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HomeMy WebLinkAboutDrainage Reports - 10/31/2012' MA This Drainage Report is consciously provided as a PDF. Please consider the environment before printing this document in its entirety. When a hard copy is absolutely necessary, we recommend double -sided printing. ' NorthernEngineering.com // 970.221.4158 16, 201Z� City of Ft Collins ro Plans Approved By Date Prepared for: Neenan Archistruction 2620 E. Prospect Rd., Suite 100 Fort Collins, CO 80525 Prepared by: NORTHERN ENGINEERING 200 South College Avenue, Suite 100 Fort Collins, Colorado 80524 Phone: 970.221.4158 Fax: 970.221.4159 v .northernengineering.com Project Number: 207-007 d I 1 1 1 NORTHERN ENGINEERING October 16, 2012 ADDRESS: PHONE:970221.4158 wanorthernengineering wm 200 S. College Ave. Suite 10 wE: Fort Collins, CO80524 FAk 970.221.4159 vrww•nor City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Final Drainage and Erosion Control Report for Engines & Energy Conversion Lab Dear Staff: Northern Engineering is pleased to submit this Final Drainage and Erosion Control Report for your review. This report accompanies the 10.16.12 Basic Development Review submittal for the proposed Engines and Energy Conversion Lab building addition. Comments from the Basic Development Review Letter dated 09.20.12 have been addressed. Written responses thereto can be found in the comprehensive response to comments letter on file with Current Planning. This report has been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM), and serves to document the stormwater impacts associated with the proposed Engines and Energy Conversion Lab project. We understand that review by the City is to assure general compliance with standardized criteria contained in the FCSCM. If you should have any questions as you review this report, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Nicholas W. Haws, PE LEER ' Project Manager AP VC�Snowdon Project Engineer NORTHERN ENGINEERING I TABLE OF CONTENTS nes and Energy Conversion Lab I. GENERAL LOCATION AND DESCRIPTION................................................................... 1 A. Location.......................................................................................................................................1 B. C. Description of Property................................................................................................................1 Floodplain....................................................................................................................................3 ' ll. A. DRAINAGE BASINS AND SUB-BASINS.......................................................................5 Major Basin Description...............................................................................................................5 B. Sub -Basin Description..................................................................................................................5 ' III. DRAINAGE DESIGN CRITERIA................................................................................... 5 A. Regulations..................................................................................................................................5 ' B. C. Four Step Process........................................................................................................................5 Development Criteria Reference and Constraints.........................................................................6 ' D. E. Hydrological Criteria....................................................................................................................7 Hydraulic Criteria.........................................................................................................................7 F. G. Floodplain Regulations Compliance..............................................................................................7 Modifications of Criteria..............................................................................................................8 ' IV. A. DRAINAGE FACILITY DESIGN....................................................................................8 General Concept..........................................................................................................................8 B. Specific Details.............................................................................................................................9 ' V. CONCLUSIONS......................................................................................................10 A. Compliance with Standards........................................................................................................10 ' B. Drainage Concept......................................................................................................................11 References....................................................................................................................... 12 APPENDICES: APPENDIX A — Hydrologic Computations APPENDIX B — Hydraulic Computations ' BA — Storm Sewers B.2 — Inlets B.4 — Water Quality Design Computations ' Preliminary Drainage Report WINORTHERN ENGINEERING LIST OF TABLES AND FIGURES: Figure1 — Aerial Photograph................................................................................................ 2 Figure 2— Proposed Site Plan................................................................................................3 Figure 3 — Existing Floodplains............................................................................................. 4 Figure 4 — FIRM Panel Number 08069 C 0977 G................................................................... 4 Table 1 — Water Quality Storage Summary ........................................................................... 