Loading...
HomeMy WebLinkAboutDrainage Reports - 01/06/2017Project Development Plan (PDP) Final Drainage Report for 625 Peterson Street Redevelopment ' MA September 20, 2016 City of Fort2CA 4Approed Phu,. - Approved by: Date: TST. INC. CONSULTING CNC.INE CI'S s 0 TST 760 Whalers Way Bldg C, Suite 200 Fort Collins, CO 80525 970.226.0557 main 303.595.9103 metro 970.226.0204 fax ideas@tstinc.com www.tstinc.com TST, INC. CONSULTING ENGINEERS September 20, 2016 Mr. Mark Taylor, P.E., CFM City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80521 Re: 625 Peterson Street Redevelopment Project No. 0663.0012.00 Dear Mr. Taylor: We are pleased to submit this Final Drainage Report for the 625 Peterson Street Redevelopment. This report analyzes the developed stormwater runoff from the project and provides stormwater infrastructure and water quality management for runoff. The 625 Peterson Street Redevelopment is located in the City of Fort Collins Old Town Moderate Risk Floodplain. It is understood that there are no floodplain elevation standards for this development, but we have taken the elevation recommendations into account when designing this site. This report has been prepared based on the City of Fort Collins Stormwater Criteria Manual and complies with the PDP submittal requirements for a final drainage report. Respectfully, TST, INC. CONSULTING ENGINEERS Jon Sweet; 2 .o 40341 m JFS/EMF/jr s`s�ONAL Eric M. Fuhrman, P.E. 0 C C Stormwater Alternative ComplianceNariance Application City of Fort Collins Water Utilities Engineering Engineer Name Jonathan Sweet Phone 970-488-2128 Street Address 748 Whalers Way, Suite 200 City Fort Collins State CO Zip 80525 Owner Name Hellmann Properties LLC Phone 970-372-9500 Street Address 1421 Rollingwood Lane City Fort Collins state co Tin 80525 Project Name 625 Peterson Street - Multi -Family Project/Application Number from Development Review (i.e. FDP123456) PDP160005 Legal description and/or address of property North half of Lot 3, Block 146 Northwest quarter Section 13 Township 7 north, Range 69 west Description of Project Existing single family lot to be converted into multi -family Existing Use (check one): C residential (-' non-residential r' mixed -use r' vacant ground Proposed Use (check one): r: residential r non-residential f mixed -use r other If non-residential or mixed use, describe in detail State the requirement from which alternative compliancelvariance is sought. (Please include applicable Drainage Criteria Manual volume, chapter and section.) Urban Storm Drainage Criteria Manual, Volume 3, Section 3 - Calculation of WQCV What hardship prevents this site from meeting the requirement? Please refer to separate sheet attached to the back of this application. What alternative is proposed for the site? Attach separate sheet if necessary Additional WQCV has been incorporated into the catchment at the back of the proposed structure to help offsite a lack of water quality at the front. Attach separate sheet if necessary C. page 2 The owner agrees to comply with the provisions of the zoning ordinance, building code and all other applicable sections of the City Code, Land Use Code, City Plan and all other laws and ordinances affecting the construction and occupancy of the proposed building that are not directly approved by this variance. The owner understands that if this variance is approved, the structure and its occupants may be more susceptible to flood or runoff damage as well as other adverse drainage issues. Signature of The engineer hereby certifies that the above information, along with the reference plans and project descriptions is correct. Signature of rho,, a 3 v I lv PE STAMP Date complete application submitted: 11 ?O 1 Date of approvaUdenial: 149 /.2Z' 17 Variance: 0 approved ❑ denied / Staff(( justification/notes/condii[t�iions: of r c a f� rC it 11' }pr L. lb or1 5. T C tlH /s 'c /'O SP G I d✓,(/' l qn S / C. / . Cl Y`4 4 C o O C S i Approved by: Entered in UtilityFile Database? yes [:]no ection Q Alternative Comoliance/Variance Information What hardship prevents this site from meeting the requirement? 625 Peterson is a small existing residential lot. This project proposes to add a tri-plex onto the existing single-family structure. Site constraints make it very challenging to accommodate water quality capture volume in 2 of the 3 proposed stormwater catchments. The basin in the rear of the lot is capable of meeting its WQCV and the 25% pervious paver requirement for the site. The 2 remaining basins consist of the existing/proposed roof area, narrow sideyards and small front yard. These basins have aback to front slopes at less than 1.0%. This minimal slope requires the use of a bioswale, or concrete trickle pan, to transfer stormwater along the narrow sideyards towards Peterson Street. There are no existing storm systems adjacent to the site and minimal drop across the site make an underdrain system challenging. Therefore bioswales, to transfer the flow to the front of the lot, and raingardens, to capture stormwater at the downstream end of the lot, are not viable options for the WQCV strategy. There is not any paved parking planned in these two basins, so pervious pavers don't make sense for WQCV either. The remaining option to fulfill the WQCV criteria is extended detention. This would require the control of stormwater leaving the site and ponding water in the small front yard adjacent to the existing structure. Ponding next to the structure would be contrary to standard stormwater design procedures. In summary this is small residential lot with minimal slope and no reasonable tie point for an underdrain system. Water quality has been implemented where possible and in places that will minimize risk to existing and proposed structures. 