The URL can be used to link to this page

Home My WebLink AboutDrainage Reports - 06/21/2019I I I I I I I I I I I I I I I I I I I City of ft Col~ Plans Apptovect By tffl Date 6-~1_-Jcj April 02 , 2019 Wes Lamarque , P .E. City of Fort Collins Utilities -Stormwater Engineering 700 Wood Street Fort Collins , CO 80521 RE: Mason Place , 3750 South Mason Street -Final Drainage and Erosion Control Letter JV A Job No. 2873c Dear Wes: JVA. Incorporated 213 Lmden Street Su,te 200 Fort Collins, CO 80524 970 225 9099 1nfo@JvaJVa .com www.jvajva.com This letter has been prepared to summarize the drainage concept, solutions and changes in impervious area associated with the site improvements for the Mason Place redevelopment project located at 3750 South Mason Street in the City of Fort Collins. Existing Drainage Patterns The existing site , platted as Lot 5A and adjoining Lot 6 (same owner), is predominantly paved asphalt and consists of the existing Midtown Arts Center building, drive aisles , and parking areas . The existing ground surface is relatively flat , generally sloping either northwest or southwest at grades ranging from 0.5 % to 2.0%. The majority of stormwater runoff is conveyed via surface flow either to the northwest into an existing curb inlet in the north parking area (into a private storm system that serves the northern portion of the site and its eastern neighbors), or to the southwest across the Lot 6 parking lot, through a curb cut and over public sidewalk and into the public storm drainage system in South Mason Street via a curb inlet. See Figure 1: Historic Drainage Map. The site is located outside FEMA and City of Fort Collins mapped 100-year and 500-year floodplains, per FEMA Flood Risk Map Panel number 08069C0987G , effective date 05 /02 /2012 . Proposed Drainage Patterns Proposed drainage patterns are to remain generally the same a the current, but will utilize landscaped areas , inlets , and underground torage to capture the majority of runoff before discharging into the public storm system without flowing over driveway approaches or sidewalks and into the street. The underground storage system will utilize StormTech technology for water quality and low impact development treatment. The site is graded as such to meet the City 's requirements of treating 75 % of the sites modified or added impervious area. In general , the proposed redevelopment of the site consists of reusing the existing building, reconfiguring the north parking area, relocating the access driveway on Mason Street further to the south, and constrncting a courtyard and greenspaces on the west side of the existing building along within new storm infrastructure to improve the drainage characteristics of the site . The site has been di v ided into two major hydrologic basin for analysis. Basin A represents the area of the site drain ing to the StormTech chambers and Basin 8 represents the portion of the site draining to the south , either collected in the sites private storm system or sheet flowing into the existing parking lot in Lot 6 and a into proposed combination inlet upstream of the private storm sys tems connection to the existing public storm system . The roof has four roof drain locations , two will be connected to the A-basin stonn system and two will be connected to the 8-basin BOULDER FORT COLLINS WINTER PARK GLENWOOD SPRINGS DENVER I I I I I I I I I I I I I I I I I I I Mason Place Final Drainage and Erosion Control Letter April 02 , 20 L 9 2 of7 storm system. Both major basins utilize grassed swales to collect runoff and also include area inlets and storm pipe systems. The majority of the A -basin will be directed into a diversion manhole where water quality flows will be sent to the StormTech chambers and larger flows will bypass the chambers. Both storm systems connect into the existing pub lic storm system in South Mason Street. There is a third major basin category, OS-basins , that include areas within the site boundary that drain offsite and do not enter the sites proposed storm system or areas that are not wi thin the site property boundary but are collected in the sites proposed private storm system . All basins eventually convey stormwater to Fossil Creek. It follows that the proposed improvements will substantially de crease the total impervious area on the site, from 84.2 % to 69 .7%. See Figure 2: Developed Drainage Map for the drainage basin boundaries and a summary of the existing and proposed impervious areas. Hydrologic and Hydraulic calculations are attached. Chapter 2 of the Urban Drainage and Flood Control District's Urban Storm Drainage Criteria Manual Volume 3 (USDCM) provides guidelines for the selection of appropriate structural BMPs for a site that is to be de veloped or redeveloped. Mason Place is best characterized as a "con ventional redev elopment" with just over l acre of imperviou s area on the project site. The BMP decision tree for such sites is provided in Figure 2 -2 of the USDCM . The site and surrounding vicinity is comprised of hydro logic soil group Type C & D soils , per the NRCS soil survey. Permeable pavement (with partial or no infiltration) and/or the use of a "green roof', rain garden, or grass swale/buffer are the recommended runoff reduction practices for this scenario . Howev er, with the proposed configuration of the site underground StormTech Chambers were cho s en to perform the LID water quality treatment . The proposed StormTech storm underground chambers located on the private storm system will treat storm runoff for a minimum of 75 % of the modified or added impervious area on the site for water quality prior to discharge into the public storm system, satisfying the City of Fort Collins Low Impact Development (LID) requirements . City staff allowed for the building to be excluded from the sites total impervious area since the overall footprint of the building will not be modified . Therefore , of the proposed 0.87 acres of impervious surface area, the buildings 0.43 acres does not need to be included in the impervious area calculations . Therefore , the required treated impervious area is 0.33 acre . The chambers treat 0.54 acres of the sites impervious area . The pro v ided chamber sizing worksheet and directions from the City of Fort Collins staff was u ed to determine the