10 MAP POCKET: C400 - Drainage Exhibit Preliminary Drainage Report WI NORTHERN ENGINEERING GENERAL LOCATION AND DESCRIPTION A. Location 1. Vicinity Map and Enersv Conversion Lab ;eli'3� �:II� �i` nisi RIIIIII!` .i ■ y ��` slu' II III �IL' .� ! i sll� I lut I■I I � ��,�„• � �` 11111 II iilllllll iillllll illlll� ..-i� iIIL ■ � 4_ ►�i �e I► � � � P Illlllil! :Ills!: !IIIII: Lql�• 1111 1! i= � ! II Is € - "111111= illllhi 51._ iill� ■ EiIG `e 1 Hill I!115."—N� ■ !!!� _ l�E III a.. _ �:N�;1111 1 rll�sc�� n ll113 - i11! +■= _'■ �! F» ITn ee en. II 2. The Engines and Energy Conversion Lab site is located in the northeast quarter of Section 12, Township 7 North, Range 69 West of the 6t' Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. 3. The project site is located on the east side of College Avenue, west of the Fort Collins Science Museum, and is border to the north and northeast by Cache La Poudre River, to the south and southeast by Burlington Northern Railroad. 4. Currently the existing lot does not have any stormwater or water quality facilities. All runoff from the site is routed via overland and swale flow and discharged directly into the Poudre River. College Avenue is slightly elevated to the project site creating a ridge line running north and south along the right-of-way line. Burlington Northern Railroad tracks are elevated to the project site creating a ridge line running southwest and northeast along the base of the tracks. The overall site grades from the south to the north. 5. College Avenue borders the site to the west. Burlington Northern borders the site to the south and east. The Poudre River borders the site to the north. B. Description of Property 1. The Engines and Energy Conversion Lab property is approximately 5.19 net acres. Preliminary Drainage Report 1 1 1 1 1 1 1 1 ■� NORTHERN ENGINEERING Engines and Energy Conversion Lab Figure 1 —Aerial Photograph 2. The subject property currently consists of the main lab and two other outbuildings with associated drives and equipment. The only access to the property is located at the southwest corner of the site and wraps around the south of the main lab to a parking area located behind the building. The area in front of the lab is well landscaped with various trees and bluegrass. The areas to the north, south and east consist of a mixture of native and non-native vegetation and gravel. The existing site is graded to convey stormwater away from the existing building with the ultimate destination being the Poudre River. The area in front of the building routes stormwater through a low gradient swale within the front 'Historic Lawn' and discharges into the river at the northwest corner of the project. The south and southeast side of the building route stormwater overland to a low gradient swale running along the railroad and discharges into the river at the northeastern corner of the lot. The north and northeastern sides of the building route stormwater completely overland to the river along the northern property line. 3. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey, the site consists of Paoli fine sandy loam, which falls into Hydrologic Soil Groups B. More site -specific exploration found varying materials including existing fill material from the existing landfill, native sand & gravel and cobble. See the Geotechnical Engineering Report by EEC (EEC Project No. 1112015) for additional information. Preliminary Drainage Report 2 I I 7 NORTHERN ENGINEERING and Eneray Conversion Lab 4. The proposed development will include a building addition for the existing Engines and Energy Conversion Lab as well as additional parking. Due to site constraints, the building addition is proposed to run parallel to the Burlington Northern Railroad Right - of -Way with an access drive separating the building and the ROW. A parking area is proposed south of the current entrance. To improve the Poudre River corridor, demolition of the site is required to maximize natural vegetation within this area. The removal of both outbuildings and the rear parking lot is proposed as well as condensing the existing utility yard. The rear parking area will be replaced with a drive aisle for deliveries. The drive aisle will consist of sections of gravel, pavers and colored concrete. The existing buildings will be replaced with the proposed water quality pond. ENGINES AND ENERGY CONVERSION LAD Figure 2— Proposed Site Plan 5. There are no irrigation ditches or related facilities in the project's vicinity. 6. The project site is within the Public Open Land (POL) Zoning District. The proposed project is not requesting a change in the land use. C. F000dplain 1. A portion of the subject property is located in a FEMA regulatory floodplain designated for Cache La Poudre River as shown in FIRM Panel 08069 C 0977 G. 2. FEMA designates the northwest comer of the subject property within Zone AE Flood Hazard Area, which constitutes an area determined to be within the 1% annual chance floodplain. The remaining property is located within Zone X, which constitutes an area determined to be outside the 0.2% annual chance floodplain. 1 Preliminary Drainage Report 3 NORTHERN c EN G'NEE R ING Engines and Energy Conversion Lab Figure 3 — Existing Floodplains ZONE X YAP SCALE 1'=M' M 0 RD IOW FF£T FIRM RANGE RATEYAPZ7.E ',fOLONAIN)� q�� PwMR N 2 reva aim ..cJ 12 E ZONE 10E 19N9LY C 9uNN� VS PANEL 0979 CmYelr ZONE LONE% dtirY �K % IAONgI fOPNT wm Rivrr �.r.Tnmwnnn.