625 Peterson Street Redevelopment PDP Final Drainage Report TABLE OF CONTENTS 1.0 Introduction Page 1.1 Scope and Purpose...................................................................................................1 1.2 Project Location and Description...............................................................................1 2.0 Existing Conditions........................................................................................................3 3.0 Developed Conditions Plan 3.1 Design Criteria for Hydrologic Analysis......................................................................3 3.2 Drainage Plan Development......................................................................................4 3.2.1 Channel Design................................................................................................4 3.2.2 Detention Requirements and Water Quality Capture Volume Design ...............5 3.3 Low Impact Development..........................................................................................5 3.4 Old Town Moderate Risk Floodplain Management....................................................7 4.0 Conclusion.......................................................................................................................7 5.0 References.......................................................................................................................8 Figures Figure1. Vicinity Map..................................................................................................................2 Figure 2. Four -Step Process for Stormwater Quality Management.............................................6 Tables Table 1. Existing VS. Proposed Impervious Area........................................................................5 Appendices Appendix A: Rational Method Hydrologic Analysis Appendix B: Channel Design Appendix C: Water Quality Capture Volume Appendix D: Low Impact Development TST, INC. CONSULTING ENGINEERS C] 625 Peterson Street Redevelopment PDP Final Drainage Report 1.0 Introduction 1.1 Scope and Purpose This report has been developed in accordance with the City of Fort Collins Stormwater Criteria Manual requirements and complies with Project Development Plan (PDP) submittal requirements which present the results of a preliminary drainage analysis for the 625 Peterson Street Redevelopment. 1.2 Project Location and Description The 625 Peterson Street Redevelopment is a 12,000 s.f. existing single family lot located in the northwest quarter of Section 13, Township 7 North, Range 69 West. The site is located on the west side of Peterson Street approximately halfway between East Laurel Street and East Myrtle Street. Please refer to Figure 1 on the next page for a Vicinity Map. This development is located within the City of Fort Collins Old Town Moderate Risk Floodplain. The Base Flood Elevation (BFE) at the rear of the property is approximately 4989.9 and the front is at roughly 4988.9 (NAVD88). This floodplain has no elevation standards for development, but it is recommended that the lowest finished floor and all duct work, heating, ventilation and air conditioning, hot water heaters, electric, etc. be elevated a minimum of 24" above the BFE. laTST, INC. CONSULTING ENGINEERS Page 1 • 625 Peterson Street Redevelopment PDP Final Drainage Report Figure 1. II;I 11I� =- �► 1 � �II�IIi �- IIIIII __ ___ _■� ._I_�1 IHam _ ---or, ii VICINITY MAP 2.0 Existing Conditions The existing site contains a single family residence, shed/garage type structures and interconnecting paver/concrete pathways and patios. The site generally drains to the east, or toward the front of the lot, at roughly 0.8%. There is an existing concrete alley in the back of the lot that flows north at approximately 0.3% and is captured by area inlets in the alley roughly 185' to the north. The front of the lot has a vertical curb and gutter. This gutter flows south at roughly 0.3% to the intersection of Peterson Street and East Laurel Street where runoff is picked up by a curb inlet. TST. INC. CONSVLTING ENGINVE"" E 625 Peterson Street Redevelopment 3.0 Developed Conditions Plan 3.1 Design Criteria for Hydrologic Analysis PDP Final Drainage Report The drainage plan presented in this report has been developed in accordance with the City of Fort Collins Stormwater Criteria Manual and the City of Fort Collins submittal requirements for a Project Development Plan (PDP). The drainage basin presented in this report is less than 90 acres, therefore, the method used to analyze drainage for this project will be the Rational Method. Runoff calculations for both the 2- year and 100-year storms will be presented here. The Rational Method is given by: Q = C(CQIA where • Q is the maximum rate of runoff in cfs • C is the runoff coefficient • Cf is the