water quality flow of 0 .57 cfs would be directed to the chambers . A restri ctor plate on the influent pipe to the chambers will restrict flows to direct the water quality capture v olume to the chambers and di vert the rest of the flows to the north. The northern diversion pipe invert will be set at t he restrict plate in v ert elevation. All flows will combine downstream of the chambers before entering the public storm sewer system. The hydraulic capacity of the chambers wa designed to capture and treat the water quality capture volume. The chamber design plans and sizing calculations are attached. These features will facilitate sedimentation and filtration while limiting erosion , providing both treatment and slow ed release of the water quality capture volume. The propo s ed redevelopment of this site will serve to reduce water quality and quantity impacts to natural drainageways by decreas ing the frequency , ra te , duration , and v olume of runoff. I I I I I I I I I I I I I I I I I I I Erosion and Sediment Control Mason Place Final Drainage and Erosion Control Letter April02 ,2019 3 of7 During construction, temporary erosion and sediment control practices will be used to limit soil erosion and sediment discharge off the site. Temporary Erosion Control A temporary erosion control plan is to be implemented for the site during construction. Temporary erosion control measures include, but are not limited to , slope and swale protection provided by the use of erosion control wattlers /sediment control logs , rock socks , etc. All temporary erosion control measures are to be removed after they are deemed unnecessary. A general erosion control plan has been provided in the civil construction documents and attached . Permanent Erosion Control Chapter 2 of the Urban Drainage and Flood Control District's Urban Storm Drainage Criteria Manual Volume 3 (USDCM) provides guidelines for the selection of appropriate permanent structural BMPs for a site that is to be developed or redeveloped. The A VN Parking Lot Expansion is best characterized as a "conventional redevelopment" with over I acre of impervious area on the project site . The BMP decision tree for such sites is provided in Figure 2-2 of the USDCM. As previously stated, the site and surrounding vicinity is comprised of hydrologic soil group Type CID soils , per the NRCS soil survey. The water quality capture volume (WQCV) for this site is accounted for in the StormTech chambers located in the northwest comer of the site. No detention is required on the site. Runoff will be collected in the private storm system before connecting to the public storm system. Stormwater Management Controls The Stormwater Management "Plan (SWMP) administrator will be determined at the time the project is bid for construction . According to the CDPHE Stormwater Fact Sh eet -Construction , construction activities produce many different kinds of pollutants which may cause storm water contamination problems. The main pollutant of concern at construction sites is sediment. Grading activities remove grass , rocks, pavement, and other protective ground covers , resulting in the exposure of underlying soil to the elements . The soil is then easily picked up by wind and/or washed away by rain or snowmelt. In addition , construction activities often require the use of toxic or hazardous materials such as fuel , fertilizers , pesticides , and herbicides , and building materials such as asphalt, sealants , and concrete , which may also pollute stormwater. These materials can be harmful to humans , plants , and aquatic life . There are no other known potential pollution sources . However, this condition should be confirmed by the owner/operator or SWMP administrator. Other pollution sources that coulp be present include: runoff from vehicle washing , vehicle maintenance and /or fueling , There are no known existing non -stormwater components of discharge (i.e ., springs , landscape irrigation return flow , and etc.), or any anticipated during construction. I I I I I I I I I I I I I I I I I I I I 1. All Disturbed and Stored Soil: Mason Place Final Drainage and Erosion Contro l Letter April 02 , 2019 4 of7 The total disturbed area will be approximately 1.2 acres. Soil stockpiles should be kept below the locally mandated maximum height of 10 feet and surrounded with sediment control longs. If the storage of these soils occurs over a period greater than 30 days , then consider temporarily seeding the soil to minimize soil loss to wind and water erosion . 2. Vehicle Tracking of Sediments: The existing site is developed residential properties with a bisecting gravel/asphalt alley. A temporary stabilized stone pad and/or Trackout Plate (Vehicle Tracking Control pad, VTC) will be provided at points of ingress and egress onto the unpaved area when the parking lot asphalt is removed. The VTC is designed to reduce the amount of mud transported onto the public roads by construction traffic. [f the site is extraordinarily muddy, then consider designating an area to wash construction vehicles before they leave the site and enter the public right -of-way. A BMP such as this is a good way to avoid the costs associated with street cleaning or accidentally discharging large amounts of sediment into other storm drain systems. When in doubt, choose methods that prevent pollution rather than ones that force clean-up at the downstream end just before the stormwater enters the receiving waters . In other words , the most efficient construction site BMPs are those that prevent erosion from happening . 3. Inlet Protection (IP): gravel inlet protection will be used on all existing downstream inlets to prevent sediment and debris from entering the storm drain system. 4. Street sweeping will be conducted as necessary to remove sediment tracked on to pavement and adjacent streets. 5. Management of Contaminated Soils: If contaminated soils are found , the contractor shall report to the SWMP administrator to be mitigated. 6. Loading and Unloading Operations: The existing entrance to the site is currently paved and loading/unloading activities will occur within the paved area of the site or a temporary gravel staging area will be provided. 