�w..o T NORTN,R E 99 WEST AND TOWNINW L%MTN, RANGE 69 WEST. Figure 4 — FIRM Panel Number 080101 0977 G Preliminary Drainage Report 4 11 NORTHERN ENGINEERING II. DRAINAGE BASINS AND SUB -BASINS and EneFav Conversion Lab ' A. Major Basin Description 1. The Engines and Energy Conversion Lab project is located within the Cache La Poudre River Drainage Basin, which is located along the perimeter of the Poudre River. ' 2. Due to flooding restrictions, the Cache La Poudre River Drainage Basin limits the amount of development within this basin resulting in lower density. The majority of ' this basin routes stormwater via overland flow directly into the Poudre River. B. Sub -Basin Description ' 1. The subject property historically drains away from the existing building. The area in front of the building routes stormwater through a low gradient swale within the front 'Historic Lawn' and discharges into the river at the northwest comer of the project. The south and southeast side of the building route stormwater overland to a low ' gradient swale running along the railroad and discharges into the river at the northeastern comer of the lot. The north and northeastern sides of the building route stormwater completely overland to the river along the northern property line. The proposed drainage patterns will maintain existing routes in many locations. All ' additional run-off created by the improvements will be intercepted by storm sewers. All areas containing improvements will incorporate a water quality facility. ' 2. College Avenue and the Burlington Northern Railroad tracks act as a drainage barrier to the project site eliminating any off -site drainage to convey across the project. ' III. DRAINAGE DESIGN CRITERIA A. Regulations ' There are no optional provisions outside of the FCSCM proposed with the Engines and Energy Conversion Lab project. B. Four Step Process The overall stormwater management strategy employed with the Engines and Energy Conversion Lab project utilizes the "Four Step Process" to minimize adverse impacts of ' urbanization on receiving waters. The following is a description of how the proposed development has incorporated each step. ' Step 1 — Employ Runoff Reduction Practices Several techniques have been utilized with the proposed development to facilitate the reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the ' current use by implementing multiple Low Impact Development (LID) strategies including: Nm Conserving existing amenities in the site including the existing vegetated areas within the northern half of the front lawn and the existing swale along the Burlington Northern Railroad ROW. ' r. Providing large vegetated open areas throughout the site to reduce the overall impervious area and to minimize directly connected impervious areas (MDCIA). Routing flows, to the extent feasible, through vegetated swales and grass buffers to ' increase time of concentration, promote infiltration and provide initial water quality. ' Preliminary Drainage Report 1 5 1 NORTHERN ENGINEERING Engines and Energy Conversion Lab NE Providing bioretention area and a low sloping grass swale with an underdrain system to intercept runoff and promote infiltration. Step 2 — Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with ' Slow Release The efforts taken in Step 1 will facilitate the reduction of runoff; however, this development will still generate stormwater runoff that will require additional BMPs and ' water quality. Stormwater from the western portion of the site will ultimately be routed through a low gradient grass swale with infiltration trench and underdrain. Stormwater from the eastern portion of the site will ultimately be routed to a water quality pond prior ' to exiting the site. Additional measures are proposed to achieve water quality for stormwater routed from the existing roof. Below is a list of BMPs that will be utilized on site. NE A grass swale and multiple grass buffersareproposed to treat all stormwater runoff to the west. N� Two snouts and bio-skirts are proposed to treat the existing stormwater routed from the existing roofs. ' NE A bioretention pond is proposed to treat all stormwater runoff to the east of the building. 1 1 1 1 1 1 1 1 1 1 Step 3 — Stabilize Drainageways The project site currently discharges to the Poudre River via overland and swale flow. While these drainage patterns are being maintained with the proposed grading, measures have been proposed to decrease the amount of run-off discharging overland to the river. The run-off discharged in front of the building will be intercepted by a proposed area inlet and routed through the City stormwater system. The run-off discharged in the rear of the building will be intercepted by the proposed bioretention pond. The bioretention pond has been designed to have capacity for the both the required water quality volume and the generated 100-year volume within this area. The area draining to the existing swale running along the railroad tracks has been decreased and will maintain the existing drainage patterns. All existing river discharge locations have been utilized and no new river outfalls are required. Step 4 — Implement Site Specific and Other Source Control BMPs. The Engines and Energy Conversion Lab project includes a building addition with an associated drive and parking area, all of which will require the need for site specific source controls including: NS Chemicals for the Lati which will be stored and handled in a manner so as to minimize the potential for pollutants to enter the stormwater system. See the Hazardous Materials Impact Analysis submitted with this project for additional information on the pool chemicals. NE A localized trash enclosure at the rear of the building for the disposal of office waste. C. Development Criteria Reference and Constraints 1. There are no known drainage studies for the existing lot. 2. There are no known drainage studies for any adjacent properties that will have any effect on the Engines and Energy Conversion Lab project. 