runoff coefficient frequency factor adjustment • I is the rainfall intensity in inches per hour for a storm duration equal to the time of concentration • A is the total area of the basin in acres The runoff coefficient C has different values depending on the design storm recurrence interval. The runoff coefficient is also dependent on land use or surface characteristics/imperviousness. Runoff coefficients were assigned using Table RO-11 from the Fort Collins Stormwater Criteria Manual. The frequency factor adjustment, Cf, varies depending on the storm frequency and can be found in Table RO-12 of the Fort Collins Stormwater Criteria Manual. The rainfall intensity is selected from Rainfall Intensity Duration Frequency Curves for the City of Fort Collins (Tables RA-7 through RA-9 of the Fort Collins Stormwater Criteria Manual). In order to utilize the Rainfall Intensity Duration Curves, the time of concentration is required. The following equation is used to determine the time of concentration tc = t; + tt where • tc is the time of concentration in minutes • t; is the initial or overland flow time in minutes • tt is the conveyance travel time in minutes The initial or overland flow time is calculated with the UDFCD equation: TST, INC. CONSULTING ENGINEERS Page 3 625 Peterson Street Redevelopment PDP Final Drainage Report t = 5.0.33 3.2 Drainage Plan Development The 625 Peterson Street project is proposed to remodel the existing single family home and expand the footprint on the west side to accommodate 3 new rental units. A new parking area will be required off the rear alley. The existing property to the north has a shallow swale along it's south property line that captures flow from this property and routes it to Peterson Street. The property to the south has roof drains directed onto their driveway, which directs runoff east, to Peterson Street. Therefore offsite flows onto the property are assumed to be zero for this analysis. Basin A, as shown on the Drainage Plan, is located in the rear of the property along the existing concrete alley. This basin consists of the parking area and trash enclosure. The parking will sheet flow in a southeast direction at a 1.65% slope toward the curb -cut and 2' gutter. Basin B is located along the south property line and extends from the front to the back of the lot. This basin is a mixture of grass, landscaping, concrete walkways and half of the existing and proposed roof area. These areas will generally sheet flow at 1 % - 2% toward the southeast where runoff will be captured in a 2' wide gutter, located on the south property line, and directed toward Peterson Street. Basin C encompasses the northern portion of the property and consisted of grass, landscaping, concrete walkways, a new concrete driveway and half of the proposed and existing roof area. This basin will drain toward the northeast and will be directed toward Peterson Street in a 2' wide concrete. Basin runoff results are provided in Appendix A. 3.2.1 Channel Design Proposed channels and swales at this project site have been analyzed using Bentley Flowmaster V8i, Select Series 1 software. These swales have been designed to include 133% of design flow. The standard 1' of freeboard above the normal water depth is not possible due to existing conditions and the flat nature of the site. Swale A -A, B-B, and C-C are 2' concrete gutters located on the south property line and sloped at a minimum of 0.5%, and maximum of 0.93%, to the east. This swale will convey runoff from TST. INC. CONSULTING ENGINEERS Page 4 40 i 625 Peterson Street Redevelopment PDP Final Drainage Report i Basin A and B. Swale D-D is a 2' concrete gutter located on the north property line and will convey Basin C at a 0.8% slope toward Peterson Street. The results of the channel design are provided in Appendix B. 3.2.2 Detention Requirements and Water Quality Capture Volume Design As per the City standard, developments with less than 5,000 sf of new impervious area are not required to provide detention. This site has a new impervious area total less than 5,000 sf and therefore this project will not provide detention. Please see Table 1 below for existing versus proposed impervious area information. Table 1 Existing VS. Proposed Impervious Area Basin/ Sub -Basin Attribute Attribute Area (sf) Total Impervious Area (sf) PROPOSED SITE Hardscape/Pavement" 3960 7018 Roof 3058 EX SITE Hardscape/Pavement 940 3318 Roof 2378 New Impervious Area 3700 'Hardscape/Pavement area excludes proposed pervious paver area. The Water Quality Capture Volume (WQCV) has been calculated using Equation 3-3 and Figure 3-2 from the Urban Storm Drainage Criteria Manual Volume 3. The WQCV for this site is 0.0039 ac-ft, or 170 cu-ft. Permeable pavement areas proposed for this project site are capable of storing approximately 0.007 ac-ft, or 293 cu-ft of WQCV within the sub -structure of these paved areas. However, this water quality will be implemented within Basin A only. Due to significant site constraints, including a small site, and the inability to daylight an underdrain, Basins B and C will not have a water quality component. A variance to cover this non-standard approach is included with this report. WQCV calculations are presented in Appendix C, and the permeable pavements storage