY CHART Job Name: Garfield County Landfill Scale House Location: Garfield County, Colorado Date: 8/12/2019 Job No. 02-5136 Figure 4 • (970)879-7888• Fav 1970879-7891 7580 Capper Podge Dave Steamboat Sennas, Cdaredo 80487 Slope 12(H):1(V) or steeper Waterproof Foundation Mirafi 140N or Equivalent Filter Fabric Compacted Backfill Per Soils Report Foundation Wall Footing Expansion Joint/Felt 2' Min. - Depth Can Var At -Grade Floor Slab Granular Fill Per Soils Report Impervious Membrane 4" dia. Perforated PVC Pipe. Slope Min. 1/8" per ft. to Daylight. Surround with Free -draining Gravels. Undisturbed Soil Compacted Backfill Per Soils Report Title: PERIMETER DRAIN DETAIL Jeb Name: Garfield County Landfill Scale House Location: Garfield County, Colorado Date: 8/12/2019 Job No. 02-5136 Figure 5 Keyed." -mewed, 0.e .,8 (970P78-7888. Fox (970)874-71381 2580 Capper Ridge Drive Bleemhoel Springs, Cdoreda 80477 NWCC, Inc. TABLE 1 SUMMARY OF LABORATORY TEST RESULTS SAMPLE LOCATION NATURAL MOISTURE CONTENT (%) DRY DENSITY (Pof) ATTERBERG LIMITS GRADATION PERCENT PASSING No. 200 SIEVE UNCONFINED COMPRESSIVE STRENGTH (PSF) SOIL or BEDROCK DESCRIPTION UNIFIED SOIL CLASS. TEST PIT DEPTH (feet) LIQUID LIMIT (%) PLASTICITY INDEX (%) GRAVEL (%) SAND (%) 1 5 6.0 23 1 38 33 29 Silty Sandy Gravel GM 2 3 7.8 24 10 17 47 36 Very Clayey Gravelly Sand SC I i I J JOB NUMBER: 02-5136 11. :11 /4..-;,..1.0::!;:i'._ oF�i�n /+ fir+ 1 t 2 i CPESC TIMOTHY W. REED \\11:411:::, .101.,..„.!40. 6686 ,• =:11.:44i3.so►MEtr KLTERSTEN UM Construction ir��Q,s10111Y �, [•C',i' .0051G13t3 DRAINAGE REPORT SCALE HOUSE PROJECT Garfield County Landfill Rifle, Colorado Garfield County Prepared for Kuersten Construction, Inc and Garfield County, Colorado File No. 4622.00 August 2019 100 TABLE OF CONTENTS 1.0 INTRODUCTION 1 2.0 GENERAL LOCATION AND EXISTING SITE DESCRIPTION 1 2.1 Location 1 2.1 Existing Site Description 1 3.0 PROPOSED SITE DESCRIPTION 2 4.0 DESIGN INTENT, SOFTWARE AND HYDROLOGIC CRITERIA 3 4.1 Design Intent 3 4.2 Software 3 4.3 Hydrologic Criteria 3 4.4 Hydraulic Criteria 4 5.0 DISCUSSION 5 6.0 MAINTENANCE PLAN 5 6.1 Inspections 5 6.2 Repairs 6 6.3 Maintenance/Cleaning 6 6.4 Vegetation 7 7.0 CONCLUSION 7 APPENDICES Appendix A Appendix B - Appendix C - Appendix D Appendix E - - Vicinity Map Web Soil Survey Runoff Calculations - Erosion Control Details Additional Calculations 1.0 INTRODUCTION This final drainage report was prepared for Kuersten Construction, Inc., the design -build contractor selected by Garfield County to construct a new scale house, truck scales, and administrative building at the entrance to the Garfield County Landfill (Facility) in Rifle, Colorado. Currently, the Facility uses a single covered truck scale attached to the facility's office building. Truck drivers delivering materials to the site are required to exit their vehicles and walk up to a window on the side of the office to conduct business with the scale operator located in the southwest corner of the office. To improve efficiency and safety, Garfield County is proposing to construct a new scale operation with dedicated inbound and outbound scales along with a new administration building. The scale house and administration building will be located in an undeveloped area between the entrance road and a well pad access road approximately 1,000 feet southwest of the scale operation. The scale house and administration building will be modular structures designed specifically for this purpose. The proposed truck scales will be positioned to allow truck drivers to conduct business without having to exit their vehicles. The scale operation will consist of one inbound scale and one outbound scale. The scales will be 11 feet wide and 70 feet long, and in -vehicle transactions will take place through service windows located on the southwest end of the scale house. Power for the buildings will come from an existing utility pole located on the opposite side of the entrance road. The project will include the installation of a 1,500 -gallon septic holding underground storage tank (UST), 1,787 -gallon potable UST, and a 500 -gallon propane above -ground storage tank (AST) that will service both buildings. The scale house will be equipped with red -green traffic lights to control traffic using the scales. 2.0 GENERAL LOCATION AND EXISTING SITE DESCRIPTION 2.1 Location The site is about 259.6 acres in size and is located within Public Land Survey System Section 6S 94W. Access to the facility is made from County Road 246 located to the southwest of the site. The facility entrance area is in the southwest corner of the property and the entrance road extends to the landfill located in the northeast portion of the property. A Vicinity Map is provided in Appendix A. 2.1 Existing Site Description The site topography generally slopes to the southwest, and elevations surrounding the project area range from about 5440 feet to about 5470 feet. The slope on the existing entrance road in this area is about 3 percent, and the area tends to drain from north to south to an intermittent drainage channel that extends beneath the entrance road through a 24 - inch diameter culvert and beneath a well pad access road through an 18 -inch diameter culvert and appears to flow in the southeast direction. There is a roadside drainage swale on the northwest side of the facility entrance road that collects runoff from areas along and north of the road and conveys it to the drainage channel. The site is designated Zone D by FEMA (Federal Emergency Management Agency), which indicates that a flood hazard August 2019 Page 2 Drainage Reportdocx 4622.00 analysis has not been prepared or a Flood Insurance Rate Map (FIRM) for the area has not been printed. The existing terrain consists mainly of grassed areas with some gravel and paved access roads that support the landfill and other operations at the Facility. According to the United States Department of Agriculture Natural Resources Conservation Service, soils at the site are Nihill channery loam, 6 to 25 percent slopes, and have a Hydrologic Group classification of Type A. A Web Soil Survey Report is provided in Appendix B. Groundwater at the site should be at least 21 feet below ground surface (bgs). According to a Geotechnical Investigation prepared by North West Colorado Consultants, Inc. (NWCC) dated June 19, 2018, test pits ranging in depths from 16 to 21 feet bgs were performed north of the entrance road in this area, and groundwater was not encountered in any of the excavations. Two of the test pits that were located farther from the project area had refusal due to boulders at around 16 feet bgs, while the other three that were located closer to the project area extended to the full depth of the equipment (about 21 feet) without refusal and without encountering water. NWCC's report describes the soils encountered within the test pits as a "relatively thin layer of natural topsoil and organic materials overlying interbedded clays, gravels and sands to the maximum depth investigated." The existing site conditions surrounding the project area are depicted on the Pre - Development Drainage Plan provided in Appendix C. The project area, located to the south of the entrance road and swale, drains to the ravine to the south of the existing entrance road. 3.0 PROPOSED SITE DESCRIPTION The proposed site conditions are depicted on the Post -Development Drainage Plan provided in Appendix C. The proposed scale house and scales will be constructed in an area along the existing entrance road. A separate administration building with parking area will be located to the northeast of the scale house. Due to the nature of the project and the function of the site, a majority of the area will be paved with bituminous asphalt or concrete. The existing entrance road slopes at about 3 percent to the south and southwest. As graded, the road in the project area will be lowered to create a relatively flat area for the scales, and the scale house and scales will be the local high point along the entrance road, causing runoff to shed away from the scale house and scales. Similarly, the areas around the administration building will slope away from the structure to either one of two catch basins within the interior portion of the project area or a swale that extends around the south of the project area. The slope of the entrance road north of the proposed scales will be increased to 7.0 percent. The slope of the swales along this portion of the entrance road will also slope at 7.0 percent; therefore, they will be armored with riprap to protect them from erosion. The newly paved area that drains to the south of the proposed scale house and administration building will be collected in catch basins and the proposed swale south of the roadway and directed through culverts beneath an existing well pad access road to a proposed retention basin where the post -development flows will be managed. August 2019 Page 3 Drainage Reportdocx 4622.00 The existing roadside swale conveys runoff from areas north of the project area. With the lowering and flattening of the project area, the slope of this swale as it passes by the scales will be reduced. To ensure that the capacity of the swale to manage the off-site flows is maintained, the slopes of the swale were reduced. A calculation comparing the capacity of the proposed swale geometry with the existing swale geometry is included in Appendix E. 4.0 DESIGN INTENT, SOFTWARE AND HYDROLOGIC CRITERIA 4.1 Design Intent This drainage report and the enclosed calculations were prepared in accordance with Article 7 of the Garfield County Land Use and Development Code and is intended to provide a comparative drainage analysis for the project to demonstrate that the design adequately manages post -development volumes and flow rates and provides suitable velocities for conveyance structures and erosion and sediment control practices. 