3. The subject property is essentially an "in -fill' development project as the property is surrounded by currently developed properties. As such, several constraints have been Preliminary Drainage Report 6 .V I NORTHERN ENGINEERING and Enerrry Conversion Lab I F identified during the course of this analysis that will impact the proposed drainage system including: Nil Existing elevations along the west and south property lines adjacent to College Avenue and Burlington Northern Railroad will be maintained. N� Existing elevations and vegetation on the north side of the subject property will be preserved. N-q As previously mentioned, overall drainage patterns of the existing site will be maintained. N3 Existing outfall locations into the river will be maintained. D. Hydrological Criteria 1. The City of Fort Collins Rainfall Intensity -Duration -Frequency Curves, as depicted in Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations associated with the Regency Lakeview development. Tabulated data contained in Table RA-7 has been utilized for Rational Method runoff calculations. 2. The Rational Method has been employed to compute stormwater runoff utilizing coefficients contained in Tables RO-11 and RO-12 of the FCSCM. 3. The Rational Formula -based Modified Federal Aviation Administration (FAA) procedure has been utilized for detention storage calculations. 4. Three separate design storms have been utilized to address distinct drainage scenarios. A fourth design storm has also been computed for comparison purposes. The first design storm considered is the Both percentile rain event, which has been employed to design the project's water quality features. The second event analyzed is the "Minor," or "Initial" Storm, which has a 2-year recurrence interval. The third event considered is the "Major Storm," which has a 100-year recurrence interval. The fourth storm computed, for comparison purposes only, is the,1O-year event. 5. No other assumptions or calculation methods have been used with this development that are not referenced by current City of Fort Collins criteria. E. Hydraulic Criteria ' 1. As previously noted, the subject property historically drains directly to the Poudre River. The majority of the site drains stormwater via overland and swale flow. The existing roofs currently discharge directly to the river through two separate pipes. 2. All drainage facilities proposed with the Engines and Energy Conversion Lab project are designed in accordance with criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District's (UDFCD) Urban Storm Drainage Criteria Manual. 3. As stated in Section I.C.1, above, a portion of the subject property is located in a FEMA designated floodplain. No improvements are proposed within or near the delineated floodplain. 4. The Engines and Energy Conversion Lab project does not propose to modify any natural drainageways. F. Floodplain Regulations Compliance 1. As previously mentioned, a portion of the property is within the FEMA 100-year Regulatory Floodplain. However, no improvements are proposed within this area and this project as a whole will not create any change to the existing floodplain. Preliminary Drainage Report .� NORTHERN ENGINEERING Engines and Energy Conversion Lai G. Modifications of Criteria 1. The proposed Engines and Energy Conversion Lab development is not requesting any . modifications to criteria at this time. ' IV. DRAINAGE FACILITY DESIGN A. General Concept ' 1. The main objectives of the Engines and Energy Conversion Lab drainage design are to maintain existing drainage patterns and ensure no adverse impacts to any adjacent properties. ' 2. The existing site does not have any off -site runoff that flows directly through the project site. 3. A list of tables and figures used within this report can be found in the Table of Contents at the front of the document. The tables and figures are located within the sections to which the content best applies. ' 4. The Engines and Energy Conversion Lab project divided the site into four (4) major drainage basins, designated as Basins B, F, R and U. The project further subdivided Basin F in to four (4) sub -basins, designated as Basins F1, F2, F3, and F4. The ' drainage patterns anticipated for each basin and sub -basin are further described below. Basin F ' Basin F consists of the improvements within or draining to the front yard area. Basin F1 encompasses the most areas within Basin F. This basin includes all of the proposed parking area and the western half of the proposed delivery drive. Runoff ' through this basin is routed through a combination of overland, gutter and swale flow. Runoff from the proposed parking area and delivery drive is discharged through a 2' curb cut into the water quality grass swale and ultimately intercepted by a proposed ' area inlet. This flow is routed into the City storm sewer system. Basin F2 consists primarily of hardscape and landscape areas. Runoff from this area drains across a water quality grass buffer before discharging into Basin F1. Basin F3and F4 consists of sidewalks and landscape areas. Runoff from this area drains overland across a ' water quality grass buffer. Basin B ' Basin B consists of the improvements within or draining to the back yard area. This basin encompasses the eastern half of the delivery drive, site amenities located directly behind the building, the roof of the proposed addition and the proposed bioretention pond. The basin routes stormwater through a combination.of overland and gutter flow and discharges directly into the bioretention pond. The biorention pond was sized to achieve water quality and capture the 100-year event to ensure ' future erosion in not caused by this development. Basin U ' Basin U consists of the improvements within