calculations are shown in Appendix D. 3.3 Low Impact Development With the building coverage and parking areas on this small lot, the amount of imperviousness on this site will be fairly high. However, the grading design aims to minimize the "directly TS- l 62S Peterson Street Redevelopment PDP Final Drainage Report connected impervious area" (DCIA) as much as possible. Strategies to minimize directly connected impervious areas follow the Four -Step Process for Stormwater Quality Management, as outlined in Volume 3 of the Urban Storm Drainage Criteria Manual. The four -step process is shown below. Figure 2. Four -Step Process for Stormwater Quality Management The Four -Step Process for Stormwater Quality Management Step 1 Employ Runoff Reduction Practices: To reduce runoff peaks. volumes, and pollutant loads from urbanizing areas, implement Low Impact Development (LID) strategies, including measures to "minimize directly connected impervious areas" (MDCIA). These practices reduce unnecessary impervious areas and route runoff from impervious surfaces over permeable areas to slow runoff (increase time of concentration) and promote onsite storage and infiltration. Step 2 Implement BMPs that Provide a Water Quality Capture Volume (WQCV) with Slow Release: After runoff has been reduced, the remaining runoff must be treated through capture and slow release of the WQCV. WQCV facilities may provide both water quality and runoff reduction benefits, depending on the BMP selected. This manual provides design guidance for BMPs providing treatment of the WQCV. Step 3 Stabilize Drainageways: During and following urban development, natural drainageways are often subject to bed and bank erosion due to increases in the frequency, rate, duration. and volume of runoff. Although Steps I and 2 help to minimize these effects, some degree of drainageway stabilization is required. Many drainage"ays within UDFCD boundaries are included in major drainageway or outfall systems plans, identifying recommended channel stabilization measures. If this can be done early, it is far more likely that natural % drainageway functions can be maintained with the addition of grade control to accommodate future devclopment. It is also less costly to stabilize a relatively stable drainageway rather than to repair an unraveled channel. Step 4 Implement Site Specific and Other Source Control BMPs: Frequently, site -specific needs or operations require source control BMPs. This refers to implementation of both structural and procedural BIv1Ps. Step 1: Runoff Reduction Practices for this project site are planned to include porous pavers in the parking area and maintaining grassed/landscaped areas where possible. The porous pavers will aid in the stormwater filtration for runoff generated by the parking area. The grassed/landscaped areas will help to minimize the directly connected impervious roof and hardscape areas. This will also provide the opportunity for runoff infiltration and increase the time of concentration. Step 2: BMP's to Provide WQCV with Slow Release for this project site will employ LID techniques such as a permeable pavement system and grassed/landscaped areas within the project site. The City of Fort Collins criteria for low impact development, as outlined in the Stormwater Criteria Manual in Volume 3, Chapter 3, are as follows: • No less than 50% of any newly added impervious area must be treated using one or a I$T. INC. CONSULTING ENLINEL �' 625 Peterson Street Redevelopment PDP Final Drainage Report combination of LID techniques, and • No less than 25% of any newly added pavement areas must be treated using a permeable pavement technology that is considered a LID technique Step 3: Stabilized Drainageways will come in the form of reseeding and/or sodding the open areas between downspout locations and the swales on the north and south property lines. Step 4: Site Specific Source Control BMP's may include things like proper maintenance of the permeable pavers. LID calculations are included in Appendix D. 3.4 Old Town Moderate Risk Floodplain Management This development is located within the City of Fort Collins Old Town Moderate Risk Floodplain. The Base Flood Elevations (BFE's) have been provided by the City Stormwater Department and are approximately 4989.9 at the rear of the property and 4988.9 (NAVD88) at the front. This floodplain has no elevation standards for development, but it is recommended that the lowest finished floor and all duct work, heating, ventilation and air conditioning, hot water heaters, electric, etc. be elevated a minimum of 24" above the BFE. The new units are to be located in the center of the site, so we have assumed a BFE of 4989.5 at this location. Due to site constraints the finished floor (and duct work, HVAC, etc.) will be set 18", rather than 24", above this BFE at 4991.00. The finished floor elevation of the existing home is 4988.21 and will need to stay at this elevation. 