4.2 Software Runoff calculations were prepared using HydroCAD 10.0 by HydroCAD Software Solutions, LLC of Chocorua, New Hampshire. HydroCAD is a computer aided design program for modeling the hydrology and hydraulics of stormwater runoff. It is based largely on hydrology techniques developed by the Soil Conservation Service (SCS) (now the Natural Resources Conservation Service), combined with other hydrology and hydraulics calculations. For a given rainfall event, these techniques are used to generate hydrographs throughout a watershed. HydroCAD is a dynamic, interactive design tool that maintains a complete database or working model for the watershed and drainage system, which allows the engineer to verify that a given drainage system is adequate for the area under consideration, predict where flooding or erosion problems are likely to occur, and quickly make adjustments as necessary. HydroCAD uses the Rational Method to generate hydrographs. These hydrographs are then incorporated by the software in the SCS Unit Hydrograph or Santa Barbara Urban Hydrograph methods to accurately route flows and generate volumes. The program also applies channel and pond hydraulics functions to evaluate the flow through swales and determine the discharge from orifices and weirs typically used for outlet control structures. A PDF version of the HydroCAD Owner's Manual, including a Technical Reference with the formulas used by the software, is available online at haps://www.hydrocad.net/pdf/HydroCAD-10%20Owners%20Manual.pdf Historic runoff calculations were prepared using the Rational Method. The results were compared to HydroCAD to verify consistency between the methods. 4.3 Hydrologic Criteria Post -development runoff calculations were prepared for the 2 -year, 25 -year, and 100 -year storm frequencies using HydroCAD stormwater modeling software. Rainfall depths were taken from NOAA Atlas 14 Point Precipitation Frequency Estimates for Rifle, Colorado. HydroCAD applied the rainfall depths using a 24-hour Type II SCS synthetic rainfall distribution. Complete reports, including routing diagrams, hydrographs, and area and soils August 2019 Page 4 Drainage Reportdocx 4622.00 listings are provided for the 25 -year storm event. Summaries only are provided for the 2 - year and 100 -year storm events to provide confirmation that adequate capacity is provided for culverts and the basin. Refer to Appendix C for copies of the runoff calculations and supporting information. Runoff curve numbers were assigned based on ground texture and hydrologic soil group (HSG) using tables available in the HydroCAD User Manual based on the SCS method and reprinted from the TR -55 manual, revised in 1986. Below is a table with the curve numbers used in the models for this project. Runoff Curve Numbers - HSG A Cover Type CN Desert shrub range, Good 49 Gravel Roads 76 Paved parking lots. roofs, driveways, etc. 98 Historic runoff calculations were prepared for the 2 -year and 25 -year storm frequencies using the rational method. Runoff coefficients were selected based on HSG A soils with a 2% imperviousness value before development. 4.4 Hydraulic Criteria Swales and catch basins with culverts were modeled in HydroCAD and sized using the Manning's Equation. Catch basins with culvert outlets modeled in HydroCAD allow headwater to build at the inlet. If the tailwater depth was expected to be greater than half the culvert diameter, it was designed for a tailwater condition. Otherwise, inlet nomographs published by the Federal Highway Administration (FHWA) were used to confirm the inlet capacity of the pipes. The stormwater basin was sized using the historic peak discharge rates for the entire area contributing runoff (Garfield County Article 7-204.C.3.a). The basin was also designed to attenuate the post -development peak flows and provide at least 1 foot of freeboard for the 100 -year storm event (Garfield Count Article 7-204.C.3.b). The basin slopes are 3H:1V with a top of berm width of 10 feet. Under low flow conditions (0.5" precipitation in 24 hours), all flow will pass through the 1.5 - inch diameter orifice, which will extend the drain time for the pond (Garfield County Article 7-204.C.3.d). Under high flow conditions, the water level will rise and flow into the top opening of the riser under weir flow conditions. The top of the riser will be equipped with a trash rack. Under extreme flow conditions, the water level will rise to the emergency spillway, which flows to the southeast (the same direction as the primary outlet). The emergency spillway was sized to pass the 100 -year flow, which corresponds to a depth of about 2.5 inches in the spillway. A weir calculation is provided in Appendix E. A sedimentation forebay will be provided at the inlet of the pond to encourage further sediment removal and improve the basin's functionality. The basin and forebay is accessible from the existing gravel road. August 2019 Page 5 Drainage Report docx 4622.00 Erosion protection in the form of riprap will be provided at the outlet of the culvert inletting to the basin, the outlet of the discharge culvert, and the emergency spillway. The riprap for the emergency spillway will extend down the outer slope of the basin and at least 10 feet at the base to allow the water to safely transition out of the basin. 5.0 DISCUSSION The historic runoff from the area tributary to the basin was extremely low (0.00 cfs for the 2 -year storm event and 0.01 cfs for the 25 -year event). Therefore, the basin is designed to retain the entire runoff for these events in the post -development condition. The only outflow provided for these storms is via the 1.5 -inch diameter orifice required to drain the basin between storm events. The table below summarizes the expected post -development storm volumes and their corresponding elevations within the proposed stormwater basin. Post -Development Volumes and Elevation Summary Storm Event Post -Development Volume (cf) Water Elevation in Basin (feet) 2 -yr 24 -hr 946 5,443.86 25 -yr 24 -hr 2,213 5,444.58 100 -yr 24 -hr 3,186 5,445.03 Based on the stormwater model results, the post -development pond elevations for both the 2 -yr and 25 -yr storm events are lower than the top opening in the riser (5,444.60') thereby retaining the entire runoff for these events. The water elevation for the 100 -year storm is 0.43 feet above the top of the riser, 0.23 feet above the invert of the emergency spillway, and 1.0 foot below the top of the pond berm, indicating that the necessary freeboard for the 100 - year storm event is provided. 6.0 MAINTENANCE PLAN Stormwater management systems require maintenance to ensure that the system will operate as designed. This section of the drainage report describes the measures that will be implemented to provide ongoing inspections and maintenance for the culverts, swales, and retention basin associated with the scale area. These features are depicted on the Post - Development Drainage Plan provided in Appendix C. A copy of this drawing should be kept at the site, and changes made to the facility over time should be noted on the drawing. 6.1 Inspections The stormwater management system, including the culverts, swales, and basin, will be inspected by a qualified person at least twice annually. The catch basins and drain manhole should be inspected at least quarterly for the first two years of operation, then twice a year for the life of the system, if a reduced schedule is appropriate. Additional inspections shall be performed following significant rain events that produce more than 0.5 inches of rainfall. Inspections will include visual confirmation that damage has not occurred due to erosion, sedimentation, or accumulation of debris. Inspections should include the following: August 2019 Page 6 Drainage Reportdocx 4622.00 ■ Grass swales - Assess uniform cover, traffic impacts, sediment accumulation, and rill and gully development. ■ Basin - Assess the amount of sediment in the forebay and look for debris at the outlet structure. ■ Culverts - Assess the amount of sediment/debris and signs of erosion at the inlet and outlet. ■ Manholes - Assess any debris inside the structure that could cause the structure to bypass water quality flows. Strong odors may also indicate issues with flow. A log of inspections should be kept onsite to demonstrate that routine inspections and maintenance are occurring. 6.2 Repairs If it is determined that damage has occurred that has the potential to impact the performance of the system or may lead to additional damage in the future, if not corrected, the damage shall be repaired promptly. If the repairs require vegetation for stabilization, temporary erosion and sediment controls shall be installed to protect the repairs until the vegetation is established. If the repairs are made during winter months, stabilization shall be provided by means of installing erosion control blankets or 3 inches of non-erosive material, such as stone riprap or gravel. 6.3 Maintenance/Cleaning Routine cleaning of sediment and debris from the drainage facilities is required to ensure proper performance of the stormwater management system. Routine cleaning shall include the removal of sediment and debris from swales, catch basins, drain manholes, culverts, the stormwater basin, the discharge structure, and the emergency spillway. Large debris that has the potential of blocking culverts or orifices shall be removed whenever observed. Small debris and sediment shall be removed when it accumulates to the point that it may impact the performance of the stormwater management system. The table below lists the sediment/debris levels at which cleaning will be performed for each feature of the stormwater system. Feature Action Level (Depth of Sediment) Swales 1/3 of Swale Depth Catch Basins/Manholes 2 feet Culverts 6 inches Basin 6 inches (invert of lowest orifice) Sediment removal can be performed by hand; however, mechanical equipment may be preferred for the basin and/or manholes. After establishment of vegetation in the swales, weeding can be completed mechanically, either by hand or by mowing. Grass should be maintained at a length of no less than six inches and invasive species should be removed from both the swales and basin, if observed. Re -seed and/or patch damaged areas to maintain healthy vegetative cover, as needed, based on inspections. Periodic sediment removal should reduce the frequency of revegetation required. August 2019 Page 7 Drainage Reportdocx 4622.00 6.4 Vegetation Stabilization for unpaved areas of the site is provided by the root structure of vegetation; therefore, it is critical that vegetation is properly established and maintained. Distressed vegetation (less than 40 percent vegetative growth) shall be reseeded and fertilized until a healthy stand of vegetation is present. 