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Home My WebLink AboutDrainage Reports - 10/24/2023October 11, 2023 City of Fort Collins Approved Plans Approved by: Dan Mogen Date: 10/24/2023 Dan Mogen, P.E. City of Fort Collins Utilities — Stormwater Engineering 700 Wood Street Fort Collins, CO 80521 RE: 9/11 Memorial at Spring Park — Drainage Memo JVA Job No. 3768c Dear Dan: This letter has been prepared to summarize the drainage concept, solutions impervious area associated with the site improvements for the 9/11 Memorial redevelopment project located at 2100 Mathews Street in the City of Fort Collins. Existing Draina�e Patterns JVA,Incorporated 273 Lmden Street Suite 200 Fort Collins, CO 80524 970.225.9099 info�jvajva.com www.jvajva.com and changes in at Spring Park The existing site is a predominately landscape/park area with concrete pedestrian paths. The existing ground surface is relatively flat, generally sloping to the northeast at grades ranging from 0.5°/o to 6.0°/o. All stormwater runoff is conveyed via surface flow to the east towards Spring Creek. The site is partially located in FEMA Flood Zone AE, Special Flood Hazard Area Subject to Inundation by the 1% Annual Chance Flood, and partially in the Floodway, per FEMA Flood Insurance Rate Map number 08069C0987G, effective date OS/02/2012. Proposed Drainage Patterns Proposed drainage patterns are to remain the same as the existing drainage patterns. In general, the proposed redevelopment of the site consists of the construction of the monument and concrete plaza, and connections to the existing concrete walk sidewalk paths. The small project site (0.22 acres of disturbance) has been analyzed as one basin as the entire project site drains towards Spring Creek. It follows that the proposed improvements will increase the total impervious area within the area of improvements from 2°/o to 46%. See Figure 2: Developed Drainage Map for the drainage basin boundary and a summary of the existing and proposed impervious areas. Hydrologic and Hydraulic calculations are attached. Although the proposed development of this site increases impervious, the added impervious is small compared to the park area and area of disturbance. Since the added impervious area is disconnected and drains towards receiving pervious areas, the WQCV is reduced by 100°/o. See attached MHFD Runoff Reduction Calculation. The project site is partially located within the floodplain, and all improvements within the floodplain are designed to match existing grade. A No-Rise Certification will be completed to verify construction meets with design within the floodplain. B O U L D E R F O R T C O L L I N S W I N T E R P A R K G L E N W O O D S P R I N G 5 D E N V E R 9/11 Memorial at Spring Park - Drainage Memo October 11, 2023 2 of 3 With the project site disturbance so small, and partially within the floodplain, it does not make sense to provide detention per standard practice. Instead, the `Beat the Peak" criteria was used to show that the peak runoff from these improvements beat the peak of Spring Creek storm flows without the detention. To prove the `Beat the Peak" is met, the existing condition 100 year hydrologic model and selected plan condition hydrologic model are to be checked with the proposed development without detention to ensure that downstream discharges, basin volumes, and basin water surface elevations do not increase as a result of the proposed development. With the model's data, May 2003, and model program ModSWMM, being outdated, the model was unable to run, and the inputs and outputs were analyzed to show that the `Beat the Peak" criteria was met. See attached figures from the model, and data analyzed below. The site is located within subbasin 232. Subbasin 232 drains into Conveyance element 432. The upstream Conveyance Element is 533. It takes 3hrs and 18mins for the peak flow to reach 432 from conveyance element 533. The TC for conveyance element 432 is 3hrs and 19 mins. Subbasin 232 input information is below. The percent impervious is 27%. The disturbed area (.22 acres) for the site has an existing percent iinperviousness is 2%, the 100 year peak flow is 0.81 cfs, and the TC is ll min. The sites developed percent imperviousness is 46%, 100 year peak flow is 1.14 cfs, and the TC is ll mins. This is an increase of 44% impervious and 0 mins within the project area, and an increase of 0.3°/o impervious and 0 mins within Subbasin 232 with an increase of 0.33 cfs at 11 minutes. The peak from the site will therefore occur 3hrs 8mins before the Spring Creek peak storm flow arrives. See below for inputs and outputs extracted from the files. From the input SC100DEV.in Basin 232: Drains to Conveyance element 432 Flow Path is 3,700ft Area= 33.9 Acres Percent Impervious=27% Slope= 0.028ft/ft 1 1Ly 41y bbbb �ti . 