4.0 Conclusion The City of Fort Collins Stormwater Criteria Manual has been used to establish the criteria for a • developed condition runoff plan within the 625 Peterson Street Redeveloped area. This PDP drainage design report has highlighted the following items: • Project site development is within the confines of the City regulatory Old Town Moderate Risk Floodplain. • Stormwater detention will not be required due to the fact that this project will add less than 5,000 s.f. of new impervious area. • Water quality has been provided through the use of permeable pavers. Areas that we have been unable to provide water quality for are covered under the attached variance. • LID techniques are planned to be implemented within the site design that include the use of minimizing directly connected impervious areas. These are through the use of permeable pavement. TST, INC. CONSULTING ENGINEERS Page 7 Lj 625 Peterson Street Redevelopment PDP Final Drainage Report 0 5.0 References City of Fort Collins Stormwater Criteria Manual, Amendments to the Urban Drainage and Flood Control District Criteria Manual, Adopted December 2011, Last Revision April 2012. 2. Urban Drainage and Flood Control District Criteria Manual, Volume 3, August 2011 3. Natural Resources Conservation Services, 2013, Web Soil Survey: Soil Survey Area Larimer County Area, Version 8, Dec 23, 2013 4. Chapter 10 of the Fort Collins Municipal Code, http://colocode.com/fcmunihtmi.html TST, INC. CONSULTING ENGINEERS Page 8 APPENDIX A Rational Method Hydrologic Analysis y x 0 M LT dot M.M.O .01 1W " Maw NNW 6ZW6W MOM" Nf $ I T a 2 � e N rn � a N rn SS U N O iA $ $ a � n � m u M c m 99 A Z-,giiiz A O ZU $ Maw (D0L6D9 Tv)z6* SW6W M IZ [ SOi aw6W MZ6w QG �6 z fn - ...§:||ttZt|)EOEO■■DHk o > z 050w m&^(!0G°m�Z5 ! | \ ■\ 2!\ \0000 ,;: 3 §R /2 0. o |! �7 w- a3 7r �� 9!!7f ��1Oa !,2 e; !!!; �m $| E,°§/ 000 !# } i ! \§)2/ 3;c § \ �k \/)§k / �0. i3 »\� - -0 ,»&:_ ; ! iWZ3 } 80 - §;§,i -0 ° .§,;. §|7 \ - /! ! � ` ! ® \0 \!n .|,a i i ;; ; . 3 « \(I}} §)§ ; e!, » ! §Q § , „ ! �i3 0 ( #! - { _ ; / 7 EF { \ 2 . � � § \ � $ j ;0 j z \ u Hydrologic Soil Group—Larimer County Area, Colorado Hydrologic Soil Group 625 Peterson Street Hydrologic Soil Group— Summary by Map Unit— Larimer County Area, Colorado (CO644) Map unit symbol Map unit name Rating Acres In AOI Percent of AOI 35 Fort Collins loam, 0 to 3 percent slopes C 0.3 100.0% Totals for Area of Interest 0.3 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long -duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff. None Specified USDA Natural Resources 2II—M Conservation Service Web Soil Survey National Cooperative Soil Survey 12/11/2015 Page 3 of 4 Hydrologic Soil Group—Larimer County Area, Colorado Tie -break Rule: Higher Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 625 Peterson Street 12/11/2015 Page 4 of 4 0 625 Peterson Street Redevelopment PDP Final Drainage Report Developed Runoff Developed condition runoff was evaluated in accordance with the criteria established by the City of Fort Collins Stormwater Criteria Manual dated February 26, 2013. Design guidelines and information were also obtained from the Urban Storm Drainage Criteria Manual (USDCM) where applicable. A full description of this method is available through those manuals. The Rational Method computes only the peak flow at a design point and does not provide hydrograph information. Rational Method City of Fort Collins The Rational Method calculates peak runoff using the equation: Q = CCflA Where: Q = The maximum rate of runoff (cfs) C = Rational Method Runoff Coefficient for the design storm frequency. City of Fort Collins runoff coefficients are found in Table 3-3 of the SDDC manual. Cf = Storm Frequency Coefficient found in Table 3-4 of the SDDC manual. I = Average intensity of rainfall in inches per hour for a duration equal to the time of concentration, To. City of Fort Collins rainfall intensity data are shown in this Appendix. A = Basin Area (acres) Rational Method Runoff Coefficients, C, are a function of the basin land use and the design storm frequency. They are listed in Table 3-3 of the Storm Drainage Design Criteria manual. For basins containing more than one land use, a weighted average runoff coefficient has been computed. Time of Concentration, To, is the sum of the overland travel time, to, and the channel or conduit flow time, tt. Time of concentration is used to select the correct rainfall intensity for the rational method equation. T,=t;+t, where: Tc = Time of Concentration (min), to = Overland Travel Time (min), tf = Channel or Conduit flow time (min). Overland Travel Time, to, is computed using the frequency adjusted runoff coefficient and is applicable to all design storm intervals. TST, INC. CONSULTING ENGINEERS Appendix A • 625 Peterson Street Redevelopment i.s(t.l —CC f) L" to = (s), PDP Final Drainage Report Where: to = Overland Travel Time (min) C5 = The Rational Method runoff coefficient for the 5 — year storm L = Length of overland flow (ft), Maximum = 400 feet. S = Average basin slope M Channel or Conduit Travel Time, tt, is determined from the velocity of flow computed for the hydraulic properties of the channel, ditch, gutter, pipe or sewer. For the purposes of this report, the following equation was used: _ L t` 60*V Where: tt = Channel or Conduit Travel Time (min) L = Length of channel or conduit flow (ft) V = Velocity of flow (fps), determined from Figure 3-2 rmTST. INC. CONSULTING ENGINEERS Appendix A 625 Peterson Street Redevelopment 50 30 P-: 20 Z uj U °' 10 z W IL' y5 W 3 0 U 2 ¢ W 4 3 1 PDP Final Drainage Report W N N N NI I I _,-A,,. K,,, W- MWEE11111//IINIFAINA