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Drainage Reports - 05/29/2018 (2)
UNITED CIVIL �\ Design Group Final Drainage Report Platte River Power Authority HQ Campus Fort Collins, CO City of Fort Col'ns Approved P ns l� Approved by: Date: Prepared for: Platte River Power Authority 2000 East Horsetooth Road Fort Collins, CO 80525 May 23, 2018 1501 Academy Ct. Ste. 203 Fort Collins, Colorado 80524 (970) 530-4044 fZ� UNITED CIVIL 7`"� Design Group LLc May 23, 2018 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Platte River Power Authority HQ Campus Fort Collins, Colorado Project Number: U16014 Dear Staff: Drainage Report Pierre River Power Authority HQ Campus Fort Collins, CO United Civil Design Group, I.I.C. is pleased to submit this Final Drainage Report for the Platte River Power Authority Headquarters Campus site in Fort Collins, Colorado. in general, this report serves to document the stormwater impacts associated with the proposed redevelopment of the existing campus. We understand that review by the City of Fort Collins is to assure general compliance with standardized criteria contained in the Fort Collins Stormwater Criteria Manual-(FCSCM). This report was prepared in compliance with technical criteria set forth in both the Urban Drainage and Flood Control District (UDFCD) Urban Storm Drainage Criteria Manual and the Fort Collins Stormwater Criteria Manual. If you should have any questions or comments as you review this report, please feel free to contact us at your convenience. Sincerely, United Civil Design Group Kevin 8razelton, PE Engineering Manager U160140n1napRepoR-F1na4doc Af�„ UNITED CIVIL Drainage Report ` Design Group «c Platte River Power Authority HgCampus Fort Collins, Co TABLE OF CONTENTS PAGE I. General Location and Description::...:::...::::::.:.:..:...................:::.6.:.::....................................... 1 A. Location.......................................................................................::::.................................1 B. Description of Property...............................................................................................::::1 C: Description of Development.................................................:........::::.............................. 2 ILDrainage Basins and Sub-Basins....................................................:::....................................... 3 A. Major Basin Description.................................................................................................. 3 B. Sub -Basin Description...................................................................................................... 3 111. Drainage Design Criteria......................................................................................................... 3 A. Regulations...................................................................................................................... 3 B. Directly Connected Impervious Area (DCIA)................................................................... 3 ' C. Development Criteria Reference and Constraints.......................................................... 4 D. Hydrological Criteria........................................................................................................ 5 E. Hydraulic Criteria............................................................................................................. 6 F. Floodpiain Regulations.................................................................................................... 6 G. Modifications of Criteria.................................................................................................. 6 IV, Drainage Facility Design - .... ............... .... ..... 6 1 A. General Concept ....A,. ................................... ........................ ..... .............. 6 B. Specific Details ....... ......... .................................................................... 9 V. Sediment/Erosion Control .......................................... .................................................. VI. Conclusions......... ...16 A. Compliance with Standards......... ........:..... :...:.:. _.........-......... 16 B. Drainage Concept ................ 16 . C. Stormwater Quality ... . ......................... ............................... .... ......16 VII. References ....... ......... - ........................: ....................... .........::.17 APPENDICES APPENDIX A — Hydrology Computations APPENDIX B — Detention and Water Quality Calculations APPENDIX C — Hydraulic Computations CA —.Storm Pipe Calculations C.2 — Inlet Sizing Calculations C.3 -. Swale Calculations APPENDIX D - Referenced Materials APPENDIX E — Drainage Exhibits U360 DminapReport-Final.doc AUNITED CIVIL Design Group VICINITY MAP Drainage Report Platte River Power Authority HQ Campus Fort Collins, CO SCALE: 1"=400' w TLD COURT O a PROJECT SITE LL Q � a c O Z � O w Z Z m w m HORSETOOTH ROAD oup � 0 III U16014-DminageRepor[-FinalAm fZ„ UNITED CIVIL Drainage Report Design Group LL Platte River Power Authority HQ Campus Fort Collins, CO I. General Location and Description A. Location The Platte River Power Authority Headquarters Campus (referred herein as "the site" or "the Campus") is a parcel of land situated in the Southeast Quarter of Section 30, Township 7 North, Range 68 West of the 6th Principal Meridian to the City of Fort Collins, Larimer County, Colorado. More specifically, the site is located at the northwest corner of Horsetooth Road and Timberline Road and is bounded by East Horsetooth Road to the south, Timberline Road to the east; existing commercial property and Danfield Court to the north, and Union Pacific Railroad right-of-way to the west. B. Description of Property The campus has an existing platted area of 16.7-acres and has acted as the headquarters for Platte River Power Authority since it was first constructed in the late 1970s. ■ . The following is a summary of the existing conditions: Ground Cover - The site currently exists as commercial property and is currently covered with various buildings, pavements and open areas. Grades — The majority of the site slopes towards one of three (3) drainage outfalls. In general, the slopes within each outfall basin range between 0 to 5 percent; with some landscaped berm areas reaching near'20%. ' Soil Type - According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey, the site consists of Nunn clay loam (Hydrologic Soil Group Q. ' Utilities — The campus includes an extensive network of existing utilities including mains and services for water, sanitary sewer, natural gas, electric, telephone and data lines. These mains and services are located within the property limits of the campus along with mains located within the rights -of - ways for Horsetooth Road, Timberline Road and Danfield Court. Detention Ponds and Storm Sewer — The campus currently has three (3) drainage outfails available to accept stormwater flows from the site. These include the existing wet pond which currently acts as an irrigation and ' stormwater retention facility for the campus, an existing 12-inch storm sewer located at the east side of the campus along Timberline Road, and the curb and gutter at the Danfield Court cul-de-sac. There are also two (2) ' other internal detention areas that drain to the 12-inch storm sewer outfall. The campus also has limited internal storm drains varying in size from flinch 1 U16614-Dmin4gegeport41na1.dm UNITED CIVIL Drainage Report \\ Design Group Platte River Power Authority HQCampus Fort Collins, CO to 15-inch. Of note, there is an existing storm inlet and drain located on the north side of Horsetooth Road that collects stormwater from the roadway and conveys it into the existing wet pond on the south side of the property. This existing system will be required to be maintained and/or replaced with the construction of the proposed project. Drainageways — No known externally owned drainageways currently exist Within the proposed development limits. Irrigation - City records indicate that there is an existing irrigation pipe located along the southern property boundary, running from west to east. Only portions of this irrigation system have been found or identified with Utility locates or site survey but from the information available it is believed that this system consists of a 20-inch concrete pipe that is located just north of the existing curb and gutter along Horsetooth Road. The existing onsite wet Pond Al also serves as an irrigation system and is supplied by an existing irrigation well located on the campus. r F/oodplains — The campus is not located within either a City or FEMA floodplain. C. Description of Development The planned campus redevelopment is planned to be constructed in phases. Ultimately, the campus redevelopment will consist of the following improvements: o The demolition of most of the existing buildings and much of the existing pavements throughout the campus.. o The construction of seven (7) proposed commercial buildings including r the main headquarters building and various other support buildings. o The construction of an internal roadway network with associated parking areas. o The construction of utilities in support of the campus including sanitary, water and storm drainage. o The construction of detention and water quality facilities located throughout the site with the main detention area located in the northeast portion of the site. ro The reconfiguration and relining of the existing wet pond. r 2 U36014DnMegeRepott-Flnal.dac UNITED CIVIL Design Group II. Drainage Basins and Sub -Basins A. Major Basin Description Drainage Report Platte River Power Authorl* HQ Campus Fort Collins, CO The site is located within the Foothills drainage basin within the City of Fort Collins Master Drainage Plan. Stormwater from this basin adjacent to the site is collected within streets and storm sewer systems and ultimately discharged into the Fossil Creek Reservoir Inlet Ditch. B. sub -Basin Description Historically, the property has been utilized as the main headquarters for Platte River Power Authority. The campus has grown over the decades but is currently largely developed containing a variety of existing buildings, utility infrastructure systems and open spaces. Stormwater from the campus is collected in one of three (3) basins that either convey water after detention to public infrastructure or retain the stormwater onsite. The proposed project will maintain the historic drainage patterns to the extent feasible, but will eliminate the stormwater retention aspect of the site and reroute that stormwater to the main detention facility to be provided on the site. III. Drainage Design Criteria A. Regulations The design criteria for this study are directly from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards Manual and the Urban Storm Drainage Criteria Manuals Volumes 2, and 3 (referred to herein as USDCM. B. Directly Connected Impervious Area (DCIA) With the adoption of the USDCM, the City has also adopted the "Four Step Process" that is recommended in Volume-3 of the USDCM in selecting structural BMPs for the redeveloping urban areas. The following portions of this summary describe each step and how it has been utilized for this project: Step 1— Employ Runoff Reduction Practices The objective of this step is to reduce runoff peaks and volumes and to employ the technique of "minimizing directly connected impervious areas" (MDCIA). This project accomplishes this by: e Routing the roof and pavement flows through bioswales, underground water quality treatment/infiltration facilities and vegetated swales to increase time of concentration, promote infiltration and provide water quality. 