7.0 CONCLUSION Calculations were performed in compliance with the Garfield County Article 7 standards. Although not specifically listed in the manuals, HydroCAD stormwater modeling software incorporates the Rational Method and the Soil Conservation Services (SCS) method, which are referenced in the manuals. In addition, the software provides a graphical routing diagram, hydrographs, and a stage -storage graph for the basin. The swales, culverts, and basin for this project are sized appropriately to attenuate the post - development peak flows and volumes. The basin is designed to retain the runoff volume produced by the 25 -year and more frequent storm events, which complies with the water laws for the State of Colorado. P:\4600s\4622.00\Source Files\Drainage Report\Drainage Report.docx APPENDIX A VICINITY MAP SANBORN 1111 HEAD Anvil Points PROJECT AREA SITE IIeCVe• Mesa Wily.. ,• Masa NOTES: BASE MAP WAS PREPARED FROM USGS 7.5 -MINUTE QUADRANGLE MAPS FOR ANVIL POINTS, RULISON, RIFLE, AND NORTH MAMM PEAK, COLORADO. wpf dean. Ell yµ�n6uy�i r 1414kk 140 Rifle Feet 5,000 0 10,000 GARFIELD COUNTY LANDFILL RIFLE, COLORADO SCALE HOUSE PROJECT VICINITY PLAN SCALE: AS NOTED DRAWN BY: TWR DATE: AUG 19 CHECKED BY: MBK FILE NO. 4622.00 • FIGURE NO. 1 APPENDIX B WEB SOIL SURVEY SANBORN 1111 HEAD APPENDIX C RUNOFF CALCULATIONS SANBORN 1111 HEAD 8/8/2019 Precipitation Frequency Data Server NOAA Atlas 14, Volume 8, Version 2 Location name: Rifle, Colorado, USA* Latitude: 39.5132°, Longitude: -107.9136° Elevation: 5462.31 ft** • source: ESRI Maps ** source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Deborah Martin, Sandra Pavlovic, Ishani Roy, Michael St. Laurent, Cad Trypaluk, Dale Unruh, Michael Yekta, Geoffery Bonnin NOAA, National Weather Service, Sliver Spring, Maryland PF tabular 1 PF graphical 1 Mips & aerials PF tabular PDS -based point precipitation frequency estimates with 90% confidence intervals (in inches)1 OgTatloR Average recurrence interval (years) 1 I2 5 10 25 50 100 200 500 1000 5 -min 0.130 (0.106-0.161) 0.159 (0.130-0.198) 0.214 (0.174-0.268) 0.266 (0.215.0.334). 0.346 (0.273-0.468) 0.416 (0.316-0.569) 0.492 {0.358.0.695) 0.575 (0.398-0.842) 0.696 (0.459-1.05) 0.795 (0.505-1.22) 10 -min 0.190 {0.156-0.236) 0.233 (0.191-0.290) 0.313 (0.255-0.392) 0.389 (0.315-0.490) 0.507 (0.399-0.685) 0.609 (0.463-0.834) 0.720 (0.524-1.02) 0.842 (0.583-1.23) 1.02 (0.672-1.54) 1.16 (0.739-1.78) 15 -min 0.232 (0.190-0.288) 0.284 (0.232-0.354) 0.382 (0.311-0.478) 0.475 (0.384-0.597) 0.618 (0.487-0.836) 0.743 (0.565-1.02) 0.878 (0.639-1.24) 1.03 (0.711-1.50) 1.24 (0.819.1.88) 1.42 (0.902-2.17) 30 -min 0.295 (0.241-0.367) 0.371 (0.303-0.462) 0.505 (0.411-0.632) 0.625 (0.506.0.787) 0.804 (0.629-1.08) 0.953 (0.722-1.30) 1.11 (0.806-1.56) 1.28 (0.883-1.86) 1.52 (0.990.2.29) 1.71 (1.09-2.62) 60 -min 0.374 (0.3064465) 0.458 (0.375-0.571) 0.606 (0.493-0.757) 0.736 (0.595-0.926) 0.930 (0.725-1.24) 1.09 (0.824-1.48) 1.26 (0.911-1.76) 1.44 (0.989-2.09) 1.69 (1.11-2.54) 1.89 (1.20-2.89) 2 -hr 0.453 (0.374-0.556) 0.545 (0.450-0.671) 0.706 (0.580-0.872) 0.847 (0.691-1.05) 1.06 (0.830-1.38) 1.22 (0.935-1.63) 1.40 (1.03-1.93) 1.59 (1.11-2.28) 1.85 (1.23-2.75) 2.06 (1.33-3.11) 3 -hr 0.517 (0.429-0.631) 0.606 (0.503-0.741) 0.762 (0.629-0.935) 0.900 (0.738-1.11) 1.10 (0.873-1.44) 1.27 (0.976-1.68) 1.45 (1.07-1.98) 1.63 (1.15-2.32) 1.90 (1.27-2.79) 2.11 (1.36-3.15) 6 -hr 0.638 (0.534-0.770) 0.739 (0.618-0.893) 0.911 (0.759-1.11) 1.06 (0.876-1.29) 1.27 (1.01-1.62) 1.44 (1.12-1.88) 1.62 (1.20-2.17) 1.80 (1.27-2.51) 2.05 (1.39-2.96) 2.25 (1.47-3.31) 12 -hr 0.792 (0.669-0.944) 0.916 (0.772-1.09) 1.12 (0.944-1.35) 1.30 (1.09-1.57) 1.55 (1.25-1.96) 1.76 (1.37-2.25) 1.96 (1.48-2.60) 2.18 (1.56-2.99) 2.48 (1.69-3.52) 2.71 (1.79-3.92) 24 -hr 0.964 (0.822-1.14) 1.11 (0.946-1.31) 1.36 (1.15-1.61) 1.58 (1.33-1.87) 1.88 (1.53-2.34) 2.13 (1.68-2.69) 2.38 (1.81-3.11) 2.65 (1.92-3.58) 3.01 (2.09-4.22) 3.30 (2.22-4.70) 2 -day 1.14 (0.980-1.33) 1.31 (1.12-1.52) 1.59 (1.36-1.86) 1.84 (1.57-2.16) 2.20 (1.80-2.70) 2.48 (1.99-3.10) 2.78 (2.14-3.59) 3.09 (2.27-4.13) 3.52 (2.47-4.86) 3.86 (2.63-5.42) 3 -day 1.25 (1.08-1.44) 1.43 (1.24-1.66) 1.75 (1.50-2.03) 2.02 (1.73-2.36) 2.41 (1.99-2.94) 2.72 (2.19-3.38) 3.05 (2.36-3.90) 3.39 (2.50-4.48) 3.86 (2.73-5.28) 4.23 (2.90-5.88) 4 -day - 1.34 (1.16-1.54) 1.54 (1.33-1.77) 1.87 (1.62-2.16) 2.16 (1.85-2.51) 2.58 (2.14-3.12) 2.91 (2.35-3.58) 3.25 (2.53-4.13) 3.62 (2.68-4.75) 4.11 (2.92-5.58) 4.50 (3.10-6.21) 7 -day 1.56 (1.37-1.78) 1.79 (1.56-2.03) 2.16 (1.88-2.47) 2.48 (2.15-2.85) 2.94 (2.45-3.51) 3.30 (2.68-4.01) 3.67 (2.88-4.60) 4.06 (3.04-5.26) 4.59 (3.29-6.15) 4.91 (3.54-6.51) 5.00 (3.48-6.82) 5.33 (3.73-7.20) 10 -day 1.77 (1.55-1.99) 2.00 (1.76-2.26) 2.40 (2.10-2.72) 2.73 (2.38-3.12) 3.21 (2.69-3.80) 3.59 (2.93-4.32) 3.97 (3.13-4.93) 4.37 (3.29-5.61) 20-day2.35 (2.08-2.62) 2.62 (2.32-2.92) 3.06 (2.70-3.43) 3.43 (3.01-3.86) 3.95 (3.34-4.60) 4.35 (3.59-5.16) 4.76 (3.79-5.81) 5.17 (3.94-6.53) 5.73 (4.18-7.47) 6.15 (4.37-8.18) 30 -day 2.82 (2.51-3.12) 3.14 (2.79-3.47) 3.65 (3.24-4.05) 4.07 (3.59-4.55) 4.65 (3.96-5.36) 5.10 (4.23-5.98) 5.54 (4.43-6.69) 5.98 (4.58-7.46) 6.56 (4.83-8.46) 7.00 (5.01-9.22) 45-day3.41 (3.06-3.74) 3.81 (3.41-4.19) 4.45 (3.97-4.91) 4.97 (4.41-5.51) 5.67 (4.84-6.47) 6.19 (5.17-7.19) 6.70 (5.40-8.01) 7.20 (5.55-8.88) 7.84 (5.81-10.00) 9.11 (6.77-11.5) 8.31 (6.00-10.8) 9.62 (6.98-12.4) 60 -day 3.90 (3.51-4.26) 4.39 (3.95-4.80) 5.18 (4.64-5.68) 5.81 (5.17-6.40) 6.64 (5.68-7.51) 7.25 (6.07-8.35) 7.83 (6.33-9.28) 8.40 (6.50-10.3) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS) Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability hat precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Beck to Top PF graphical https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=39.5132&Ion=-107.9136&data=depth&units=english&series=pds 1/4 8/8/2019 Precipitation Frequency Data Server PDS -based depth-duration-frec:uency f DDF: curves Latiturie: 39.5132:. Longitude -137.9136° NOA.A atlas 14. 'Volume 2.'Version 2 10 25 50 _00 Average recurrence Irter:'a' ('y'ears! 200 300 :0 )0 Created (Gr'T:: Thu Auy - =7 34:42 2019 Back to Top Maps & aerials Small scale terrain r,,:,,rritrn-r Dor,r.L.r -h� https://hdsc.nws.noaa.gov/hhdsc/pfds/pfds_printpage.html?lat=39.5132&Ion=-107.9136&data=depth&units=english&series=pds 2/4 8/8/2019 Precipitation Frequency Data Server Rufisort Large scale terrain • Gram] Jur;p:tir•n Large scale map t+I .11 Hl .I l rltrticl r Large scale aerial https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=39.5132&Ion=-107.9136&data=depth&units=english&series=pds 3/4 8/8/2019 Precipitation Frequency Data Server Saclj tp TOR US Department of Commerce National Oceanic and Atmospheric Administration National Weather Service National Water Center 1325 East West Highway Silver Spring, MD 20910 Questions?: HDSC.Questlonsannaa.94y Disclaimer https://hdsc.nws.noaa.gov/hdsc/pfds/pfds.printpage.html?lat=39.5132&Ion=-107.9136&data=depth&units=engllsh&series=pds 4/4 PRE -DEVELOPMENT DRAINAGE PLAN SANBORN 1111 HEAD C.O.D. BOUNDARY RY BASEDON NWCC. INC. GENERAL FACILITY MAP UNDERGROUND GAS LINE OVERHEAD ELECTRICAL i TEST H°LE PU // iii //F r EXISTING 24'6 CMP CULVERT EXISTING 1B'6 CMPCULVERT PRE -DEVELOPMENT RATIONAL METHOD CALCULATION SANBORN 1111 HEAD SANBORN IIII HEAD File No. 4622.00 Page 1 of 2 Project Scale House / Administration Building Location Garfield County Landfill - Rifle. CO Subject Historic Runoff Value Calculated By L. Teal Date 8J1 J19 Checked By T_Reed Date 8/27/19 P:\4600s\4622.00\Work\Calculations\20190813 Historic Runoff Value.docx PURPOSE: Garfield County standard 7-204.C.3.a indicates that "detention facilities shall ensure the post -development peak discharge rate does not exceed the pre -development peak discharge rate for the 2 -year and 25 -year return frequency, 24-hour duration storm." Historic peak discharge rates (predevelopment) is calculated using the entire area contributing runoff with a 2% impervious value before any development. METHOD: Rational method as described in Volume 1, Chapter 6, Section 2.1 of the Urban Storm Drainage Criteria Manual (USDCM). CALCULATION: Rational Formula: Q= CIA Where: Q = the peak rate of runoff (cfs) C = Runoff coefficient (unitless) I = average intensity of rainfall for a duration equal to the time of concentration (inches/hour) A = tributary area (acres) Time of concentration: tc = ti + tt Where: tc = computed time of concentration (minutes) ti = overland (initial) flow time (minutes) tt = channelized flow time (minutes) Initial or Overland Flow Time Channelized Flow Time 0.395(1.1— C5) Li ti S 0.33 0 Where: ti = overland (initial) flow time (minutes) C5 = runoff coefficient for 5 -year frequency (from Table 6-4) Li = length of overland flow (ft) So = average slope along the overland flow path (ft/ft) tt Lt 60K 50 Where: tt = channelized flow time (travel time, min) Lt = waterway length (ft) So = waterway slope (ft/ft) Vt = travel time velocity (ft/sec) = KIIT0 K = NRCS conveyance factor (see Table 6-2) 9 Sanborn, Head & Associates, Inc. SANBORN IijI HEAD File No. Project Location Subject 4622.00 Page 2 of 2 ScaleBousejAdministrationfUlding