the Utility Yard. The proposed Utility Yard has been reduced from the current layout. All runoff from this area is conveyed overland flow to a perimeter curb and intercepted by an area inlet. The storm sewer connects to the existing outfall of the west roof drain. A snout and bio-skirt is ' proposed on the outlet pipe to achieve water quality for the Utility Yard as well as the existing roof. Preliminary Drainage Report 8 I NORTHERN ENGINEERING Engines and Energy Conversion Lab ' Basin R Basin R consists of the existing roof area. The building was constructed with two roof leaders discharging directly to the river. The western roof, Basin R2, outfalls to the river through an 8" PVC pipe. The eastern roof, Basin R1, outfalls to the river through a 10" metal pipe. To achieve water quality to the existing roofs, a snout and bio-skirt is proposed within two additional manholes at the outlet pipe. ' Basin OS1 Basin OS1 consists of the remaining area between the proposed drive aisle and the ' existing railroad tracks. This area has been reduced from the historic condition with no proposed improvements and will maintain the existing drainage patterns to the river. Basin OS2 Basin OS2 consists of the northern property boundary. No improvements are proposed in this area and historic drainage patterns will be maintained. A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of this report. ` B. Specific Details 1. The main drainage problem associated with this project site is the deficiency of water quality present within the existing site. Currently the drive aisle and rear parking area drain overland and discharge directly into the river. The main building discharges directly to the river through two roof leaders. The existing two outbuildings also drain without any water quality. The proposed site will mitigate this issue by instituting the following water quality devices: All improvements within or draining to the front yard area will be routed across a grass buffer or swale. The existing roof and remaining Utility Yard will be mitigated by use of a snout and bio-skirt. xEI All improvements within or draining to the back yard area will be routed through the proposed bioretention pond. 2. The project is located directly next to the Poudre River. Due to the proximity of the river, the peak runoff generated from this site will pass before the peak of the surrounding systems, therefore detention is not required for this project. To eliminate any erosions issues generated from this project, the bio-retention has been designed to have capacity for the 100-year event and discharge through an existing 10" metal outlet pipe. An FAA method computation has been performed for the entirety of Basin B to determine the detention storage volume to be provided within the pond. 3. Table 1, below, summarizes the water quality information for the bioretention pond located in the back yard. Preliminary Drainage Report 9 .� NORTHERN ENGINEERING Li and Table 1 — Water Quality Storage Summary Required Water Quality Water Quality Provided Water Surface Pond Spillway Pond Volume Basin ID Storage (ac-ft) Quality (ac-ft) Elevation (ft) Elevation (ft) (ac-ft) B 0.028 0.028 4967.92 4969.00 0.27 Lab 4. Proper maintenance of the drainage facilities designed with the Engines and Energy Conversion Lab development is a critical component of their ongoing performance and effectiveness. The stormwater detention and water quality pond, as well as the BMP facilities contained therein, may be easily accessed by maintenance staff via the gentle slope provided to the bottom of the pond from the west side. Operations and maintenance of the bioretention areas and sand filters shall follow the recommendations for bioretention (rain garden) facilities, as outlined in the UDFCD manual. Appendix E will contain with future FCP submittals applicable excerpts to serve as guidance for the professional maintenance staff and subcontractors ' responsible for maintenance of these facilities at the Regency Lakeview development. Maintenance of the stormwater water quality Snouts provided shall follow the recommendations provided by the manufacturer. Appendix E will contain with future ' FCP submittals applicable excerpts to serve as guidance for the professional maintenance staff and subcontractors responsible for maintenance of these facilities at the Regency Lakeview development. ' 5. The drainage features associated with the Engines and Energy Conversion Lab project are all private facilities, located on private property. No drainage easements are proposed for this project. ' 6. As previously mentioned, the four existing river outfalls will be maintained with the proposed project. The existing 8" PVC outfall will be maintained and used to drain the existing roof and the remaining Utility Yard. The existing 10" metal pipe will be ' maintained and used to the drain the existing roof and all areas within Basin B. Within Basin F1 & F2, as proposed storm sewer will route the stormwater into the City stormwater system. The existing swales will remain and convey a peak runoff ' less than historic. ' V. CONCLUSIONS A. Compliance with Standards 1. The drainage design proposed with the Engines and Energy Conversion Lab project complies with the City of Fort Collins' Stormwater Criteria Manual. 2. The drainage design proposed with the Engines and Energy Conversion Lab project ' complies with the City of Fort Collins' Master Drainage Plan for the Foothills Drainage Basin. 