7. Outdoor Storage Activities: Materials storage should be designated to a protected area of the site and surrounded by construction fencing and sediment control logs to reduce the potential for runoff to occur. 8. Vehicle and Equipment Maintenance and Fueling: Materials should be stored and handled in covered areas to prevent contact with stormwater, and chemicals should be stored within berms or secondary containment devices to prevent leaks and spills from entering stormwater runoff. I I I I I I I I I I I I I I I I I I I Sp ill Management Ma on Place Final Drainag e and Erosion Control Letter April 02 , 2019 5 of7 In general, spill prevention and response should inc lude the following: a) Notification procedures to be used in the event of an accident. At the very least , the SWMP Administrator should be notified. Depending on the nature of the spill and the material involved , the Colorado Department of Health, downstream water users , or other agencies may also need to be notified. b) Instructions for clean-up procedures. c) Provisions for absorbents are to be made available for use in fuel areas , and for containers to be available for used abso rbents. d) Procedures for properly washing out concrete trucks and other equipment in a manner and location so that the materials and wash water cannot discharge from the site, and never into a storm drain system or stream . 9 . Significant Dust or Particulate Generating Processes: Disturbed areas not yet ready to be eeded, landscaped, paved, or otherwise stabilized shall be watered, or ripped as necessary to preclude visible dust emissions. Contractor shall make every effort to minimize particulate emissions from vehicles performing the work, including but not limited to regular maintenance of construction equipment. Contractor shall control dust in accordance with the City Fugitive Dust Control Ordinance. 10. Routine Maintenance Activates Involving Fertilizer, Pesticides , Detergents , Fuels Solvents , Oils Etc : Materials should be stored and handled in covered areas to prevent contact with stormwater, and chemicals should be stored within berms or secondary containment devices to prevent leaks and spills from entering stormwater runoff. 11. On-site Waste management Practices (Waste Piles , Liquid Wastes , Dumpsters, etc): Waste management on the site shall be contained in dumpsters that are placed in an area that can be enclosed with temporary fencing and accessed through a gate with a lock. Additional measures such as sediment control logs shall be used to protect potential ediment from migrating our of the waste area. 12 . Concrete Truck/Equipment Washing: A concrete washout facility will be provided onsite. Properly wash out concrete trucks and other equipment in a manner and location (a minimum of 50 feet away from any inlet structures) so that the materials and wash water cannot discharge from the site , and never into a storm drain ystem or stream. 13. Dedicated A phalt and Concrete Batch Plants: There will be no dedicated batch plant on site. 14. Non-[ndu trial Waste Source Such as Workers Trash And Portable Toilets : Garbage can shall be located at break areas and portable toilet hall be provided if onsite bathroom facilities cannot be used. Locate dumpsters and portable toilets away I I I I I I I I I I I I I I I I I I Mason Place Final Drainage and Erosion Control Letter Apri l 02 2019 6 of7 from drainage courses (minimum 50 feet from any inlet structures) and stake down toilets to prevent tipping. 15. Other Areas or Procedures where Potential Spills can Occur: Records of spills , leaks , or overflows that result in the discharge of pollutants must be documented and maintained . Record all spills that are responded to, even if they do not result in a discharge of pollutants . Information that should be recorded for all occurrences includes the time and date weather conditions, reasons for the spill , etc. Some spills may need to be reported to immediately. Specifically, a release of any chemical, oil, petroleum product, sewage, etc., which may enter waters of the State of Colorado (which include surface water, ground water and dry gullies or storm sewers leading to surface water) must be reported . More guidance is available on the web at www.colorado.gov. The Division's toll-free 24-bour number for environmental hazards and chemical spills and releases is 1-877-518-5608 . Sequence of Construction Activities Constmction Start Date (This is the day you expect to begin disturbing soils , including grubbing, stockpiling, excavating, demolition, and grading activities): May, 20 19 Final Stabilization Date (this is when the site is finally stabilized. This means that all disturbed areas have been either built on, paved, or a uniform vegetative cover reaching over 70% of the initial vegetative density has been established.) Even if you are doing one part of the project, the estimated completion date must be for the overall project: May, 2 020 . Construction Sequencing: (Detailed constmction sequencing to be determined by the contractor) I. Installation of temporary erosion and sediment control measures. This includes all sediment control logs, rock socks, erosion control blankets , and silt fence where all land disturbing activities will occur. 2. Sequence of all land disturbing activity. Demolition of existing features in preparation of construction of proposed site features. Installation of Stonntech chambers will occur after demolition . 3. Sod/Seed Disturbed areas will be sodded and/or seeded upon completing of finish grading. Refer to the Landscape plans for detailed planting and seeding schedule. 4. Mulching. Spread straw mulch uniformly over seeded areas at a rate of 90 lbs per 1000 square feet of ground. No more than 25% of the ground should be visible. Crimp or pinch mulch into soil 2-4 inches by using either a mulch anchoring tool , a farm disk operating on the contour of the slope, or by cleating with bulldozer tracks operating up and down the slopes (to prevent tracks from forming gullie ). 5. Required maintenance activities (e.g. after-storm checks of all BMPs, etc.). All temporary sediment control BMPs shall be inspected after each rain event to ensure proper protection and to determine if cleaning is necessary. Final cleaning of all storm facilities shall be provided upon final stabilization of site. I ,·I I I I I I I I I I I I I I I I I I Mason Place Fi:nal Drainage and Erosion Co ntrol Letter April 02, 2019 7 of7 Please feel free to contact me to discuss any questions you may have. Sincerely, JV A, IN CORPORA TED By: Bri~ Regional office Manager Senior Associate :,.