Garfield County Landfill - Rifle. CO Historic Runoff Value Calculated By L. Teal Date 8/13/19 Checked By T. Reed Date 8/27/19 P:\4600s\4622.00\Work\Calculations\20190813 Historic Runoff Value.docx From table 6-4, Cs for Type A soils: = 0.86(0.02)1.276 = 0.00584 From the pre -development drainage plan, the total flow length is 230 ft and the initial slope is 0.070 ft/ft. This is less than the maximum 500 ft for overland flow in rural areas therefore, use the Overland Flow Time equation: _ 0.395(1.1 — 0.00584) 230 tc = ti 0.070° 33 = 15.76 min From Table 6-4 for Type A soils and 2% impervious area: C2 = 0.8411.302 = 0.84(0.02)1.302 = 0.005 C25 = 0.88i1.124 = 0.88(0.02)1.124 = 0.011 From Equation 5-1, the rainfall intensity, 1, is: 1 = (10+Td)0.786 28.5P1 Where: 1= rainfall intensity (inches/hour) Pi = 1 -hour point rainfall depth (inches) Td = storm duration (minutes) From the NOAA Atlas 14, Volume 8, Version 2 Point Precipitation Frequency Estimates table for Rifle CO, Pi = 0.374 inches. Therefore, 28.5(0.374) 1 = _ (10 + 15.76)0 786 0.83 inches/hour The post -development area for the drainage basin is 0.862 acres. Therefore, Q2 = C21A = 0.005 x 0.83 x 0.862 = 0.00 cfs Q25=C251A=0.011x0.83x0.862=0.01cfs RESULTS: The historic 2 -year runoff value for the project is 0.00 cfs. The historic 25 -year runoff value for the project is 0.01 cfs. wwwsanbornhead.corn Sanborn, Head & Associates, Inc. POST -DEVELOPMENT DRAINAGE PLAN SANBORN 1111 HEAD 7 C.O.D. BOUNDARY BASED ON NWCC, INC. GENERAL FACILITY MAP UNDERGROUND GAS LINE OVERHEAD ELECTRICAL TEST HOLE ' TEST /7;' /a ! f// •565 �'� 41# 0% AO* I / I 0 POTABLE WATER UST COSTING 24.0 CMP CULVERT EXISTING 1B76 CMP CULVERT 500 -GALLON PROPANE AST POST -DEVELOPMENT NODE SUMMARIES 0.5 -INCH, 2 -YR, 25 -YR, AND 100 -YR, 24 -HR SANBORN 1111 HEAD 2 1 / 4 ) Subcat. Reach :'Fond`• Link DMH -1 3 :/\ 3 1R Gra Lined Swale 4 4P Basin Routing Diagram for Post Development Prepared by {enter your company name here}, Printed 8/27/2019 HydroCAD® 10.00-13 sin 08733 © 2014 HydroCAD Software Solutions LLC Post Development Type 11 24 -hr 0.5", 24 -Hr Rainfall=0.50" Prepared by {enter your company name here} Printed 8/27/2019 HydroCAD® 10.00-13 s/n 08733 © 2014 HydroCAD Software Solutions LLC Pacte 2 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR -20 method, UH=SCS, Weighted -CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1: 1 Subcatchment2: 2 Subcatchment3: 3 Subcatchment4: 4 Runoff Area=10.648 sf 87.93% Impervious Runoff Depth=0.09" Flow Length=94' Slope=0.0326 '1' Tc=5.0 min CN=92 Runoff=0.04 cfs 0.002 af Runoff Area=10.370 sf 92.79% Impervious Runoff Depth=0.14" Flow Length=203' Slope=0.0529 '1' Tc=5.0 min CN=94 Runoff=0.06 cfs 0.003 af Runoff Area=8,892 sf 34.63% Impervious Runoff Depth=0.00" Flow Length=341' Slope=0.1826'/' Tc=5.0 min CN=66 Runoff=0.00 cfs 0.000 af Runoff Area=7,635 sf 0.00% Impervious Runoff Depth=0.00" Flow Length=54' Slope=0.1404'1' Tc=5.0 min CN=57 Runoff=0.00 cfs 0.000 af Reach 1 R: Grass Lined Swale Avg. Flow Depth=0.11' Max VeI=1.50 fps Inflow=0.06 cfs 0.003 af n=0.022 L=124.0' S=0.0242 'P Capacity=121.72 cfs Outflow=0.06 cfs 0.003 af Pond 1P: CB -1 Pond 2P: CB -2 Pond 3P: DI -1 Pond 4P: Basin Pond 5P: DMH -1 Peak EIev=5,454.12' Inflow=0.06 cfs 0.003 af 12.0" Round Culvert n=0.012 L=54.0' S=0.0185 'P Outflow=0.06 cfs 0.003 af Peak EIev=5,452.09' Inflow=0.04 cfs 0.002 af 12.0" Round Culvert n=0.012 L=52.0' S=0.0100 '1' Outflow=0.04 cfs 0.002 af Peak EIev=5,446.85' Inflow=0.09 cfs 0.005 af 12.0" Round Culvert n=0.012 L=63.0' S=0.0300 '/' Outflow=0.09 cfs 0.005 af Peak EIev=5,443.23' Storage=197 cf Inflow=0.09 cfs 0.005 af Outflow=0.00 cfs 0.000 af Peak EIev=5,451.37' Inflow=0.04 cfs 0.002 af 12.0" Round Culvert n=0.012 L=51.5' S=0.0850 '1' Outflow=0.04 cfs 0.002 af Total Runoff Area = 0.862 ac Runoff Volume = 0.005 af Average Runoff Depth = 0.06" 41.23% Pervious = 0.355 ac 58.77% Impervious = 0.507 ac Post Development Type 11 24 -hr 2 -Yr, 24 -Hr Rainfall=1.11 " Prepared by {enter your company name here} Printed 8/27/2019 HydroCAD® 10.00-13 s/n 08733 © 2014 HydroCAD Software Solutions LLC Page 3 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR -20 method, UH=SCS, Weighted -CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1: 1 Subcatchment2: 2 Subcatchment3: 3 Subcatchment4: 4 Runoff Area=10.648 sf 87.93% Impervious Runoff Depth=0.49" Flow Length=94' Slope=0.0326 '/' Tc=5.0 min CN=92 Runoff=0.22 cfs 0.010 af Runoff Area=10.370 sf 92.79% Impervious Runoff Depth=0.60" Flow Length=203' Slope=0.0529'P Tc=5.0 min CN=94 Runoff=0.26 cfs 0.012 af Runoff Area=8,892 sf 34.63% Impervious Runoff Depth=0.00" Flow Length=341' Slope=0.1826 '/' Tc=5.0 min CN=66 Runoff=0.00 cfs 0.000 af Runoff Area=7,635 sf 0.00% Impervious Runoff Depth=0.00" Flow Length=54' Slope=0.1404 '1' Tc=5.0 min CN=57 Runoff=0.00 cfs 0.000 af Reach 1R: Grass Lined Swale Avg. Flow Depth=0.20' Max Vel=2.18 fps Inflow=0.26 cfs 0.012 af n=0.022 L=124.0' S=0.0242 'P Capacity=121.72 cfs Outflow=0.26 cfs 0.012 af Pond 1P: CB -1 Pond 2P: CB -2 Pond 3P: DI -1 Pond 4P: Basin Pond 5P: DMH -1 Peak Elev=5,454.25' Inflow=0.26 cfs 0.012 af 12.0" Round Culvert n=0.012 L=54.0' S=0.0185 '1' Outflow=0.26 cfs 0.012 af Peak EIev=5,452.23' Inflow=0.22 cfs 0.010 af 12.0" Round Culvert n=0.012 L=52.0' S=0.0100 'P Outflow=0.22 cfs 0.010 af Peak EIev=5,447.04' Inflow=0.48 cfs 0.022 af 12.0" Round Culvert n=0.012 L=63.0' S=0.0300 'P Outflow=0.48 cfs 0.022 af Peak EIev=5,443.86' Storage=946 cf Inflow=0.48 cfs 0.022 af Outflow=0.00 cfs 0.000 af Peak EIev=5,451.51' Inflow=0.22 cfs 0.010 af 12.0" Round Culvert n=0.012 L=51.5' S=0.0850 'P Outflow=0.22 cfs 0.010 af Total Runoff Area = 0.862 ac Runoff Volume = 0.022 af Average Runoff Depth = 0.30" 41.23% Pervious = 0.355 ac 58.77% Impervious = 0.507 ac Post Development Prepared by {enter your company name here) HvdroCAD® 10.00-13 s/n 08733 © 2014 HydroCAD Software Solutions LLC Type 11 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Printed 8/27/2019 Pace 4 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR -20 method, UH=SCS, Weighted -CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment1: 1 Subcatchment2: 2 Subcatchment3: 3 Subcatchment4: 4 Flow Length=94' Flow Length=203' Flow Length=341' Flow Length=54' Runoff Area=10.648 sf 87.93% Impervious Runoff Depth=1.13" Slope=0.0326 '1' Tc=5.0 min CN=92 Runoff=0.50 cfs 0.023 af Runoff Area=10.370 sf 92.79% Impervious Runoff Depth=1.28" Slope=0.0529 '1' Tc=5.0 min CN=94 Runoff=0.54 cfs 0.025 af Runoff Area=8,892 sf 34.63% Impervious Runoff Depth=0.12" Slope=0.1826'1' Tc=5.0 min CN=66 Runoff=0.02 cfs 0.002 af Runoff Area=7,635 sf 0.00% Impervious Runoff Depth=0.02" Slope=0.1404 '1' Tc=5.0 min CN=57 Runoff=0.00 cfs 0.000 af Reach 1 R: Grass Lined Swale Avg. Flow Depth=0.26' Max Vel=2.63 fps Inflow=0.55 cfs 0.028 af n=0.022 L=124.0' S=0.0242 '/' Capacity=121.72 cfs Outflow=0.55 cfs 0.028 af Pond 1P: CB -1 Pond 2P: CB -2 Pond 3P: DI -1 Pond 4P: Basin Pond 5P: DMH -1 12.0" Round Culvert n=0.012 12.0" Round Culvert n=0.012 12.0" Round Culvert n=0.012 Peak Elev=5,454.37' Inflow=0.54 cfs 0.025 af L=54.0' S=0.0185 '/' Outflow=0.54 cfs 0.025 af Peak Elev=5,452.35' Inflow=0.50 cfs 0.023 af L=52.0' S=0.0100 '/' Outflow=0.50 cfs 0.023 af Peak Elev=5,447.23' Inflow=1.05 cfs 0.051 af L=63.0' S=0.0300'1' Outflow=1.05 cfs 0.051 af Peak Elev=5,444.58' Storage=2,213 cf Inflow=1.05 cfs 0.051 af Outflow=0.00 cfs 0.000 af Peak Elev=5,451.63' Inflow=0.50 cfs 0.023 af 12.0" Round Culvert n=0.012 L=51.5' S=0.0850 '/' Outflow=0.50 cfs 0.023 af Total Runoff Area = 0.862 ac Runoff Volume = 0.051 af Average Runoff Depth = 0.71" 41.23% Pervious = 0.355 ac 58.77% Impervious = 0.507 ac Post Development Type 11 24 -hr 100 -Yr, 24 -Hr Rainfall=2.38" Prepared by {enter your company name here} Printed 8/27/2019 HydroCAD® 10.00-13 s/n 08733 © 2014 HydroCAD Software Solutions LLC Page 5 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR -20 method, UH=SCS, Weighted -CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1: 1 Subcatchment2: 2 Subcatchment3: 3 Subcatchment4: 4 Runoff Area=10.648 sf 87.93% Impervious Runoff Depth=1.58" Flow Length=94' Slope=0.0326 '/' Tc=5.0 min CN=92 Runoff=0.69 cfs 0.032 af Runoff Area=10.370 sf 92.79% Impervious Runoff Depth=1.75" Flow Length=203' Slope=0.0529'1' Tc=5.0 min CN=94 Runoff=0.73 cfs 0.035 af Runoff Area=8,892 sf 34.63% Impervious Runoff Depth=0.28" Flow Length=341' Slope=0.1826 '1' Tc=5.0 min CN=66 Runoff=0.08 cfs 0.005 af Runoff Area=7,635 sf 0.00% Impervious Runoff Depth=0.09" Flow Length=54' Slope=0.1404 '/' Tc=5.0 min CN=57 Runoff=0.00 cfs 0.001 af Reach 1 R: Grass Lined Swale Avg. Flow Depth=0.30' Max Vel=2.88 fps Inflow=0.80 cfs 0.040 af n=0.022 L=124.0' S=0.0242 '1' Capacity=121.72 cfs Outflow=0.79 cfs 0.040 af Pond 1P: CB -1 Pond 2P: CB -2 Pond 3P: DI -1 Pond 4P: Basin Pond 5P: DMH -1 Peak EIev=5,454.43' Inflow=0.73 cfs 0.035 af 12.0" Round Culvert n=0.012 L=54.0' S=0.0185'1' Outflow=0.73 cfs 0.035 af Peak EIev=5,452.42' Inflow=0.69 cfs 0.032 af 12.0" Round Culvert n=0.012 L=52.0' S=0.0100 '/' Outflow=0.69 cfs 0.032 af Peak EIev=5,447.35' Inflow=1.48 cfs 0.072 af 12.0" Round Culvert n=0.012 L=63.0' S=0.0300 '/' Outflow=1.48 cfs 0.072 af Peak EIev=5,445.03' Storage=3,186 cf Inflow=1.48 cfs 0.073 af Outflow=0.00 cfs 0.000 af Peak EIev=5,451.70' Inflow=0.69 cfs 0.032 af 12.0" Round Culvert n=0.012 L=51.5' S=0.0850 '1' Outflow=0.69 cfs 0.032 af Total Runoff Area = 0.862 ac Runoff Volume = 0.073 af Average Runoff Depth = 1.02" 41.23% Pervious = 0.355 ac 58.77% Impervious = 0.507 ac POST -DEVELOPMENT 25 -YR 24 -HR MODEL SANBORN 1111 HEAD Post Development Type 1124 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Prepared by Sanborn Head & Associates Printed 8/14/2019 HydroCAD® 10.00-24 s/n 08733 © 2018 HydroCAD Software Solutions LLC Page 1 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR -20 method, UH=SCS, Weighted -CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment 1: 1 Subcatchment2: 