3. There is a FEMA 100-year regulatory floodplain within the northwest corner of the site. No improvements are proposed in or near this delineated area. 4. The drainage plan and stormwater management measures proposed with the Engines and Energy Conversion Lab development are compliant with all applicable State and ' Federal regulations governing stormwater discharge. ' Preliminary Drainage Report 10 W I NORTHERN ENGINEERING nes and Energy Conversion Lab B. Drainage Concept 1. The drainage design proposed with this project will effectively limit any potential damage or erosion associated with its stormwater runoff by providing a water quality pond that will service the proposed western half of the Engines and Energy Conversion Lab development and existing. Through the use of existing storm sewer and the over sizing of the water quality pond, overland discharge to the river will be decreased. 2. The proposed Engines and Energy Conversion Lab development will not have any impact on the Master Drainage Plan recommendations for the Cache La Poudre River Drainage Basin. Preliminary Drainage Report NORTHERN ENGINEERING References nes and Energv Conversion Lab 1. City of Fort Collins Landscaoe Design Guidelines for Stormwater and Detention Facilities, November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services. 2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code. 3. Subsurface Exploration Report, Proposed 50,000 SF Multi -Tennant Office/Lab Addition CSU — Engines and Energy Conversion Lab, 430 North College Avenue, Fort Collins. Colorado, June 14, 2011, Earth Engineering Consultants, Inc.(EEC Project No. 1112015). 4. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007. 5. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture. 6. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Wright -McLaughlin Engineers, Denver, Colorado, Revised April 2008. 7. Flood Insurance Rate Map (FIRM). City of Fort Collins. Colorado, Larimer County, Federal Emergency Management Agency (FEMA), Community -Panel No. 080101 0977 G, Revised Date: June 17, 2008. Preliminary Drainage Report 12 APPENDIX A HYDROLOGIC COMPUTATIONS J C O I 1 1 in J r 6n LON-F E v m C o d N y w c o a& d i.oac V N V Z 3� cT u cotD0 O c c T p E 0 0 0 0 CO fn T O r1 V g w0 �; 0 T r J m T y C C V o_ N i. d o w N 000 Lo V Q ^o Eom t0 �j `o cT E Z 0) LLJO i j C V U 6 C N O V m N E m d 000 R a Cg V W O ti 00 *no n CO c .. 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U ; ! §# 2 U �\ E ) , ) &f r r5 C m C W r r r r I r e '= w Hz OZ Z W OF O ff, t W N-ct In CY v O. 6 0 .+O N-4O o lil . cV Ln O N 0) U') m 0 In N Q V (\i O O O M O O '+ O O u C_ I? I? O O Il O O O N M 0 E W In Il') LL7 In In un In ti 00 rl T C O N 00 O O O O M N 0 H E ^ In In In k6 In If) ui 01 rl �.y 8 m m -cr to m 0 0 0 rn m n n Lo in co O O O -. ti 000001 :100 m rn M v io in to n Ln n W in v v to M MM --. 0(500000000 J Q N a! a0 — O O M O m 0 Q U 6 0 6 0 .+ O O O '+ O Z N M V ( 04 Q OO m JC,41� Z .. C\j CY) a N~ N W p 2] 3 0 0 Qa J m r APPENDIX B HYDRAULIC COMPUTATIONS B.1 — Storm Sewers B.2 — Inlets (reserved for future use) B.3 — Water Quality Facilities APPENDIX B.1 STORM SEWERS I 1 0 I M E 1 n I� 1 I n 1 c 0 c a F c c c O O O N z z z o N N m m cS d c w r m OJ 2 jO O c J o m c m m m m J 0 C^ M m M co co u m S n_ v v v c O m N ) c C7 0^ CD�$ (D E a a It z S O � m 0 N N 1,- O m C O N M fV J tlJ^ N M O w pNp f0 m CW�'^. J 7 C 7 _ N OR 9 m > J ^ C W x V V 0) L O O m C c 1� UD N N J m � m m toU cL U U J m ap aO aO O. E m m ^ C N C a J fO� O O tD C •m IL L - G C J E m c m O O U n c c J M V C J N a n a c S 0 C 'aa a U m W F O m a z C O N t0 J2 / / @ I I I I I I « « « &! £ 0. wk E Lu ° ■■£ o o.o c } § §!£ ( (D !!£ A § G | ! _ 46 i J $ cl E § ƒ £ m S X!£ § \ ( ; q £» § 12 !a£ 7 7 7 \ £ t ■ . ■ 7 CL * # q f 2 ! 2m It \ §!£ « ■ « !!£ 3§ / r � CD 7 £ ° �!£ co to B a) % 4 E k r_ !!£ ( � � 00 OD co - 1 & r ƒ ] - , m § k | �J r 11 I O O O O O O Gi o a T a v co a CD a m a 0 0 0 0 ;no as neo'13 'AuI e9.990 ,13 'Puiv � U d :ul • Kc'fii+O ME � _J UI t9'E9e9 I3 AUI ;M0 i9'i9611'I3 'AUI o a 11'99e913'PWO :ul • Ki'LE+O I78 O J N LU W O J S ul O9 69e7'13 .AUI UlDe9 13 ' PuJO 0 o s s o o s w S io O J r 0 0 O O O O O N Z Z Z Z Z 0 N m c C W N M a N J Z m C 7 O N N n Q' x� v v v v v C N c M N to m ii C ^ co ((O (O (O co w N N x�r m m a v v c O N O O R N N N N c m 0) (D m m E C7 0— a 0) 0) a 0)z xox O N 0) O N m C c 0 W N O N O M O M O M N co O fM H ONO i+ C co R co O O O _ W N N O M lr� Y c m 0 Nm m 0 (It mo CO c W x m V 0) V 0) 7 0) V 0)J R r n Y NOD N m O/ C C^ J 0 � N N Y m r O) w c C U U U U U J M C N C J fA- ^y O N N N N N y �F LL � N to In In E of } i O O m m O J N m m M .0 E a w a w a w a w a O ll N � W o O m a z JZ m 1. 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J N CO r N r M N M COO r m n r CO N N M O O O O N r O n N 7 7 O It w m a v v It x 0 a R � ONi N N N II > t — o 0 0 a O1 r r o r r O r O Cl) o 11 mm G c m U Q ul LP IQ 0 O Q O p, uo m m E C o oq 0 0 cq 0 0 21 v � J m r v (•i v •f v �t v C S m a a U O N r O r E � c Y O COpf CNp N J m CD V C < a^ N L _ N N O O N c J N a N Q C 0 0 0 o O m V N C LL i • O C N M V 0 11 Z J s 8 8 0 8 o S 0 N }np g :uj 0 0 m �np � E:ulca L o m m w L :ul v J W N N J O � II O O O O C O O � i "rn CV)ai M ui � r w am v v v v v a W IY APPENDIX B.2 INLETS Area Inlet Performance Curve: Engines & Energy Conversion Lab - Design Point fl Combined Flows fo Basin F1 8 F2 Governing Equations: At low flow depths, the inlet will act like a weir governed by the following equation: 'where P = 3.1418'Dia.ofgrate Q - 3 P H ' 's where H corresponds to the depth of water above the flowline .0 At higher flow depths, the inlet will act like an orifice governed by the following equation: /� = • where A equals the open area of the inlet grate i� 0.67 A 2 gH ) 0.5 • where H corresponds to the depth of water above the centroid of the cross -sectional area (A) The exact depth at which the inlet ceases to act like a weir, and begins to act like an onfice is unknown. However, what is known, is that the stage -discharge curves of the weir equation