IM ME 11FAFA ►' ,M �I FA . ,n I . � LI IN, I■■�■�■M�nl� �■■�M�■n. �r�r��/MlI1 MMMI►��M�i����■M� .2 .3 .5 1 2 3 5 10 20 VELOCITY IN FEET PER SECOND FIGURE 3-2 ESTIMATE OF AVERAGE FLOW VELOCITY FOR USE WITH RATIONAL FORMULA TST. INC. CONSULTING ENGINEERS Appendix A 625 Peterson Street Redevelopment City of Fort Collins OF Curves DUf8t10j MIU2:Yr =1_0_yr illil 5 2.85 4.87 9.95 6 2.67 4.56 9.31 7 2.52 4.31 8.80 8 2.40 4.10 8.38 9 2.30 3.93 8.03 10 2.21 3.78 7.72 11 2.13 3.63 7.42 12 2.05 3.50 7.16 13 1.98 3.39 6.92 14 1.92 3.29 6.71 15 1.87 3.19 6.52 16 1.81 3.08 6.30 17 1.75 2.99 6.10 18 1.70 2.90 5.92 19 1.65 2.82 5.75 20 1.61 2.74 5.60 21 1.56 2.67 5.46 22 1.53 2.61 5.32 23 1.49 2.55 5.20 24 1.46 2.49 5.09 25 1.43 2.44 4.98 26 1.40 2.39 4.87 27 1.37 2.34 4.78 28 1.34 2.29 4.69 29 1.32 2.25 4.60 30 1.30 2.21 4.52 31 1.27 2.16 4.42 32 1.24 2.12 4.33 33 1.22 2.08 4.24 34 1.19 2.04 4.16 35 1.17 2.00 4.08 36 1.15 1.96 4.01 37 1.13 1.93 3.93 38 1.11 1.89 3.87 39 1.09 1.86 3.80 40 1.07 1.83 3.74 41 1.05 1.80 3.68 42 1.04 1.77 3.62 43 1.02 1.74 3.56 44 1.01 1.72 3.51 45 0.99 1.69 3.46 46 0.98 1.67 3.41 47 0.96 1.64 3.36 48 0.95 1.62 3.31 49 0.94 1.60 3.27 50 0.92 1.58 3.23 51 0.91 1.56 3.18 52 1 0.90 1.54 1 3.14 53 0.89 1.52 3.10 54 0.88 1.50 3.07 55 0.87 1.48 3.03 56 0.86 1.47 2.99 57 0.85 1.45 2.96 58 0.84 - 1.43 2.92 59 0.83 1.42 2.89 60 0.82 1 1.40 2.86 From the City of Fort Collins Storm Drainage Design Criteria and Construction Standards PDP Final Drainage Report Appendix A 625 Peterson Street Redevelopment 12.00 10.00 8.00 c r a 6.00 m 2.00 0.00 0 City of Fort Collins 10 10 20 30 40 Storm Duration (min) PDP Final Drainage Report �,.......... Appendix a 625 Peterson Street Redevelopment PDP Final Drainage Report City of Fort Collins Rational Method Runoff Coefficients Runoff Coefficient Lawn, Heavy, <2% Slope 0.20 Lawn, Heavy, >7% Sloe 0.35 Lawn, Heavy, 2-7% Sloe 0.25 Lawn, Sandy, <2% Slope 0.10 Lawn, Sandy, >7% Slope 0.20 Lawn, Sandy, 2-7% Slope 1 0.15 Roofs 0.95 Streets: Permeable Pavers 0.30 Streets: Gravel 0.50 Streets: Paved0.95 From Table 3-3 of the City of Fort Collins, Stormwater Criteria Appendix A | • / ( § (. I - / ( $ ` \ | - d � § � )J § ! | {a E § § k § ! § {{§§§§§§|§§|§ ! r s n m � Y � o m Y � s $ s � 0 :5 U U »_ a oe 0 x o a_g n �� � O 5 7 3 E� u. �� a o u Y8; e 2R; 3 �'� '3y' �% 4°< �y; 3 3 —4 m m M J -i A d ��, P n o n � N O P N 9 R n d N 0 R P R `n 3 9 0 P O z Y u rc w R C C L 6 G 6 °o L u N ao d y d N A d � a N m N N Y o O O � Y 0 0 o e 0 a° T o O O O Y '� 2 � e e a F rc i e E i v. m in V gO t a F m E 8 ' t ¢' o 0 0 'a e' g a � a a o c Q ® U F r APPENDIX B Channel Design m x C CI. O V U 0 0 0 0 0 0 N 7 C C C C C C O a` 0� 0 O In f,- CO V f-- f` N f-- O N f-- CO V N V Ch N LO V x L a o , co 0 CO Cam') CO N O 3` o 0 0 0 0 0 0 LL N a _ 0 U U N= CO (fl CO M O O > O > 6 r c '' c) O O c7 N N O z 0 m a 0 8 0 0 0 0 0 v or)0000 a Un rn n CO o 0 0 0000vuS C CD� 0 C d U Cf ` 0 0 0 0 0 0 U 3 [O CD (O f-- CD f-- an a o CD CD o LL 0 c C W W O 0 O Q Q 0 _ = N U U U 0 0 Y Y @ 0 Q Q U o y s Q[OUC) U U) U Q p a !-!_- a) — o o U) E Worksheet for Peterson Gutter Flow A -A Solve For Spread Channel Slope 0.00500 Wit Discharge 0.80 Wis Gutter Width 2.00 ft Gutter Cross Slope 0.15 ft/ft Road Cross Slope 0.15 ft/ft Roughness Coefficient 0.013 Spread 1.98 it Flow Area 0.29 ft' Depth 0.30 ft Gutter Depression 0.00 ft Velocity 2.71 ft/s Bentley Systems, Inc. Haestad Methods SdbAkbjX WNaster V8i (SELECTseries 1) [08.11.01.03] 12/16/2015 8:48:29 AM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203.755-1666 Page 1 of 1 Lj Worksheet for Peterson Gutter Flow B-B Solve For Spread Channel Slope 0.00930 ft/ft Discharge 1.60 ft'/s Gutter Width 2.00 ft Gutter Cross Slope 0.15 ft(ft Road Cross Slope 0.15 fVft Roughness Coefficient 0.013 Spread 2.29 ft Flow Area 0.39 ft' Depth 0.34 ft Gutter Depression 0.00 ft Velocity 4.07 ft/s Bentley Systems, Inc. Haestad Methods SdSMWa)CEgbsMaster V81 (SELECTseries 1) [08.11.01.031 12/16/2015 8:47:58 AM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1.203.755.1666 Page 1 of 1 Worksheet for Peterson Gutter Flow C-C Solve For Spread Channel Slope 0.00500 ft/ft Discharge 1.60 ft3/s Gutter Width 2.00 ft Gutter Cross Slope 0.15 ft/ft Road Cross Slope 0.15 ft/ft Roughness Coefficient 0.013 it 'z. " i s z a 4. -d„T ^�1,"".'� - e.. ..:...=, Spread 2.57 ft Flow Area 0.50 ft' Depth 0.39 ft Gutter Depression 0.00 ft Velocity 3.23 ft/s Bentley Systems, Inc. Hassled Methods Sdb@d6b% kMNaster V8i (SELECTseries 1) [08.11.01.03] 12/16/2015 8:47:38 AM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1 C' • Worksheet for Peterson Concrete Swale D-D Project Description Friction Method Solve For Manning Formula Normal Depth CoefficientRoughness 0.013 SlopeChannel 0.00800 ftift Left .