2 Subcatchment3: 3 Subcatchment4: 4 Runoff Area=10.648 sf 87.93% Impervious Runoff Depth=1.13" Flow Length=94' Slope=0.0326 1/1 Tc=5.0 min CN=92 Runoff=0.50 cfs 0.023 af Runoff Area=10.370 sf 92.79% Impervious Runoff Depth=1.28" Flow Length=203' Slope=0.0529 '1' Tc=5.0 min CN=94 Runoff=0.54 cfs 0.025 af Runoff Area=8,892 sf 34.63% Impervious Runoff Depth=0.12" Flow Length=341' Slope=0.1826 '1' Tc=5.0 min CN=66 Runoff=0.02 cfs 0.002 af Runoff Area=7,635 sf 0.00% Impervious Runoff Depth=0.02" Flow Length=54' Slope=0.1404 '1' Tc=5.0 min CN=57 Runoff=0.00 cfs 0.000 af Reach 1 R: Grass Lined Swale Avg. Flow Depth=0.26' Max Vel=2.63 fps Inflow=0.55 cfs 0.028 af n=0.022 L=124.0' S=0.0242 '/' Capacity=121.72 cfs Outflow=0.55 cfs 0.028 af Pond 1 P: CB -1 Pond 2P: CB -2 Pond 3P: DI -1 Pond 4P: Basin Pond 5P: DMH -1 Peak Elev=5,454.37' Inflow=0.54 cfs 0.025 af 12.0" Round Culvert n=0.012 L=54.0' S=0.01851/1 Outflow=0.54 cfs 0.025 af Peak Elev=5,452.35' Inflow=0.50 cfs 0.023 af 12.0" Round Culvert n=0.012 L=52.0' S=0.0100'/1 Outflow=0.50 cfs 0.023 af Peak Elev=5,447.23' Inflow=1.05 cfs 0.051 af 12.0" Round Culvert n=0.012 L=63.0' S=0.0300 '1' Outflow=1.05 cfs 0.051 af Peak Elev=5,444.58' Storage=2,213 cf Inflow=1.05 cfs 0.051 af Outflow=0.00 cfs 0.000 af Peak Elev=5,451.63' Inflow=0.50 cfs 0.023 af 12.0" Round Culvert n=0.012 L=51.5' S=0.0850 '1' Outflow=0.50 cfs 0.023 af Total Runoff Area = 0.862 ac Runoff Volume = 0.051 af Average Runoff Depth = 0.71" 41.23% Pervious = 0.355 ac 58.77% Impervious = 0.507 ac Post Development Type 11 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Prepared by Sanborn Head & Associates Printed 8/14/2019 HydroCAD® 10.00-24 s/n 08733 © 2018 HydroCAD Software Solutions LLC Page 2 Summary for Subcatchment 1: 1 Runoff = 0.50 cfs @ 11.96 hrs, Volume= 0.023 af, Depth= 1.13" Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Area (sf) CN Description 8,740 98 Paved parking, HSG A 623 98 Roofs HSG A 1.285 49 Desert shrub range, Good. HSG A 10,648 92 Weighted Average 1,285 12.07% Pervious Area 9,363 87.93% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.7 94 0.0326 0.91 Laq/CN Method, 1.7 94 Total, Increased to minimum Tc = 5.0 min Subcatchment 1: 1 Hydrograph /1 0.55 0.5 0.45 0.4 0.35 0.3 2 0.25 0.2 0.15 0.1 0.05 Type II 24 -hr 25 -Yr 24 -Hr Rainfall=1.88" Runoff Area=10,648 sf Runoff Volume=0.023 af Runoff Depth=1.13" Flow Length=94' Slope=0.0326 '1' Tc=5.0 min CN=92 I 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) ri Runoff Post Development Type l/ 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Prepared by Sanborn Head & Associates Printed 8/14/2019 HydroCAD® 10.00-24 s/n 08733 © 2018 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment 2: 2 Runoff = 0.54 cfs @ 11.96 hrs, Volume= 0.025 af, Depth= 1.28" Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Area (sf) CN Description 8,326 98 Paved parking, HSG A 1,296 98 Roofs HSG A 748 49 Desert shrub range, Good, HSG A 10,370 94 Weighted Average 748 7.21% Pervious Area 9,622 92.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.3 203 0.0529 1.49 Lag/CN Method, T. 2.3 203 Total, Increased to minimum Tc = 5.0 min 0.6 0.55 0.5 0.45 0.4 I 0.35 I 0.3 0.25 0.2 0.15 0.1 0.05 Subcatchment 2: 2 Hydrograph 0.54 cfs Type II 24 -hr 25 -Yr 24 -Hr Rainfall=1.88" Runoff Area=10,370 sf Runoff Volume=0.025 af Runoff Depth=1.28" Flow Length=203' Slope=0.0529 '1' Tc=5.0 min CN=94 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) El Runoff Post Development Type 1124 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Prepared by Sanborn Head & Associates Printed 8/14/2019 HydroCAD® 10.00-24 sin 08733 © 2018 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 3: 3 Runoff = 0.02 cfs @ 12.01 hrs, Volume= 0.002 af, Depth= 0.12" Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Area (sf) CN Description 3,079 98 Paved parking, HSG A 5,813 49 Desert shrub range. Good, HSG A 8,892 66 Weighted Average 5,813 65.37% Pervious Area 3,079 34.63% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 4.7 341 0.1826 1.22 Lag/CN Method, 4.7 341 Total, Increased to minimum Tc = 5.0 min Subcatchment 3: 3 Hydrograph 0.018 (1 0.017 0.016 0.015 0.014 0.013 0.012 0.011 0.01 0 0.009 / LL 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 I 0 0.02 cfs Type II 24 -hr 25 -Yr 24 -Hr Rainfall=1.88" Runoff Area=8,892 sf Runoff Volume=0.002 af Runoff Depth=0.12" Flow Length=341' Slope=0.1826 '1' Tc=5.0 min CN=66 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) f7 Runoff Post Development Type 11 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Prepared by Sanborn Head & Associates Printed 8/14/2019 HydroCAD® 10.00-24 s/n 08733 © 2018 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment 4: 4 Runoff = 0.00 cfs @ 18.15 hrs, Volume= 0.000 af, Depth= 0.02" Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type 11 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Area (sf) CN Description 2,371 76 Gravel roads HSG A 5,264 49 Desert shrub range, Good, HSG A 7,635 57 Weighted Average 7,635 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.5 54 0.1404 0.59 Lag/CN Method, 1.5 54 Total, Increased to minimum Tc = 5.0 min Subcatchment 4: 4 Hydrograph 0.000 0.000 1 0.000 1 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0 0 0 0 0 2 4 Type II 24 -hr 25 -Yr 24 -Hr Rainfall=1.88" Runoff Area=7,635 sf Runoff Volume=0.000 af Runoff Depth=0.02" Flow Length=54' Slope=0.1404 '/' Tc=5.0 min CN=57 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) i Runol Post Development Type 11 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Prepared by Sanborn Head & Associates Printed 8/14/2019 HydroCAD® 10.00-24 s/n 08733 © 2018 HydroCAD Software Solutions LLC Page 6 Summary for Reach 1R: Grass Lined Swale Inflow Area = 0.442 ac, 65.94% Impervious, Inflow Depth = 0.75" for 25 -Yr, 24 -Hr event Inflow = 0.55 cfs @ 11.96 hrs, Volume= 0.028 af Outflow = 0.55 cfs @ 11.97 hrs, Volume= 0.028 af, Atten= 1%, Lag= 0.6 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Max. Velocity= 2.63 fps, Min. Travel Time= 0.8 min Avg. Velocity = 0.96 fps, Avg. Travel Time= 2.2 min Peak Storage= 26 cf @ 11.97 hrs Average Depth at Peak Storage= 0.26' Bank -Full Depth= 2.00' Flow Area= 12.0 sf, Capacity= 121.72 cfs 0.00' x 2.00' deep channel, n= 0.022 Earth, clean & straight Side Slope Z -value= 3.0 '1' Top Width= 12.00' Length= 124.0' Slope= 0.0242 '1' Inlet Invert= 5,453.00', Outlet Invert= 5,450.00' 0.6 0.55 0.5 0.45 0.4 0.35 0.3 LL 0.25 0.2 0.15 0.1 0.05 0 Reach 1 R: Grass Lined Swale Hydrograph 0.55 cf Inflow Area=0.442 ac Avg. Flow Depth=0.26' Max Vel=2.63 fps n=0.022 L=124.0' S=0.0242 '1' Capacity=121.72 cfs 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) F; Inflow n Outflow Post Development Type l/ 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Prepared by Sanborn Head & Associates Printed 8/14/2019 HydroCAD® 10.00-24 s/n 08733 © 2018 HydroCAD Software Solutions LLC Page 7 Summary for Pond 1 P: CB -1 Inflow Area = 0.238 ac, 92.79% Impervious, Inflow Depth = 1.28" for 25 -Yr, 24 -Hr event Inflow = 0.54 cfs @ 11.96 hrs, Volume= 0.025 af Outflow = 0.54 cfs @ 11.96 hrs, Volume= 0.025 af, Atten= 0%, Lag= 0.0 min Primary = 0.54 cfs @ 11.96 hrs, Volume= 0.025 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 5,454.37' @ 11.96 hrs Flood Elev= 5,456.40' Device Routing Invert Outlet Devices #1 Primary 5,454.00' 12.0" Round Culvert L= 54.0' CPP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 5,454.00' / 5,453.00' S= 0.0185 '1' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 0.79 sf rimary OutFlow Max=0.54 cfs @ 11.96 hrs HW=5,454.37' TW=5,453.26' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.54 cfs @ 2.07 fps) 0.6 0.55 0.5 0.45 0.4 t 0.35 0.3 " 0.25 0.2 0.15 0.1 0.05 Pond 1P: CB -1 Hydrograph ince. cis 0.54 cfs Inflow Area=0.238 ac Peak Elev=5,454.37' 12.0" Round Culvert n=0.012 L=54.0' S=0.0185 '1' 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) III Inflow III Primary El Inflow I [1 Primary Post Development Type /l 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Prepared by Sanborn Head & Associates Printed 8/14/2019 HydroCAD® 10.00-24 s/n 08733 © 2018 HydroCAD Software Solutions LLC Page 8 Summary for Pond 2P: CB -2 Inflow Area = 0.244 ac, 87.93% Impervious, Inflow Depth = 1.13" for 25 -Yr, 24 -Hr event Inflow = 0.50 cfs @ 11.96 hrs, Volume= 0.023 af Outflow = 0.50 cfs @ 11.96 hrs, Volume= 0.023 af, Atten= 0%, Lag= 0.0 min Primary = 0.50 cfs @ 11.96 hrs, Volume= 0.023 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 5,452.35' @ 11.96 hrs Flood Elev= 5,455.75' Device Routing Invert Outlet Devices #1 Primary 5,452.00' 12.0" Round Culvert L= 52.0' CPP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 5,452.00' / 5,451.48' S= 0.0100'/' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 0.79 sf rimary OutFlow Max=0.50 cfs @ 11.96 hrs HW=5,452.35' TW=5,451.63' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.50 cfs @ 2.02 fps) 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 ! 