and the orifice equation will cross at a certain flow depth. The two curves can be found below: Stage - Discharge Curves 18.00 16.00 Weir Flow 14.00 Onnm Flow - 10.00 8.00 a 6.00 0 4.00 -- 2.00 0.00 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 stage (ft) If H > 1.792 (A/P), then the grate operates like an orifice: otherwise it operates like a weir. Input Parameters: Type of Grate: Nyloplast 2401 DI Minor Flow 1.90 cfs Diameter of Grate (ft): 2 (Historic 0.9 cfs allowed to bypass) Open Area of Grate (ft): 1.15 Flowline Elevation (ft): 0.000 Major Flow 5.20 cfs Reduction Factor: 0% (Historic 2.3 cfs allowed to bypass) Depth vs. Flow: Shallow Orifice Actual Elevation Weir Flow Flow Flow Depth Above Inlet (ft) (ft) (cfs) (cfs) (cfs) 0.00 0.00 0.00 0.00 0.00 0.10 0.10 0.60 1.95 0.60 0.20 0.20 1.69 2.75 1.69 0.22 0.22 1.90 2.86 1.90 Q2 0.30 0.30 3.10 3.37 3.10 0.40 0.40 4.77 3.89 3.89 0.50 0.50 6.66 4.35 4.35 0.60 0.60 8.76 4.77 4.77 0.70 0.70 11.04 5.15 5.15 0.71 0.71 11.36 5.20 5.20 Q100 0.80 0.80 13.49 5.51 5.51 0.80 0.80 13.49 5.51 5.51 0.90 0.90 16.09 5.84 5.84 1.00 1.00 18.85 6.16 6.16 I 1 I 1 1 r- L F 1 1 1 1 it 1 1 1 1 Area Inlet Performance Curve: Engines & Energy Conversion Lab - Design Point u1 Governing Equations: At low flow depths, the inlet will act like a weir governed by the following equation: ` where P = 3.1416'Dia.of grate Q = 3 .0 P H • where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: = 0.67 A 2 gH • where A equals the open area of the inlet grate • where H corresponds to the depth of water above the centroid of the cross -sectional area (A) The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown. However, what is known, is that the stage -discharge curves of the weir equation and the orifice equation will cross at a certain flow depth. The two curves can be found below: Stage - Discharge Curves 9.00 8.00 weir Flow 7.00 Onfice Flow 6.00 5.00 t 4.00 °m 3.00 O 2,00 1.00 0.00 -------- 0.00 0.10 020 0.30 0.40 0.50 0.60 0.70 0.60 0.90 1.00 Stage (ft) If H > 1192 (A/P), then the grate operates like an orifice; otherwise it operates like a weir. Input Parameters: Type of Grate: Nyloplast 1201 DI Minor Flow 0.30 cfs Diameter of Grate (ft): 1 Major Flow 1.10 cfs Open Area of Grate (ft): 0.28 Flowline Elevation (ft): 0.000 Reduction Factor: 0% Depth vs. Flow: Shallow Orifice Actual Elevation Weir Flow Flow Flow Depth Above Inlet (ft) (ft) (cfs) (cfs) (cfs) 0.00 0.00 0.00 0.00 0.00 0.10 0.10 0.30 0.47 0.30 Qz 0.20 0.20 0.84 0.66 0.66 0.30 0.30 1.55 0.81 0.81 0.40 0.40 2.38 0.94 0.94 0.50 0.50 3.33 1.05 1.05 0.60 0.60 4.38 1.15 1.15 Qioo 0.70 0.70 5.52 1.24 1.24 0.80 0.80 6.74 1.33 1.33 0.80 0.80 6.74 1.33 1.33 0.90 0.90 8.05 1.41 1.41 1,00 1.00 9.42 1.48 1.48 APPENDIX B.3 WATER QUALITY FACILITIES J 1 II II II 11 Design Procedure Form: Grass Swale (GS) Sheet 1 of 1 Designer: Cody Snowdon Company: Northern Engineering Date: July 23, 2012 Project: Engines and Energy Conversion Lab Location: Fort Colllins CO 1. Design Discharge for 2-Year Return Period Qz= 1.30 cfs 2. Hydraulic Residence Time A) : Length of Grass Swale Ls= 86.0 ft B) Calculated Residence Time (based on design velocity below) T,rm= 5.3 minutes 3. Longitudinal Slope (vertical distance per unit horizontal) A) Available Slope (based on site constraints) S,,,,,i = 0,020 ft / ft B) Design Slope So = 0.015 ft / It 4. Swale Geometry A) Channel Side Slopes (Z = 4 min., horiz. distance per unit vertical) Z = 50.00 fi / ft B) Bottom Width of Swale (enter 0 for triangular section) We = 0.00 It 5. Vegetation Choose One A) Type of Planting (seed vs. sod, affects vegetal retardance factor) O Grass From Seed (9) Grass From Sad 6. Design Velocity (0.287 ft / s maximum for desirable 5-minute residence time) V; = 0.27 ft / s 7. Design Flow Depth (1 foot maximum) D; = 0.31 ft A) Flow Area A, = 4.8 sq ft B) Top Width of Swale W r = 31.0 it C) Froude Number (0.50 maximum) F = 0.12 D) Hydraulic Radius Rt, = 0.15 E) Velocity -Hydraulic Radius Product for Vegetal Retardance VR = 0.04 F) Manning's n (based on SCS vegetal retardance curve D for sodded grass) n = 0.200 G) Cumulative Height of Grade Control Structures Required Ho = 0.40 ft 8. Underdrain (is an underdram necessary?) Choose One 0 YES O NO AN UNDERDRAIN IS REQUIRED IF THE DESIGN SLOPE <2.0% 9. Soil Preparation (Describe soil amendment) r Choose One 10. Irrigation I 0 Temporary Permanent Notes: water quaury Tor oasm r i ' WQ F1 UD-BMP_v3_01.xls, GS 7/23/2012, 4:16 PM I ' Project No. 207-007 Northern Engineering Services, Inc. Engines Energy Conversion Lab Calculations By: CNS I 1 I Project Number : 207-007 Project Name : Engines & Energy Conversions Lab Project Location : Fort Collins, Colorado Pond No Pond B Input Variables Results Design Point B1 Design Storm 100-yr C = 0.83 Tc = 5.70 min A = 1.30 acres Max Release Rate = 2.00 cfs Required Detention Volume W ac-ft Time (min) Ft Collins 100-yr intensity in/hr Inflow Volume (ft3) Outflow Adjustment Factor Qa (cfs) Outflow Volume s (ft) Storage Volume (fts) 5 9.950 3221 1.00 2.00 600 2621 10 7.720 4998 0.79 1.57 942 4056 15 6.520 6332 0.69 1.38 1242 5090 20 5.600 7251 0.64 1.29 1542 5709 25 4.980 8060 0.61 1.23 1842 6218 30 4.520 8779 0.60 1.19 2142 6637 35 4.080 9245 0.58 1.16 2442 6803 40 3.740 9685 0.57 1.14 2742 6943 45 3.460 10080 0.56 1.13 3042 7038 50 3.230 10456 0.56 1.11 3342 7114 55 3.030 10789 0.55 1.10 3642 7147 60 2.860 11109 0.55 1.10 3942 7167 65 2.720 1 11446 0.54 1.09 4242 7204 70 2.590 11737 0.54 1.08 4542 7195 75 2.480 12042 0.54 1.08 4842 7200 80 2.380 12326 0.54 1.07 5142 7184 85 2.290 12602 0.53 1.07 5442 7160 90 2.210 12877 0.53 1.06 5742 7135 95 2.130 13100 0.53 1.06 6042 7058 100 2.060 1 13336 0.53 1.06 6342 6994 105 2.000 13595 0.53 1.05 6642 6953 110 1.940 13816 0.53 1.05 6942 6874 115 1.890 14071 0.52 1.05 7242 6829 120 1.840 14295 0.52 1.05 7542 6753 *Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2. Page 1 of 1 207-007 DetentionVolume FAAModified Method.xls N NORTHERN ADDRESS: PROW- 970221.4158 WEBSITE: 200S. College Ave. Suite 100 E N G I N E E R I N G Fort Collins, CO 80524 FAX: 970.221.4159 vvvnv.northernengmeenng.com Project Title Engines & Energy Conversion Lab Date: July 18, 2012 Project Number 207-007 Calcs By: C. Snowdon Client CSURF Pond Designation Pond B WQCV = a 0.91i'-1.19i'- + 0.78i WQCV = Watershed inches of Runoff (inches) a = Runoff Volume Reduction (constant) i = Total imperviousness Ratio (i = I,,a/100) Water Quality Capture Volume 40 h r 1 54.00% 0.5 OAS r 0.4— c 0.35 - w 0.3 — L - `m 0.25 - 3 0.2 15 00.1 3 1 0.05 i 0 O O O O o O O O O O .