1 3 U16010.0minagelkeport•Flnal.dot 0 UNITED CIVIL Design Group , Drainage Report Platte River Power Authority HQ Campus Fort Collins, CO Step 2 — Provide Water Quality Capture Volume (WQCV) The objective of providing WQCV is to reduce the sediment load and other pollutants that exit the site. For this project WQCV is provided within underground treatment facilities and a campus water quality pond. Step 3 — Stabilize. Drainageways The site is not adjacent or near a major drainageway; however, this project will pay stormwater development and stormwater utility fees which the City uses, in part, to maintain the stability of the City drainageway systems. Step 4 — Consider Need for Site Specific and Source Control BMPs Site specific and source control BMPs are generally considered for large industrial and commercial sites. The redevelopment of the existing campus will include multiple site specific and source controls, including: • Covered storage areas for vehicles and materials • A warehouse for materials storage • A vehicular maintenance building with appropriate internal waste collection systems • Dedicated maintenance personnel providing landscape maintenance and snow and ice management C. Development Criteria Reference and Constraints The campus has most recently been included within the Drainage Study entitled, "Platte River Power Authority Maintenance Facility", prepared by RBD ' Engineering Consultants Inc:, and. dated March 1984. With the proposed complete redevelopment of the site and the age of the previous studies, this report relies very little on previous drainage information and studies prepared for the site. Four (4) drainage constraints for the campus have been identified and include the following: Existing Storm Outfall The existing 12-inch storm sewer outfall for the site conveys stormwater north down Timberline Road. Utilizing invert and hydraulic grade line information provided within the construction plans entitled, "Collindale Industrial Park Storm Sewer Extension", prepared byMeline & Irelan Consulting Engineers and dated February 1995, the existing system has been analyzed to determine the maximum allowable release rate from the campus to. this existing 12-inch outfall. Refer to Appendix C for the hydraulic analysis of the existing storm drain and Appendix D for the information used to create the hydraulic model. U16M4-Ora1nspRepo-Flnaldac AUNITED CD CIVIL IL Drainage Report -, Design Group LLc Platte River Power Mt1iddlyHQCanipus Fort Collins, CO Utilizing the mentioned information, it was determined that the release rate from the main detention area will be limited to 3.15 cfs. Danfeld Court Outfall 1 Storm sewer does not exist at the west end of Danfield Court; therefore, any drainage outfall at the north property line will be required to tie into the curb and gutter of the street or construct offsite storm sewer. The current design does not include offsite storm.sewer and the elevation of the existing curb and gutter in relation to site grades limits the feasibility of providing a significant amount of detention or water quality. To limit the impact of these constraints, the design proposes to maintain the existing parking_ lot with its' current parking lot detention system. Per information provided by City personnel, maintaining 1 the existing parking lot and detention system will be acceptable with the condition that no new impervious area is added to this existing outfall and only minor improvements are made to the existing parking area. Horsetooth Road Drainage Approximately 1-acre of Horsetooth Road drains to an existing inlet located Immediately west of the south entrance to the existing site. Drainage collected via the existing inlet is conveyed to the existing wet pond and retained onsite. The proposed design will alter the design of this existing system but will be ' required to collect, treat, detain, and convey the Horsetooth Road runoff through the proposed redeveloped campus. Existing Offsite Storm Sewer The existing property north of the main campus (formerly the "LSI property") has existing storm sewer along the west and south perimeters of that property. 1 Documentation of the design of these storm sewers is not available; therefore, it -- has been :assumed that the offsite system has only been designed for the ' existing property and impervious areas that currently drain to the existing storm inlets. The proposed design will be required to limit the area draining to the offsite storm sewer system and ensure that existing flowrates to the system are not exceeded. In addition, Platte River Power Authority and the offsite property owner are preparing an agreement to allow Platte River Power Authority property that has historically flowed to this offsite storm sewer to continue to do so. D. Hydrological Criteria In accordance with the Fort Collins policy, a minor and major storm for the Fort Collins area is identified as the 2-year and 100-year storms, respectively. A major storm for the Fort Collins area has a recurrence interval of 100 years and has a peak intensity of 9.95 in/hr. t5 u16014-DminageRepp-Flnal.dnc A-N UNITED CIVIL Design Group ,c 1 IV Drainage Report Platte River Power Authority HQ Campus Fort Collins, CO These storms have been used as a basis for planning and system design. The peak flow rates for design points have been calculated based on the Rational Method as described in the USDCM with storm duration set equal to the time of concentration for each sub -basin. This method was used to analyze the developed runoff from the 2-year (minor) and the 100-year (major) storm events. The Rational Method is widely accepted for drainage design involving small drainage areas (less than 160 acres) and short time of concentrations. The Rational Method is ideal for storm sewer sizing and small detention pond sizing (for tributary areas no larger than 9.0 to 160 acres). Runoff coefficients were assumed based on impervious area and soil type and are given in Appendices. E. Hydraulic Criteria The redeveloped campus will convey runoff to the proposed pond(s) via swales, gutters, concrete pans; and pipes. The FCSCM and USDCM were referenced for all hydraulic calculations. In addition, the following computer programs were utilized: • Hydraflow Storm Sewers Extension for AutoCAD Civil 3D • Hydraflow Express Extension for AutoCAD Civil3D • UD-Inlet by UDFCD F. Floodplain Regulations The campus is not located within either a City or FEMA floodplain. G. Modifications of Criteria The drive lane that extends south onto the property from Danfield Court is being regraded with this project. As such, water quality treatment is typically required. Due to the small area and the unchanging imperviousness of the area, the project has been granted a variance to criteria to allow the continued drainage in its' current configuration without water quality treatment.. Drainage Facility Design A. General Concept The project includes the redevelopment of a vast majority of the existing campus including the headquarters (HQ) building, support buildings and supporting roadway, parking and utility infrastructure. In general, the site is being graded to maintain existing drainage patterns, where feasible, and will ' collect stormwater runoff via swales, pans and storm sewer and direct them to the proposed detention and water quality pond located at the east side of the 6 U16014-0m1ne6eReport-F1ne1.doc A ,, UNITED CIVIL Design Group LLc Drainage Report Platte Rhrer Power Authority HQ Campus Fort Collins, CO site. The pond will discharge to the existing 12-inch storm sewer located along the west edge of Timberline Road. All referenced tables, charts, formulas, etc. are included in the Appendices. The area, time of concentration, and runoff of each proposed sub -basin is summarized in Appendix A. The project site was divided into multiple developed sub -basins as explained further below: Basin A Basin A consists of Basins Al-A33 which are designed to be collected via a series of swales, pans and storm drains that will discharge to the proposed detention Pond Al. at the east side of the property. Basin A will contain the majority of the proposed improvements and will ultimately consist, of rooftop, sidewalk, roadway, and landscaped areas. Specifics to each sub - basin within Basin A include the following: Basin Al consists of approximately 3.3 acres and includes the proposed detention Pond Al and portions of the proposed paving improvements around the HQ building. Approximately 8,500 square feet (sf of future building is also included within the hydrology and detention Pond Al calculations. A pond outlet and emergency overflow are provided at the northeast end of the pond that are directed towards Timberline Road. Refer to Appendix A for additional information. Basins A2-A5 consist of approximately 2.3 acres and includes a portion of the proposed HQ and the employee parking areas for the project north of HQ. These basins are collected with proposed storm sewer and conveyed to the proposed detention pond in Basin Al. Basins A6-All consist of approximately 3.3 acres and includes the maintenance yard facility north of HQ and the employee parking areas. These basins are collected with proposed storm sewer and conveyed to the proposed detention pond in Basin Al. Basin Al2 consists of approximately 1.2 acres and includes minimal proposed improvements with this project. The area is planned for future expansion of an unknown type. For storm sewer calculations the basin has been assumed to have a percent imperviousness of 90%. Due to the unknown nature of the future improvements, Basin Al2 will be required to provide detention, water quality and LID improvements either within Basin _ Al2 or within Basin Al with the future improvements. Refer to Appendix A for additional information. 1 1 7 u16014-DminnpReportF1nald)c ' UNITED CIVIL Drainage Report ' Design Group LL� Platte River Power Authority NQ Campus Fort Collins, CO Basin A13 consists of approximately 0.3 acres and includes the southern ' portion of the HQ building. The basin will be collected with a proposed roof drain system and conveyed to the detention pond in Basin Al.. Basing Basin 8 includes Basins Bl-B2 which consist of approximately 1..9 acres south of HQ and will include the proposed visitor parking area and landscaping. The basins are designed to be collected via a bioswale and storm drain that will discharge to the proposed detention pond in Basin Al. Approximately ' 10,000 (sf) of future paving is also included within the hydrology and detention Pond Cl calculations to accommodate for future visitor parking on the west end of Basin B2. Refer to Appendix A for additional information. Basin C Basin C includes Basin Cl which consists of approximately 1.3 acres south HQ and primarily includes the proposed wet Pond C1 and landscaping. Detention will be provided for Basin C1 over the permanent watersurface,of the proposed wet pond. A pond outlet and emergency overflow are provided at the east end of the pond that are directed towards Basin Al.. Offsite Basins The site includes Hive (5) existing offsite basins that are being maintained with the proposed redevelopment. Specifics to each offsite basin include the following: Basin OSl consists of approximately 0.7 acres of onsite property that drains offsite towards the north and east ultimately draining to Timberline Road, The area of this basin has increased from historic conditions but due to the removal of pavement area within the basin the percent -imperviousness has been reduced. Ultimately, the runoff generated from this basin has increased slightly with the proposed conditions (approximately 0.5 cfs in the 100-year event); however, the additional flow is not anticipated to negatively impact the street capacity of Timberline Road or downstream infrastructure. Basin OS2 consists of approximately 1.1 acres of Horsetooth Road and onsite ' property that drain to an existing inlet located just west of the Horsetooth Road entrance into the property. Drainage from this inlet is currently conveyed into the existing wet pond located south of HQ. The redevelopment is raising the permanent water surface of the wet pond by approximately 3-feet; therefore, Basin OS2 will be collected with a proposed storm drain system and routed around the proposed wet pond to the detention pond in Basin Al where flows from the basin will be treated and detained prior to being released from the pond. 8 U16010-DminegeReport•Flnel.doc Ak „ UNITED CIVIL Design Group Drainage Report Platte River Power Authority HQ Campus Fort Collins, CO Basin OS3 consists of approximately 0.5 acres of onsite property that drains offsite to the adjacent commercial property east and north of the redevelopment (formerly the "LSI property"). This basin was originally owned by, and was designed to drain towards, the offsite property but has been recently purchased by Platte River Power Authority. In the existing conditions, Basin OS3 includes approximately 2.2 acres or property. The proposed redevelopment alters the drainage patterns to minimize the size of Basin OS3; and therefore, the amount of drainage that flows offsite. Much Of the existing basin is now included within the onsite Basins A7-A11. Refer to the Drainage Plans and Appendix A for additional information. in addition, note that Platte River Power Authority and the offsite property owner are preparing an agreement to allow Platte River Power Authority property that has historically flowed offsite to continue to do so. Basin CS4 consists of approximately 1.3 acres of onsite