\\\\\\\\\111111111111,,,, ~ oORSGI, ~ ~o~tl ........ '8.,..r-~ Ni' •• I') L,·•'-'.t\~ §§0:,.,.•;,s n . 'Vf ••~l"t\ ~ ~ • V ''JQ •"() =::::;, ~ 0 i~ 6/04/1 9 ;\ ~ i :1 37146 :...: E -. ..-. .... f4 ,. $: :,-.; -.. ~ ~s ...... ,·~&~~ ' ~SIONA\..€#° "11111111111111\\\\\\\\\~ Enclosures: Figure I: Historic Drainage Map, Figure 2: Developed Drainage Map , Rational Calculations, Storm Tech Chamber Figures and Sizing Calculations, CD 1.0 Grading & Drainage Details, CEI.O Erosion Control Plan. CELI SWMP and Erosion Control Details , CEI.2 Erosion Control Details CC: Kristin Fritz, Housing Catalyst I I I I I I I I I I I I I I I I I I I Project Information: Job Name: Job Number: Date : Designed by: Municipality : Runoff Calculations: Minor Design Stom,: Major Design Stomi : Detention Calculations: Minor Stom, Detention : Major Stom, Detention : Detention Volume by: JVA Incorporated 213 Linden St, Suite 200 Fort Collins, CO 80524 Ph: (970) 225 9099 2 100 s5ac FAA >Sac FAA+20% Allowable Release Rates (if applicable): Max release rate 1 cfs / acre? y year year year year Version 2016_XT: 9/2/2016 Soil Type : .._ __ II,¥, __ _. plus plus EnterWQCV : Site Area : 1=--%WQCV 100 % WQCV ___ ... o ___ cf (GB , PP , PLO , SFB , EDB ,etc.) .._ __ .._ ___ _. acres Enter Offsite flows to bypass site (these will be added to the all owable release rates) as= ____ o_.o_o ____ cfs (bypass flows) Q5allow= 0.00 cfs 0100 = 0 .00 cfs (bypass flows) Q100allow= 0.00 cfs Rainfall Data Information: Enter City, Town, or County: ___ F~o_rt~C_ot __ l-in._s ____ _ Frequency of Design One Hour Point Rainfall P1 Event Do you need to Cale P1? No 2 yr 0 .82 in s yr 1.14 in 10 yr 1.40 in 100 yr 2 .86 in Runoff Coefficient Calculations: Use UDFCD Equations? No Intensity Duration Values: 1-D-F FortColli nslDF 2873c -Rational Calculations INTRO Page 1 of 16 - -Mason Place - -JVA Incorporated 213 Linden St, Suite 200 Fort Collins, CO 80524 Ph: (970) 225 9099 - - --Job Name: Mason Place Job Number: 2873c Date: 4/2/19 By: LAL -Historic Runoff Coefficient & Time of Concentration Calculations Location: Fort Collins Minor Design Storm: BE Major Design Storm: 100 Soil Type: CID Basin Desian Data 1(%)= 100% 90% 90% 40% 10% 25% 0% 0% 1(%) A,,.,.. A,;,;,..,a, Ai.-18 Ai.-Basin Design A,.,, Ag,..,. A,,w.. A"'"" Aro<a1 Aro<a1 Imp C2 Name Point ...... . nc (sf) (sf) (sf) (sf) (sf) ool) (OOaoil) (sf) (ac) (%) (sf) (sf) (sf) A 1 13.497 2 299 8810 2,832 27,438 0.63 85.6% 0.88 B 2 7,580 3 207 9911 2.696 23,394 0.54 82.9% 0.87 051 3 655 156 811 0.02 72.7% 0.82 0 0.00 0 0.00 TOTAL SITE 21,077 6,161 18,721 0 0 0 0 5,684 51,643 1.19 84.2% 0.87 Runoff Coeffs Rainfall Intensities (in/hrl Area Basin Design Time of A, .... Cone C2 cs C10 C100 2 5 10 100 Arm• (sf) 02 Name Point (tc) (ac) A 1 5.0 0.88 0.00 0.88 0.93 2.85 0.00 4.87 9.95 27,438 0.63 1.58 B 2 5.0 0.87 0.00 0.87 0.92 2.85 0.00 4.87 9.95 23,394 0.54 1.33 051 3 5.0 0.82 0.00 0.82 0.87 2.85 0.00 4.87 9.95 811 0.02 0.04 0 0 0 0.00 0 0 0 0.00 TOTAL SITE 51,643 1.19 2.95 2873c -Rational CalculaUons -- -- - -----' 1% C2 cs C10 C100 Streets Paved 100% 0.95 0.00 0.95 1.00 Concrete Drives/Walks 90% 0.95 0.00 0.95 1.00 Roof 90% 0.95 0.00 0.95 1.00 Gravel 40% 0.50 0.00 0.50 0.63 Landscaping (B soil) 0% 0.15 0.00 0.15 0.19 Landscaping (C/0 soil) 0% 0.25 0.00 0.25 0.31 Playground 10% 0.11 0.00 0.11 0.14 Artificial Turf 25% 0.20 0.00 0.20 0.25 Runoff Coeffs lnltlal Overtand Time (~) Travel Time (~) ~=Lengthl(Velocity le Comp tc Urbanized Check le x60) ON Final Upper Time of Total cs C10 C100 most Slope ~ Length Slope Type of Land Surface K Velocity ~ Cone Length le=(U180)+ Min length (%) (min) (ft) (%) (fps) (min) 10 (min.) (fl) ~+~=le (ft) le 0.00 0.88 0.93 5 20% 3.6 150 13% Paved areas & shallow 20 2.3 1.1 4.7 155 10.9 5.0 caved swales 0.00 0.87 0.92 5 20% 3.6 190 18% Paved areas & shallow 20 2.7 1.2 4.8 195 11.1 5.0 oaved swales 0.00 0.82 0.87 5 20% 3.6 5 15% Paved areas & shallow 20 2.4 0.0 3.6 10 10.1 5.0 paved swales Paved areas & shallow 20 0 10.0 oaved swales Paved areas & shallow 20 0 10.0 oaved swales 0.00 0.87 0.92 Flow Rates (cfsl as 010 0100 0.00 2.69 5.82 0.00 2.27 4.92 0.00 0.07 0.16 0.00 5.04 10.90 Historic Page 2 of 16 I I JVA Incorporated Job Name: Mason Place 1% C2 cs C10 C100 213 linden St, Suite 200 Job Number: 2873c Streets Paved 100% 0.95 0.00 0.95 1.00 Fort Collins, CO 80524 Date: 4/2/19 Con crete Drives/VValks 100% 0.95 0.00 0.95 1.00 I Ph : (970) 225 9099 By: LAL Roof 90 % 0.95 0.00 0.95 1.00 Gravel 40% 0.50 0.00 0.50 0.63 Lands caping (B soil) 2% 0.1 5 0.00 0.15 0.19 Mason Place Landscaping (CID s oil) 2% 0.25 0.00 0.25 0.31 I I Composite Runoff Coefficient Calcu lations Playg rou nd 25 % 0.11 0.00 0.11 0 .14 Location: Fort Collins Artificial Turf 25% 0.20 0.00 0.20 0.25 Minor Design Storm : §Is Maj or Design Storm : Soil Type: D Basin Desian Data I (%)= 100% 100% 90% 40% 25% 25% 2% 2% 1(%) Ru noff Coeffs I Design A,,.vea Ao nves/c Amor Agravel Ai,1ygnd A art.tu rr A.scape (B A.scape A Total A Total Imp Basin Name C2 cs C10 C100 Poi nt streets (sf) (sf) (sf) (sf) (sf) soil ) (CID s oil ) (sf) (ac) (%) (sf) on e (sf) (sf) I A1 1 13 ,100 13,100 0.30 90.0% 0.95 0.00 0.95 1.00 A2 2 2,194 2,194 0.05 1.8% 0.25 0.00 0.25 0.31 I A3 3 8,070 2,182 1,948 12 ,200 0.28 84 .5% 0.84 0.00 0.84 0.89 A4 4 75 2,550 2,625 0.06 3.3% 0.27 0.00 0.27 0.33 OSA5 4 22 604 626 0.01 7 .2% 0.27 0.00 0.27 0.34 I OSA6 5 223 87 1 163 1,473 0.03 21 .0% 0.40 0.00 0.40 0.46 B1 6 7,467 7,467 0.17 90 .1% 0.95 0.00 0.95 1.00 B2 7 92 306 398 0.01 23 .9% 0.41 0.00 0.41 0.47 I B3 8 243 149 392 0.01 81 .0% 0.68 0.00 0.68 0.74 B4 9 2,490 3,728 6,218 0.14 40.6% 0.53 0.00 0.53 0.59 I BS 10 960 2,029 1,643 4 ,632 0.11 66.1% 0.70 0.00 0.70 0.76 OSB6 10 23 ,840 1,193 3,577 28,6 10 0.66 87 .5% 0.86 0.00 0.86 0.91 OSC1 11 810 810 0.02 100.0% 0.95 0.00 0.95 1.00 I OSC2 12 115 115 0.00 100.0% 0.95 0.00 0.95 1.00 0 0.00 I Total A 4 8,070 2,257 13 ,100 0 0 0 0 6,692 30,119 0.69 73 .8% 0.79 0.00 0.79 0.85 Total B 10 960 4 ,854 7,467 0 0 0 0 5,826 19,107 0.44 65 .6% 0.74 0.00 0.74 0.79 Total Site OS 5, 11 , 12 0 925 0 0 0 0 0 0 925 0.02 100.0% 0.95 0.00 0.95 1.00 I 0 0.00 Property 20 9,253 8,123 20 ,567 0 0 0 0 13 ,681 51 ,624 1.19 69.7% 0.76 0.00 0.76 0.82 Boundary I Area to Chambers 20 8,070 2,258 13 ,100 0 0 0 0 4 ,142 27 ,570 0.63 80.2% 0.84 0.00 0.84 0.90 (A1-A3 ) I I I I 2873c -Rationa l Calculations Developed C Page 3 of 16 I I I I I I I I I I I I I I I I I I I Mason Place JVA Incorporated 213 Linden St, Suite 200 Fort Collins, CO 80524 Ph : (970) 225 9099 Time of Concentration Calculations Location : Fort Collins Minor Design Storm : Major Design Storm : Soil Type : I: I Job Name: Mason Place Job Number. 