- Slope 3.00 SlopeRight Side 3.00 Discharge r [ r- Normal Depth Flow Area Wetted Perimeter Hydraulic Radius Top Width Critical Depth Critical Slope Velocity Velocity Head Specific Energy Froude Number Flow Type Supercritical 0.29 ft 0.26 ft' 1.85 ft 0.14 ft 1.75 ft 0.32 ft 0.00486 ft/ft 2.74 ft/s 0.12 ft 0.41 ft 1.26 Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Normal Depth 0.29 ft Critical Depth 0.32 ft Channel Slope 0.00800 ft/ft Critical Slope 0.00486 ft/ft Bentley Systems, Inc. Haestad Methods SdilltfiElef3hobaMaster V81 (SELECTseries 1) [08.11.01.03] 5/1812016 3:01:13 PM 27 Slemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1 • Worksheet for Peterson South Sidewalk Chase rojeet Description Friction Method Manning Formula Solve For Normal Depth Input Data Roughness Coefficient 0.013 Channel Slope 0.04000 Rift Bottom Width 2.00 ft Discharge 1.60 ft3/s Results Normal Depth 0.14 ft Flow Area 0.28 ft' Wetted Perimeter 2.28 ft Hydraulic Radius 0.12 ft Top Width 2.00 It Critical Depth 0.27 ft Critical Slope 0.00524 ft/ft Velocity 5.67 ft/s Velocity Head 0.50 ft Specific Energy 0.64 ft Froude Number 2.66 Flow Type Supercritical 773 Input Data Downstream Depth 0.00 ft Length 0.00 It Number Of Steps 0 MFIOTtput�Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Normal Depth 0.14 ft Crifical Depth 0.27 ft Channel Slope 0.04000 ft/ft Critical Slope 0.00524 ft/ft Bentley Systems, Inc. Haestad Methods SdMMM)CRkbWaster V8i (SELECTserles 1) [08.11.01.03] 5118/2016 2:55:15 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA ♦1-203.755-1666 Page 1 of 1 E • Friction Method Solve For Worksheet for Peterson Nouth Sidewalk Chase Manning Formula Normal Depth Roughness Coefficient 0.013 Channel Slope 0.05000 ft/ft Bottom Width 2.00 ft Discharge 0.70 ft3/s Normal Depth Flow Area Wetted Perimeter Hydraulic Radius Top Width Critical Depth Critical Slope Velocity Velocity Head Specific Energy Froude Number Flow Type Downstream Depth Length Number Of Steps Upstream Depth Profile Description Profile Headloss Downstream Velocity Upstream Velocity Normal Depth Critical Depth Channel Slope Critical Slope Supercritical 0.08 It 0.16 ft' 2.16 ft 0.07 ft 2.00 ft 0.16 ft 0.00555 ft/ft 4.47 ftls 0.31 ft 0.39 it 2.81 0.00 ft 0.00 ft 0 0.00 ft 0.00 ft Infinity fills Infinity ft/s 0.08 ft 0.16 ft 0.05000 ft/ft 0.00555 ft/ft Bentley Systems, Inc. Haestad Methods ScMdbt63%*khWaster V8i (SELECTseries 1) [08.11.01.03] 5/18/2016 3:00:15 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1.203-755-1666 Page 1 of 1 APPENDIX C Water Quality Capture Volume Calculating the WQCV and Volume Reduction Chapter 3 Once the WQCV in watershed inches is found from Figure 3-2 or using Equation 3-1 and/or 3-2, the required BMP storage volume in acre-feet can be calculated as follows: V = (WQCV 12 A Equation 3-3 Where: V = required storage volume (acre-ft) A = tributary catchment area upstream (acres) WQCV = Water Quality Capture Volume (watershed inches) 0.500 O:A50 0.400: O 350 6.300 0:250 0;200 0.150 0:100 0:050 0.000 I-----�' -M I-------M M 0 0.1 0.2 0:3, 0A 0:5 O:6 Oi7 0:8 0:0 1 Total Imperviousness Ratio (i = IA/100) Figure 3-2. Water Quality Capture Volume (WQCV) Based on BMP Drain Time 3-6 Urban Drainage and Flood Control District Urban Stone Drainage Criteria Manual Volume 3 August2011 625 Peterson Street Redevelopment PDP Final Drainage Report Table C-1 Water Qualitv Caoture Volume (WQCVI % Imperviousness 59.74% WQCV inches" 0.17 inches Volume = (WQCV/12)xA 1 0.0039 ac-ft 'WQCV in 12-hr drain time from Figure 3-2. Water Quality Capture Volume (WQCV) Based on BMP Drain Time UDFCD Storm Drainage Criteria Manual Volume 3 Appendix C • APPENDIX D Low Impact Development 635 Peterson Street Redevelopment POP Final Drainage Report Low Impact Development (LID) Table D•1 No lee. than 50%a1 eny newly ended lmperviaue arae must be trealea uelne one or s combinatlon of LID techniques volume 1. chanter 3. section 31 Ln Imnact Devalonmant Drltada Basin Proposed Impervious Area (acres) Overall Area (acres) Impervious Area routed to LID (acres) LID Technique to be Applied A 0 057 0.079 0.O79 B 0.040 0,096 0.000 None C 0037 0.100 0.000 None Total 0.134 0.275 0.079 59.05% 11:;T Appendix D 625 Peterson Street Redevelopment POP final Drainage Report Table D-2 No lees than 25% of any newly added Pavement Brame must be treated uMnB a p rmaade pavement technom, that is considered as LID..M1Meue Volume 3. Chanter 3. Section 3.1 Low enoam Development Criteria Basin Newly Added Pavement Area (acres) Permeable Pavement Area (acres) %of Permeable Pavement A 0.079 0.022 27.05% B 0.000 0.000 0.00% c 0.000 0.000 0.00% Tubl 0.079 0.022 27A5% r :r Appel 0 625 Peterson Street Redevelopment PDP Final Drainage Report Table D-3 Permeable Pavement Reservoirs Slooetl Installations UDFCD Design Procedure Form for Permeable V = Plf6 sl.-1112A Pavements stems PPS Slope of Permeable Length Between Permeable Pavement Volume Available in Reservoir length Between 6dn Pavement (ftflt) Lateral Flow Banters Area IR'i lateral Flow k Barnerc fl 0.0165 '66 293 185 AA Te tl fl 293 Tool I.meatl 1 0.007 P 4xv-1n)- Oa D(depth in ncbee)= 12 e (elope m Will vanes, see table L (Lenglb betwean Dow twnwra) vanes, sae ratio A (Area in Irr voles, see table Appendix D D.elen.r'. Company'. 0.1.' N.J.& Design Procedure Form: Permeable Pavement Systems (PPS) 51ee11 of 2 Jon Sweet TST, olo. Consulting Engineers D—ma r16, 2015 625 Pat-... Rorl.—Imintsnl Location: Fur- A arc 1 Type d of Permeable Pavement Salon a 0 Hn InfY4AYa1 A) Who, type of .