0.1 I 0.05 Pond 2P: CB -2 Hydrograph nin -f 0.50 cfs Inflow Area=0.244 ac Peak Elev=5,452.35' 12.0" Round Culvert n=0.012 L=52.0' S=0.0100 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) Post Development Type 1124 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Prepared by Sanborn Head & Associates Printed 8/14/2019 HydroCAD®10.00-24 s/n 08733 © 2018 HydroCAD Software Solutions LLC Page 9 Summary for Pond 3P: DI -1 Inflow Area = 0.687 ac, 73.77% Impervious, Inflow Depth = 0.88" for 25 -Yr, 24 -Hr event Inflow = 1.05 cfs @ 11.97 hrs, Volume= 0.051 af Outflow = 1.05 cfs @ 11.97 hrs, Volume= 0.051 af, Atten= 0%, Lag= 0.0 min Primary = 1.05 cfs @ 11.97 hrs, Volume= 0.051 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 5,447.23' @ 11.97 hrs Flood Elev= 5,450.00' Device Routing Invert Outlet Devices #1 Primary 5,446.70' 12.0" Round Culvert L= 63.0' CPP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 5,446.70' / 5,444.81' S= 0.0300 '1' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=1.04 cfs @ 11.97 hrs HW=5,447.23' TW=5,443.77' (Dynamic Tailwater) 1=Culvert (Inlet Controls 1.04 cfs @ 2.48 fps) u. Pond 3P: DI -1 Hydrograph 1.05 cfs Inflow Area=0.687 ac Peak Elev=5,447.23' 12.0" Round Culvert n=0.012 L=63.0' S=0.0300 '1' 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) U inflow • Primary Post Development Prepared by Sanborn Head & Associates HydroCAD®10.00-24 s/n 08733 © 2018 HydroCAD Software Solutions LLC Type 11 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Printed 8/14/2019 Page 10 Inflow Area = Inflow = Outflow = Summary for Pond 4P: Basin 0.862 ac, 58.77% Impervious, Inflow Depth = 0.71" for 25 -Yr, 24 -Hr event 1.05 cfs @ 11.97 hrs, Volume= 0.051 af 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 100%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 5,444.58' @ 25.65 hrs Surf.Area= 1,997 sf Storage= 2,213 cf Plug -Flow detention time= (not calculated: initial storage exceeds outflow) Center -of -Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 5,443.00' 5,756 cf Elevation (feet) 5,443.00 5,444.00 5,445.00 5,446.00 0 LL Surf.Area Perim. (sq -ft) (feet) 756 120.2 1,627 216.0 2,288 233.1 3,016 252.0 Custom Stage Data (Irregular)Listed below (Recalc) Inc.Store (cubic -feet) 0 1,164 1,948 2,644 Pond 4P: Basin Hydrograph Cum.Store (cubic -feet) 0 1,164 3,112 5,756 Wet.Area (sq -ft) 756 3,325 3,976 4,744 1.05 cfs Inflow Area=0.862 ac Peak Elev=5,444.58" Storage=2,213 cf 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) r Inflow Post Development Type /l 24 -hr 25 -Yr, 24 -Hr Rainfall=1.88" Prepared by Sanborn Head & Associates Printed 8/14/2019 HydroCAD® 10.00-24 s/n 08733 © 2018 HydroCAD Software Solutions LLC Page 11 Summary for Pond 5P: DMH -1 Inflow Area = 0.244 ac, 87.93% Impervious, Inflow Depth = 1.13" for 25 -Yr, 24 -Hr event Inflow = 0.50 cfs @ 11.96 hrs, Volume= 0.023 af Outflow = 0.50 cfs @ 11.96 hrs, Volume= 0.023 af, Atten= 0%, Lag= 0.0 min Primary = 0.50 cfs @ 11.96 hrs, Volume= 0.023 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 5,451.63' @ 11.96 hrs Flood Elev= 5,455.75' Device Routing Invert Outlet Devices #1 Primary 5,451.28' 12.0" Round Culvert L= 51.5' CPP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 5,451.28' / 5,446.90' S= 0.0850 '/' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.50 cfs @ 11.96 hrs HW=5,451.63' TW=5,447.23' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.50 cfs @ 2.02 fps) Pond 5P: DMH -1 Hydrograph 0.50 cfs 0.2 0.15 0.1 0.05 Inflow Area=0.244 ac Peak Elev=5,451.63' 12.0" Round Culvert n=0.012 L=51.5' S=0.08501/' 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 Time (hours) 1_11 Inflow ❑ Primary APPENDIX D EROSION CONTROL DETAILS SANBORN 1111 HEAD s 7/\ o / % e f `/ , r / / r77-./ i v / 4, r `.� /♦ J i y ,' GRAS3IJNED SWALE F 6 f * /c. cc A TEST PTT I > f/fo r° RPRAP-LINED SWALE 4/ RIPRAP•LINET. SWALE f / P O g0STING 2415 CMP CULVERT EXTEND EXISTING 24'0 CMP CULVERT 10 FEET — RIPRAP OUTLET PROTECTION APRON (TYP) EXISTING 18••0 CMP CULVERT Ilk CID 0 EMERGENCY SPILLWAY FENCE SURROUNDING EXISTING WELL PAD N DISCHARGE STRUCTURE CUP SILT FENCE Aft IMP CONCRETE WASHOUT LOCATION i NOTES: 1. SEE SHEET C1 FOR ADDITIONAL NOTES AND LEGEND. 2. BASIN IS DESIGNED TO CAPTURE AND INFILTRATE VOLUMES FOR STORMS WITH FREQUENCY LESS kk THAN OR EQUAL TO 25 -YR 24 -HR EVENT. STORMS BETWEEN 25 -YR AND 100 -YR WILL BE RELEASED THROUGH THE HORIZONTAL ORIFICE ON THE DISCHARGE STRUCTURE. STORMS GREATER THAN 111 100 -YR WILL DISCHARGE OVER EMERGENCY SPILLWAY (SEE THE DRAINAGE REPORT). 3. REFER TO CONSTRUCTION SEQUENCE ON SHEET C1. CONTRACTOR SHALL INSTALL AND MAINTAIN ALL EROSION AND SEDIMENT CONTROL MEASURES IN ACCORDANCE WITH BEST MANAGEMENT PRACTICES. REFER TO STORMWATER MANAGEMENT PLAN AND NOTES ON SHEET C14 FOR INSPECTION AND MAINTENANCE REQUIREMENTS. LEGEND (EXISTING FEATURES): LEGEND (PROPOSED FEATURES): EROSION CONTROL KEY: IS EXISTING 1 -FOOT ELEVATION CONTOUR EXISTING 5 -FOOT ELEVATION CONTOUR EXISTING PAVEMENT 2 -FOOT ELEVATION CONTOUR 10 -FOOT ELEVATION CONTOUR BITUMINOUS ASPHALT SUBCATCHMENT LINE SUBCATCHMENT AREA DESIGNATION \r"" SHEET FLOW DIRECTION 0 CONCRETE WASHOUT LOCATION SILT FENCE CRUSHED STONE CHECK DAM SWALE GRAPHICAL SCALE 30' 15 0' 30 60'c. NO QATE DESCRIP11.14 AY DRAWN BY: T. REED DESIGNED BY: T. REED REVIEWED BY: M. KOZLOWSKI PROJECT MGR: M. KOZLOWSKI PIC: T. REED DATE: AUGUST 2019 LANDFILL SCALE HOUSE PROJECT GARFIELD COUNTY LANDFILL RIFLE, COLORADO PROJECT NUMBER: 4622.00 PROPOSED EROSION AND SEDIMENT CONTROLS PLAN SHEET NUMBER: C6 OF C15 HOT BITUMINOUS ASPHALT (GRADING SX) Ala 9p • 4.• HOT BITUMINOUS ASPHALT 4' (GRADING S) COOT CLASS 5 ROAD BASE ,000•7 CUSS 2 ROAD BSS„),„ ^:q' Y, : j4' `yf ryye�a ..riw?w + SUBGRADE PAVEMENT SECTION PAVEMENT SECTION ORDINARY FILL GRANULAR FILL ink NOT TO SCALE PAVED AREAS GRASSED AREAS TOPSOIL AND SEED PIPE DIA. +1r MIN 2' MIN EXISTING SOIL - CORRUGATED POLYETHYLENE DRAIN PIPE (CPP) (SEE CULVERT SCHEDULE FOR PIPE DIAMETER) NOTE: 1 THE DEPTH OF GRANULAR FILL PIPE BEDDING SHALL BE INCREASED TO AT LEAST 12 INCHES IN AREAS WHERE LEDGE OR UNSUITABLE SOILS ARE ENCOUNTERED. CULVERT TRENCH NOT TO SCALE PAVEMENT SECTION ORDINARY FILL 1'0 POLY WATER PIPE OR 4"0 SCH 80 PVC SEWER PIPE GRANULAR FILL PAVED AREAS GRASSED AREAS TOPSOIL AND SEED 4/4 4 4 1' MIN. NOTE: Com" 2 MAX 1. THE DEPTH OF GRANULAR FILL PIPE BEDDING SHALL BE INCREASED TO AT LEAST 12 INCHES IN AREAS WHERE LEDGE OR UNSUITABLE SOILS ME ENCOUNTERED. 3' MIN EXISTING SOIL 3 WATER / SEWER PIPE TRENCH NOT TO SCALE 118 x 18' REBAR r ANCHOR PIN (TYP) - I- L 'II 1r I` 1 _ 1Y 2.1-171— 6' MIN. ELEVATION VIEW 2. 4' 2' 3' SECTION VIEW NOTES: 86 REBAR 1 CONTRACTOR MAY SUBMIT 'LOCAL STANDARD' FOR APPROVAL. CONCRETE WHEELSTOP NOT TO SCALE PAVEMENT SECTION 4r0 PRECAST CONCRETE MANHOLE SLOPE 4'-0' TYP. CONCRETE ROUNDED SMOOTH PAINTED TWO (2) COATS OF SAFETY YELLOW ENAMEL PAINT 8' DIA. STANDARD STEEL PIPE FILLED WITH CONCRETE (TYP) 4'-0" TYP. MIN. 8" TYP, ALL WAY AROUND 11 5 BOLLARD NOT TO SCALE - 2 e' CATCH BASIN FRAME AND GRATE MODEL NO R3570 -A BY NEENAHFOUNDY CO OR EQUIVALENT APPROVED BY THE ENGINEER PLAN VIEW SLOPE CORRUGATED PIPE ADAPTER J A' 12'0 CPP CULVERT KOR-N-SEAL CONNECTOR (TYP) PRECAST CONCRETE MANHOLE 12' Fm IN! J CRUSHED STONE SECTION A -A' ' CATCH BASIN NOT TO SCALE KOR-N-SEAL CONNECTOR (TYP) FLOW 12'0 CPP - cd&AMATED PIPE ADAPTER (TYP) 1117 24.0 CONCRETE NOTES: PAVEMENT SECTION 1. THE USE OF PRE -FABRICATED BOLLARDS APPROVED BY THE ENGINEER IS ACCEPTABLE PAVEMENT SECTION 48'0 PRECAST CONCRETE MANHOLE CULVERT SCHEDULE CULVERT TYPE DIAMETER (IN) LENGTH (FT) SLOPE (FT/FT) INLET END OUTLET END INV. IN (FT) INV. OUT (FT) C -I CPP 12 64 0.0185 CB -1 PROJ 545400 5453.00 C-2 CPP 12 52 0.0100 CB -2 DMH -1 5462.00 5451.48 C-3 CPP 12 52 0.0850 DMH -1 DI -1 545128 6448.80 C-4 CPP 12 83 0.0300 01-1 BASIN 544870 544451 C-5 CPP 18 50 0.0100 DS PROJ 5443.00 5442.50 C-6 CMP 10 10 MATCH MATCH MATCH MATCH MATCH NOTES 1 THE PROPOSED INVERT ELEVATIONS SHOWN IN THE SCHEDULE ABOVE REPRESENT DESIGN ELEVATIONS WHICH ARE BASED ON DESIGN OR EXISTING SWALE INVERT ELEVATIONS INTERPOLATED FROM AERIAL TOPOGRAPHY. THE INTENT IS THAT THE CULVERTS BE INSTALLED WITH THE PROPOSED SLOPE AND ELEVATIONS AT THE INVERTS OF CORRESPONDING EXISTING SWALES OR CHANNELS. IF THE ACTUAL SWALE INVERT ELEVATIONS DIFFER SIGNIFICANTLY DURING INSTALLATION FROM THOSE INDICATED, OBTAIN APPROVAL FROM ENGINEER PRIOR TO BACKFILLING THE PIPES. GRADES SHALL BE CONFIRMED FOR SHOP DRAWING APPROVAL BY ENGINEER. 3r FRAME AND SOLID COVER LETTERED"DRAIN' MODEL NO. R-1743 BY NEENAH FOUNDRY CO. OR EQUIVALENT APPROVED BY THE ENGINEER CORRUGATED PIPE ADAPTER PLAN VIEW J A' 1r0 CPP CULVERT KOR-NSEAL CONNECTOR (TYP) PRECAST CONCRETE MANHOLE 11h1111111111 12' CRUSHED STONE SECTION A -A" KOR-N-SEAL CONNECTOR (TYP) 4 12'0 CPP COF)TED PIPE ADAPTER (TYP) DRAIN MANHOLE NOT TO SCALE 48'0 PRECAST CONCRETE MANHOLE KOR-N-SEAL CONNECTOR (TYP) LEGEND: CB = CATCH BASIN DPP = CORRUGATED POLYETHYLENE PIPE DMH a DRAINAGE MANHOLE DS = DISCHARGE STRUCTURE HW = HEADWALL PROJ =PROJECTING MATCH=MATCH EXISTING 48' CONE GRATE TRASH RACK BY HAALA DUSTRIES OF SLEEPY MN .HAALA.COM) 12'0 CPP CULVERT (C-2) ANV PRECAST CONCRETE MANHOLE 12"0 CPP CULVERT (C-3) PLAN VIEW 4 12' SUMP 1 CORRUGATED PIPE ADAPTER 12'0 CPP CULVERT (C-3) TO A' BASIN 12' CRUSHED STONE SECTION A -A' KOR-N-SEAL CONNECTOR (TYP) 7 FLOW 1r0 CPP CULVERT (C-4) CORRUGATED PIPE ADAPTER (TVP) DROP INLET STRUCTURE B NOT TO SCALE SCALE: AS NOTED !IP 0415 OEaCRIPti(Y4 rn DRAWN BY: T. REED DESIGNED BY: T. REED / LUKE T. REVIEWED BY: M. KOZLOWSKI PROJECT MGR: M. KOZLOWSKI PIC: T. REED DATE: AUGUST 2019 LANDFILL SCALE HOUSE PROJECT GARFIELD COUNTY LANDFILL RIFLE, COLORADO PROJECT NUMBER: 4622.00 TYPICAL DETAILS AND SECTIONS SHEET NUMBER: C12 OF C15 • rr, 4s /DI -1 EXISTING 10•0 CMP CULVERT w EMERGENCY SPILLWAY OUTLET PROTECTION APRON 3 2•10 -1"/ GRAPHICAL SCALE I I I 1 I 20' 10 0' 20' 40' DROP INLET STRUCTURE 41131 -.•--- FOREBAY STORMWATER BASIN PROFILE STORMWATER PLAN SCALE AS NOTED 5460 CB -2 STA. 0+12.03 RIM=5455.80 INV.OUT=5452.00 5455 INV 545200 1 5450 4131 CATCH BASIN 5445 DMH -1 STA 0+68.05 RIM=5456.6 INV.IN=5451.48 INV.OUT=5451.28 1, X12"0 CPP (C-2) L=52' S= 0010.r INV 545146 - AEI TIP DRAIN MANHOLE DI -1 STA 1+23.60 RIM=5450.1 INV.IN=5446.90 INV.OUT=5446 70 5440 0+00 0+25 0+50 0+75 ink DROP INLET 1 STRUCTURE TIP OUTLET CONTROL RISER IN5 544300 10.0' 441 18" C0 PP (C•4)� INV. 5442.60 ae•_ 1+00 1+25 1+50 1+75 2+00 2+25 2+50 2+75 3+00 3+10 VERTICAL SCALE 4.0 2.0 0' 4.0' 1 I I I 20 10' Cr 20 HORIZONTAL SCALE 40 STORMWATER BASIN PROFILE SCALE AS NOTED 1 516 SCH 130 PVC PIPE INV. = 5449.5 BOTTOM OF BASIN TOP OF RISER EL = 644460 15•0 HEAVY DUTY BAR GUARD BY AORI-DRAW OR EQUIVALENT APPROVED BY THE ENGINEER CRUSHED STONE 12.0 MIN. DRAINAGE CULVERT (SEE CULVERT SCHEDULE) 6" GRANULAR FILL BEDDING 18"0 CPP CULVERT INV. = 5443.0 0 DISCHARGE STRUCTURE DETAIL 3 NOT TO SCALE �+r 18"0 CPP •r>✓rrrn v.