property that drains to Danfield Court. The basin currently exists as a parking lot that includes a small amount of parking lot detention prior to being released to Danfield Court. The existing outlet structure consists of curb cut with a single B-inch outlet pipe. This existing parking lot is remaining largely unmodified with the proposed redevelopment; therefore, per communications with City personnel, no drainage improvements are beingrnade to the basin. Basins OS5 consists of approximately 0.5 acres of landscaped area that historically drains west offsite and onto Union Pacific Railroad property. The proposed redevelopment is proposing to maintain the existing drainage patterns, size and percent imperviousness of this basin. B. Specific Details Detention The proposed redevelopment includes two (2) extended detention ponds for the proposed improvements. These ponds are located within Basins Al and CS and are shown within this report as Pond Al and Pond C1. Pond Al includes detention and water quality for all of Basins A, B and OS2. The release rate from the pond is limited by the existing'12-inchstorm sewer outfall for the site which conveys stormwater north down Timberline Road. As previously mentioned, the release rate from Pond Al was determined to be 3.15 cfs by analyzing the existing 12-inch storm sewer system. Refer to Appendices C and D for additional information. Also, note that neither detention or water quality are provided for the future conditions of basin A32. Due to the unknown nature of the future improvements, Basin Al2 will be required to provide detention, water quality and LID improvements 9 u16014-Dra1nageRep"rnr1na1.d= AUNITED CIVIL \ Design Group ,. Drainage Report Platte River Power Authority HQ Campus Fort Collins, CO either within Basin Al2 or within Basin Al with the future improvements. Refer to Appendix A for additional Information.. A pond outlet structure and emergency overflow are at the northeast end of the pond that are directed towards Timberline Road. Pond Cl includes only Basin Cl and will provide detention over the permanent water surface of the proposed wet pond. The pond is designed to require less than 6-inches of ponding from the permanent water surface to the 100-year water surface. A pond outlet and emergency overflow are provided at the. east end of the pond that are directed towards Basin Al. A summary of both detention ponds are as follows: Pond Detention Detention 100-year Pond WQCV WQCV Water Top of Designation Volume volume WSU Release Required Provided Quality Pond Required Provided Rate (ac-ft) (ac-ft) WSEL Elevation (ac-ft) (ac-ft) (cfs) Pond Al 2.37 2.89 4952.25 3.15 0.18 0.24 4949.50 4953.25 Pond C1 0.30 0.35 4955.50 0.50 0.01 0.02 4955.03 4956.50 Stormwater Quality Several long-term stormwater quality measures have been selected for the site that will provide treatment of stormwater prior to it being discharged from the site. For this project the following measures have been included: Grass Swales The soft bottom/overbank areas of the swales allow for infiltration to occur as well as including a flow path across a vegetated surface slowing the conveyance rate of storm water runoff while also removing sediment and other pollutants. These have been utilized to convey and treat stormwater prior to entering the storm sewer systems or Pond Al. Grass Open Areas/Buffers — Grass open areas and/or grass buffers allow 1 for infiltration to occur as well as including a flow path across a vegetated surface slowing the conveyance rate of storm water runoff while also removing sediment and other pollutants. These have been utilized to convey and treat stormwater prior to entering the storm sewer systems or Ponds Al and Cl. ' Bioswales — Bioswales remove sediment and pollution from stormwater runoff via infiltration through an engineered sand media. This slows the conveyance.rate of storm water runoff, reduces runoff and provides a flow path across a vegetated surface. These have been utilized to convey and treat stormwater prior to entering the storm sewer system and Pond Al. 10 A6614-Drainagaftport•nnaLmx f�„ UNITED CIVIL �\ Design Group «< Drainage Report Platte River Power Authority HQ Campus Fort Collins, CO Underground Water Quality — Underground water quality diverts storm water runoff during the water quality event and treats the flows through infiltration prior to being collected within an underdrain system. This provides for the removal of sediment and other pollutants from the runoff while also promoting infiltration. Underground water quality chambers have been utilized to collect and treat storm water runoff prior to it entering Pond Al. Wet Pond (Pond Cl) — A wet pond provides water quality by acting as a permanent. sedimentation basin which collects and stores the runoff prior to discharging to the pond outlet structure. This removes sediment from the flows entirely which settle to the bottom of the pond. The existing onsite wet pond is being redeveloped as part of this project and will collect and treat only those areas that drain immediately to the wet pond itself. ' Extended Detention Basin — Extended detention basins, in conjunction with the use of a water quality plate, collect, store and slowly release minor storm events. This allows runoff to pond, infiltrate into the grass bottom of the pond, and settle out particulates prior to being discharged from the site. An extended detention basin has been selected as a highly effective last treatment option prior to discharging runoff from the site. Low Impact Development a1D) In December of 2015, Fort Collins City Council adopted the revised Low Impact Development (LID) policy and criteria which requires developments within City limits to meet certain enhanced stormwater treatment requirements in addition to more standard treatment techniques. The proposed development will be required to meet the newly adopted LID criteria which requires the following": • Treat no less than 75% of any newly added impervious area using_ one or a combination of LID techniques. • Treat no less than 50% of any newly added impervious area using one or a combination of LID techniques when at least 25% of any newly added pavement is provided with permeable pavement. The following measures are being implemented with this proposed development: Underground Water Quality — Basins A3-All(with 148,620 sf of proposed impervious area) will be routed through an underground water quality system located north of HQ. The underground water quality system will have an overall volume of approximately 3,782 cubic feet which exceeds the minimum design requirements for the area. Refer to Appendix B for additional information. 11 U1601MDra1negeReport-F1m1.d= UNITED CIVIL Drainage Report Design Group uc Platte River Power Authority HQCarnpus Fort Collins, CO Bioswales Basins 131-132, with 27,050 sf of proposed impervious area, will be routed through a bioswale with a surface area of 3,035 sf (an approximate run-on rate, pavement to bioswale, of 9:1). Basin B-2 will include future parking area of approximately 10,000.sf. Once the future parking area is constructed, the bioswale will also require extension to provide LID treatment of the future parking lot expansion. With future construction, the, bioswale within Basins B1 and B2 will treat approximately 37,050 sf of impervious area. Wet Pond — Basin C1(with 8,650 sf of proposed impervious area) will drain directly into the wet pond within the basin. The basin is approximately 1..23 acres in size and contains largely either water or pervious surface area (approximately 85% of the basin); therefore, through communications with the City, the wet pond will be allowed to act as a permanent 1 sedimentation basin which will remove sediment and pollution from storm water runoff prior to releasing it downstream. Note that this is an acceptable LID treatment for this project only due to the small amount of impervious area draining to the pond. Future LID Treatment —At the end of construction, Basin Al2 will be left as open space but is planned for future expansion. With the future -- development of the basin, future impervious area will be required to be treated to maintain a total treatment for the campus of 75%. ' In total, the development is proposing to collect and treat 196,550 sf (75%) of the overall 263,801 sf of impervious area developed (including both proposed and future developments) with this project. in addition, the site is also being designed with other various open landscaped areas and ' vegetated swales and buffers to provide additional water quality in addition to the areas being treated with LID techniques. ' Standard Operating Procedures (SOPS) In order for physical stormwater Best Management Practices (BMPs) to be effective, proper maintenance is essential. Maintenance includes both t routinely scheduled activities, as well as non -routine repairs that may be required after large storms, or as a result of other unforeseen problems.. Standard Operating Procedures should clearly identify BMP maintenance ' responsibility. BMP maintenance is typically the responsibility of the entity owning the BMP. Identifying who 1s responsible for maintenance of BMPs and ensuring that an adequate budget is allocated for maintenance is critical to the long-term 12 U16014-DmInageRepar4FlnaLdw UNITED CIVIL Design Group LLc Drainage Report Platte fter Power Authority HQ Campus Fort Collins, CO success of BMPs. Maintenance.responsibility may be assigned either publicly or privately. For this project, the privately owned BMPs including vegetative swales and bioswales, underground water quality, and the extended detention ponds are to be maintained by the property owner. Storm Sewers Multiple storm sewer systems are being proposed with the redevelopment of the campus that include storm.sewer mains, roof drains and underdrains. All storm sewer on the property will be private. The system that collects and conveys the public storm water from Horsetooth Road Will be included within a drainage easement._ Due to the complexities of the proposed site and constraints of the existing site, all storm sewer mains and roof drains are sized to accommodate the 100-year storm event. Refer to Appendix C for more information. Wet Pond As previously mentioned, the existing wet pond on the site is also being redeveloped/reconfigured with the project. As part of the reconfiguration, the following design elements are being provided: • A 12-foot depth is being provided in the pond to allow for increased water quality and to allow for the use of a geothermal mechanical system for HQ, Related to these elements, the elevation difference between the finished floor of HQ and the permanent water surface of the pond has been minimized to accommodate a deeper pond while minimizing the impacts to existing groundwater. The existing pond sits approximately 6-feet below the existing building. The design has set the proposed permanent lake water surface 3-feet below the proposed finished floor. • The amount of surface drainage conveyed to the pond is being minimized to limit the amount of storage required above the permanent Water surface due to storm runoff. e The pond is being provided with an emergency overflow and outlet. Currently the pond does not have an emergency overflow or any means of draining the lake other than through irrigation. The proposed design has located both an emergency overflow and outlet structure on the east side of the lake. Phasing As mentioned previously, the redevelopment of the campus will be accomplished in phases due to the requirement that the existing Engineering/Operations (E/0) and Headquarters (HQ) buildings remain fully foperational during the construction of the proposed HQ building. Only when the proposed HQ is fully operational and in use will the existing E/O and HQ 13 U16014.Dm1napReport-F1neLdm UNITED I CD CIVIL Drainage Report Design Group LLc Plane River Power AuthorRyHQCampus Fort Collins, CO buildings be demolished. Due to this, it is currently expected that two major 1 phases of construction will be required.. The initial phase of construction will construct much of the proposed drainage infrastructure apart from the southern portion of Pond Al as this is where the existing HQ building is located. The final phase of construction will construct the remainder of Pond Al. Through communication with City personnel, it is currently anticipated that the Stormwater Department will issue a full CO for the proposed HQ building with an escrow provision as required. 