4 �b .. b15 1 230 43010000110.2 51. .010 1 232 432 37@8 33.9 27. .028 1 233 433 38@0 33.9 79. .020 � vn n�n �rnn �o � nr n�� From the Output File SC100DEV.out Shows basins drains into channel 432 SUBAREA GUTTER WIDTH AREA PERCENT SLOPE RESISTANCE FACTOR NUAIBER OR h1ANHOLE (FT) (AC) IMPERV. (FT/FT) IMPERV. PERV LL7 4L7 bl�tltl.l� �2f.4 �tl.tl .11L7tl .tllb .L�l'/ 230 430 10000.0 110.2 51.0 .0100 .016 .250 232 432 3700.0 33.9 27.0 .0280 .016 .250 233 433 3800.0 33.9 79.0 .0200 .016 .250 SURFACE STORAGE(IPd) IPIPERV. PERV. .ltll� .5tltl .100 .300 .100 .300 .100 .300 INFILTRATION RATE(IN/HR) GAGE h1AXIP1Uh1 MINIPIUPI DECAY RATE NO .�1 .7tl .tltl12Stl 1 .51 .50 .00180 1 .51 .50 .00180 1 .51 .50 .00180 1 9/11 Memorial at Spring Park - Drainage Memo October 11, 2023 3 of 3 Channe1432:TC 3hr 18 min Upstream of channe1533: 3hrs 18 mins COPJVEYr�PJCE PEAK STAGE ELEt�1EPJT:TYPE (CFS) (FT) 4L7.4 430:4 432:4 433:4 SjE�:1 533:4 J114.V 524.5 3051.6 3050.4 5.25 3050.9 / . V 1.4 6.9 7.9 . tS 6.9 > 0 3 3 j 3 LV. 37. 19. 17. 15. 18. Therefore, the project without the required detention will not increase the downstream discharges, basin volumes, and basin water surface elevations on the existing and selected condition models as a result of the proposed development and will only increase the 100 year peak at time step 11 minutes by 0.33 cfs. Erosion and Sediment Control During construction, temporary erosion and sediment control practices will be used to limit soil erosion and sediment discharge off the site. Please feel free to contact me to discuss any questions you may have. Sincerely, JVA, INCORPORATED By: �:u-G, Eric Kohnen, P.E. Senior Project Engineer STORAGE TIP1E (AC-FT) (HR/h1IN) Cody Gratny, P.E. Principal ��QP'0�. RE;/S� �i , O �. R . � , . O�' y F G � �`� ' ViO 9�;i4 �" 453�3 �` �__ �r�/23/2��%. ��/��rr,;s ��NA L •��G\��Q Enclosures: Developed Drainage Map, Hydrologic Soil Rating, FEMA Firm Map, MHFD Runoff Reduction, Rational Calculations, Spring Creek Basin Baseline Condition Composite and Schematic Figures, Variance Request / � _� 4965.9 � � � � , - ; __- -� -- -- - -�� -�- - �� / � /� � � � � � � � �CDI_I,�� a Soil Map—Larimer County Area, Colorado 493750 493760 493770 45378� 493790 4F�3800 493810 493820 4�38.'�0 493840 493ft5 40° 33' 44" N `MI � i , -�� . . r�� " �� - - -� _ � � �� -=_. — �� -� '� . , , r� - . � 00 � :1� � � ' � . 4v , . � . +� ' r y� � .- � _ ! � �_ �-` - q i � � - � �— . � ,� � � T ��'�.�I i! �j ! 1 0 � �� ' �ni� 8 a �� f � _ . � • � :+�..e � s - Soil Map may not be valicl at this-,sPcajl�e�. - �, � `�` i � 40° 33' 41" N�' �� I I 4937y0 4937E0 493770 4937�0 493790 4�J.3@�0 493810 4�St620 4�Si�,'0 4�3840 4�J385 � � � Map Scale: 1:597 if printed on A la�dscape (11" x 8.5") sheet. ° N Meters � 0 5 10 ZO 30 � Feet 0 25 50 100 150 Map projection: Web Mercator CAmer coordinates: WGS84 Edge bcs: UTM Zone 13N WGS84 Usbn Natural Resources Web Soil Survey � Conservation Service National Cooperative Soil Survey Soil Map—Larimer County Area, Colorado MAP LEGEND Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons . . Soil Map Unit Lines 0 Soil Map Unit Points Special Point Features V Blowout ��:�` Borrow Pit �tt Clay Spot Closed Depression Gravel Pit Graveliy Spot Landfili Lava Fiow ^ Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop ' Saline Spot _i_ Sandy Spot — Severely Eroded Spot Sinkhole . Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other , Special Line Features Water Features Streams and Canals Transportation ,� Raiis ti Interstate Highways US Routes Major Roads Local Roads Background � Aerial Photography MAP INFORM, The soil surveys that comprise your AO 124, 000. Warning: Soil Map may not be valid at t Enlargement of maps beyond the scale misunderstanding of the detail of mappi line placement. The maps do not show contrasting soils that could have been : scale. Please rely on the bar scale on each m measurements. Source of Map: Natural Resources Cc Web Soil Survey URL: Coordinate System: Web Mercator (E Maps from the Web Soil Survey are ba: projection, which preserves direction ar distance and area. A projection that pre Albers equal-area conic projection, sho accurate calculations of distance or are This product is generated from the USC of the