„ur POND5 BERM v•r..a}V%y y'�h'Jvf4+YJ l' 'e'} Wu= 3Do A PLAN W4 11111111111111111 12"MNNT.) 1 HDPE ANTI -SEEP COLLAR BY LANE ENTERPRISES OR EQUIVALENT APPROVED BY ENGINEER NOTES: 1. CPP SHALL BE WATERTIGHT N-12 PIPE BY ADVANCED DRAINAGE SYSTEMS (ADS) OR EQUIVALENT APPROVED BY THE ENGINEER 2. ALL CONNECTIONS SHALL BE WATERTIGHT INSTALLED IN ACCORDANCE WTTH MANUFACTURER'S RECOMMENDATIONS. NOTE: NONWOVEN GEOTEXTILE SHALL BE MIRAFI 140N FROMTENCATE GEOSYNTHETICS NORTH AMERICA OR EQUIVALENT APPROVED BY THE ENGINEER. DRAINAGE CULVERT (SEE CULVERT SCHEDULE) RIPRAP APRON NONWOVEN GEOTEXTILE (SEE NOTE 1) SECTION A -A1- PROFILE 0 OUTLET PROTECTION APRON DETAIL ¢ NOT TO SCALE B T 10 TOPOP POND 12" (TYP) RIPRAP RL 6446-00 FLAW 2, ,T 'f� rt N. 1 3 a VARIES ORDINARY FILL X INV. = 5544.80 NONWOVEN GEOTEXTILE BENEATH RIPRAP (SEE NOTE 1) DAYLIGHT GEOTEXTILE (TYP) 12" OF RIPRAP • 11 3 MIN NONWOVEN GEOTEXTILE (SEE NOTE 1) 10' r TOP OF POND ■ EL 5446.00 1.2' 1-1 III WEIR fEL. 5444.80 E{ II -� 3 MIN. O MIN SECTION B -B' EMERGENCY SPILLWAY NOT TO SCALE NOTE: 1. NONWOVEN GEOTEXTILE SHALL BE MIRAFI 140N FROM TENCATE GEOSYNTHETICS NORTH AMERICA OR EQUIVALENT APPROVED BY THE ENGINEER. SCALE: AS NOTED NO DATE DESCRIPTION BY DRAWN BY: T. REED DESIGNED BY: T. REED REVIEWED BY: M. KOZLOWSKI PROJECT MGR: M. KOZLOWSKI PIC: T. REED DATE: AUGUST 2019 LANDFILL SCALE HOUSE PROJECT GARFIELD COUNTY LANDFILL RIFLE, COLORADO 1 PROJECT NUMBER: 4622.00 STORMWATER BASIN PLAN, PROFILE, AND DETAILS SHEET NUMBER: C14 OF C15 GENERAL NOTES: 1. CONDUCT EARTH WORK ACTIVITIES SO THAT THE SMALLEST PRACTICAL AREA IS EXPOSED AT ANY ONE TIME PRIOR TO FINAL GRADING AND STABILIZING WITH SEED AND MULCH UNSTABIUZED AREA NOT WITHIN THE LANDFILL FOOTPRINT SHALL BE LIMITED TO NOT MORE THAN 2 CONTIGUOUS ACRES AT ANY ONE TIME THE TERM 'STABLE' IS DEFINED AS MEETING ONE OF THE FOLLOWING CRITERIA A B. C. D. BASE COURSE GRAVELS HAVE BEEN INSTALLED IN AREAS TO BE PAVED; A MINIMUM OF 85% VEGETATED GROWTH HAS BEEN ESTABLISHED; A MINIMUM OF 3 INCHES OF NON-EROSIVE MATERIAL SUCH AS STONE RIPRAP HAS BEEN INSTALLED; OR EROSION CONTROL BLANKETS HAVE BEEN PROPERLY INSTALLED 2 APPLY SEED, LIME, FERTIUZER AND HAY MULCH TO DISTURBED AREAS, NEWLY -PLACED FILL SLOPES, AND GRASS-UNED SWALES WITHIN 7 DAYS OF ACHIEVING FINAL GRADE. ALSO APPLY SEED AND HAY MULCH TO THOSE AREAS OUTSIDE OF THE LANDFILL FOOTPRINT WHICH WILL NOT BE RE -DISTURBED FOR A PERIOD OF 30 DAYS OR MORE. HAY MULCH SHALL BE APPLIED AT THE RATE OF 1 5 TO 2 TONS PER ACRE 3 SILT FENCE/HAY BALE EROSION CONTROL STRUCTURES SHALL BE INSTALLED AT THE DISCRETION OF THE ENGINEER AND OWNER SILT FENCE SHALL BE INSTALLED ALONG THE CONTOUR AND TOED UPSLOPE SILT FENCE/HAY BALE BARRIERS ARE TO BE MAINTAINED AND CLEANED UNTIL VEGETATIVE COVER IS ESTABLISHED. 4 ALL EROSION CONTROLS SUCH AS SILT FENCE SHALL BE INSPECTED WEEKLY DURING THE LIFE OF THE PROJECT AND AFTER EACH STORM EVENT WHICH PRODUCES 025 INCHES OF RAINFALL ALL DAMAGED SILT FENCE SHALL BE REPAIRED PROMPTLY. 6 TRACK UP AND DOWN REGRADED SLOPES (GROUSER TRACKS PERPENDICULAR TO THE SLOPE) WITH A BULLDOZER TO LIMIT EROSION 6 REMOVE SEDIMENT FROM DETENTION PONDS RESULTING FROM CONSTRUCTION ACTIVITY AS NEEDED TO MAINTAIN STORAGE CAPACITY AND AT THE DIRECTION OF THE ENGINEER OF OWNER. 7 REMOVE SEDIMENT BUILD UP FROM BEHIND EROSION AND SEDIMENT CONTROL DEVICES. MAINTAIN TEMPORARY EROSION AND SEDIMENT CONTROL DEVICES UNTIL FULL ESTABLISHMENT OF PERMANENT GROUND COVER. B DITCHES, SWALES, AND PONDS SHALL BE STABIUZED BEFORE RUNOFF IS DIRECTED TO THEM 9 CONDUCT SOIL BORROW EXCAVATION ACTIVITIES IN SUCH A MANNER THAT ALL RUNOFF FROM THE EXCAVATION AREAS IS CONTAINED WITHIN THE EXCAVATION SPECIFICATIONS: TOFSO:L AAA.) SEE [:INC. VA I E R:,LS A. TOPSOIL SHALL BE FERTILE SOIL CAPABLE OF SUSTAINING VIGOROUS PLANT GROWTH, FREE FROM ROOTS, STICKS, PEAT, WEEDS, AND SOD R SHALL NOT CONTAIN MATERIAL HARMFUL TO PLANT GROWTH B FERTILIZER (10-10-10) SHALL BE LOW PHOSPHATE AND SLOW RELEASE NITROGEN AND APPUED UNIFORMLY OVER THE DISTURBED AREA AT A RATE OF TWENTY (20) POUNDS PER 1,000 SQUARE FEET (APPROXIMATELY 875 POUNDS PER ACRE) C GRASS SEED SHALL BE FROM THE SAME OR PREVIOUS YEAR'S CROP; EACH VARIETY OF SEED SHALL HAVE A PERCENTAGE OF GERMINATION NOT LESS THAN NINETY (90), APERCENTAGE OF PURITY NOT LESS THAN EIGHTY-FIVE (85), AND SHALL HAVE NOT MORE THAN ONE PERCENT (1%) WEED CONTENT GRASS SEED SHALL BE APPLIED AT A RATE OF NO LESS THAN 1/2 L63. PER 1.000 SF. D MULCH SHALL CONSIST OF DRY HAY OR STRAW AND BE FREE OF NOXIOUS WEEDS OR MOLD E APPLICATION OF FERTILIZER, LIME, SEED, AND MULCH SHALL ONLY BE PERFORMED DURING THOSE PERIODS WITHIN THE SEASONS WHICH ARE NORMAL FOR SUCH WORK AS DETERMINED BY THE WEATHER AND LOCALLY ACCEPTED PRACTICE, AND AS APPROVED BY THE ENGINEER F ANY PART OF THE SEEDED AREA WHICH FAILS TO YIELD AN ACCEPTABLE STAND OF GRASS AS DETERMINED BY THE ENGINEER OR OWNER SHALL BE RETREATED WITH ADDITIONAL SEED, FERTILIZER, AND MULCH. Mir INSTAL 1 EROSION COHCROL BLANKETS IF REQUIRED PER WINTER NOTES ON THIS SHEET 1 4' TOPSOIL MIN. 4 '4 4 4 '4 4 4 4 -.A .�' N 1F '4 VEGETATION f - COMPACTED OR UNDISTURBED SUBGRADE 0- TYPICAL LOAM AND SEED 2 NOT TO SCALE NONWOVEN - GEOTEXTILE (SEE NOTE 2) NOTES: 1 1' MIN. (SEE NOTE 1) 11 \ _1 /�1 3 __ 3 i2' THICK RIPRAP 1. RIP RAP SHALL EXTEND ON SIDESLOPES TO THE TOP OF PIPE ELEVATIONS IN &WALES THAT CONTAIN CULVERT INLETS OR OUTLETS. 2. NONWOVEN GEOTEXTILE SHALL BE MIRAFI 140N FROM TENCATE GEOSYNTHETICS NORTH AMERICA OR EQUIVALENT APPROVED BY THE ENGINEER. RIPRAP-LINED SWALE NOT TO SCALE (TRAPAZOIDAL) WINTER NOTES: 1 ALL PROPOSED VEGETATED AREAS WHICH DO NOT EXHIBIT A MINIMUM OF 65% VEGETATIVE GROWTH BY OCTOBER 15TH, OR WHICH ARE DISTURBED AFTER OCTOBER 15TH, SHALL BE STABILIZED BY SEEDING AND INSTALLING EROSION CONTROL BLANKETS ON SLOPES GREATER THAN 3:1, AND SEEDING AND PLACING 3TO 4 TONS OF HAY MULCH PER ACRE, SECURED WITH ANCHORED NETTING, ELSEWHERE THE INSTALLATION OF EROSION CONTROL BLANKETS OR MULCH AND NETTING SHALL NOT OCCUR OVER ACCUMULATED SNOW OR ON FROZEN GROUND AND SHALL BE COMPLETED IN ADVANCE OF THAW OR SPRING MELT EVENTS; 2 ALL DITCHES OR SWALES WHICH DO NOT EXHIBITA MINIMUM OF 65% VEGETATIVE GROWTH BY OCTOBER 15TH, OR WHICH ARE DISTURBED AFTER OCTOBER 16TH, SHALL BE STABILIZED TEMPORARILY WITH STONE OR EROSION CONTROL BLANKETS APPROPRIATE FOR THE DESIGN FLOW CONDITIONS; AND 3 AFTER NOVEMBER 15TH, INCOMPLETE ROAD OR PARKING SURFACES, WHERE WORK HAS STOPPED FOR THE WINTER SEASON, SHALL BE PROTECTED WITH A MINIMUM OF 3 INCHES OF CRUSHED GRAVEL PER CDOT COURSE AGGREGATE FOR CLASS 6 ROAD BASE TEMPORARY EROSION (YCITROL MEAS'1RES 1 THE SMALLEST PRACTICAL AREA OF LAND SHALL BE EXPOSED AT ANY ONE TIME. 2 SILT FENCE/HAY BALE EROSION CONTROL STRUCTURES SHALL BE INSTALLED ALONG THE EXISTING CONTOUR IN LOCATIONS SHOWN ON THE PLANS. SILT FENCE/HAY BALE BARRIERS ARE TO BE MAINTAINED AND CLEANED UNTIL ALL SLOPES HAVE BEEN ADEQUATELY STABIUZED 3 ALL DISTURBED AREAS SHALL BE FINE GRADED BEFORE BEING SEEDED AND MULCHED. 4 FILL MATERIAL SHALL BE FREE FROM STUMPS, WOOD, ROOTS, ETC 5 THE BOTTOM OF THE DETENTION PONDS SHALL BE PERIODICALLY CLEANED, WITH THE SEDIMENT REMOVED TO A SECURE LOCATION SO AS TO PREVENT SILTATION OF NATURAL WATERWAYS 6 AFTER ALL DISTURBED AREAS HAVE BEEN STABIUZED, THE TEMPORARY EROSION CONTROL STRUCTURES ARE TO BE REMOVED AND ACCUMULATED SEDIMENT DISPOSED OF IN A SECURE LOCATION 7 SILT FENCES SHALL BE PERIODICALLY INSPECTED DURING THE LIFE OF THE PROJECT AND AFTER EACH STORM SEDIMENT DEPOSITS SHALL PERIODICALLY BE REMOVED LOW GROW GRASS SEED MIX SPECIES (COMMON NAME) MIX (PERCENT) EPHRAIM CRESTED WHEATGRASS 30% SHEEPS FESCUE 25% VIBRANT PERENNIAL RYEGRASS 20% CHEWINGS FESCUE 15% CANADA BLUEGRASS 10% TOTAL 100% NOTES: 1 AVAILABLE FROM RIVENDELL DISTRIBUTION AND SOD FARM TEL (970) 945-2566. 2 SEED SHALL BE APPLIED ATA RATE OF 1/2 LBS. PER 1,000 SF. ANGLE FIRST STAKE TOWARD PREVIOUSLY LAID BALE FLOW TOP OF - SLOPE HAY BALE (TYP) SHOULDER L VEGETATED SLOPE CPP CULVERT (SEE CULVERT SCHEDULE) S#° rTOE OF FLOW 1 SLOPE FLOW! INSTALLATION (ISOMETRIC VIEW) LOAM AND SEED NOTES: 1. INTERMITTENT CHECK SLOT CHANNEL INSTALLATION DIMENSIONS GIVEN IN THE DRAWINGS ARE EXAMPLES; DEVICE SHOULD BE INSTALLED PER MANUFACTURER'S SPECIFICATIONS. 2. CHECK SLOTS TO BE CONSTRUCTED PER MANUFACTURER'S SPECIFICATIONS. 3. STAKING OR STAPLING LAYOUT PER MANUFACTURER'S SPECIFICATIONS. NOTE 2 LONGITUDINAL ANCHOR T€RMINAL SLOPE ANO CHANNEL TRENCH ANCHOR TRENCH .'Y Y•. y ..�Yr CHECK SLOT AT 25' INTERVALS ISOMETRIC VIEW EROSION CONTROL BLANKET INSTALLATION 1 NOT TO SCALE VARIES (SEE NOTE 1) SECTION VIEW NOTE2 INSTALL EROSION CONTROL BLANKETS IF REQUIRED PER WINTER NOTES ON THIS SHEET GRASS -LINED SWALE NOT TO SCALE NOTES: 1. SWALES WILL VARY IN DEPTH BUT SHOULD BE NO LESS THAN 1 FOOT IN DEPTH. 2. SLOPE OF SWALE ADJACENT TO SCALE IS 3.5H:1V. SLOPES ELSEWHERE SHALL BE 3H:IV. rxr STAKES in TO2'IN THE GROUND FLOW—� EXISTING SOILS TEMPORARY HAY BALE INLET PROTECTION NOT TO SCALE Elm WIRE OR NYLON BOUND BALES PLACED ALONG THE CONTOUR ANCHORING (ELEVATION VIEW) 4" VERTICAL FACE (TYP) l4 4I4 1 EXISTING GRADE WOODEN POSTS I PLAN VIEW A - WOVEN POLYPROPYLENE SILT FENCE FABRIC ATTACHED TO POSTS r, •:.•*i•►► .�r.*.••. •0�.r•. if »ii..• •. •..••i•.