2873c Date : 4/2/19 By: LAL Sub-Basin Data Initial Overland Time (~) Travel Time (t,) t,=Length/(Veloclty x 60) Upper Bas in Name Design Ar..,, cs most Slope ~ Length Slope(%) Type of Land Surface Point (ac) Length (%) (min) (ft) (tt) A1 1 0.30 0.00 165 15% 22 .6 Paved areas & shallow n;;ivP.d swalP,c:;. A2 2 0.05 0.00 30 49% 6.5 68 09% Grassed waterway A3 3 0.28 0.00 75 2.1% 13.7 70 06% Paved areas & shallow o;wed ~wales A4 4 0.06 0.00 66 34% 10.9 21 10% Grassed waterway OSA5 4 O.Q1 0.00 10 73% 3.3 Grassed waterway OSA6 5 0.03 0.00 15 61% 4.3 Grassed waterway 81 6 0.17 0.00 165 15% 22 .6 Paved areas & shallow oaved swales 82 7 0.01 0.00 9 44% 3.7 27 36% Grassed waterway 83 8 0.01 0.00 20 43% 5 .5 Paved areas & shallow oaved swales 84 9 0.14 0.00 27 46% 6.3 103 12% Grassed waterway 85 10 0.11 0.00 65 42% 10 .1 Paved areas & shallow naved swales OSB6 10 0.66 0.00 230 17% 25 .7 Paved areas & shallow naved swales OSC1 11 0.02 0.00 5 15% 3.9 Paved areas & shallow caved swales OSC2 12 0.00 0.00 40 37% 8 .2 Paved areas & shallow naved swales 0 0 0.00 Paved areas & shallow naved swales Property Boundary Total Site 20 1.19 0.00 Paved areas & shallow oaved swales Area to Chambers (A1-A3) 20 0.63 0.00 75 21% 13.7 70 06% Paved areas & shallow o;:ived swales 2873c -Rational Calculations Developed Tc lo Comp tc Urbanized Check lo ON Final Time of Total c... Veloclty t, Cone Length lo=(U180)+ Min (fps) (min) t,•t,=lo (ft) 10 (min) lo 20 a.a a.a 22 .6 165 10.9 10 .9 15 1.4 0.8 7.3 98 10.5 7.3 20 1.5 0.8 14 .4 145 10.8 10 .8 15 1.5 0 .2 11 .1 87 10 .5 10.5 15 0.0 0.0 3.3 10 10 .1 5.0 15 a.a a.a 4 .3 15 10 .1 5.0 20 a.a a.a 22 .6 165 10.9 10 .9 15 2.9 0.2 3 .8 36 10 .2 5.0 20 0.0 0.0 5.5 20 10.1 5.5 15 1.7 1.0 7.3 130 10 .7 7.3 20 0.0 a.a 10.1 65 10 .4 10 .1 20 0.0 0.0 25.7 230 11 .3 11 .3 20 a.a a.a 3.9 5 10.0 5.0 20 a.a 0.0 8 .2 40 10.2 8 .2 20 0 10.0 20 a.a a.a a.a 0 10 .0 5.0 20 1.5 0.8 14.4 145 10 .8 10.8 Page 4 of 16 ---Mason Place Design Storm : 100 Q) c O= Q) E ·o 0 "' a. u u z C ~ O= C O> 0 ;;; ·;;; 111 C "' Q) !" ::, ID 0 < I?'. Al 1 0.30 1.00 A2 2 0.05 0.31 A3 3 0.28 0.89 A4 4 0.06 0.33 0SA5 4 O.ol 0.34 Bl 6 0.17 1.00 B2 7 O.ol 0.47 B3 8 O.ol 0.74 84 9 0.14 0.59 BS 10 0.11 0.76 0586 10 0.66 0.91 OSC1 11 0.02 1.00 OSC2 12 0.00 1.00 OSA6 5 0.03 0.46 2873c -Rational Calculations --JVA Incorporated 213 Linden St, Suije 200 Fort Collins, CO 80524 Ph: (970) 225 9099 - --Job Name: Mason Place Job Number. 2873c Date: 4/2/19 By: LAL --Developed Storm Runoff Calculations Year Point Hour Rainfall (P1): 2.86 Direct Runoff Total Runoff C E u Q) u £ "' 0. '2 "' -;:-i ~ i ~ .E < 1 ~ ]j .S! 0 u (J -£ -0 ... .., -0 -'= 10.90 0.30 7.45 2.24 10 90 030 7.45 2.24 7.30 0.02 8.67 0.14 7 30 002 8.67 0.14 24• Area Dram TOTAL DS of A2 11 34 0 32 7.42 2.35 10.80 0.25 7.48 1.86 10 80 0 25 7.48 1.86 Combo TOTAL DS of Chamber IN MH 11 55 0 57 7.42 4.20 TOTAL DS of Chamber OUT MH 11.55 0 57 7.42 4.20 10.50 O.o2 7.57 0.15 1050 0.02 7.57 0.15 5.00 0.00 9.95 0.05 500 000 9.95 0.05 Total At DP 4 11 55 0.59 7.42 4.38 Tota BASIN A 11 55 0.59 7.42 4.35 10.90 0.17 7.45 1.28 10 90 0 17 7.45 1.28 5.00 0.00 9.95 0.04 5.00 0 00 9.95 0.04 24" Area Drain TOTAL DS of B2 11 06 0.18 7.42 1.30 5.50 0.01 9.63 0.06 5.50 001 9.63 0.06 12" Area Drain DS of B3 and B2 11 20 0 18 7.42 1.35 7.30 0.08 8.67 0.73 7 30 008 8.67 0.73 24" Area Drain DS 0184 11 32 0 27 7.42 1.98 10.10 0.08 7.69 0.62 10 10 008 7.69 0.62 TOTAL BASIN B 11.32 0 35 7.42 2.57 11.30 0.60 7.42 4.45 11 30 060 7.42 4.45 Combo DS of0SB6 11.30 0 95 7.42 7.03 5.00 0.02 9.95 0.19 500 0 02 9.95 0.19 8.20 0.00 8.31 0.02 8 20 000 8.31 0.02 TOTAL SITE BASIN OS 5 00 0 02 9.95 0.21 5.00 0.02 9.95 0.15 5 00 0 02 9.95 0.15 Total Site Flow 7.48 Q100 --- -- - ----1 Inlets Pioe Pioe/Swale Travel Time "Cl !~ .; ~ "' 2 .. " 0. > "' 2 l 3 u € g Q) Q) a,-u 0 "' ~ "' 111 0 .9-~ z:. E .9i t "' 1/) ~ ::; ii: .c '2 F 0. ::, Cl) a. ·o 01 0 "' C ~ >, "a Cl) 0. £'~ ""' 0 .E S£ 2 -.0 0. Q) 0. 0 "' 0. C ,; 0 Q) ;;-0 0 0 a:: a a: iii ::; ,"l ...J > ~ E z 12m PVC 05% 2 24 3.52 73 28 0.44 11.34 12 tn PVC 0.5% 2.35 3.52 36 28 0.21 11.55 10 in PVC 05% 1 9 2.2 26 2.5 0.18 10.98 121n PVC 37% 42 9.6 17 76 0.04 11.59 151n PVC 05% 42 6.4 17 32 0.09 11.64 Outside of Site Boundary 81n PVC 10% 13 1.7 29 30 0.16 11.06 81n PVC 1 O'A, 1.3 1.7 25 30 0.14 11.20 61n PVC 10% 01 0.8 32 25 0.21 5.71 8 in PVC 10% 14 1.7 22 3.0 0.12 11.32 12m PVC 1.0% 2.0 5.0 4.0 0.00 11.32 15 tn PVC 10% 70 9.0 46 0.00 11.30 Page 5 of 16 - - - -Mason Place Design Storm : 2 QI C "' E ·a 8 .. Q. u u z C .!!!. "' C .11' 0 in ~ .. C .. !! " m Q <( "' A1 1 0.30 0.95 A2 2 0.05 0.25 A3 3 0.28 0.84 A4 4 0.06 0.27 OSA5 4 0.01 0.27 81 6 0.17 0.95 82 7 O.Q1 0.41 83 8 0.01 0.68 84 9 0.14 0.53 BS 10 0.11 0.70 OSB6 10 0.66 0.86 OSC1 11 0.02 0.95 OSC2 12 0.00 0.95 OSA6 5 0.03 0.40 --JVA Incorporated 213 linden St, Suite 200 Fort Collins, CO 80524 Ph: (970) 225 9099 --Job Name: Mason Place Job Number: 2873c Date: 4/2/19 By: LAL - -Developed Storm Runoff Calculations Year Point Hour Rainfall (P,) : 0.82 Direct Runoff Total Runoff c E u 8. u .!l ~ c .,,. ~ ?=' I .!!!. 