1 14 U16014Dm1negeRePOn-Find:d= UNITED CIVIL l Design Group - Drainage Report Platte River Power Authority HQ Campus Fort Collins, CO Drainage Summaries The following is a basin summary table for existing and proposed conditions: Basin Design Pt. Existing Area Basins %I Runoff Coefficients Peak Discharge C2 Ciao Q2 Q1W acre Cfs cfs Exl EX1 3.75 48.6% 0.57 0.71 6.10 26.62 Ex2 Ex2 2.38 32.3% OA4 0.55 2.07 9.04 EX3 Ex3 2.19 80.4% 0.82 1.00 5.10 21.75 Ex4 Ex4 2.33 18.9% 0.34 0.42 1.68 7.33 Ex5 Ex5 1.35 12.5% 0.28 0.35 0.81 3.53 OS-1 05-1 0.31 20.5% 0.35 0.43 0.30 1.32 05-2A OS-2A 0.33 26.6% 0.39 0.49 0.37 1.61 OS-213 OS-28 0.93 80.2% 0.81 1.00 2.00 8,62 05-3 OS-3 2.22 20.3% 0.34 0.43 1.46 6.39 OS-4 OS-4 1.28 73.1% 0.75 0.93 2.73 11.91 05-5 OS-5 0.54 2.0% 0.20 0.25 0.24 1.05 Totals 22.87 99.18 Proposed Basins Basin Design Pt. Area %I Runoff Coeffldents Peak Discharge C2 Ciao Q Qiw acre cfs CIS A-1 A-1 3.34 15.6% 0.32 0.39 2.03 8.85 A-2 A-2 0.91 82.3% 0.83 1.00 2.15 9.10 A-3 A-3 0.37 90.0% 0.95 1.00 1.01 3.71 A-4 A-4 0.57 86.5% 0.86 1.00 1.39 5.64 A-5 A-5 0.40 84.7% 0.84 1.00 0.95 3.96 A-6 A-6 0.51 53.2% 0.64 0.80 0.93 4.05 A-7 A-7 0.32 52.7% 0.63 0.79 0.54 2.37 A-8 A-8 0.21 65.3% 0.74 0.92 0.44 1.92 A-9 A-9 0.64 89.9% 0.95 1.00 1.74 6.41 A-10 A-10 0.68 86.7% 0.92 1.00 1.78 6.74 A-11 A-11 0.97 26.7% 0.41 0.51 1.06 4.63 A-12 A-12 1.15 5.9% 0.23 0.29 0.68 2.95 A-12 (Future) A-12 (Future) 1.15 90.0% 0.87 1.00 2.86 11.43 A-13 A-13 0.26 90.0% 0.95 1.00 0.72 2.63 B-1 B-1 0.42 53.4% 0.61 0.76 0.74 3.22 8-2 B-2 1.45 43.4% 0.52 0.65 1.90 8.28 C-1 C-1 1.27 15.8% 0.32 0.40 1.15 5.01 OS-1 OS-1 0.68 2.0% 0.20 0.25 0.33 1.42 OS-2A OS-2A 0.21 2.0% 0.20 0.25 0.12 0.51 OS-28 OS-26 0.93 80.2% 0.91 1.00 2.00 8.62 OS-3 05-3 0.51 87.0% 0.87 1.00 1,25 5.05 OS-4 05-4 1.26 68.9% 0.72 0.90 2.58 11.25 06-5 05-5 0.54 2.0% 0.20 0.25 0.24 1.05 Totals 25.72 107.35 15 U1601FOralnagegepon-Final.doc 1 UNITED CIVIL Drainage Report Design Group Platte RhrerPower Authority HQCampus Fort Collins, CO V. Sediment/Erosion Control Erosion control, both temporary and permanent, is a vital part of any development project. For this project, the site disturbance will be over 1-acre; therefore, a comprehensive Erosion Control Report has been completed under a separate cover. The Erosion Control Report will be utilized for site construction activities and will be prepared in accordance with City and Colorado Department of Public Health and Environment requirements for use as the Stormwater Management Plan for the project. VI. Conclusions A. Compliance with Standards Storm drainage designs for the Platte River Power Authority Headquarters campus have typically followed the guidelines provided by the Fort Collins Stormwater Criteria Manual and/or the Urban Storm Drainage. Criteria Manual. In addition, the site drainage has been designed to meet City requirements in 1 terms of detention, water quality and Low Impact Development standards. B. Drainage Concept The drainage system has been designed to convey the runoff to the designated design points and the existing public infrastructure in an effective, safe manner. No negative impacts are anticipated to the City of Fort Collins Master Drainage Plan or to downstream properties or infrastructure due to the proposed improvements. C. Stormwater Quality Several long-term stonmwater quality measures have been selected for the site that will provide treatment of stormwater prior it to being discharged from the site. For this site this includes grass swales, grass open areas/buffers, a bioswale, underground water quality and an extended detention basin. 16 u16014-D lnegeaepcn-FinalA < 1 UNITED CIVIL Design Group ,< tVII. References Drainage Report Platte River Power Authority HQ Campus Fort Collins, CO 1 1. Fort Collins Stormwater Criteria Manual. City of Fort Collins, as adopted in 2031. 2. Urban Storm Drainage Criteria Manual. Urban Drainage and Flood Control District, Wright Water Engineers, Inc., Denver, Colorado, Revised April 2008. 3. Larimer County Urban Area Street Standards. Larimer County, Colorado, Repealed and Reenacted, Effective April 1, 2007. 4. Geotechnical Engineering Report — PRPA New Headquarters Campus. Terracon Consultants, Inc., October30, 2017. S. Storm Drainage Studv for Platte River Power Authority Maintenance Facility. RBD Engineering Consultants, March 1984. 6. Coliindale Industrial Park Storm Sewer Extension Construction Plans. Meline & 1 Irelan, Inc., Revised May 1995. 7. Collindale Industrial Park Construction Plans, James H. Stewart & Associates, Revised October 1978. 8. Natural Resources Conservation Service Web Soil Survey at websoilsurvey.nres.usda.gov/app 17 U160140ralnageReparFFinaUm No Text � I | 66... ! &!!!« &!!&!! ! !|_ , �. -,�. l! ; | |mw�N. ;�� . : � | .�.. | ! ;;! ! ) { ! 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E!§B!§ !| !|!!§ !!|§!! { §]I;; ! ::_ !, _::__, - !!!§!!!§!!!!B!§ i.. §B ...... || ;]|;I; | , , APPENDIX B Detention and Water Quality Calculations Dention Pond Volume (FAA Method) UNITED CIVIL Platte River Power Authority Campus, Fort Collins, CO Design Group POND e POND Al 100 Year Storm into Detention Facility A,. 581A90 spuare fret Aren - 13.34 apes Cim - 071 D'm = 58.44 ds (Total flows from Basins and BI Release Rate Out of Pond Om, 3.15 As Unit Fbw = 0.24 pfV.. Tr 15.8 minutes Notes: 1. Release Rate limited by the a lging 12" outfall opacity In Timbenine Road. 2. Pond area Includes all of Basins A, Band 0i2 but excludes 'BaslnA-12(Futurel" Detention Volume Calculations Rainfall Duration IT) .in Rainfall Intemslty lQ irlhr Inflow Rate Oo-s cy Inflow Volume V;=IO,.'T'60) nr Adjustment Factor m• O.S(1 a 1jr) Avenge Outflow Rate O•,• m'0,,, 42s Outflow Volume V,O„'T-60 jf' Repuired Storage Volume V,=V, V, Ra 5 9.95 94.7 28.418 1.00 3.15 945 27,473 W 7.72 73.5 44,09E 1.00 3.15 1,890 42,20E 15 6.52 62.1 55,866 1.00 3.15 2,835 53,031 20 5.60 53.3 63.977 1.00 3.15 3,780 60,197 25 4.98 47A 71.117 1.00 3.15 4,725 66,392 30 4.52 43.0 7U58 1.00 3.15 5,670 71.788 35 4.08 MS 81,571 Lm 3.15 61615 74.956 40 3.74 35.6 85,455 IN 3.15 7,560 77,995 45 3.46 32.9 88,939 1.00 9.15 8,505 80,434 50 3.23 30.8 92,253 1.00 3.15 9,450 82.803 55 3.03 28.8 95,194 I'm 3.15 10,395 84,799 60 2.66 27.2 98.022 1.W 3.15 31,340 86.682 70 2.59 24.7 103,563 I'm 3.15 13,230 90,333 Al 2.38 2217 10$761 1A0 3.35 15,120 93,641 90 2.21 21.0 113,616 1.00 3.15 17,010 96,606 100 2116 19.6 117,672 1.00 3.15 181900 99,772 110 1.94 I8.5 121,899 1.00 3.15 20,790 101,109 120 1'" 17.5 126.126 1.00 3.15 22,680 303,446 Required Detention Volume Vim = 103,446 cubicfeet Vim = 2.37 acre-ft v1U16014 PRPAC=pP lReponslDrolnapelColalations1U16014-Drain Cola.xRm 1 Dention Pond Volume (FAA Method) �e UNITED CIVIL Platte River Power Authority Campus, Fort Collins, CO / \ \ Design Group ' POND a POND 100 Year Storm Into Detention Facility ' A, 55,258 s9uam Feet A, - 1.22 ave. Cen = 1.00 ' Q ue = 5.01 cis (total flows from Basin CI Release Rate Out of pond 0.50 eft unit Flow = 0.39 efs/ane T, = 5.0 minutes Notes 1, Release Rate limited to maximize detention volume but keep maximum pending to less than 6". 2. For Pond C Calculations, Ce, has been assumed to be 1. W assuming that he Band water sudsce is at the maximum elevation and all water that falls on the wet pond will pass through the outlet Detention Volume Calculatlons Rainfall Duration ITl .in Rainfall Inenalty(1) Ini Inflow Rate Q-IC'm'A.-I Cfs Inflow Volume Vi>tOm'T'60) jt° Adjustment Factor ew 0.5(1 x T,/T) Average Outflow Rate Q..=m=Qaa c6 Outflow Volume V=C,,'T'60 W Re9ulred Storage Volume Ve VV. h' 5 9.95 12.6 3,787 1.00 0.50 150 3,637 10 7.72 9.8 5,976 IN 0.50 300 5,596 15 6.52 113 7,444 1.00 0,50 450 6,9B4 20 5.60 7.1 9.525 1.00 0.50 6o0 2,925 25 4,98 6.3 9,476 1.00 0.50 250 8,226 30 4.52 5.2 10,321 1.00 0.50 900 9,421 35 4.08 5.2 10,g69 IN 0.S0 1,050 9,819 40 3.74 4.2 11,386 3M 0.50 1,200 10,186 45 3.46 4.4 11,851 1.00 0.50 1,350 10,501 50 3.23 4.1 12,292 1.00 0.50 1,500 10,792 55 3.03 3.8 12,684 1.00 0.50 1,65D 11,034 60 2.86 3.6 13,061 1.00 0.50 1,800 11,261 TO 2.59 3.3 13,799 1.00 0.50 2,100 11,699 80 2.39 3.0 14,492 1.00 0.50 2,400 12,092 90 2.21 2.8 15,139 1.00 0.50 2.200 12,439 too 2.06 2.6 15,679 1.00 0.50 3.000 12,679 110 1.94 2.5 16,243 100 0.50 3.300 12.943 120 184 2.3 16,806 1.00 0.50 316M 13.206 Reputed Detention Volume V,. = 13,206 cubefeet Visa = 0.30 acre-ft Date 4/9/2018 P'IU36W4, PRPa Campus(Report5(DMlnVelCOICUIONOnSIUl6014�OMIn COla.xhm I 1 STAGE STORAGE TABLE.- POND Al NORTH AREA . ft. OEFRN ft AVG END INC. VOL. W. ft. AVG END ._ TOTAL VOL. = ft. CONIC _. INC. VOL. eu. fl CONIC TOTAL VOL. cu. tL - 4.90-?W 137.66 WA WA 0.00 WA 0.00 4.948.400 _ 1,084.72 02DO 123M 123.23 10802 108A2- 4,948.600 3.133.01 02DD 4228E 848.09 405.39 513.41 4,W8.800 8,000.79 02M 91347 1459.58 898.09 _1411.50 4.949.0D0 0,570.39 020D 1557.12 3016.88 1543.30 2954.n 4,9492D0 13,103.81 0.200 2276.42 5293.10 2206.75 5221.51 _ 4.949A00 18,829.9E 0200 3002.38 8296.46 2995.01 8216.55 4,949.600 20.811A0 0.200 3764.14 12059.62 3757.10 11973.85 a949.800 24.268.D8 0.200 4500.75 16566.38 450235 16476.00 4.960.000 27A57A0 0.200 51f1.37 2173713 5168.05 216N.07 4.950200 30.53ae9 0.200 5799.75 27537.48 5797.02 27441.08 4,950.490 33.057.44 0.200 698273 3=21 8361A9 33W2.12 4960.11M 34.901.34 0.2D0 6798.88 40M..09 BM07 40600.19 4,960A00 98,320.28 0200 712218 47121.28 7121.89 47721.88 4,851.000 37,381.81 0200 _. _. 7371.79 6510245 7370.93 _ 56082.81 4,951200 38.350.30 02M 7574.80 U767M 7574AD 621167.41 4,951.400 39.341.32 0260 neg." 70637.02 7719.58 70436.97 4.851.600 40,353.45 02M 796948 78508.49 7959.26 78406:23 4,951.800 41.3E7.19 0.200 8115.06 88881.56 8174.84 88581.07 4.882000 42.672.11 0.200 $396.90 95078.55 8306.72 9477.79 aas2:2aD 43,BB1.n 0.200 8648.45 10372A00 8646.12 103023.91 4,952.400 45,220Af 0200 8911.20 112638.27 8910.93 112534.84 STAGE STORAGE TABLE - POND Al SOUTH Ft FV AREA . R DEPTH R AVG END INC. VOL a. ft. AVG END TOTAL VOL a. R CONIC INC. VOL cu. R. CONIC TOTAL VOL. cu. fL 4.949.000 1.34 WA WA 0.00 WA 0.00 4,949.200 237.70 0.200 23.91 23.91 17.13 17.13 4,949AD0 1.075.11D 0.200 131.35 155.27 121.29 138.41 4,949.600 2.606.69 0.200 355.47 613.74 348A1 486.92 4,949.600 4,404.37 0.200 091.33 120.06 682.5D 1168.42 4,050.000 6=35 0.200- -106877 MM83 1060.38 2220AD 4,960200 7,63m 0.200 1389.10 3869.93 13116.79 0816.1 4,950A00 8,240.94 0200 1837.86 i617.n 1656.15 52T2.14 _ 4A50.60D 10.218.26 020D 1913.98 7253.78 1914.57 718f.31 4.950AW 11A82.66 0.200 216&16 9401.94 2166,97 9354.23 4,951.000 12.66301. 0.200 2412.56 11814M 2411.W 11755.84 4,951.200 13,750.96 0.200 2541.40 14455.89 2540.05 14400.49 4,051" 14.634.70 0.2M 2838.57 17294.47 2838.12 17244.00 4,951.500 15.276.37 o200 2991.12 20285.55 2990.8E 20235.49 4,951A00 15ABA1 0200 3097.62 233MIO 3097.42 23332.91 4,952400 16,080.60 0200 31n.96 20581.06 3177.69 26510.80 4A52200 16010722 0.200 3254.80 29815.89 3254.73 297 52 4.952.400 16,85&9B 0.200 3332.62 33148A8 3332.54 33088.07 4,0.52.800 17,258.1E 0.200 3411.62 38580.00 3411.44 38509.51 4,11M.800 17,858,48 0.200 3491.47 4DD.51.e7 .3491.39 40000.90 -105,852 d Q 4952.26 4 136.451 of total volume (3.13 aaft) • 2.37 a0•R reg6lied for detention (2:69 416i1 Provided) • 0.1e aoA required for water quality (6.24 =4 provided) ---30,599 d @ 4952.25 F Stormwater Detention and Infiltration Design Data Sheet Stormwater Facility Name: Platte River Power Authority HQ Campus - Pond Al Facility Location & Jurisdiction: Fort Collins, CO user (Input) Watershed Characterlst Watershed Slope = Watershed Length -to -Width Ratio= Watershed Area= Watershed Imperviousness= Percentage Hydrologic Soil Group A = Percentage Hydrologic Soil Group B = Percentage Hydrologic Soil Groups C/D= 0.030 1.15 13.34 47.6% 0.0% 0.0% 100.0% User Input: Detention Basin Characteristics WQCV Design Drain Time = 40.00 hours After completing and printing this worksheet to a pdf, go to: hnps://mapenure.digitafdatasemices.com/avh/?viewer=cswdff. create a new stormwater facility, and attach the pdf of this worksheet to that record. Routed Horograph Results Design Storm Return Period = Two -Hour Rainfall Depth = Calculated Runoff Volume = OPTIONAL Override Runoff Volume = Inflow Hydrograph Volume = Time to Drain 97%of Inflow Volume = Time to Drain 99% of Inflow Volume = Maximum Panting Depth = Maximum Ponded Area - Maximum Volume Stored = I tSDI_Design_Dota_FC_Ralnfoll.xlsm, Design Data tr � rr WQCV 2Year 5Year 10 Year 25 Year 50 Year 100 Year 0.53 0.98 1.36 1.71 2.31 2.91 3.67 0.220 0.487 0.958 1.210 1.875 2.482 3.333 0.219 0.487 0.858 1.210 1.874 2.482 3.333 37 42 41 40 38 37 37 40 47 47 47 47 48 49 1.40 1.78 2.17 2.51 3.08 1 3.55 4.16 0.421 0.641 0.835 0.964 1.163 1.255 1.375 0.22 0.410 0,697 1,007 1.612 2.177 2.988 n acre-ft acre-ft acre-ft iaurs lours 4 acres acre-ft 415/2018, 6:14 AM Stormwater Detention and Infiltration Design Data Sheet !oD ' �100YR IN 90 --100YR OUT �50YR IN ' 80 50YR OUT I — —ISYR IN ' 70 25YR OUT IDYR IN 60 - --- 30YR OUT ' £ —SYRIN 3 w S ..... SYR OUT 40 2YR IN ' _ _ _ 2YR OUT 30 � WON IN — ' ^^^ WON OUT — - 20 ' 10 0 OS as a t 3.5 3 FC E p 2.5 0 8 2 ' 1.5 1 1 OS 1 0 0.1 ' SDI De Ign_Data_FC Ralnfall.alsm, Deslgn Data 1 TIME [hr] 10 1 10 100 DRAIN TIME [hr[ 4/5/2018, 6:14 AM I � { J r 7 a�«fl•m! !