❖E;•i• .i i • fr •rf f•• 1f Q A ELEVATION VIEW FLOW ci SILT FENCE FABRIC ATTACHED TO POSTS 0 1' WOODEN POSTS 1Y MIN 2'X 2'X 4' GRADE STAKES HAY BALES SHALL BE INSTALLED WHERE NECESSARY TO SUPPORT SILT FENCE 4' MINIMUM EMBEDMENT 12" MIN EXISTING GRADE EXCAVATE TRENCH FOR 6' FABRIC OVERLAP AND BACKFILL WITH EXCAVATED MATERIAL SECTION A -A SILT FENCE DETAIL NOT TO SCALE SCALE: AS NOTED '�ti,iirJ 1 . NO DATE DESCRIPTION BY DRAWN BY: T. REED DESIGNED BY: T. REED REVIEWED BY: M. KOZLOWSKI PROJECT MGR: M. KOZLOWSKI PIC: T. REED DATE: AUGUST 2019 LANDFILL SCALE HOUSE PROJECT GARFIELD COUNTY LANDFILL RIFLE, COLORADO PROJECT NUMBER: 4622.00 EROSION AND SEDIMENT CONTROL DETAILS SHEET NUMBER: C15 OF C15 APPENDIX E ADDITIONAL CALCULATIONS SANBORN 1111 HEAD File No. Project 4622.00 Page 1 of 1 Location Garfield County Landfill - Rifle. C:0 S A N B O R NHEAD Subject Water Quality f arriirr VPlume and Orifice Sizing iiji Calculated By L. Teal Scale Howe /Adminikrration Building Checked By T. Reed P:\4600s\4622.00\Work\Calculations\20190814 Drain Time.docx Date 8/14/19 Date 8/27/31 PURPOSE: Garfield County standard 7-204.C.3.d indicates that "Removal of pollutants shall be accomplished by sizing dry detention basins to incorporate a 40 -hour emptying time for a design precipitation event of 0.5 inches in 24 hours, with no more than 50% of the water being released in 12 hours." Select an orifice size to produce the appropriate drain time. METHOD: Calculate the volume of water to be emptied over a 40 -hour emptying time using the SCS TR -20 method modeled using HydroCAD. Calculate the orifice size using the orifice equation. From HydroCAD the volume of water to be emptied is 197 cubic ft. Size the orifice to release the water over a 40 -hour period. 197ft3 lhour 40 hours x 3,660 sec =0.001 cfs Try using a 1/4 -inch diameter orifice with the orifice equation. Orifice Equation: a= Q = Cda 2gh Where: Q = discharge (cfs) Cd = Discharge coefficient (0.60) a = submerged area (ft2) g = gravitational constant (32.2 ft/s2) h = effective head (ft) 2 rcdz 3.142 x (--) 0.254 4 = 0.00034 ft2 According to the stage -storage table for the basin, the volume of 197 ft3 corresponds to a depth of about 0.24 feet. Therefore, Q = 0.6 x 0.00034 x 2(32.2)(0.24) Q = 0.6 x 0.00034 x 3.93 = 0.001 cfs RESULTS: The volume of water to be emptied is 197 cubic ft. With a 1/4 -inch orifice and 0.24 foot of head, the release rate is 0.001 cfs, which matches the required rate for a 40 -hour drain time. This is impractical considering as it will very likely get clogged. We are providing a 1.5 -inch orifice to ensure that the pond can drain without clogging. www sanhoollead.rnm Sanborn, Head &Associates, Inc. SANBORN File No Project Location HEAD Subject 4622.00 Page 1 of 1 Srale House / Administration Building Garfield County Landfill - Rifle. Co Emergency Spillway Welt- l:low Calculator' Calculated By L. Teal Date R/14/19 Checked By T. Reed Date 8/27/19 P:\4600s\4622.00\Work\Calculations\20190814 Weir Flow Calculation.docx PURPOSE: Garfield County standard 7-204.C.3.b indicates that "all permanent stormwater detention facilities must demonstrate that there is a safe passage of the 100 -year storm event without causing property damage." Therefore, the emergency spillway should be able to pass the 100 -year developed site flow at a flow depth no greater than 6 inches and a foot of freeboard. METHOD: Use the method described in Volume 2, Chapter 12 (Storage), Section 5.14.2 of the Urban Storm Drainage Criteria Manual (USDCM). CALCULATION: L Horizontal Portion: Sloping Portion: L .. • L - H: E',TF : „EI'< E. 1:411 QH = CBCW 1,111.5 (—s)CBcw 2l Qs = ZH2.5 Where: Q = discharge (cfs) CBcw = broad -crested weir coefficient (a value of 3 is often used in practice). L = broad -crested weir length (ft) Z = side slope (horizontal: vertical) H = head above weir crest (ft) According the spillway detail, the length is 10 -ft with 3H:1V slopes and a flow depth of 0.2 feet (about 2.4"). Therefore, Q=QH+2Qs Q = (3x10x0.21.5)+2xK(5)3x3x0.22.5]=2.81cfs RESULTS: As shown on the construction drawings, the emergency spillway can pass 2.81 cfs with 0.2 inches of flow depth (less than the necessary 6 inches) and a foot of freeboard, which is greater than the flow into the basin for the 100 -yr storm event (1.48 cfs). www.s:u bornlu ad.com Sanborn, Head & Associates, Inc. SANBORN IIII HEAD File No. 4622.00 Page 1 of 2 Project Srale}rnuse / Administrat1pn Rj Ijding Location Garfield Counlvv Landfill - Rifle. CO Subject Swale Capacity Calculated By L. Teal Date 08/15/19 Checked By T. Reed Date 08/27/19 P:\4600s\4622.00\Work\Calculations\20190815 Swale Capacity Calc.docx Purpose: Confirm that the capacity of the proposed swale along the north side of scales provides equivalent or greater capacity than the existing roadside swale. Given: The existing triangular swale slopes at 3 percent and is 1 -foot deep with 2H:1V sideslopes. The proposed triangular swale slopes at 1 percent and is 1 -foot deep with 3.SH:1V sideslopes. Method: Estimate the capacity of both swales using the Manning's Equation. Calculation: Estimate the capacity of the existing swale using Manning's Equation. (±)ARVQ= Where: Q = flow (ft3/sec) n = Manning's coefficient (0.03) A= Cross-sectional area of pipe (ft2) R = Hydraulic radius (ft) S = Slope of pipe (ft/ft) The existing swale geometry is presented below. ,4h1 A =;;.1.1 .•"CTT=CD =c,.ir..:—=r. The hydraulic radius, R, is equal to the area of flow divided by the wetted perimeter. Therefore, 2.0 _ R 4.47= 0.45 ft 1.49 2 Q = \0.31(2.0)(0.45)3 0.03 = 10.03 cfs Sanborn, Head &Associates, Inc. SANBORN IIII HEAD File No. 4622.00 Page 2 of 2 Project Scale House,/ A dinipistrAtimBuilding Location Darfield County Landfill - Rifle. CO Subject Swale Capacity Calculated By L. Teal Date 08/15/19 Checked By T. Reed Date 08/27/19 P:\4600s\4622.00\Work\Calculations\20190815 Swale Capacity Calc.docx The proposed swale geometry is presented below. F-ni —T1P, �r� The hydraulic radius, R, is equal to the area of flow divided by the wetted perimeter. Therefore, 3.5 R= 728=0.48ft (3.5)(0.48)3 0.01 = 10.64 cfs Q = \0.031 CONCLUSIONS: The proposed swale has greater capacity than the existing swale. mug sanbornhead.coin Sanborn, Head &Associates, Inc. COLORADO Department of Public Health 8 Environment CERTIFICATION TO DISCHARGE UNDER CDPS GENERAL PERMIT COR400000 STORMWATER ASSOCIATED WITH CONSTRUCTION ACTIVITIES Certification Number: COR406660 This Certification to Discharge specifically authorizes: Owner Garfield County Landfill Operator Garfield County Landfill to discharge stormwater from the facility identified as Garfield County Landfill To the waters of the State of Colorado, including, but not limited to: Colorado River Facility Activity : other Municipal Development - Scale/admin buildings for landfill facility. Disturbed Acres: 1.34 acres Facility Located at: 75 CR 246A Rifle CO 81650 Garfield County Latitude 39.517367 Longitude -107.905987 Specific Information (if applicable): Certification is issued and effective: 8/29/2019 Expiration date of general permit: 3/31/2024 This certification under the permit requires that specific actions be performed at designated times. The certification holder is legally obligated to comply with all terms and conditions of the permit. This certification was approved by: Meg Parish, Section Manager Permits Section Water Quality Control Division 4300 Cherry Creek Drive South, Denver, CO 80246 303-692-3500 www.colorado.gov/cdphe/wgcd COLORADO Department of Public Health & Environment Dedicated to protecting and improving the health and environment of the people of Colorado Debra Fiscus, Landfill Manager Garfield County Landfill 0075 CR 246A Rifle, CO 81650 Debra Fiscus, Landfill Manager Garfield County Landfill 0075 CR 246A Rifle, CO 81650 DATE: 2019-08-29 MEMO RE: Certification, Colorado Discharge Permit System Permit No., COR400000, Certification Number: C0R406660 DIVISION CONTACTS: Joseph Sturgeon, 303-691-4019, Joseph.Sturgeon®state.co.us ATTACHMENTS: Certification COR406660, COR400000 General Permit The Water Quality Control Division (the Division) has reviewed the application submitted for the Garfield County Landfill facility and determined that it qualifies for coverage under the CDPS General Permit for Stormwater Discharges Associated with Construction Activities (the permit). Enclosed please find a copy of the permit certification, which was issued under the Colorado Water Quality Control Act. FEE INFORMATION: 1.34 acres An application fee of $175 (50% of the annual fee) will be assessed for all new applications. Beginning July 1, 2019 an annual fee of $350 category 7, subcat - Stormwater Construction 1-30 acres disturbed [per CRS 25-8-502] will be assessed and invoiced every July for as long as the permit certification is in effect. It is the responsibility of the permittee to submit a termination application when the permit is no longer needed. Fees are assessed and invoiced for every permit that is active July 1 of the fiscal year. Permits for which termination applications are received by June 30 of the current fiscal year will not be invoiced for the new fiscal year. CERTIFICATION RECORDS INFORMATION: The following information is what the Division records show for this certification. For any changes to Contacts - Owner, Operator, Facility, or Billing - a "Notice of Change of Contacts form" must be managed through the Division's new platform called the Colorado Environmental Online Services (CEOS). The Notice of Change of Contacts form must be electronically signed by both the owner and the operator. Facility: Garfield County Landfill Garfield County Construction Activities other Municipal Development - Scale/admin buildings for landfill facility. Owner (receives all legal documentation pertaining to the permit certification): Debra Fiscus, Landfill Manager Phone number: (970) 618-5864 Garfield County Landfill Email: dfiscus®garfield-county.com 0075 CR 246A Rifle, CO 81650 Operator (receives all legal documentation pertaining to the permit certification): Debra Fiscus, Landfill Manager Phone number: (970) 618-5864 Garfield County Landfill Email: dfiscus@garfield-county.com 0075 CR 246A Rifle, CO 81650 Facility Contact (contacted for general inquiries regarding the facility): Debra Fiscus, Landfill Manager Phone number: (970) 618-5864 Garfield County Landfill Email: dfiscus®garfield-county.com 0075 CR 246A Rifle, CO 81650 Billing Contact (receives the invoice pertaining to the permit certification): Debra Fiscus, Landfill Manager Phone number: (970) 618-5864 4300 Cherry Creek Drive South, Denver, CO 80246 303-692-3500 www.colorado.gov/cdphe/wqcd Garfield County Landfill 0075 CR 246A Rifle, CO 81650 Email: dfiscus®garfield-county.com