1 <( ,E .I') :i: " s u j () :§. -0 -.!l u -0 I-.. -0 .E 10.90 0.29 2.14 0.61 10 90 0 29 2.14 0.61 7.30 0.01 2.48 0.03 7 30 0 01 2.48 0.03 24 • Area Drain TOTAL OS of A2 11 34 0 30 2.11 0.63 10.80 0.23 2.15 0.50 10 80 0 23 2.15 0.50 Combo TOTAL OS of Chamber IN MH 11 55 0 53 2.09 1.11 TOT AL OS of Chamber OUT MH 11 55 0 53 2.09 1.11 10.50 0.02 2.17 0.04 10 50 0 02 2.17 0.04 Total A BASIN 11 55 0 55 2.09 1.15 5.00 0.00 2.85 0.01 5 00 0 00 2.85 0.01 Total At DP4 11 55 0 55 2.09 1.16 10.90 0.16 2.14 0.35 1090 016 2.14 0.35 5.00 0.00 2.85 0.01 5 00 000 2.85 O.Q1 24• Area Drain TOTAL OS of B2 11 06 0 17 2.13 0.35 5.50 0.01 2.76 0.02 5 50 0 01 2.76 0.02 12• Area Drain OS of 83 and B2 11 20 0 17 2.12 0.37 7.30 0.08 2.48 0.19 7 30 0 08 2.48 0.19 24• Area Drain OS ofB4 11 32 0 25 2.11 0.52 10.10 0.07 2.20 0.16 10 10 0 07 2.20 0.16 Total B BASIN 11 32 0 32 2.11 0.68 11.30 0.57 2.11 1.19 11 30 0 57 2.11 1.19 Combo OS of OSB6 11 30 0 89 2.11 1.87 5.00 0.02 2.85 0.05 5 00 0 02 2.85 0.05 8.20 0.00 2.38 0.01 8 20 000 2.38 0.01 TOTAL SITE BASIN OS 5 00 0 02 2.85 0.05 5.00 0.01 2.85 0.04 500 0 01 2.85 0.04 CHAMBER FLOW WQCV (use 1/2 the Intensity calculated for the 2 year event) Area to Chambers 20 0.63 0.84 10.80 0.53 1.07 0.57 10 80 0 53 1.07 0.57 fA1-A3) Total Site Flow 1.91 2873c -Rational Calculations Q Minor --- ------Inlets Pioe Pioe/Swale Travel Time 'O Ii ]i tl ~ s iii C. > "' .!i ~ 3: g ~ QI 0 .~ ~ :ii.-~ "' .. .Q .~ t .. ::; ii: 'E .r:: ;:: ~ C. "'" 8. u. "6, u -~ "' rl ,.. 8. if 8. 8."' >< .. .Q s:? s D C .Q ~ ,, QI QI ;; 0 0 a 0 a: ~ ii: "' o:u ...J > 8 E z 12 In PVC 0.5% 06 3.5 73 28 0.44 11.34 12 in PVC 0.5% 06 3.5 36 28 0.21 11.55 10 In PVC 0.5% 05 2.2 26 25 0.18 10.98 12 In PVC 3.7% 11 9.6 17 76 0.04 11.59 15 In PVC 0.5% 11 6.4 17 32 0.09 11.64 Outside of S1te Boundary 8 In PVC 1.0% 03 1.7 29 30 0.16 11.06 8 In PVC 1.0% 04 1.7 25 30 0.14 11.20 6 In PVC 1.0% 00 0.8 32 25 0.21 5.71 8 in PVC 1.0% 04 1.7 22 30 0.12 11.32 12 in PVC 1.0% 05 5.0 114 40 0.48 11.80 15 in PVC 1.0% 19 9.0 28 46 0.10 11.40 Page 6 of 16 I I I I I I I I I I I I I I I I Mason Place JVA Incorporated 213 Linden St , Suite 200 Fort Collins , CO 80524 Ph : (9 70 ) 225 9099 Job Name : Mason Place Job Number: 2873c Date : 4/2/19 By: LAL LID AREA Calculations per City of Fort Collins -Option 2 The implementation of LID systems requires one of the following two options : 1) 5°" of the newly added or modified impervious area must be trea ed by UD techniques and 25% of new paved (vehicle use) areas must be pervious. 2) 75% of all newly iKlded or modi eel impervious area must be treated by LID techn·ques .• Total Site Area = Total Site Impervious Area = Roof Area= Added or Modified Impervious Area = Required Impervious Area to be treated by LID Acres 1.19 0.87 0.43 0.44 0 .33 Tota l Si te Area to Chambers = 0.63 Notes Area within the property boundary Area within the property boundary Roof area excluded per CoFC (roof not conside red as being modified) 75% of added or modified impervious area Provided Im pervious Area to LID = 0.54 Includes Roof area that drains to chambers Impervious surfaces are de ned as hardscape surfaces that do not a low stormwate< o inti rate into e ground. pervious surfaces include asphalt and concre e surfaces, concrete curbs, gutters, sidewalks, patios and rooftops. (Impervious surface ar-eas must be assumed for-s:i g.le family residential lots when overall impervious areas are being determined for residential developments. The assumed areas must · en be induded in LID calrula ions.) I I I I I I I I I I I I I I I I I I I Mason Place JVA Incorporated 2 13 Linden St, Su ite 200 Fort Co lli ns, CO 80524 Ph : (970) 225 9099 Job Name: Mason Place Job Number: 2873c Dat e: 4/2/19 By: LAL Water Quality Capture Volume (WQCV) Calculations (UDFCD Volume 3 Chapter 3) WQCV = a(0 . .9LL 1.19.a+ 0 .78/) Where : WQCV = Water Quality Capture Volume (watershed inches) a = Drain Time Coefficient (see t ab le below ) I= Imperviousness (%/100 ) Drainaae T ime /hrs) Coefficient, a 12 0.8 24 0.9 40 1.00 a= 0.80 12 hour drawdown ti me I= 0.802 %/1 00 WQCV= 0.264 watershed in ch es V = r-:~AXL2 WQCV= 0.264 wa tershed inches A= 0.63 acre V= 729 cf V= 0.017 acre-ft Equation 7-1 Eq11ation 7 -2 Fort Collins Stormwater Criteria Manual Fort Coll ins Stormwater Criteria Manual - -·-- ---- ----- -- ---Mason Place JVA Incorporated 213 Linden St, Suite 200 Fort Collins, CO 80524 Ph: (970) 225 9099 Job Name: Mason Place Job Number: 2873c Date: 4/2/19 By: LAL StormTech Chamber Sizing Calculation (per City of Fort Collins Example) 1 2 3 4 5 6 7 Total Required Chamber Chamber Installed Chamber Flow, WQ Chamber Minimum No. of Vault ID WQVolume (cfs) Release Rate' Volume• Volumew/ Chambers• (cf) Type (cfs) (cf) Aggregate< (cf) EXAMPLE 660 0.55 SC-160 0.011 6.85 15 44 A 729 0.57 SC-310 0.016 14.7 29.3 25 a. Release rate per chamber, limiled by flow through geotextile with accumulated sediment b. Volume wilhin chamber only, nol accounting for void spaces in surrounding aggregate c. Volume includes chamber and void spaces (40%) in surrounding aggregate, per chamber unit d. Number of chambers required to provide full WQCV within lotal installed system, including aggregale. e. Release rate per chamber limes number of chambers. f. Number of chambers required to provide required FAA storage volume stored within the chamber only (no aggregate slorage). g. Volume provided in chambers only (no aggregate storage). This number must meet or exceed the required FAA storage volume. 8 Total Release Rate• (cfs) 0.50 0.39 h. System volume includes total number of chambers, plus surrounding aggregate. This number must meet or exceed the required WQCV. Chamber Flow Rate Conversion (gpm/sf to cfs) 9 -10 11 Required Storage Storage Volume Minimum No. of Provided within by FAA Method Chambers f the Chambers• (cf) (cf) 59 9 62 118 9 132 StormTech Chamber Data Flow Rate• 0.35 loom/sf Chamber Dimensions SC-160 SC-310 1 cf= 7.48052 1gal Width(in) 25.0 34.0 1 gallon~ 0.133681 cf 1 GPM = 0.002228 cfs Length (in) 84.4 85.4 Height (in) 12.0 16.0 Floor Area (sf) 14.7 20.2 "Flow ,aw b.ised on 1/2 of Nov 07 <l.w.,. In Figure 17 of UNH TeUing Report •Allowable flow rate thru fabric considering rate is reduced by sedimentalion between Isolator Row cleanings Chamber Volume (cf) 6.9 14.7 Chamber/Aggregate Volume (cf) 15.0 29.3 Chamber Flow Rate SC-160 I SC-310 SC-740 Flow Rate/chamber (cfs) 0.0114261 0.015724 0.023586 12 Total Installed System Volume• (cf) 660 733 SC-740 51.0 85.4 30.0 30.2 45.9 74.9 -- I I I I I I I I I I I I I I I I I I I Maso n Plac e JVA Incorpo rated 213 Linden St, Suite 200 Fort Collin s , CO 80524 Ph: (970) 225 9099 Job Name : Mason Place Job Number: 2873c Date : 4/2/19 By: LAL De te nt ion Pond Volume Calcul ations: Modifed FAA Procedure Modified FAA Procedure (1966) detention sizing method as modified by Guo (1999a) Dra inage Basin Design Storm Composite "C" Factor Basin Size Release Rate Calculations A 2 year 0 .84 0 .63 Allowable Release Rate for Site 0.39 cfs (Historic