- 2 &t-..-.- ' ¥ � � \ , ! f ! k§§!§| \ ,! 53: § I 3 3�- 3 7�C E � 0 0 x Dention Pond Volume (FAA Method) /b� UNITED CIVIL Platte River Power Authority Campus, Fort Collins, CO / \ Design Group POND r r WQ Min Ch rreuteristla ' Area = 108.287 square tee- Area - 249 acres Cr = 0,51 Q,,, 2.01 ds WQ Release Rate Determined from Number of Chambers and Chamber Release Rate Qen, 0.dcre ' = unit Flow 030 30 ds/a rr 15.8 minutes Notes: 1. Release rate out of pond based on number of chambers multiplied by release rate per chamber. 2. Rainfall intensities approximated as one -hall the 2-yr peak runoff rate. 3. Cs utilized for water quality event detention calculation. Detention Volume Calculations Rainfall Duration(T) .in Rainfall intensity (1) InAr Inflow Rate Q, JC,m'Ama'I cis Inflow Volume ViyQ�*T'W) Ra Adjustment Factor m•0.5(1 a T,H) average Outflow Rate o -m'Cia "A Oudow Volume Vo Q„'T'60 /r' Required Storage Volume V,Vi V„ R' 5 1.425 1.8 542 1.00 0.75 226 316 10 1.105 1.4 "1 1.00 0.75 453 398 15 0.935 1.2 1,057 1.00 0.75 679 388 20 0.805 1.0 1,225 1.00 0.75 906 319 25 0.71S 0.9 1,360 1.00 0.75 1.132 228 30 0.650 0.9 1,483 1.00 0.75 11359 125 35 0595 017 1,558 1.00 0.75 1.585 -27 40 0.535 0.7 11628 1.00 on 1,811 -184 45 0.495 0.6 116N 1.00 0.75 21038 343 SO DAN 0.6 1,750 1.00 0.75 2,264 -535 S5 0.435 0.6 I've 1.00 015 2,491 .671 50 0.410 0.5 1.871 1.00 0.75 2,717 -1146 65 0.395 0.5 2,g04 1,00 0.75 2,944 -1,0a0 70 0.365 0.5 1,944 LOD 0.75 3,170 -1.226 75 0.345 0.4 1,968 1.00 0.75 3.396 1,428 80 0.330 0.4 2.008 1.00 0.75 3.623 -1,615 85 0,315 0.4 2,037 1.Do 0,75 3,849 1,812 90 0.305 OA 2,M 1.00 0.75 4,076 1,988 95 0.290 0.4 2096 100 0.75 4,302 -2,206 1W 0.280 OA 2.130 1.00 0.75 4.528 -2,3% 105 0.270 0.3 2,157 too, 0J5 4.755 -2,598 110 0.2W 0.3 2,176 1.00 Mn 4,991 2,806 125 0.255 0.3 2,231 1 W 0.75 5,208 2,977 120 0.245 0.3 2,236 1.W 0.75 5,434 -31198 Required Detention Volume Vlgq = 388 Cubicfeet Vspo ° 0.01 acre-h ' Date: 4/9/2018 P:1W6014 PRPAComWs(Repartsl0mino8el[olmbrlpmW16011-Drvin Cola.xam Dention Pond Volume (FAA Method) /1a1(� UNITED CIVIL Platte River Power Authority Campus, Fort Collins, CO / \ ` Dealgn Group WQ Basin Characaterlstics Area - 145,137 square liter Area - 3.33 acre: C, = OJO q u, = 3.22 ph wQ Release Rate Determined from Number of Chambers and Chamber Release Rate a., . 1,16 cfs Unif Flow • 0.35 efa/ecre Te ' 15.8 minutes "a, 1. Release rate out of pond based on number of chambers multiplied by release rate per chamber. 2. Rainfall lntensltles appra4lmated as one-half the 2,r peak moon rate. 3. Cr utllbM for water quality event detentlon calculatlon. Detention Volume Calculations Rainfall Duane nIT) .In Ralidall laterally 111 m1hr Manor Rabe QA'lCupaA l p/s Infbw Volume ViHan'T'W) hr Adluatment Factor m, 0.5(1 a Tjr) Average OuIDOW Ree 0„+m'Q_ 0 Outflow Volume V„aQ„'T'W /t. Ra4ulred Storage Volume V,V, V„ hr 5 1.425 3.3 99D 1.00 1.16 349 641 ]0 1.205 2.6 1,536 1.00 1.16 698 838 15 0.93S 2.2 1.949 1.00 1.16 1.047 902 20 aim 1.9 2,238 1.00 L36 1.396 "1 25 M715 1.7 2.484 IN 2.16 1,745 739 W 0.60 1.5 2,710 1.00 ills 2,094 616 35 0.585 1A 2,846 1.00 2.16 2,443 402 40 0.535 11 2,974 1.00 1.16 2,793 182 45 0.495 1.1 3,M SAO 1.16 3,142 46 So a" 1.2 3,197 1.00 1.16 3,491 -294 55 0A35 1.0 3.325 1.00 1.16 3.840 -515 60 0.4W 0.9 31419 1.00 1.16 4,189 -770 65 0.385 0.9 3,478 1.00 1.16 4,538 11060 70 0.30 0.8 3.551 1.00 1.16 4,887 1.336 75 0.345 0.8 3,596 1.00 1.16 5.236 -1,640 00 a" 0.9 3,669 1.00 1.16 5.585 -1,916 85 0.315 0.7 3,721 1.00 1.16 5,934 -2,213 90 0.305 0.7 3,815 1.00 1.16 6,283 2,468 95 0.290 OJ 3,829 1.00 1.16 6,632 -2,803 100 O.M 0.6 3,891 1.00 1.16 6,981 .3,090 105 0.270 0.6 3,"0 1.00 1.16 7.330 3,390 110 0.260 0.5 3,9T5 1.W Ills 7.680 -3.705 115 0.255 0.6 4,076 1.00 1.16 8.029 -3,953 120 0.245 0.6 4,D86 1.00 1.16 8.378 4,292 Required Detention Volume Vsm a 902 cubic feet Vim - 0.02 acre-ft Oahe A/9/3018 PaU16014 - PRPAC4mpm1Rrp4rtsl0ralrmpelCalml4tlonslU16011 Dmin Calcsxlsm m •=N°— r m e yy fi = i i E $ 8 E�=`d �°s88 8 �aE � o 0 i I egeeee ee -- -- --- - -N nee G !Ii Jm 4 3 d'd 5a 4" I Lol 5 \;f |;l•;! 5 inju !B | Platte River Power Authority HQ Fort Collins, Co Inlet Capacity INLET ID: Outlet Govenning Equations: Inlet rapadry equation at to. fl . iu eir mlmlot.A) Q = 3 .0 P H I .5 Where: P.2(L . W) H, depth of water above the flowllne inlet copohv e4uards, at hphernows lode catrvlatlonl: Q = 0.67 A(2gH �4'1 Where: A=open ores of the Infet Irate H = depth of water above the mntmld of the cross-sertloap) area (Al Input Parameters: Grind Custom W let Perimeter. 15.00 Open Area of Grate I1121: C% Grate Elevatlon(fr): 495oW Qryp. 3.15 Ch 411owabk Capacity: 50% Depth vs. Flow, Above Inlet A (h) weir Flow lard Flow (pra) Flow (Chi 0.00 4950.00 0.00 0.00 0.00 0.05 4950.05 0.25 3.00 0.25 0.10 4950.10 0.71 4.24 0.71 0.15 4950.15 1.31 5.19 1.31 0.20 4950.20 2.01 6.00 2.01 0.25 4950.25 2.81 6.70 2.81 017 4950.27 3.15 6.96 3.15 <-- SUU.Year Flow 0.35 4950.35 4.66 7.93 4.66 0.40 4950.40 5.69 8.48 5.69 0.45 4950.45 6.79 8.99 6.79 0.50 4950.50 7.95 9.48 7,95 0.55 4950.55 9.18 9.94 9.18 0.60 4950.60 10.46 10.39 10.39 0.65 4950.65 11.79 10.81 10.81 0.70 4950.70 13.18 11.22 11.22 0.75 4950.75 14.61 11.61 11.61 0.90 4950.80 16.10 11.99 11.99 0.85 4950.85 17.63 12.36 12.36 0.90 4950.90 19.21 12.72 12.72 0.95 4950.95 20.83 13.07 13.07 k - UNITED CML 1C1 Dc+, G'o.�o Calculations bV: NKS Dote: 41912018 P IU16014. PBPA ComWsIRep nslOralnaAelColeulatOns1U16014-Draln Cala.xlsm Platte River Power Authority HQ Inlet Capacity UNITED CIVIL Fort Collins, CO Jar Ll-,, 1, -°, lGoverning Equations: Inlet eapacurmaaHonarrow7mw.(yyelremramHpn): Q = 3.0P H Lt where: P•2(1. w) H • depth of water above the powllne hurt woman, eguanon at hlgherflows forlhre calculation): Q = 0.67 A(2gH �0.1 where A +open area of the Inlet ghee H - depth of water, above the centnud of the cross-secrlonal area (A) Input ammeters: Grate', Type Wier Perimeter'. 12.29 Open Area of Grate (ft)'. 4.09 Grate Elevatlon(ft 4955.00 Cdo 0.50 cf4 Allowable Calvet": 50% Depth vs. Flow: Above Inlet (h) (h) Weir Flow (cts) Flow (4fs) Flow (CM 000 4955.00 0.00 0.00 0.00 0.05 4955.05 0.21 2.46 0.21 0.09 4955.09 0.50 3.30 O.SO <- 100-Year Flow 0.15 4955.15 1.07 4.26 1.07 0.22 4955.22 1.93 5.18 1.93 0.25 4955.25 2.30 5.50 2.30 0.30 4955.30 3.03 6.02 3.03 0.35 4955.35 3.82 6.50 3.82 0.40 4955.40 4.66 6.95 4.66 0.45 4955.45 5.56 7.37 5.56 0.50 4955.50 6.52 7.77 6.52 0.55 4955.55 TS2 8.15 7.52 0.60 4955.60 8.57 8.51 8.51 0.65 4955.65 9.66 8.86 8.96 0.70 4955.70 10.80 9.20 9.20 0.75 4955.75 11.97 9.52 9.52 0.80 4955.80 13.19 9.83 9.83 0.95 4955.85 14.45 10.13 10.13 0.90 4955.90 15.74 10.43 10.43 0.95 4955.95 17.07 10.71 10.71 1.00 4956.00 18.44 10.99 Mira Calculations by: Nay Oare: 4/9/2028 P:IU16014-PRPACompusl6eWnSIDralnugelCalculoOo SJU36o14-Dn nCvla.abm Weir Report ' Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Pond Al - Emergency Overflow Weir ' Trapezoidal Weir Highlighted Crest = Sharp Depth (ft) 'Bottom Length (ft) = 40.00 Q (Cfs) Total Depth (ft) = 1.00 Area (sqft) Side Slope (z:1) = 4.00 Velocity (ft/s) 'Top Width (ft) Calculations Weir Coeff. Cw = 3.10 t Compute by: Known Q Known Q (cfs) = 62.13 1 1 1 � 11 IMP] Pond Al - Emergency Overflow Weir Thursday, Feb 1 2010 = 0.62 = 62.13 = 26.34 = 2.36 = 44.96 Depth (ft) 2.00 1.50 [111M -0.50 1 weir W.S. Length (ft) Weir Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3138 by Autodesk, Inc. Pond C1 - Emergency Overflow Weir Trapezoidal Weir Crest Bottom Length (ft) Total Depth (ft) Side Slope (z:1) Calculations Weir Coeff. Cw ' Compute by: Known Q (cfs) t -0.50 1 = Sharp = 10.00 = 1.00 = 4.00 = 3.10 Known Q = 4.27 Highlighted Depth (ft) Q (cfs) Area (sqft) Velocity (ftls) Top Width (ft) Pond C1 - Emergency Overflow Weir Weir W.S. Thursday. Feb 1 2018 = 0.26 = 4.270 = 2.87 = 1.49 = 12.08 Depth (ft) 2.00 1.50 1.00 0.50 M Q41M Length (ft) APPENDIX C Hydraulic Calculations No Text ; § \ . p !!0 W ` k LU ME § & \\ ; § 2 xo_ m ■ .}£ ff k\§ )i{ -Lu^ $ § e®ƒe !f£ ) 0- CO 20 -� \c C C \{// all f k � ( # Lm IL! ) ! ! _ @ ! � � \\ / �� { M. {« !! \ ( :31� w I g � N g � d pd 7 � A p„p„ O O � ul IN C qq A C A N W W N 0 CD N 1d31 O O F a� �s A � A C A lig so 8� a o 0 a u"1 n o � I1Lt o •� it J 0 ln0 w Q Z : uZ9966+991S�S 1 19 L06t, 13 AUJ$ uI I 1n0 9i �:ul 3 o o � M N N J W O u16 6 L" III o s g�g a v g�g a W L O . ■ 9 3 ■! - O�z S!£ § \ § 3 § § § f■E # * k 2 § § § I$a �}E ]£./ / § t|4 § § } ) § § § ! / # k! : ■ % � . . � d ::13 .. T 3 f . , , § � | N 8 8 8 m ae Qjq�. G o 0 0 0 o p c _ N �y it n A � y X o 0 0 0 0 0 W' 'a V a a. 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Thursday, Jan 18 2018 Storm Line 4 Invert Elev Dn (ft) = 4948.87 Calculations Pipe Length (ft) = 50.00 Qmin (cfs) = 23.76 Slope (%) = 0.26 Qmax (cfs) = 23.76 Invert Elev Up (ft) = 4949.00 Tailwater Elev (ft) = (dc+D)/2 Rise (in) = 24.0 Shape = Circular Highlighted Span (in) = 24.0 Qtotal (cfs) = 23.76 No. Barrels = 1 Qpipe (cfs) = 23.76 n-Value = 0.012 Qovertop (cfs) = 0.00 Culvert Type = Circular Culvert Veloc Dn (ft/s) = 7.79 Culvert Entrance = Smooth tapered inlet throat Veloc Up (ft/s) = 7.56 Coeff. K,M,c,Y,k = 0,534, 0.555, 0.0196, 0.9, 0.2 HGL Dn (ft) = 4950.73 HGL Up (ft) = 4951.23 Embankment Hw Elev (ft) = 4951.92 Top Elevation (ft) = 4952.92 Hw/D (ft) = 1.46 Top Width (ft) = 20.00 Flow Regime = Inlet Control Crest Width (ft) = 100.00 en !ni SM. 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(o0re rak.hation): Q - 0.67 A (Z gH 10.5 Whem: A- area area of the man grate N = death of water above the rentrold of the rrouanrponal area (A) Input Parameters: Grate: 15" NytoPlast w/ 0omed Grate Wler Perlme.r; 8.45 open A..., or Grate in): D85 qr • 0.24 cis ilowbne fl,M,pa ihl: 4954.61 nuo• 1.17 eh Allowable Capacity: 50% Depth vs. Flow: AIwvP Inlet chi (it) Weir Flow (4ts) Flow lei.) Flow (ass) 0.00 4954.61 0.00 0.00 am 0.05 495416 0.14 0.51 0.14 0.07 4954.68 0.24 0.61 0.24 <---- 2-Year Flow CAS 4954,76 0.74 0.88 074 0.2D 4954.81 1.13 1.02 1.02 0.26 4954.97 1.70 1.17 2.27 <- 100-year Flow 0.30 4954.91 2.08 1.25 1.25 0.35 4954.96 2.62 1.35 1.35 0.40 4955.01 3.21 1.44 1.44 0.46 4955.07 3.95 1.55 1.55 0.50 495511 4.48 1.62 1.62 0.55 4955.16 5.17 1.69 1.69 0.59 4955.20 5.74 1.75 1.75 <-- Spill Elevation 0.65 4955,26 6.64 1.84 1.84 070 4955.31 742 1.91 1.91 0.75 4955.36 8.23 1.98 1.98 0.80 4955.41 9.07 2.04 2.04 0.85 4955.46 9.93 2.11 2.11 0.90 4955.51 10.82 2.17 2.17 0.95 4955.56 11.74 2.23 2.23 folaabrlons by: NICS Date: 41912018 P:1U18014 PRPACampu4iReportsl0minogelCalmlationsW]6014-Drain Golrsxlsm I 1 Platte River Power Authority HQ Fort Collins, CO Inlet Capacity 1 Govemin Equations: ' Wet capacity equation at low flows(welr calculation): Q = 3.0P H S Where: P • 2(U W) ' H • depth enwater above the flowllne Inlet capactry, equation at higberfliets oloor cokulation): Q = 0.67 A(2gH )0.5 Where A = open area of the inlet grate ' H • depth of water above the centrold of the erase -sectional area lA) Input Parameters: ' Grate: 15" Nyloplast w/ Coined Grate Wier perimeter. SAS Open Area of Grate(h): 0.85 C'. 0.25 cis FlowOne Elevation Qt): 4954.75 Osm 1.20 de ' Allowable Capacity: 50% IDepth vs. Flow: ' Depth Elevation Shallow Ornice Actual Above Inlet Weir Flow Flow Flow I1t) (kl (dFl Ids) (ds) 0.00 4954 75 0.00 0.00 0.00 ' 0.05 4954,90 0.14 0.51 0.14 0.07 4954.82 0.25 0.62 0.25 <-- 2-Year Flow 0.15 4954,90 0.74 0.88 0.74 0.20 4954.95 1.13 1.02 1.02 ' 0.28 4955.03 1.83 1.20 1.20 <--- IN -Year Flow 0.30 4955,05 2.08 1.25 1.25 0.35 4955.10 2.62 1.35 1.35 <--- Spill Elevation 0.40 4955.15 3.21 1.44 1,44 0.45 4955.20 3.83 1.53 1.53 ' 0.50 4955.25 4A8 1.62 1.62 0.55 4955.3C 5.17 1.69 1.69 0.60 4955.3S 5.89 1.77 1.77 0.65 4955.40 6.64 1.84 1.94 ' 0.70 49SSAS 7.42 1.91 1.91 0.75 4955.50 8.23 1.98 1.98 0.80 4955.55 9.07 2.04 2.04 0.85 4955.60 9.93 2.11 2.11 ' 0.90 4955.65 10.82 2.17 2.17 0.95 4955.70 11.74 2.23 2.23 1 1 Calculorlons by: NKS Case: 4/9/2018 1 UNITED CIVIL o.., , r A: U16014. ARPA CompwIReponslOmirwgelCokulotwmIU16014Drain Caks.alsm Platte River Power Authority HQ Inlet Capacity UNITED CIVIL Fort Collins, CO /� Governing Equations: Infer topp'k,"on ot. of I.. Paws lwerr tnmalatroN: Q = 3 .0 P H -' where: P.2a. w) H - depth of waterabove Me flowllne inlet appeal, to atmn at hlph"N. (."fa Q = 0.67 A(2gH )ps Where: A a open area of the Inlet prate H = depth of to, above the cerrond of the cross-sectlonnl areo (A) Input Parameters: Grate: Type C Wier Perimeter: 12.19 Open Area of Grate (n'): 4.0 Q]= 1.74 ds Flowllne Elevation Ih): 4955.14 Qlw 6.41 ch Allowable CapMny: 561i Depth vs. Flow: Above Inlet ie) In) Weir Flow (ds) Flow (ds) Flow Ictsl 0,00 4955.14 0.00 0.00 0.00 0.05 4955.19 0.21 2A6 0.21 0.10 4955.24 0.58 3.48 0.58 0.15 4955.29 1.07 4.26 1.07 0.21 4955.35 1.74 5.00 1.74 <--- 2-Year Flow 0.25 4955.39 2.30 5.50 2.30 0.30 4955.44 3.03 6.02 3.03 0.35 4955.49 3.82 6.50 3.82 0.40 4955.54 4.66 6.95 4.66 0.45 4955.59 5.56 7.37 5.56 0.49 4955.63 6.41 7.73 6.41 <- 300-ye"Flow 0.55 4955.69 7.52 8.15 7.52 0.60 4955.74 8.57 8.51 9.51 0.65 49SS 79 9.66 8.86 8.86 0.70 4955.84 10.80 9.20 9.20 0.75 4955.89 11.97 9.52 9.52 0.80 4955.94 13.19 9.83 9.83 0.85 4955.99 14.45 30.13 10.13 0.90 4956.04 15.74 10.43 10.43 0.95 4956.09 17.07 10.71 10.71 1.00 4956.14 18." 