- $ o 0 0 0 0 0 0 0 0$ Total Imperviousness Ratio (/= i,„4100) Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event 1.30 ac IV=(W112V1"A 1.2 JJ 0.0283 ac-ft V = Water Quality Design Volume (ac-ft) WQCV = Water Quality Capture Volume (inches) A = Watershed Area (acres) 1.2 = 20%Additional Volume (Sediment Accumulation) bhr L' hr 24 hr 40 hr NORTHERN ENGINEERING Project Title Project Number Client Pond Designation AWRESS: 200 S. College Ave. Side 100 Fort Collin¢, CO 80524 PHONE: 970.221.4158 WEB .. wwxuprlMrnonginemingwm rAx: 970221.4159 Engines & Energy Conversion Lab Date: July 18, 2012 207-007 Calcs By: C. Snowdon CSURF Pond B _1. _ 4967.28 ft Water Quality Volume 0.0283 ac-ft 1® 0.1700 ac-ft 0.1983 ac-ft 3 D = Depth between contours (ft.) A3 = Surface Area lower contour (ft) A7 = Surface Area upper contour (W) Elevation Surface Incremental Incremental Total Vol. Total Vol. (ft) Area (ft) Depth (ft) Vol. (ft') (ft') (ac-ft) 4967.40 175.44 0.12 7,02 7,02 0.0002 4967.60 1442.87 0.20 141.43 148.45 0.0034 496T80 3826.77 0.20 507.96 656.41 0.0151 4968.00 5777.46 0.20 953.75 1610.16 0.0370 4968.20 7524.73 0.20 1326.39 2936.54 0.0674 4968.40 9173.99 0.20 1667.15 4603.69 0.1057 4968,60 10974.26 0.20 2012.14 6615.83 0.1519 4968.80 12612.54 0.20 2356.78 8972.61 0.2D60 4969.00 13931.93 0.20 2653.35 11625.96 0.2669 Elevation Depth Volume WQCV 4967.92 0.64 0.0283 100-yr Detention 4968.67 1.39 0.1700 Overall Detention 4968.77 1.49 0.1983 Circular Perforation Sizing Dia (in.) Min Sr 1 n t 1/3 Area/Row 0.1 Required Area 0.385 sq-in Per Row No. of Rows 2 Total Outlet 0.20 sq. in. Area 41 9J � N O O o _ W) '^ 0 x c o 0 O + It 0 cl `O o m o 0 ' a v Q a a w a a a = lG V1 V Af N rl O I I I 0 (14-ane) awnlOA ain;de:) A;ilenb ja;eM Y R m• m 00 0 O c u O Q N 0 J O 0 0 ME I [1 1 1 1 1 1 1 1 i I 1 1 1 1 i Release Rate 2.00 cfs Composite C 0.81 Area 1.510 acres Required Volume 0.188 ac-ft Pond Grading Volume Elevation (ac-ft) (ft) WQSE 0.028 4967.92 HWSE 0.170 4968.67 Top of Pond 0.198 4968.77 1 MAP POCKET C400 - DRAINAGE EXHIBIT �nIIIIMO�ffi_— „ „IF/I to ra wain Wn%eDFTER ""A y 1 \ / / /WATER WAUn NABS BD�R > '. MASS T'IREARM HO HOPE UNNBpRMN (]RLDW ITNSHED' GIVZO (. j EXISTING Y V. IN11T 10151 IOU AN MINE { f �/ zWRB% ar .•III F1 \ % 1 / I ( I \ i rti 1 / 1 1 ' i 1 L 1 1 ENGINES AND ENERGY CONVERSION IABORATORY 1 (EECL)BUILOING 1 1 1 1NATURAI. HABITAT BUFTq ZCAE L ien-\ CACHE IA PoUORE RIVER _- unB OF nAI1N9A9n rarmnrmrnnrTWr isle m°`a"IP uWE ` � \ ��-,�="` IPPROYJYAIIE IXlIP IF i � � \ _ �l1EErCLUSIIER DRIP ME \ - SVT SEE SHEET CS.q I \b' _ AND F �+Z+ONIFR ® A �M 91RIIBTIIRE + + . WRIER R Q0.0aUA-W POID I ^ ♦ i. +14, WO EL4191179S ♦ PdO ICI OLIN a109 Ac AC-P4, f 'Ud' w WE 1 1 II PROPOSED BI ADDITION 4 � ' 00 PON I «T L Ft I i /i / 1 /iUi /79' j ost r r r ( I I I X "Fill, y\� 1 1 1 1 i _ RZ AZTI.AN COMMUNITY CENTER YBUNIN BAEM ID AREA ME cw C100 TIC NEW R MNow Q1100 S1m WIN) O FI ORI 06R 0.A rA 6A Zz 59 e R 0.19 Om 0.T8 31 6A 0.5 IA a Om QA9 BUN SD 6A OA al F am o.W ax s0 s0 sz DA III BI 130 am BOBs.T 33..9 m 01 aH a m 5 s-0 d PI Om 0.% Im SA SA 0J ,M A a R 0YL 0.% Im BUT 6A iD 92 1 %1 1.11 0.13 0.10 b.9 I11 03 IA mE %Z Om 0.I3 al9 91 RAW uz 0.5 GRAPHIC SCALE ® NORTH m D w BD 90 Fail Is FEET) 1I h- SOR LEGEND PROPERN BOUNDAnr - - — UATS OF I0O-1R 110CMi-NN ,.. NATURAL HABITAT DUMB ZONE UNITS ----- ---- PROPOSE) BASIN UNES . . . EXISTING SI SEWER LINE W/ NH �' O PROPOSED UNDwORAIN —Ufl— PROPOSED STMM qUx � 1 tw EXISTING NET CRATE TO PROPOSED COUPON EXISTING CCMWR - - PRCRYD SMAIE .. - RAMMED VERTICAL CURB A GUTTER PROPMEO RIBBM CURB PROPWN DKRUND FLOW DIRECTOR r� PROPOSED CRASS BUFFER BYP PROPOSED MASS SWALE BYP BC -RETENTION BYP PROPOSED GRASS PANRS llII PROPOSED GRAVEL I PRCPCQD BASIN DELINEATOR UBP KINDRED MINN RMOPT COMN EAT PROPOSED YASR RUNOPT CO6BCIgT ASIN PROPOSED BAACREAGE /\ PROPOSED DE5W PENT NOTES: I. THE SIM T9E AND Um TON OF ALL RICAN UNDENTANAUND OREM ARE AITROMINAIE WHEN SHOWN ON THESE ORAIWNGS. IT Slnu BE THE RUFNINE1Un OF THE CONTRACTOR m Y967 THE EASTENCE o' ALL UNDERGROUND UMBER % THE AREA GF THE NOUN. BEFORE COWENCING NEW COWSMUCTOx, THE CONTRACTOR SHI BE RESPOWN E FOR LOCATING All UNDERGROUND UTUTES AND NH BE RESPON9EIP FOX NOR A.. UNKNOWN UNMRGW WND UTUTES. Z SE MOTOR 14.1 OF THE -AND USE CODE FOR ALLOWAIBIE UECS WTAN THE BUPRR ZONE AND EXHI&T G OF THE LEASE 6RGENENT BETWEw ME On AND CiURF, WIN Al PERMITS ME EWSTNG BUILDING THE WIVE RISE, AND NT4BR EXISTING LAND USES TO RgNN WMIN THE BUFFER ZONE BENCHMARK II-mulk TOR BASIN AT THE SdIMEAST CdgER OF THE W1FR.4CMM or NNE DRI AND Cd1ECIE AEHUE ELgATON - NBSsr (NOYD 39 UNADJUSTED) AT THE N00. ORTHWEST WgR¢RWa DENS ST NE ��E �4BASE H AT o rWATW . KRABP (MIND ID UNREASONED) FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION COLORADO Rum IOW. ur)ON M NI OFBluac M UWAVAKND M City of Fort Collins, Colorado UTILITY PLAN APPROVAL APPROVED: [�y neel' 'B� clMcxm In: a r k WesT_Or NECKED DI r CHENCED Dr: vP ]mom CREDITED BY _ —maple NECKED BY BRvlroumeRtpl PlmvpT ��