Flows for Basin H1) _L_e_ss_U_nd_e_ta_in_e_d_O_ff_s_it_e_F_lo_w_s _________ o_.O_O_c_fs ___ (From Basin X) Allowable Release Rate for Pond 0 .39 cfs Rainfall Intensity Calculations Point Hour Rainfall (P 1 ): Rainfall Intensity : Volume Calculations Inflow Volume = C * I * A * (60 * T) 0.82 FortCollinslDF Outflow Volume= Alowable Release Rate * time (sec) Storage Volume = lnvflow Volume -Outflow Volume Detention Storage Calculations Time Time Intensity WQ Intensity lnTIOW T T I 1/2 Vin (min) (sec) (in/hr) (in/hr) (ft3) 5 .0 300 2.85 1.43 229 10 .0 600 2 .21 1.11 355 15 .0 900 1.87 0 .94 450 20 .0 1,200 1.61 0 .81 517 25 .0 1,500 1.43 0 .72 573 30 .0 1,800 1.30 0.65 626 35 .0 2 ,100 1.17 0.59 658 40 .0 2 ,400 1.07 0 .54 688 45 .0 2 ,700 0 .99 0 .50 716 50.0 3 ,000 0 .92 0.46 740 55 .0 3 ,300 0 .87 0.44 768 60 .0 3 ,600 0.82 0.41 789 65 .0 3 ,900 0 .78 0.39 813 70 .0 4 ,200 0 .73 0.37 820 75 .0 4 ,500 0 .70 0 .35 842 80 .0 4,800 0 .66 0 .33 847 85.0 5 ,100 0 .64 0.32 873 90 .0 5,400 0 .61 0 .31 881 95 .0 5 ,700 0 .58 0 .29 884 100.0 6 ,000 0 .56 0 .28 898 105 .0 6 ,300 0.54 0 .27 910 110 .0 6 ,600 0.52 0 .26 918 115 .0 6 ,900 0.51 0 .26 941 120.0 7 ,200 0 .49 0 .25 943 UUUIOW Vout (ft3) 118 236 354 473 591 709 827 945 1,063 1,181 1,300 1,418 1,536 1,654 1,772 1,890 2 ,008 2 ,127 2 ,245 2,363 2,481 2 ,599 2 ,717 2,835 Maximum Volume (ft3) 2873c -Rational Ca lculations Modified FAA WQ :storage Vstor (ft 3) 110 118 96 44 -17 -83 -169 -257 -347 -442 -531 -628 -723 -834 -930 -1 ,043 -1 , 136 -1 ,246 -1 ,361 -1,464 -1 ,571 -1 ,682 -1,776 -1 ,892 118 Page 10 of 16 I I I I I 11 I I I I I I I I I I I I I JVA Incorporated 213 Linden St, Suite 200 Fort Collins , CO 80524 Ph : (970) 225 9099 FLOW CALCULATIONS -GRATE INLET SUMP CONDITION Job Name: Mason Place Job Number: 2873c Date: 4/2/19 By : LAL (Reference : Urban Dra in age and Flood Control District Drainage Criteria Manual , 2001 , V.1 , Section 3 .3.6) (Note: Spreadsheet assumes orifice condition for fully developed flow .) INLET TYPE: 24" Area Drain BASIN: A1 + A2 Orifice Equation: Q = Cd *Ao*(2gH)A0 .5 K = Clogging Coefficent value Adjust Ao (open area) due to clogging as follows : Effective Area Opening Ae = (1-C) Ao , where : C=K*Co/N N = Number of Inlets Co = Single Inlet Clogging Factor: Co(grate) = 0 .5 (50% clogg ing) Number of inlets : Inlet Dimensions and Effective Open Area: Grate Opening: Allowable depth: Constants : Flow Calculations: Grate Flow: N= 1 Ao(g) = 1 .6 Total Ao(g) = 1.60 K = 1.00 C = K*Co/N = 0 .50 Ae(g) = (1-C)Ao = 0.80 H= 4 .0 g = 32.20 Cd= 0 .67 Q = Cd * Ae(g) * (2g*H)"0.5 Qg= 2.48 ft"2 ft"2 ft"2 in = ft/s"2 CFS for multiple inlets N Grate 1 1 2 1.5 3 1.75 4 1.88 5 1.94 6 1.97 7 1.98 8 1.99 0.3333333 ft Total Intercepted Flow with an allowable depth of __ 1 __ inlet(s) and Required Flow (Q 2 Required Flow (Q 100 2873c -Rational Calculations ~ : t-1--~-:~-:---11::: A2 -Grate-Sump(UDFCD) 4 inches is Bypass= Bypass= 2.5 ===== 0.0 0.0 cfs cfs cfs Page 11 of 16 I I I I I I I I I I I I I I I I I I I JVA Incorporated 213 Linden St, Suite 200 Fort Collins, CO 80524 Ph : (970) 225 9099 Job Name: Mason Place Job Number: 2873c Date: 4/2/19 By: LAL FLOW CALCULATIONS -COMBINATION INLET SUMP CONDITION (Reference: Urban Drainage and Flood Control District Drainage Criteria Manual , 2001, V .1, Section 3 .3 .6) (Note: Spreadsheet assumes orifice condition for fully developed flow. Vertical curb opening only.) INLET TYPE: S ing le Combination Inlet BASIN: A3 Orifice Equation: Q = Cd *Ao*(2gH)A0 .5 Adjust Ao (open area) due to clogging as follows : K = Clogging Coefficent value Effective Area Opening Ae = (1-C) Ao, where: C=K*Co /N N = Number of Inlets Co = Single Inlet Clogging Factor: Co(grate) = Co(curb opening) = Number of inlets : Inlet Dimensions and Effective Open Area : Grate Opening: Curb Opening: 0 .5 0.1 (50% clogging) (10% clogging) N = Ao(g) = 2 .32 Tota l Ao(g) = 2.32 K = 1 .00 C = K*Co/N = 0 .50 ft"2 (per inlet) ft"2 (total, a ll inlets) Ae(g) = (1-C)Ao = 1.16 ftA2 length (I) = 36 height (h) = 6 Total Ao(c) = 1.50 K = 1.00 C = K*Co/N = 0 .10 in = 3 .00 in = 0 .50 ft"2 (tota l, all inlets) Ae(c) = (1-C)Ao = 1.35 ft2 N 1 2 3 4 5 6 7 8 for multiple in lets Grate 1 1.5 1 .75 1.88 1.94 1.97 1 .98 1 .99 ft (per inlet) ft Curb 1 1.25 1.31 1 .33 1 .33 1 .33 1.33 1.33 Allowable depth : H = 4.0 in = 0.333333 ft Constants : Flow Calculations: Grate Flow: Curb Flow: Total Intercepted Flow with an allowable depth of g = 32 .20 ft/s"2 Cd= 0 .67 Q = Cd * Ae(g) * (2g*H)"0 .5 Qg= 3.60 CFS Q =Cd* Ae(c) * (2g*D)"0 .5 D = H -h/2 = 0.083333 Qc= 2.10 CFS 1 inlets and ----4 inches is Required Flow (Q 2 Required Flow (Q 100 ; : 1-1--~-::-~--1::: 2873c -Rational Calculations A3 -COMBO-Sump(UDFCD) Bypass = Bypass = 5.7 0.0 0.0 cfs cfs cfs Page 12 of 16 I I I I .I I I I I I I I I I I I I I I JVA Incorporated 213 Linden St, Suite 200 Fort Collins , CO 80524 Ph : (970) 225 9099 FLOW CALCULATIONS -GRATE INLET SUMP CONDITION Job Name: Mason Place Job Number: 2873c Date : 4 /2/19 By: LAL (Reference : Urban Drainage and Flood Control District Dra inage Criteria Manual , 2001 , V.1 , Section 3 .3 .6) (Note : Spreadsheet assumes orifice condition for fully developed flow .) INLET TYPE: 24 " Area Drain BASIN: 82 Orifice Equation: Q = Cd *Ao*(2gH)"0 .5 K = Clogg ing Coefficent value for multiple inlets Adjust Ao (open area) due to clogg ing as follows: Effective Area Opening Ae = (1 -C) Ao , where : C=K *Co/N N = Number of Inlets Co = S ingle Inlet Clogg ing Factor: Co(grate ) = 0 .5 (50% clogging) Number of inlets: Inlet Dimens ions and Effective Open Area : Grate Opening : Allowab le depth : Constants : Flow Calculations: Grate Flow: N= 1 Ao(g ) = 1 .6 Total Ao(g ) = 1.60 K = 1.00 C = K*Co/N = 0 .50 Ae(g) = (1-C)Ao = 0.80 H = 0 .5 g = 32 .20 Cd= 0 .67 Q = Cd * Ae(g) * (2g *H)"0.5 Qg= 0 .88 ft"2 ft"2 in = ft/s"2 CFS N 1 2 3 4 5 6 7 8 0.0416667 ft Total Intercepted Flow with an allowable depth of __ 1 __ inlet(s) and Required Flow (Q 2 Required Flow (Q 100 2873c -Rational Calculations 82 -Grate-Sump(UDFCD) 1 inches is Bypass= Bypass= Grate 1 1.5 1.75 1.88 1.94 1.97 1.98 1.99 0.9 0.0 0.0 cfs cfs cfs Page 13 of 16 I I I I I I I I I I I I I I I I I I JVA Incorporated 213 Linden St, Suite 200 Fort Collins , CO 80524 Ph : (970) 2-25 9099 FLOW CALCULATIONS -GRATE INLET SUMP CONDITION Job Name: Mason Place Job Number: 2873c Date : 4/2/19 By: LAL (Reference: Urban Drainage and Flood Control District Drainage Criteria Manual , 2001 , V .1, Section 3 .3 .6) (Note: Spreadsheet assumes orifice condition forfully developed flow.) INLET TYPE: 12" Area Dra in BASIN: 8 3 Orifice Equation: Q = Cd*Ao *(2gH)11 0 .5 Adjust Ao (open area ) due to clogging as follows : K = Clogging Coefficent value for multiple in lets Effective Area Open ing Ae = (1-C) Ao , where : C = K *Co/ N N = Number of Inlets Co = S in gle Inlet Clogging Factor: Co(grate) = Number of inlets : Inlet Dimens ions and Effective Open Area : Grate Opening: Allowab le depth: Constants: Flow Calcu lations : 0 .5 (50% clogging) N= 1 Ao(g) = 0 .38 ft112 Total Ao(g) = 0 .38 ft11 2 K = 1.00 C = K*Co/N = 0.50 Ae(g) = (1-C)Ao = 0.19 ft"2 H= 2 .0 g = 32 .20 Cd= 0 .67 in = Grate Flow: Q = Cd * Ae(g) * (2g*H)II0.5 Qg= 0.42 CFS N Grate -1 I 2 1 .5 3 1.75 4 1.88 5 1.94 6 1.97 7 1.98 8 1.99 0.1666667 ft Total Intercepted Flow with an allowable depth of 1 inlet(s) and Required Flow (Q 2 Required Flow (Q 100 2873c -Rational Calculations ----2 inches is : : 1-, --~-:~-:---11::: 83 -Grate-Sump(UDFCD) Bypass= Bypass= 0.4 cfs ==== 0.0 0 .0 cfs cfs Page 14 of 16 I I I I I I I I I I I I I I I I I I I JVA Incorporated 213 Linden St, Su ite 200 Fort Colli ns , CO 80524 Ph : (9 70 ) 225 9099 FLOW CALCULATIONS -GRATE INLET SUMP CONDITION Job Name: Mason Place Job Number: 2873c Date : 4/2/19 By : LAL (Reference: Urban Drainage and Flood Control District Drainage Criteria Manual , 2001 , V.1 , Section 3 .3 .6) (Note : Spreadsheet assumes orifice condition for fully developed flow.) INLET TYPE: 24" Area Drain BASIN: 84 Orifice Equation: Q = Cd *Ao*(2gH)"0.5 Adjust Ao (open area) due to clogging as follows : K = Clogging Coefficent va lue for multiple inlets Effective Area Opening Ae = (1-C) Ao , where : C=K*Co/N N = Number of Inlets Co = S ingle Inlet Clogging Factor: Co(grate) = 0 .5 (50% clogg ing) Number of inlets: Inlet Dimensions and Effective Open Area : Grate Opening: Allowable depth : Constants: Flow Calculations : Grate Flow: N= Ao(g) = 1 .6 Total Ao(g) = 1.60 K = 1.00 C = K*Co/N = 0 .50 1 Ae(g) = (1-C)Ao = 0.80 H= 0 .5 g = 32 .20 Cd= 0 .67 Q = Cd * Ae(g) * (2g *H)"0.5 Qg= 0.88 ft"2 ft"2 in = ftls"2 CFS N Grate 1 I 2 1.5 3 1.75 4 1 .88 5 1.94 6 1.97 7 1.98 8 1.99 0.0416667 ft Total Intercepted Flow with an allowable depth of __ 1 __ inlet(s) and 1 inches is Required Flow (Q 2 Required Flow (Q 100 ~ : 1---~-: ;-:----11::: 2873c -Rational Calcu lations 84 -Grate-Sump(UDFCD) Bypass= Bypass= 0.9 cfs ==== 0.0 0.0 cfs cfs Page 15 of 16 I I I I I I I I I I I I I I I I I I I JVA Inco rporated 213 Linden St, Suite 200 Fort Collins , CO 80524 Ph: (970) 225 9099 FLOW CALCULATIONS-COMBINATION INLET SUMP CONDITION Job Name: Mason Place Job Number: 2873c Date: 4/2/19 By: LA L (Reference : Urban Drainage and Flood Control District Drainage Criteria Manual , 2001, V .1, Section 3 .3 .6) (Note : Spreadsheet assumes orifice condition for fully developed flow . Vertical curb opening o nly.) INLET TYPE: Sin g le Combination Inlet BASIN: OSB6 Orifice Equation: Q = Cd*Ao*(2gH)A0 .5 Adjust Ao (open area) due to clogging as follows : K = Clogging Coefficent value Effective Area Opening Ae = (1-C) Ao , where : C=K*Co/N N = Number of Inlets Co= Single Inlet Clogging Factor: Co(grate) = Co(curb opening)= Number of inlets: Inlet Dimensions and Effective Open Area : Grate Opening: Curb Opening: 0.5 0 .1 (50% clogging) (10% clogging) N = Ao(g) = 2 .32 Total Ao(g) = 2.32 K = 1.00 C = K*Co/N = 0 .50 ftA2 (per inlet) ftA2 (total , all inlets) Ae(g) = (1-C)Ao = 1.16 ftA2 length (I) = 36 height (h) = 6 Total Ao(c) = 1.50 K = 1.00 C = K*Co/N = 0.10 in = 3 .00 in = 0.50 ftA2 (total , all inlets) Ae(c) = (1-C)Ao = 1.35 ft2 N I 2 3 4 5 6 7 8 for multicle inlets Grate I 1.5 1.75 1.88 1.94 1.97 1.98 1.99 ft (per inlet) ft Curb 1 1.25 1.31 1.33 1.33 1.33 1.33 1.33 Allowable depth : H = 4.0 in = 0.33 3333 ft Constants : Flow Calculations : Grate Flow: Curb Flow: Total Intercepted Flow with an allowable depth of 9 : 32 .20 ft/5A2 Cd= 0.67 Q = Cd • Ae(g) • (2g*H)A0 .5 Qg= 3.60 CFS Q =Cd* Ae(c) * (2g*D)A0 .5 D = H -h/2 = 0 .083333 Qc= 2.10 CFS 1 inlets and ----4 inches is Required Flow (Q 2 Required Flow (Q 100 ~ : t-l --!-:!-:--1::: 2873c -Rational Calculations OSB6 -COMBO-Sump(UDFCD) Bypass= Bypa ss = 5.7 0 .0 0.0 cfs cfs cfs Page16of16 I I I I I I I I I I I I I I I I I I I Project: MASON PLACE (5119791) ~ Chamber Model -SC-310 Storm iech9 Units -1-,1;::m::~~-::;---J._C_tic-k H-e-,e-fo-, M-e-tri-c Deten&cxl • Retent,on • Water Ouallty JI rlivisio n of ~- Number of chambers - Voids in the stone (porosity) - Base of ST ONE Elevation - Amount of Ston e Above Chambers - Amount of Stone Below Chambers - Area of system - Height of System finchesJ 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Incremental Single Chamber (cubic feetJ 0 .00 0.00 0.00 0 .00 0 .00 0.00 0 .06 0 .15 0 .27 0 .54 0.70 0.82 0.92 1.01 1.09 1.15 1.21 1.27 1.32 1.36 1.40 1.43 0.00 0 .00 0 .00 0 .00 0 .00 0 .00 Incremental Total Chamber (cubic feetJ 0 .00 0 .00 0 .00 0 .00 0 .00 0 .00 1.47 3.87 6.65 13 .62 17 .60 20 .61 23 .11 25 .37 27 .36 28.86 30 .37 31 .87 33 .11 34.12 35 .12 35 .87 0 .00 0.00 0 .00 0 .00 0 .00 0 .00 25 40 5036.28 6 6 841 lnaemental Stone (cubic feetJ 28 .03 28 .03 28 .03 28 .03 28 .03 28.03 27.45 26.49 25 .37 22 .59 20 .99 19 .79 18 .79 17 .88 17 .09 16 .49 15.88 15 .28 14.79 14 .38 13 .98 13 .69 28.03 28 .03 28 .03 28 .03 28.03 28 .03 % j 0 Include Perimeter Stone in c.atculations ft in in sf Min . Area -593 sf min . area lnaemental Ch &St (cubic feetJ 28 .03 28 .03 28 .03 28.03 28.03 28 .03 28 .92 30 .35 32 .02 36 .21 38 .59 40.40 41 .90 43.26 44.45 45.35 46 .26 47 .16 47 .90 48.51 49 .11 49 .55 28 .03 28.03 28 .03 28 .03 28 .03 28 .03 Cumulative Chamber (cubic feet) 1006 .34 978 .30 950 .27 922 .24 894 .20 866 .17 838 .14 809 .22 778.87 746 .84 710 .64 672 .05 631 .64 589.74 546.48 502 .03 456 .68 410.43 363 .27 315.37 266 .86 217 .75 168 .20 140 .17 112.13 84 .10 56.07 28 .03 Elevation (feet) 5038 .61 5038.53 5038.45 5038 .36 5038.28 5038 .20 5038 .11 5038 .03 5037 .95 5037 .86 5037 .78 5037 .70 5037 .61 5037.53 5037.45 5037.36 5037.28 5037.20 5037 .11 5037 .03 5036 .95 5036 .86 5036 .78 5036.70 5036 .61 5036 .53 5036.45 5036 .36