10.99 10.99 Calculations by: NKS Date: 4191201E P:IU16014-PRPACompuslR,p n IDminopelCakulatwns1U16014-Omin Col ,,ism Platte River Power Authority HQ Inlet Capacity R _ UNITED CIVIL Fort Collins, CO �C� 'INLET ID: 16creming Equations: ' Inlet rapacity mothrion or lownaws (welr mkalurlo r) Q = 3 A P H " Where P•2(LaW) ' H • death of water above the fro wide eas 0 Howe lodfice rnlcubnon): Inlet capar yIt at,. at hl her Q = U7 A(2gH )bs Where' A- open area of the Inlet prate ' H • depth of water above the red [mid of the crass-serrlivin area (Af Input Parameters: ' Grate: TVpe C Wier Perlmetio: 12.29 Open Area of Grate(rt'I: 4.09 Qr= 1.78 cfa Flowllne Elevation (hl: 4955.64 qI� = 6.74 cif A6owable Capacity: 5W IDepth vs. Flow: oePth Elevation Shallow Orifice Actual ' Above Inlet Weir Flow Flow Flow (n) (hI (rt4I (n:l (cfs) 0.00 4955.64 0.00 0.00 0.00 0.05 4955.69 0.21 2.46 0.21 0.10 4955,74 0.58 t 3.48 0.58 OAS 4955.79 1.07 4.26 1.07 0.21 4955.85 178 5.04 1.75 <-- 2-Year Flow 0.25 4955.89 2.30 5.50 2.30 0.30 4955.94 3.03 6.02 3.03 0.35 4955.99 3.82 6.50 3.82 0.40 4956,04 4.66 6.95 4.66 0.45 4956.09 5.56 7.37 5.56 ' 0.51 4956.15 6.74 7.96 6.74 <---• 100-Year Flow 0.55 4956,19 7.52 8.15 7.52 0.60 4956.24 8.57 8.51 8.51 0.65 4956.29 9.66 8.96 8 86 ' 0.70 4956.34 10.80 9.20 9.20 0.75 4956.39 11.97 9.52 9.52 0.80 4956 44 13.19 9.83 9.83 0.85 4956.49 14AS 10.13 10.13 ' 0.90 4956.54 15.74 10.43 10.43 0.95 4956.59 17.07 10.71 10.71 1.00 4956.64 18.44 10.99 10.99 P1(116014 PRPACampuslREp nSt0mina4e%ColrulotionslU16014-Dmm Calcs.elsm Platte River Power Authority HQ Inlet Capacity ^ UNITED CIVIL Fort Collins, CO IGmeming Equations: laletropach, e4upflon ae bw jiows(warr kdkfmh): Q = 0P H I � When: P•2(!e W) H • depth of water abase thr fiowllne inlet capacity e4uartm at highernam (orifice cmmlafion): Q = 0.67 A (2 gH ) 0 5 Where: A =open area of the inlet grate H. depth of water above the etaland of the eressaeenonal area (A) nput Parameters: Grate: type C Will Perimeter: 1239 Open Area of Grate Intl: 4.09 0, 1.05 bfs Flowline Elevation(ft) 4954.38 Q,w= 4.63 cis Allowable Capatlty: 50R Depth vs. Flow, Depth Elevation Shallow or k. Actual Above Inlet Weir Flow Flow Flow (RI (it) (rfsl ids) le(s) 0.00 495438 0.00 0.00 0.DO 0,05 495443 0.21 2.46 0.21 0.10 4954.48 0.58 3.48 038 0.15 4954.53 1.06 4.24 1.05 <-- 2-Year Flow 0.20 495458 1.65 4.92 1.65 0.25 4954.63 2.30 5.50 2.30 0.30 4954,68 3.03 6.02 3.03 0.35 4954,73 3.82 6.50 3.82 0." 4954.78 4.63 6.93 4.63 <-- 100-Yeer Flow 0 45 4954.83 5.56 7.37 5.56 0.50 4954.88 6.52 7.77 6.52 0.55 4954.93 7.52 8.15 7.52 0.60 4954,98 8.57 8.51 8.51 0.65 4955.03 9.66 8.86 8.86 0.70 4955.08 10.80 9.20 9.20 0.75 4955.13 11.97 9.52 9.52 0.80 4955,18 13.19 9.83 9.83 OAS 4955.23 14.45 10.13 10.13 0.90 4955.28 15.74 10.43 10.43 0.95 4955.33 11.07 10.71 10.71 1.00 4955.38 18.44 10.99 10.99 [arm loin, 61 rie5 Dote 41912018 P:1U16014 PRPACompuslRewlslOmimgelColeuktnns(UI60140min Coles.alsm Platte River Power Authority HQ Inlet Capacity UNITED CML / r Fort Collins, CO lGoventing Equations: Inlet rap"Ity"patio" at low flowe/weir Calculation)` = 3.0 P H " Where: P • 2(L a W) H I depth of water above the flowllne Inlet.'onYeOuatlon nr Mpherflowe lorifkemkulationk Q - 0.67 A(zgH �0.5 Where: A open arm of the In let aratr N = depth of water above the android of the Cron-settlood area (A) Input Parameters: Grate: Type 0 Wier Perimeter: 17.17 Open Area of Grate (ha): 7.69 OL = 2.86 ers Flowline Elevation (ft): 4954.31 Qrau - 11.43 CIS Allowable Cepaotp: 5M Depth vs. w: Depth Elevation Shallow WMce Actual Above Inlet Weir Flow Flow Flow 0.05 4954.16 0.29 4.62 0.29 0.10 4954.21 0.81 6.53 0.81 0.15 4954.26 1.50 8.DO 1.50 0.20 4954.31 2.30 9.24 2.30 0.23 4954.34 2.96 9.93 2.86 <---- 2.Yeer Flow 0.30 4954,41 4.23 11.32 4.23 0.35 4954.46 5.33 12.22 5.33 0.40 4954,51 6.52 13.07 6.52 0.45 4954.56 7.77 13.86 7.77 0.50 4954.61 9.11 14.61 9.11 0.55 4954,66 30.51 15.32 10.51 0.58 4954.69 11.43 15.76 11.43 <--- 300-Year Flaw 0.65 4954.76 13.50 16.66 13.50 0.70 4954.81 15.08 17.29 15.08 075 4954.86 16.73 17.90 16.73 0.80 4954.91 18.43 1848 18.43 0.85 4954.96 20.18 19.05 19.05 0.90 4955.02 21.99 19.60 19.60 0,95 4955.06 23.85 20.14 20.14 Culculmlons by: NKS Date: A1912018 PrI016014 PBPACamPuslReports10mi.g9e Cokvlutkn5lU16014-Oroln Coka.Klsm Platte River Power Authority HQ Inlet Capacity UNITED CIVIL Fort Collins, CO \ 11 "ram 1'-, Govem ng Equations: Inlet maopoyequation allow flows fwelr.1,vioNan): Q = 3.0! H l,} Where: P•2(1. W) H = depth of water above theflawllne We cc,i equclion of h19he,f1ows (ol(ficr calculofloo): Q = 0.67 A (2 gH � hd Where, A= open area of the Inlet prate H - depth of were, above the cenfmid of the cross sectional arts (A) Input Parameters: Gratc Type Wier perimeter: 1219 Open Area of Grate (ftl): 109 QI = 0.69 ch Flgwline Elevation (it)'. 4954.99 Co.= 3.22 cfs Allowable C.,61,: 511% Qtm Carryover 1.57 cfs To Basin B2 Depth vs. Flow: Depth Elevetlon Shallow Orifice Actual Above Inlet Weir Flow Flow Flow (h) (ft) (4fs) (cf.) (cfs) 0.00 4954.89 0.00 0.00 0.00 0.05 4954.94 0.21 2.46 0.21 0.11 4956.00 0.69 3.6g 0.69 <-- 2-Year Flow 0.15 4955.04 1.07 4.26 1.07 0.20 4955.09 1.65 4.92 1.65 <- Nighpoint location 0.25 4955.14 2.30 5.50 2.30 031 495S.20 3.22 6.14 3.22 <- 1myear Flow 0.35 4955.24 3.82 6.50 3.82 0.40 4955.29 4.66 6.95 4.66 OAS 4955.34 5.56 7.37 5.56 0.50 4955.39 6.52 7.77 6.52 0.55 4955.44 7.52 8.15 7.52 0.60 4955.49 8.57 8.51 8.51 0.65 4955.54 9.66 8.86 8.86 0.70 4955.59 10.80 9.20 9.20 0.75 4955.64 11.97 9.52 9.52 0.80 4955.69 13.19 9.83 9,83 0.85 4955.74 14.45 10.13 10.13 0.90 4955.79 15.74 10A3 10.43 0.95 4955.94 17.07 10.71 10.71 1.00 4955.89 18.44 10.99 10.99 Culc hanons by NKS Date: 419120J$ P.W16014 - PRPA CompuslReportslDralnupelCal(ulotknsiU16014 0101. C.10,xlsm Platte River Power Authority HQ Inlet Capacity UNITED CIVIL Fort Collins, CO [1 "', 1—., INLET ID: Govemi oils: Inks cupodtye9aotlon of bwflows(wrlr<olculaflon)r 0 = 3 AP H l.5 ` Where: P= 2(U W) H - death of wafer above fbeffcwhne Inlet mpxRy e4ua6on at hl0herjl..irnfke cnaulanon): Q = 0.67 A(29H Where: A= open area of the In1R prone H = d111h of water above the cennrold of the.-tealonol area (Al Input Parameters: Grate: Type D Wier Penmeter: 17.17 Open Arca of GIM (ft): 7.59 On = 1.90 cfs Flowllne Elevation If): 4954.37 Qrw= 9.85 ah 'Includes 1.57 cis Allowable capacity: 50% carryover from 81 Depth vs. Flow: Abave Inlet (n) lit) Weir Flow (cfs) Flow Ids) Flow (cfs) 0,00 4954.37 0.00 0.00 0.00 0.05 4954.42 0.29 4.62 0.29 0,10 4954,47 0.91 6.53 0.01 0.15 4954.52 1.50 800 1,50 0.32 4954.59 2415 9.69 2.66 <- 2.Year Flaw 0.25 4954.62 3.22 10.33 3.22 0.30 4954.67 4.23 11.32 4.23 0.35 4954.72 5.33 12.22 5.33 0.40 4954.77 6.52 13.07 6.52 OA5 4954.82 7.77 13.86 7.77 0.50 4954.87 9.11 14.61 9.11 053 4954.90 9.85 15.00 9.95 <- 1MYear Flow 0.59 4954.96 13.57 15.83 11.57 0.65 4955.02 13.50 16.66 13.50 0.70 4955.07 15.08 17.29 15.08 0.75 4955.12 16.73 17.90 16.73 0.80 4955. 17 18.43 18.48 18.43 0.85 4955.22 20.18 19.05 19.05 0.90 4955.27 21.99 19.60 19.60 0.95 4955.32 23.85 20.14 20.14 1.00 4955.37 25.76 20.66 20.66 Calculations by: NKS Data: 41912DIR P.1016014 � PRPACampuslRepprtslDralnoprlCalculotionsl U]60]0-Drain Coloalsm Inlet V. ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) 11 mum Allovnhle Width for Spread Behind Curb Teal 10.0 Slope Behind Curb (leave blank for no donveyerds credit behind curb) Sexx 0.020 sng's Roughness Behind Curb (IyplCWly between 0.012 end 0.020) nesor 0.013 1t of Curb at Ou0er Flow Line Hauw 8.00 Inproe Inca from Curb Few to Street Crown Tato"i • 40.0 If Width W 2.O0 Ift itTranwane Snipe S. 0020 If Crow Slope (typically 2Inches over 24 inclose or 0.063 fuel Sw O.OBB it Longitudinal Slope. Enter 0 for sung condition Sb p.000 nng's Rougnnew for Street Section (rypirelly beMen 0.012 and 0.020) hrvn 0,013 Minor Storm Melor Storm iIdf.ble Spread for Mina, 8 Main, St., Tea. 18.5 400 It Allowable Ceplh at Culler Flowlme for'i 3 Motor Storm d. .1 5.0 B.] inomi A boxes are not applicable In SUMP Cocoons 1R STORM Nloenble Cap idwy la based on Depth Criterion Minor Stonn major Starm OR STORM Allowable C."Clty le based on Depth Criterion a-- SUMP SUMP ch UD61nle v4.O5-Proposed Inbixism, Existing Hometcoth Inlet 41912018, 1:37 PM ' INLET IN A SUMP OR SAG LOCATION Version 4.05 Released March 2017 - Lo(C)---,r ' H-Curb H-Vert �-� WO W Wp o� LO (G) on IrllomMiton lingual of inlet CDOT/Denror l3 Cm obied non Depressors iaCdnn,re to mnhnuous gutter depassalon'a' hom above) ier of Unit Inlets (Grate or Curb Opening) v Depth al Flowllne (coal of local depressor) r Information th of a Unit Grate 1 a e Unit Greta Opening partner for a Grata (typicel values 0.1" QO) ping Factor for a Single Grate (typical value 0.50 - 0 70) i Weer Coeffidenl (Npicel value 215. 3.80) i Onfine Coded (Iypical value 0.60 - 0.80) Opening baorrtMOon th of a Unit Curb Opening of Vertical Curb Opening m Inches tt of Curb Onfice Throat in Incas 1 of TLroet (see USOCM Figure STS) Width for peprea lan Pen (typically the gutter el of 2 feat) ping Factor for a Single Cum Opening (typical value 0. 10) Opening War Coefficient typical value 2,&3.7) Owing OriSce Coalfictern (typical value Otto-o.7a) Or Grate Midvnah or Cum Opening Wail Equation Baton Inlet personas. Reduction Factor for Long Inlele penirg Perlomiance Reduction Fedor for Long Inlets Inlet Pedcrmance Reduction Factor for Long Inlets Inlet Interception Capacity (assumes clogged condition) Typo Se. No Padding Depth • 4 fGl• W. A.== Cr(G) Ce (G)+ CC•(G)+ CDOTRteres r 13 Denali mcnes Inches Overrate Depths feat feet 2.00 2 So 8.3 MINOR MAJOR 3,00 173 0.43 0.50 0.50 3.30 Di dear' does RForesse RFa,a RFae ulN YYIr1R 0.510 0,714 O.A7 0.83 0.70 O.gB 1.00 1,00 0.70 0.98 IUD-Inlet_v4.05-Propoaeo InM.xism, Existing Horerluolh Inlet 402018, 1:37 PM Prged: Inlet ID: ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor 3 Major Storm) r/. iM. (KomaM IEMerEN In IN blw belief IavMum Mtewable W Idm for Spread Behind Gum had Slope Se11hM CUM (kave bknh fin no canveyands credit behind what tannings Roughness Behind CUM pyplooly between 0 012 and O.OID) algM of CUM al Cutlet Fltw U1. 1ebna them CUM F..la Sroel C.., lunar WINK iron T.... veree Slope ,utter Chose Slope (ypkalH 2Inches drr 24 Mated. oA800Im Mean kdngwdleal Sege- Enter 0for wrap condition lwhing'a Rwghmss for Snort Secddn (tplully betwdor 0.012 and 0020) lox. Nlmable Spread for Minor d Major Sonm ex. MMweble Depth n Guder Muslim for Mbwr S MaW Sarm hock baxee ors not ep,l,.bi.In SUMP wMhlons IINOR STORM Miserable Copecity Is bess d on Depte Criterion IIJOR STORM AllevabM Capacity Is bard on Depth CdiMnn Td.«• 50 Be,.• 0.020 nwzi,• 0.010 Hcu+e• 8.00 Inwea T.—" m 0 W. 2.W d 6x• 0020 nitt B 000 m Sh• O.Ido don ha,aa•.• Do1a Miwr Shoo, fil Blond T— 10.0 20.0 S Csu• e.0 ]0 Inches Morbormh Myar Semi c.—.j SUMP I SUMP Jobs UDJnIM_v4. 06-Proposed Inlet dsm, 2-1 (Basin P2) 4/e12G18, 1 37 PM INLET IN A SUMP OR SAG LOCATION Vmion a06 Releuea March m1T H.Cwe H-Vart W WP \\ ,lion Inwmntton Ilnoutl ype a I" CDOT Typo R Curl Opening i)pa. owl Dam.".(bol.nal 1D CDMlnuoul, yeller Gpw9{bn'Y'ft. above) oz. umber W U." mian (Gan,a CW! OyT1111y) Mp Jon, DeWh al Flmllne (outside o11MJl a sum) PpMq Dopon iMe Mfonrullon aryl, of a UmI Grab L rca) non a, una Gme w, raa Opatnly Rego (W a anne (low vaNbe 0, 160m) A.' layybng Faaw fora Single Onto ft" value O.m-0.70) C,(0) role W W OwIDN X Ityplwl value 215- 3.m) C. (0). nola 015w CwRlpWp OYpwl wlw em- 0.80) 1- um Opening b flonewbn angtn0/e um cum,DpA,ng L.(0)• "in a Vaetwl cub OpNWy In Irc1Rs H•• aqm in cum Orinee lnotl In ocnes Hen• N* a Tmoal (aea li=M Flgun ST-5) tine Me Wloln for DePrwenn Pen (Igp1w0y1. yuw With 02 M0 W logging FadarIw a Slrlylo CUN Openblg nyp" value 0. 