—,.a .1 ...hisp tyramm Is aced, Q martin Samuel Soots (Be.al oa in. land... and —".I., mounaly to adlacom ® full Vsta. union structural am sell co megenetics I B) What mrs.1 weans, r4nn.'1 D�.OR ® mLv O cernmk cm nsmwAt O setae rmoaw O somes, Events 2 Reauead Sloops Volume A) Efleslbe lmparvbueneea of Arse TdbuMry to Permeable Peeamnl.1, 1,= 721 % 0)TMutaryAmes lmparvmueaees Ralw(1=1.1 IN) I= DT21 C) Tntelary Wabash.] A em A,- 9.M5 soft flo,su lag also of mmarroWle pavement eytlan) 0) Area of Permeable Pavement system A, = IN so it (Min.. recmmmer W la ,smbW reveal erect' 910 ea N) E) Immmkue Trans, Rarer Rr= 1.9 (Contributing Committees Amea I Pnneabk Pavement Runs) FI Water Ouse, Capture Volume(WOCV) eaeea on 12-rots Done Time WOCV- 65 euh (VADCV = (0.8- to.91- la-1,19' It a 0.78' 11,112)' Areal d normal G) Is Need vrllumen min9 added'! 0 rEs No 9 D.pin of Raamvna A) Minimum Depth of Ramor lr Dls,- 12,0 ran — (Minimum recommeMed depth Is 61nsMe) Dqp .0m, B) le the earl, of the reaemarkubprade lnksl.ea equal 0 ter O YPS.ftel Cr SamuelloMlWlpn ® No- seams anus n Ca Partial, (Porous Gravel Pnvemem_O.3. Oeme 1 OAO) P= 0.e0 0) Slim, of the Bee. Coumr'SOrgntle Intedace 5= 0.017 11111 E) Larglh Belwnn Lateral Flow Swayes (mail a 20.65 IL) I. = 1115 ff F) Volume Provided Bend on Dope of Beea Course V 293 so fl Flat or snipped- V e P - (jD„e,.1y12) - Area Sleped'. V= P' f(O,rn,.(D., WSL-I))1121-Aron Volume assumeir sense. Wens Canyon. Ile vebme.f .e.h—111ruli.'ii.....'. a. lateral Flow Bank, owme me A) Type of usual Flew Bemere O fm,Re Walk ® m 9 aterwmnbnw ernati l mmai b Nvr O Omv(oerowq'. B) Number of Permeable Pevemnl CO. Cliffs = 1 5. Penal. Beasts A) Is a sameralw bamm pmvNad on all aNaa at Ilse r nvv M ®YES a ,vor, 0 to mnnl (R seedeit d lot tom PICP, wnnslo qnd pneomunt. or for any rro-InlNhalron Ill .l LID BASIN A.alsm. PPS 121162015, 922 AM Design Procedure Form: Permeable Pavement Systems (PPS) viral z ul z Dilations,,. Jan Sw.t comwm: TST. Ine. Consulting Engineers Data DwemMr 18, 20+6 Protect: 625 Pommaon R..—m,l Lmnllon: Beale A fins Filtm Material earl Undom em Syelem A( le me underdml. pieoed below a 6Irth Nita Wyar of Cleea C filler mateealy nmCDOT F 8)Oamear of SbMd Ppe(abl dimension. per Teats PPe-2) Onwe Oat I O e.— &Nm C) Distance Mm the Lowest EWvetbn o1 the S Wrpe Volume y e 0.2 tt (I,e. the bottom of ins base wales to IM.1. al the odfxe) T. Impermeable Geomembmm Liner and Geoletlile Separator Fabwc A)1. there a mimeo. 30 mil IMck Imparmeabia PVC B.membrene aware ore liner on the bottom arel adea of the Noah, a atending up to the top yD of the Mae wumea • NO 8) CDOT Cla.B Separator Fabric rOmse One Ra[G Wre Ne. Q pWutl .4xeaM Lebw tlt tub B.0 (Aam (Assumes mcn cell lw eimtler arm, aungratla elope. eM bgln lateral (anima eubgretlo u IIaN. cekulele se11e imlvmualiy while Ine vad..) Wividua r the v A) Depth of WOCV In the Rea.1, Dwocv 3.88 inches (Elevehan of Me Fbad Cartel Outlet) 8) Diameter of Oehw for 12-hour Drain Time Doe. a 0.30 Inch. Lim a minimum on0u dlarmam of 318.Inch.) Nome: LID BASIN A.elsm. PPS 12116QO15, 922 AM I L_J--L-1--I--L-J--L-J I I I I I I I I L-J--L-T--1--T-J--L-, EMSTNG PARKING FOR APARTMENT EMI 0 CONCRETE PAYERS. SEE CONCRETE PAYER CROSS SECTON DETAIL ON STREET DETAIL SHEET 9. LEGEND UNITS Be DEVELOPMENT seem 10eweew NI-C - BASIN NUMBER AB—C K - AREA INACROSS r - Is0-YR RVNCiF % Y PROPOSED CONTOURS COEFFICIENT 'C IASI Sterol �� / DESIGN PONT Q WfPOSED UD PANNC AREA CONCRETE WASHOUT AREA El O 1MWDYd FLOW ARROW ELBOW RI SOON fly PROPOSED FwlsxCD GRACE R6GZ&19 WATTLE WE � O DEVELOPED BASIN BOUNDARY m — NNKIE TRARIC f/AtlR0. ® O CURB SOM O I I I I I I I I � I I I I I I I I I I , ExISINNG 2—STORY I I APARTMENT BLDG I I I I I ------------------------------------ I 2' CONCRETE TRICKLE PAN ZCONCRETE TRICKIE PAN ' In ae*_J 2' CONWETE GJi SEE - VERTCAL CARRY DUMB DUAL ON STREET DETAIL SHEET 9. PROPOSED TOP OF FOINDATUN se 4991.00 Mae, sam was was saw, � mew y E%ISTNC SINGLE \ FAMILY HOUSE P� F==9B6�21 ---T7w -- saw, wee, ,//,— r In 'L)ilu 0 ElFl -\ /RY / U 9' V.E. 7 EYJSTNG E%ISTNG DRIVEWAY 2' CONcflEa WTTE�R. QEEt r — — 9RmGARAGE — — — — — — — ON STREET DETAIL vE4T 9� — — — — II L_ - EIOSTNG HOUSE /_�i \ / RRY awry as as must be ueamnulnO A Po+meaen pewmam dmtmt los I, comlanaan umohmiss, a Seclbn 41n Oq (Il) OWBI m(ft) W-K DepU (ft) 100-y w (pp) ZI Z2 W m swe 00 Channel Surface A -A* 0.50 0.50 0.]B 0.6 e.] 0 OW B. OSO 0.34 I.fi fi.] 0 B.93 C-C• GUM B.SO 0.39 1.6 6.] 0 abD g D-Dee B.33 0.33 0.29 0.] J J 0 COM • Swale A. Band C are 2 foot gutter sees Swale D Is a 2 fool trial pm. i1Ini m"""( I i ns `.DID0232Ta5% OAA 0000 000%C0W0 am am ToolaAl9 O-0Yf zr.M w eas than 5O%p any ml+ 'Oxl WPervmue ate^ mustbe vented usvN Basin sitDischarge 09010 rB 0] m OB DID Ol OJ n] Basin Pmposea lmpervlcus Ovanll Ar t Area RemesH ImpetViouS At ea ulewi dto LID(acres) LID TecOniane to he Applied ,A "'7 0.079 Oul9 B ONO 0M RCCO Nano C O.OJT 01W 20 Nox Tg MN Burls 9atv 5109% Y 9CEWA GiASE. SEE DETAIL D-NCB ON STREET DETAIL SHEET 9. w tm Q `f Q a— Nei T SIDEWALK CHASE. SEE DETM 0-109 ON STREET DETAIL SHEET 9. U w W cr 0) z O C* YL W Few a L0 N (0 FS wess JFS JFS z a J O cr Fee O U z 0 ,_ M O cm W 0 z a W Q z Q cc 0 City of Ft. Collins, Colorado TOT, M UTILITY PLAN APPROVAL CON91LTIx0 DHGNE MO Mtlws War BULmny C. SuNe 200 APPROVED: Felt com compete Engineer pate PFme 9]0.P25.C5A Few 970226.02" CHECKED BY Water k Wastewater UN9ty pate We No 0663.0012.00 CHECKED BY: swrmWaer ue9lr Data SpurY-to' CHECKED BY: Puke A Recreation Data wtGECEMBFR 13, 2016 CHECKED BY: 14aHic Easineer Oew CHECKED 9Y: 6 a 9 NetwY Resources pate