10) w(C) urb Opening Wolr Coe'l M(typal value 213.7) C.(C) um Olnruy Omw cwlnmem (typlUl volue 0.1-0.T0) Ca(C) He Haae Pe0pripi w RoeuglbnIGIcuMb01 eptn for Gwte Mnvv m 46- elan far Can Ownlny Wcr EOuallw III omblwlm Inlet PMomlanw RebuEYon Fa br Lmly IMen RFov e,m., um Openlny Penomlanw Heoucbw F. for W, Inlele RF_ .1. Inlet P Ifn.Nw Ruludlan FadW Ix Lmy InMe RFu,� Otal Inlet Intarcapticn Capacity (twoumaa cloggW cOntlltion) Oa iM capecny IS GOoutur MWuana but" &.mlj,Q PEMI Da..i.naue[o• GDOTTypoRGul xm 1 3.a T.0 WA WA WA WA EIAJ WA WA N MWOR an rcnes rol»s Ipna M MAAM WA e Oat n WA O.fa O.3T O.m O.Ta O.W WA WA UD-INet_v4.05-ProWaetl Inletxlem. 2-1 (Beeln A2) 4A@018, 137 PM I ALLOWABLE CAPAC(Y FOR ONE44ALF OF STREET (Mirror i MRJor Storm) f s C411r1e for USA.. AII.We R. DeelR srlrl Renal mum PYvxNle WIUpI ror SpreW BaMM Gr0 Sbpe BeMM LuN (baro OI+Mt b n0 caMAObNSMYItl OeS) Ilna'e RwMt1mM SehIM Cer0 (typlr�lly GMeeen0.042�1a O.SSij S of Cut M GMMr Flax Line nu Imm Cut Face to Shell Crown WIEIh tl Trenevene Sbpe rc Cmn Slope (t/plcMN 21n 4 oust 741nches w 0.0e3 M) n lwpnualul Sbpe - EMw 01w sump Cwm111w1 Illpb Ro h. far a'"s .(I Au D .. 0.012 Mb 0020) naxahle S ,r br MMw 8 Mrpr 9 Ilwrshle 0,Sh. GMM N.U. W Mmm A Mapr St. times we nw epplluls 1n SUMP Wp Inane I STORM AIIOMOM Cspsclty Is WW On Oeplh Cr WftO i STORM Alb W Cepechy 4 "mW on Oepth CMMion Ter. • S0 a.— 0020 4.• 0013 Moue• 0.00 InCM6 Tcnnxx • 20.0 A W • I00 11 S. om Sx• SOW eo • o.m M m • 0.013 mi. Sbnn MMw Sbrtn T— too 20.0 0 Ora' E.0 10 1. Mlnw 9 MY Slplm 0,..' SUMP I SUMP cis UD-Inlet_v405-PmpoW lnlotAsm, 25 (Basin A4) 49=10 1 3] PM INLET IN A SUMP OR SAG LOCATION Vermilion ♦W Felee.ed Wrcn W17 r—W (C)We ~ N�Cum, N•Vet .— Lp (0) COOT T)p. R Cum, Opatng I11OU. gM*r O.geencrl'.• frcin .hove) IY.r O.ph tl f1oMIIM (OMtl.e of taint amro.Wanl rMe Mbrttl*n e.,gh me UM one. 110h Of. Unit one. 1 .Open, R.W. her .Ora* (e/piml wlun 0,1}090) *ggpN Fedor far. elnpM Ortle (1,wil v.I. ON - 0.70) rtle WMr Coetdtla pyplral value 3.16- 3 W) rat. OH" Cost.hinl 0yp1ce1 vaue ON - 0J0) um owl" Int urinal Inge of . Um cue Opening eight V vom"Cut Opening In Indroa eight of cut OMIU T1.o a In Inchn ngle 0 TAroat (.N U6OCM Figure ST-5) Ice With for Oepreee*n Or (yplullY the putter wlNll of 3 fat) *aging FW> for a Slog* Cue Opening ("iml vedie 0.10) ut Opening Weer CoaelcMre (ti v t. I.}3.7) umowngc,dm.ccem,hN(t".l.;.0W OM e* Heed pw.ann.nn linemen, IGI.u**tl1 .pllWOr.Y MIOeItlVI Wh W Cue OPW*Q WolfEquation Minion INeI Peft mmm Redi Fact, for LON Wine ut Opening P.r(0rmenm Raeudl. IWn' In' Long miete .. Inne PMomleiYe Reuu ,l , Facia Iw LON Inlets peal Inlet Interception Capacity (aaeunle t clogged condition) iM Capacity IS 0000 for Minor ana Wjor Lormyop PF 1 es..' RFCtla: RFy� µ'e, f90TTypeRCW aro 1 J.a 10 WA WA ale a.x Ul9 aW WA I WA rpw. IEe Dept. 410201e. 1:0] PM Project: Intel to: ALLOWABLE CAPACITY FOR ONE•MALF OF STREET (Wnw 3 Major Sftm) e lulmom Ailowable Wldln for Sproan Banta Corn lee Sbpe Board Curb (lea. blank for no canveyp¢e bn bl DMnd curb) lannitp'a Rouonneu BMIM Curb (tWorily belwer 0.012 and 00m) lelgln of Curb a GMer Flux Line Illdr. fmm Curb Feu to Street Crown WOer Wrenn ]rM Trane.ree Sbpe Witter Criss Sope (tyoWly 2lncbes b.r 24 inches ar 0033 M0 ifM LanplWdlnM Sops Emer0forsumpeakoibn lannbq'a ROuonuu W SrM SMlon (typically bMwrn 0.012 aM 002G) Ma. Ailoeabla Spread for Mona S Ma(or Storm I., AJla.ae Cean I Goner Rattle, tot Minor S Major Sam Ibplt bore arb not appllW,l.In SUMP unllXlan IINOR STORM Allovani Cower, q eased on Depth CMeden WOR STORM AIIomble Capacity la bard on Depth Craftsman wP 30 Syu' AR-0 MI rle.c. • 0.013 Rcwe' 8.00 IncOoe Tcxoxr�^ m.0 W. 2,W ft s, • 0 m Sw• aon Sc • 0000 M Mmser • 0.013 Minor See. Major Stone T,.- 100 m,0 e o.u• E.0 ]0 bpiw4 Mlnpt 9grin M Slprtn O,r,.• SUMP SUMP cb UD-Inlel_v4 05�Proposed Inlet dsrn, 2E (D ,rr A5) 4R12018, 1:3] PM INLET IN A SUMP OR SAG LOCATION V&Vw &ad RSIHaaa MIN.n 2017 r-- w(c).—r Ndum N.V." \ We \ W ,w 7- � l et COOTTgaRCMC CybWfp • pgaMlon(aEMMnaIboMMnYus OUler upraaabllVagn aEeuy L.• i beets(GrOaCUU Opi W• Dapin 0 rm n Depth (uOIEa alloui Eaprapul OaWrp DaOm mFMYWM blonnMlon r. of i UYI GMU 4 @l' 0. um Grete W. Opening RYIo W aGUM (WWI values 01S0 W) An, • bq FSGM for a SetpM GfMe pipdet vMW 0.W 0.)0) G(G)- Wetr Cumtleet (lyplul vMW 7.1s- 3 w C. (0)' GIIIIU Cumcwn PWeUl vYw 0f10 0 BOI C. (G)' Oparra, Internment h of a um CUE OW" to (c) t of VedMel CUb Opanab In ItICMe N...' 1 Y Cufb Otmu Thoet in IncMs Nns • oITMOM lase GSOCM Flpun SI.S) TMM NM0 for Deere mor, Pan O,"Ily 1M OMIM MItlb of 2 fall W> M0 Flutter M a SlnpM Curb OeMAN (IyplcM slue 0.10) Cl (C) Ounbq Well CUII1cMm (lyplcat value 2.10.I) 0. (c) 0pening0m0.coetECWlf("c,wveto0.b0 0,M) C,(C) *Md panacmanu g0oallan (CMnuYMO) for G'. MIOxMh Qvw for OUN OWMA2 Well Equamn Eon Motion inlet Performance Reduction Faclor for lone Inlets RF.• Opening Perfminmu Reduction Fades for lyre Inlet. RFon' ] Into PMntmanu Rsduchan `ac r for ltmB Inlets RFosa 1 Inlet Interception Capacity )oaumeS Clopped CDndi8on) t7. ;apacay is GGOD for Minot and Motor slarmWG V ) Grt..nmaco• COOTT ItCUE 0.00 0'p NICIIM ].0 bcEsa MAKKt G daMtle CeptlU WA WA Net WA WA WA WA WA MINI MAECNt b.bo a00 Inc m ircnee e.m tl.b depress 200 0,10 0.f0 100 0.01 MMOR MeK WA WA Dee oat 0.E0 0.00 1.m I= WA WA 11D Inlet_Va 05-Proposed inlet vlsai. 2A (Base Ab, a92D10, 1.37 PM ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (M6Ror & Major Storm( . tha, be, mald brslank Sanded Curti .I mam AIIanned Tway Curb M Slope Banned Cum (leeye blank for no aonveyenm c.aft behind cum) Se.0 • 0.011 enMnp'.Routine..B.blea C.lIyplcwlly b...m 0.012.a 0020) IWai• 0.013 Ia. of Curt, M Ouller Fiaw Line Have • QW hard. IMce born Cum Fete to Simon Chi T..• 30.0 after Wbpn W • la0 reel Tr....e Sbpe s. p.aao uft.C.0 won.(Mpaelly 2 a". over 24 a". or 00n N0) Sh• O.OSJ armed lonMtuMnel slope- FMer 0 for..P condiven Sou• 0.000 0Ift enndda'eR.upbm.for SbeelSedlon llWlulM bernedn 0.012 de00.Gold re..r• 0.013 MImr SMrm Mrym Slam u. Allowable Spread for Minor 3 M.1m Mo. Te.• 10.0 20.0 .. Allowable Depth el Gufter Fl.wllne for Manni Major Sloum ae.a•1 3.9 1 5.5 Ieblae nook ba.e ere nor epolceble In SUMP mdpnlom F MINOR STORM Allaweble Cepecby le earned on Deem Cheshire Mahn SMdm M or Slams AJOR STORM Allowable Oep..e ny is beo on Need Crltehon O..e wave SUMP . U0.1M._v4.05.Pmwsbaln .Asm.3.3(E)(Burin AB) 419=18. 1:37 PM INLET IN A SUMP OR SAG LOCATION Veralon 4.05 ReMase Marc, =17 —Lo (0) MAurb e.Ven Wa w WP ----. L antalmoonmlenlln,t) "CDOTI}➢eRCUN OIIanDls '. Warta Tppa • ]Gl DeplesatormMbIW 10 caMnunus Outer 6prenbn Y'mm stye) • cater of Unit InMb (Orate a Curs Opping) Hp I" Cost a Rov11hM (nature of Iamt Conclusion) Patients Bell less Norman., anOt & a Unit BrMe L. (G) ANIM.1. Und Can. • W. rem Opping RMIo M1s a GCW (tWlnl values 01&0.m) A— bpplpfatly N a 91mb Orals OYBIOM valor O.m 0.M) Cr (G) • +ate Wmr Coel6oaml ("cal wham 2.16- 3 W) C. (01. roe Carlos Coenhclpt gyMul who Om - O80) Ce (0) am opening aria lon srpm of a Uryt curb Oppsp L" (C) alga of van" curs owm an latlaa m_ • "M o1 Curb Dal a Ttaa In moss M•.r apt of TNOM bee USOCM Figure ST-5I Tarts lea Won for DapMabn P11 aW.11Y ter Canal e.h W 21.) Wu- Jmgnp FWaW a Sur fat Cat Openar, aWue value D.10) Cr (C) - at Op.N Wear Coartfl ea (1y cal value 213 TI C. (C) - ors Orono, Orin. Craton p,acal value 0 W 0.70) C, (C) - a 11mae Mellaanam senator,fGlculaMl eahwarsw asserm e. • "M As CUD oamma War Epualla, it —heal Pefoanance Raduaam F-xbr for .1111.1 W. MD opMltq PeaorTance aeaFtba Factor for Long Inlirs R,— calms IMal Pertdrmen. Reduction Factor 'or Loos lams RFw_ dial Inlet Intem0plion Capacity (assumss Clogged condii O. net Oanoty IS O0OD for Mloor and Mdof SoraM�d FEW Gwxr•pyyan• Warrants TM M&h of unll r Watt rnan 1. Bartel with. UD4nlat_v4.05 Pmpowcl Inlet last, 3 (E) (Basin AO) CDOT Type R CUD Openbry 0.m 1B InCMs 6.6 Ila[Me MAJOR 1 Oeeads Depths fund feet WA WA WA WA WA WA WA mOAD raves rang WA WA 0.16 O3e am 0.71 m 1.00 WA WA as, nvnea note Mprps art 41012018. 1:37 PM ( ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor& Major Storm) 11 r.rn <rnan um Ximidale WIMh for Spread Behind Curb one Behind Curb (lem bMMI for rm wnve oo color behald whit O's Rwiphnau BMind Corb lbonally bMween 0,012 and 0.02(l) or Curb M GO., Floe Une s fmm Curb Face to StreM Crown WMIh Tournieree Slope Croea Skye (ryplCMty 2lndMe Ov. 24 Inchad, m 0 o8J MR) -I nOnudlnel Slope- EMer 0 W sump cm1tl111w i0'e Rouphnau for SUMN SaMn (lyp"Ily behveen 0012 and 0.020) Ihwabla Snoild for Minor S Melar Storm 11a abis Depth st Goiter Rosanne for Mlnw B Malor Storm boves are ndl applcebe In SUMP OUwilidns t STORM Allumble Cepacdy Is Magid on Goodin Criterion F STORM Anambra Capeclry Is Magid on Depth CMerlon a e0 Sava • —ow riarx• 0.01J Rums• e.BJ Mlroe Twwva• 20.0 W . 2.Oe Sn• DOW Sa. • 0.0B0 Sa • 0.000 nmxffr• o.013 MIrcT Eiwm Sbrtn Tw• 10.0 20.0 tlux• e.0 8.0 IrcMa Mlwr Sloan Malor Slarm O_. 9UMP I 9UMP de UD-Inlet v4. 05-Prdposed in etdsm, 35 (Basin AS) 4MM18, 1:37 PM INLET IN A SUMP OR SAG LOCATION VaMon 4.06 Released Match 2g1] H-Vert - W P _ Malon IMOrmall.n Ilnoull C001'i�a RCuN Opanitry ,,as MMal T Wa' mal Deprsslon(amXlonM to cpMlnuoua guru OaPraaated Y'npn ageaa) a,w' lumbar W Urn Ines (Grain a cure open,) No vale. Dean 0 Flmvlina (00side 0Incal "preview) Pending Depth Im. Mrprmanpn mgth ole Un4 GMe VIM af. Unit Orate Wa' ran OpmIW Ratio b a Grate (typical aahlas 0,1&0,W) A.M 'logging FMor fw a Single Oral. (lyplcal value 0.W- 0.70) (G) hale Welr Cdalgclud (typical value 2.15- 3,W) C. (G) iMe OnSca CcalecMni (typ1Utl value Dm 0 BD) C. (G) IUID Opening Information elplh pia Urn curt Opming IaMN W Vence Cur OWI, In lndroe 14— I0gla of CMb Orlllce Throat In I.ft. H— • ngle of ThtOal (nee USOCM Figure ST-S) Ruud. Ida WIMh Im oeprauim Pan (n unlilV the guner widb d 2 fW) Wo logging Fads Im a &,In Cme Opening (t pl al value 0.10) cr (c) um Opining Weir CneMdar (typical value 2137) C. (C) um Opining Orince coenider (typical value 0 W - 0 70) cv (0)' ow Htad Padmmence Redudiun ICalcuumu l Imth for Grme MIdwIMh d.— leplh for Cur Opening Wnlr Egoatim 1y ombinmm lMet Perlmmanca Reaudlon F"r Mr Long Inlets RF—• ur Openlrq Performance Reduelbn Fades Igt Long hilt, RF_ iraim tnim Petlonnmu Redudlon Fodor for Lang Inlets RFC •otal Inlet Interception Capacity (assum, clopped condition) 4 IM Capachy 15 GOOD for Min .... d Major SlorrN>O plq ) 0—rai . COOT Type R Curt Opening 3mi 3g 1 e.0 WA WA WA WA WA NIA WA MIN.. MAION mm WA WA Fn 0.33 0 50 0 n 103 1m WA I WA xnec xne5 override DepMe ev1 an fee IncMe Inchn degree M I JD -Inlet v4. 054Iropoeed IMel.alem, 3E (Basin AB) 4r 018, 13] PM Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 30® by Autodesk. Inc. Basin A7 Swale - Downstream at SE corner of Substation Garage User -defined Highlighted Elev (ft) = 4954.60 Depth (ft) 'Invert Slope (%) = 0.50 Q (Cfs) N-Value = 0.029 Area (sqft) Velocity (f /s) Calculations Wetted Perim (ft) Compute by: Known Q Crit Depth, Yc (ft) Known Q (cfs) = 1.60 Top Width (ft) EGL (ft) (Sta, El, n)-(Sta, El, n)... ( 0.00. 4955.60)44.50, 4954.68, 0.035)-(5.50, 4954.60, 0.013)-(6.50, 4954.68, 0.013)-(12.00. 4955.20, 0.035) Flowrate is equivalent to 1/2 Basin A7 flowrate x 1.33 for freeboard. Note that Basin A7 is split equally between Inlets 3-3.1 and 3-3.2. ' Elev (ft) 4956.00 ' 4955.50 4955.00 7 i 4954.50 i ' 4954.00 -2 Section Thursday, Feb 8 2018 = 0.37 = 1.600 = 1.31 = 1.22 = 6.54 = 0.27 = 6.49 = 0.39 0 2 4 6 8 10 12 14 Sta (ft) Depth (ft) 1.40 wo 0.40 -0.10 E Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3138 by Autodesk, Inc. Basin All Swale - Downstream at SW corner of Fleet Parking A Thursday, Feb 12018 User -defined Highlighted Invert Elev (ft) = 4954.63 Depth (ft) = 0.66 Slope (%) = 0.50 Q (cfs) = 5.120 N-Value = 0.013 Area (sgft) = 1.31 Velocity (ft/s) = 3.92 Calculations Wetted Perim (ft) = 3.87 Compute by: Known Q Crit Depth, Yc (ft) = 0.69 Known Q (cfs) = 5.12 Top Width (ft) = 2.95 EGL (ft) = 0.90 (Sta, El, n)-(Sta, El, n)... ( 0.00, 4955.97)(4.50, 4955.21, 0.013H4.55, 4954,71, 0.013){5.55, 4954.63, 0.013)-(6.55, 4954.71, 0.013M6.60, 4955.21, 0.013)-(8.60, 4955.64, 0.013) Elev (ft) 4956.00 4955.50 4955.00 4954.50 ' 4954.00 -1 Flowrate is equivalent flow at the point of interest x 1.33 for freeboard. Section 0 1 2 3 4 5 6 7 8 9 10 Sta (ft) Depth (ft) 1.37 0.87 0.37 -0.13 -0.63 Channel Report Hydraflow Express Extension for Autodesk®AutoCAD® Civil 3D® by Autodesk, Inc. Thursday, Feb 1 2018 Basin B2 Swale - Downstream at Bioswale User -defined Highlighted Invert Elev (ft) = 4954.30 Depth (ft) = 0.43 Slope (%) = 0.50 Q (cfs) = 11.01 N-Value = 0.024 Area (sgft) = 6.51 Velocity (ft/s) = 1.69 Calculations Wetted Perim (ft) = 26.27 Compute by: Known Q Crit Depth, Yc (ft) = 0.35 Known Q (cfs) = 11.01 Top Width (ft) = 26.23 EGL (ft) = 0.47 (Sta, El, n)-(Sta, El, n)... ( OM, 4954.82)-(17. 00, 4954.43, 0.013)-(18.50, 4954.40, 0.013)-(23.50, 4954.30, 0.035)-(28.50, 4954A0, 0.035)-(33.50, 4955.40, 0.035) Foowrate Basin B2 flowrate x 1.33 for freeboard. IElev (ft) 4956.00 4955,50 1 4955.00 ' v 4954,50 4954.00 Section 0 5 10 15 20 25 30 35 Sta (ft) 40 Depth (ft) 1.70 MIM 0.70 0.20 -0.30 Channel Report ' Hydraflow Express Extension for AutodeskO AutoCAD® CMI 3DO by Autodesk, Inc. ' 2- CURB CUT (MAXIMUM CAPACITY) Rectangular 'Bottom Width (ft) = 2.00 Total Depth (ft) = 0.50 'Invert Elev (ft) = 100.00 Slope (%) = 2.00 N-Value = 0.025 ' Calculations Compute by: Known Depth Known Depth (ft) = 0.50 ' Elev (ft) ' 101.00 — 1 100.75 - ' 100.50 - 1 100.25 - 0 .5 Highlighted Depth (ft) Q (cfs) Area (sqft) Velocity (ft/s) Wetted Perim (ft) Crit Depth, Yc (ft) Top Width (ft) EGL (ft) MAXIMUM FLOW RATE INTO CURB CUT IS 3.5 CFS LOCATED SOUTH OF THE MICROWAVE BUILDING. Section 1 1.5 2 Reach (ft) Wednesday, Feb 7 2018 = 0.50 = 4.040 = 1.00 = 4.04 = 3.00 = 0.50 = 2.00 = 0.75 2.5 3 Depth (ft) 1.00 0.75 0.50 0.25 1 I, -0.25 I ' Kevin Brazelton From: Heather McDowell <hmcdowell@fcgov.com> Sent: Thursday, May 10, 2018 12:01 PM To: Kevin Brazelton Cc: William Welch; "Don Watkins' (don@bwgarch.com)' ' Subject: RE: Platte River - Final Utility and Drainage Comments ' Hi Kevin, I've reviewed the updated plans and comments below. It looks like you've addressed all the remaining comments so I've "resolved" all the comments in our database. When you are ready to submit mylars, please remember to also provide 2 paper copies of the final drainage report, stamped/signed/dated by you. If you want an "approved" t stamped report for your files, you're welcome to submit a third report or just the cover sheet and I can stamp it "approved" for you. Let me know if any other questions come up before DCP. ' Thanks again for being a great communicator and submitting a clear, complete and thorough set of plans each time. Hardly anyone makes it through the City's review process in this few of submittals. Q ' Heather McDowell, P.E. Water Utilities Engineering City of Fort Collins Office 970.224.6065 ' Mobile 970.218.9225 hmcdowell (dfcoov.com From: Kevin Brazelton[mailto:kevin.brazelton@UnitedCivil.com) Sent: Monday, May 07, 2018 4:11 PM To: Heather McDowell <hmcdowell@fcgov.com> Cc: William Welch <wwelch@wmtwelch.com>; "Don Watkins' (don @bwgarch.com)' <don@bwgarch.com> Subject: Platte River - Final Utility and Drainage Comments Heather, Here is a link to the revised plans with the revisions that we have discussed. Responses to your comments are below. https://www. d rop box.com/s/Omtw78k to lr8em 7/Utility%20PIa ns. pdf 7d I=0 Comment Number: 19 04/3012018: Appendix C: How did you determine the downstream HGL in both pipes that outlet to Pond A? The 100-yr WSEL in this pond is 52.25, which should be used as the downstream HGL elevation in this case. Response: HGL calculations have been provided per the critical depths at each pipe outlet. Per a conversation with City personnel on 5/7/2018, using critical depth in these instances is acceptable as the peak volume within in the pond (estimated at 120-minutes) will lag the peak flows in the pipe (estimated at 10-15 minutes per time of concentration calculations). A copy of this email will added to Appendix C of the drainage report. Comment Number: 3 04/30/2018: C4.00 and C4.10 - The note has been modified but also needs to be clarified to state that all water and sewer work within the ROW or utility easements will be inspected. 1 03/08/2018: C4.00 Please note that the City will inspect the connection of the new sewer service to the ' existing sewer service that is located within the ROW. The City will not inspect the sewer service beyond what is located in the ROW. Response: The notes have been revised. Comment Number:13 04/30/2018: C7.21 For the water vault details, it looks like you are still showing a separate strainer outside of the meter itself. Also, our water/wastewater inspector has reviewed the vault details and has made some comments regarding fittings for constructability with two vaults being placed so close together. See redlines. Response: The strainer has been removed, solid sleeves added and the dimension between the vaults has been increased to 5-feet. Comment Number: 14 05/02/2018: For water services to each building, it is recommended that you provide an isolation valve or curb stop (depending on the size of the service) on the service line. Response: Isolation vaives or curb stops have been added. A couple of other items: Regarding the joint wrap. We added a note to the standard City details 8 and 9 on sheet C7.20 keeping the information generic and requiring City engineer/inspector approval. The inlet on Horsetooth has been labeled as public on sheets C4.01, C4.02 and C4.37. You had asked a question in the redlines about the demo sheets not being sequential. This is intentional throughout the set to help distinguish between phase 1 and phase 2 improvements. Thanks Heather and feel free to give me a call if there are follow up questions or comments. If you are ready for the Utility Plans to go to mylar let me know and please copy Ted. Kevin Brazelton, PE UNITED CIVIL DESIGN GROUP, LLC 1501 Academy Ct. Ste 203 Fort Collins, CO 80524 0:970 530 4044 C:970 397 2147 APPENDIX D Referenced Materials 44 q,'den No Text Custom Soil Resource Report Map Unit Legend Lorimer County Area, Colorado (C0644) Map UnU$ymbol - Map. Untt Name Acres in A01 Percent of Adl 6 Aquepts, ponded 3.5 1.0% 34 Fort Collins loam, 0 to 1 percent slopes 8.6 2.4% 35 Fort Collins loam, 0 to 3 percent slopes 4.2 1.2% 36 Fort Collins loam, 3 to 5 percent slopes 5.7 1.6% 73 Nunn clay loam, 0 to 1 percent slopes 160.2 50.8% 74 Nunn clay loam, 1 to 3 percent slopes 131.4 37.1% 75 Nunn day loam, 3 to 5 percent slopes 13.3 3.8% 76 Nunn day loam, wet, t to 3 percent slopes 7.6 2.2% Totals for Area of Intaiest 364.E 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the. characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which It is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a 11 Custom Soil Resource Report 73—Nunn clay loam, 0 to 1 percent slopes Map Unit Setting National map unitsymbol., 2dng Elevation: 4,100 to 5,700 feet Mean annual precipitation: 14 to 15 inches ' Mean annual air temperature: 48 to 52 degrees F Frost -free period: 135 to 152 days Farmland classification: Prime farmland if irrigated ' Map Unit Composition Nunn and similar soils: 85 percent Minor components:: 15 percent Estimates are based on observations, descriptions, and transacts of the mapunit. Description of Nunn Setting Landiorm: Terraces Landform position (three-dimensional):Tread Down -slope shape: Linear Across -slope shape. Linear Parent material: Pleistocene aged alluvium and/or eolian deposits Typical profile Ap - 0 to 6 inches: Gay loam Bit - 6 to 10 inches. day loam Bt2 - 10 to 26 inches., clay loam Btk - 26 to 31 inches. clay loam Bkl - 31 to 47 inches: loam Bk2 - 47 to 80 inches: loam Properties and qualities Slope., 0 to 1 percent Depth to restrictive feature: More than 80 Inches Natural drainage class: Well drained Runoff class. Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to 0.20 inlhr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum in profiler 7 percent Salinity, maximum in profile: Nonsaline (0.1 to 1.0 mmhos/cm) Sodium adsorption ratio, maximum in profile: 0..5 Available water storage in profile: High (about 9.1 inches) Interpretive groups Land capability classification (irrigated): 3e 1 Land capability classification (nonirrigated): 4e 18 Custom Soil Resource Report Hydrologic Soil Group: C Ecological site: Clayey Plains (R067BY042CO) Hydric soil rating: No Minor Components Heldt Percent of map unit: 10 percent Landform: Terraces Landform position (three-dimensional): Tread Downs/ope shape: Linear Across -slope shape: Linear Ecological site: Clayey Plains (R067BY042CO) Hydric soil rating. No Wages Percent of map unit. 5 percent Landform: Terraces Landform position (three-dimensional): Tread Down -slope shaper Linear Across -slope shape: Linear Ecological site: Loamy Plains (R067BY002CO) Hydric soil rating: No 74—Nunn clay loam, 1 to 3 percent slopes Map Unit Setting National map unit symbol• 2tlpl Elevation: 3,900 to5,840 feet Mean annual precipitation: 13 to 17 inches Mean annual air temperature: 50 to 54 degrees F Frost -free period: 135 to 160 days Farmland classification: Prime farmland If irrigated Map Unit Composition Nunn and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transacts of the mapunit. Description of Nunn Setting Landform: Terraces Landorm position (three-dimensional): Tread Down -slope shape: Linear Across -slope shape: Linear Parent material: Pleistocene aged alluvium and/or eolian deposits Typical profile Ap - 0 to 9 inches: day loam Bt - 9 to 13 Inches., day loam 19 Custom Soil Resource Report Btk - 13 to 25 inches: day loam Bk1 - 25 to 38 inches. clay loam Bk2 - 38 to 80 inches: clay loam Properties and qualities ' Slope: 1 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class. Well drained Runoff class. Medium Capacity of the most limiting layer to transmit water (Kset): Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency ofponding. None Calcium carbonate, maximum in profile: 7 percent Salinity, maximum in profile: Nonsaline to very slightly saline (0.1 to 2.0 mmhos/cm) Sodium adsorption ratio, maximum in profile. 0.5 Available water storage in profile: High (about 9.9 inches) Interpretive groups e Land capability classification (irrigated): 2e Land capability classification (nonimgated): 3e Hydrologic Soil Group: C Ecological site. Clayey Plains (R067BY042CO) Hydric soil rating: No Minor Components Heldt Percent of map unit: 10 percent Landform: Terraces Landform position (three-dimensional): Tread Down -slope shape: Linear Across -slope shape: Linear Ecological site: Clayey Plains (R067BY042CO) Hydric soil rating: No Satanta Percent of map unit: 5 percent Landi'orm: Terraces Landform position (three-dimensional): Tread Downs/ope shape: Linear Across -slope shape: Linear Ecological site: Loamy Plains (R067BYO02CO) Hydric soil rating: No 76--Nunn clay loam, 3 to S percent slopes Map Unit Setting National map unit symbol. 2tlpm 20 Custom Soil Resource Report Table —Hydrologic Soil Group (Platte River Power Authority) Hydrologic Soil Group— Summary by Map Unit— Lorimar County Area, Colorado (Coo") Map unit symbol Map unit name Rating Acres In AOI. Percent of AOI 6 Aquepts, ponded AID 3.5 1.0% 34 Fat Collins loam, 0 to 1 percent slopes B 8.6 2.4% 35 Fort Collins loam, 0 to 3 percent slopes C 4.2 1.2% 36 Fort Collins loam, 3 to 5 percent slopes B 5.7 1.6% 73 Nunn clay loam, 0 to 1 percent slopes C 180..2 50.8% 74 Nunn day loam, 1 to 3 percent slopes C 131.4 37.156 75 Nunn day loam, 3 to 5 percent slopes C 13.3 3.8% 78 Nunn day loam, wet, 1 to 3 percent slopes C 7.6 2.2% Totals for Area of Interest 354.8 - 100.0% Rating Options —Hydrologic Soil Group (Platte River Power Authority) Aggregation Method: Dominant Condition Component Percent Cutoff., None Specified Tie -break Rule: Higher 1 28 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep -water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0,.2006. Field indicators of hydric soils In the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nres.usda.gov/wpstportal/ nres/detail/national/soi Is/?cid=nres 142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www. nres. usda.gov/wps/portal/nres/deta i I/national/soils/?cid=n res l 42p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www. nres. usda. gov/wps/portal/nres/detail/national/soils/?cid=nres l42p2_053580 Tiner, R.W., Jr. 1986. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http:/hvw.nres.usda.gov/wps/portal/nres/detaii/soils/ United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://Www.nres.usda.gov/wps/portal/nres/ detail/nationalAanduse/rangepasture/?cld=stelprd b 1043084 29 Custom Soil Resource Report United States Department of Agriculture, Natural Resources Conservation National soil survey handbook, tipe 430-VI. http://www.nres.usda.gov/wps/ United States Department of Agriculture, Natural Resources Conservation Service 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nres.usda.gov/Wps/portal/nrs/detail/national/soils/7 cid=nres 142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. 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