version date(s) listed below. Soil Survey Area: Larimer County Are Survey Area Data: Version 17, Sep 7, Soil map units are labeled (as space all 1:50,000 or larger. Date(s) aerial images were photograph 2021 The orthophoto or other base map on �n compiled and digitized probably differs imagery displayed on these maps. As a shifting of map unit boundaries may be Usbn Natural Resources Web Soil Survey � Conservation Service National Cooperative Soil Survey Soil Map—Larimer County Area, Colorado Map Unit Legend Map Unit Symbol Totals for Area of Interest Map Unit Name Altvan-Satanta loams, 0 to 3 percent slopes Acres in AOI I Percent of AOI 1.4 100.0% 1.4 100.0% USDn Natural Resources Web Soil Survey 8/2/2023 � Conservation Service National Cooperative Soil Survey Page 3 of 3 Map Unit Description: Altvan-Satanta loams, 0 to 3 percent slopes---Larimer County Area, Colorado Larimer County Area, Colorado 3—Altvan-Satanta loams, 0 to 3 percent slopes Map Unit Setting National map unit symbol: jpw2 Elevation: 5,200 to 6,200 feet Mean annual precipitation: 13 to 15 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 135 to 150 days Farmland classification: Prime farmland if irrigated Map Unit Composition Altvan and similar soils: 45 percent Satanta and similar soils: 30 percent Minor components: 25 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Altvan Setting Landform: Benches, terraces Landform position (three-dimensional): Side slope, tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Mixed alluvium Typical profile H1 - 0 to 10 inches: loam H2 - 10 to 18 inches: clay loam H3 - 18 to 30 inches: loam H4 - 30 to 60 inches: gravelly sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Low Capacity of fhe most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 2.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum content: 10 percent Available water supply, 0 to 60 inches: Low (about 5.4 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 3e Hydrologic Soil Group: B Ecological site: R067BY002C0 - Loamy Plains USDn Natural Resources Web Soil Survey 8/2/2023 � Conservation Service National Cooperative Soil Survey Page 1 of 3 Map Unit Description: Altvan-Satanta loams, 0 to 3 percent slopes---Larimer County Area, Colorado Hydric soil rating: No Description of Satanta Setting Landform: Terraces, structural benches Landform position (three-dimensional): Side slope, tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Mixed alluvium and/or eolian deposits Typical profile H1 - 0 to 9 inches: loam H2 - 9 to 18 inches: loam H3 - 18 to 60 inches: loam Properties and qualities Slope: 0 to 1 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 2.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum content: 10 percent Available water supply, 0 to 60 inches: High (about 10.1 inches) Interpretive groups Land capability classification (irrigated): 1 Land capability classification (nonirrigated): 3c Hydrologic Soil Group: B Ecological site: R067BY002C0 - Loamy Plains Hydric soil rating: No Minor Components Nunn Percent of map unit: 10 percent Ecological site: R067BY002C0 - Loamy Plains Hydric soil rating: No Larim Percent of map unit: 10 percent Ecological site: R067BY063C0 - Gravel Breaks Hydric soil rating: No Stoneham Percent of map unit: 5 percent Ecological site: R067BY002C0 - Loamy Plains USDn Natural Resources Web Soil Survey 8/2/2023 � Conservation Service National Cooperative Soil Survey Page 2 of 3 Map Unit Description: Altvan-Satanta loams, 0 to 3 percent slopes---Larimer County Area, Colorado Hydric soil rating: No Data Source Information Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 17, Sep 7, 2022 USDn Natural Resources Web Soil Survey 8/2/2023 � Conservation Service National Cooperative Soil Survey Page 3 of 3 NOTES TO USERS This map is for use in administering the National Flood Insurance Program. It does not necessarily identify all areas subject to flooding, particularly from local drainage sources of small size. The community map repository should be consulted for possible updated or additional flood hazard information. To obtain more detailed information in areas where Base Flood Elevations (BFEs) and/or floodways have been determined, users are encouraged to consult the Flood Profiles and Floodway Data and/or Summary of Stillwater Elevations tables contained within the Flood Insurance Study (FIS) report that accompanies this FIRM. Users should be aware that BFEs shown on the FIRM represent rounded whole-foot elevations. These BFEs are intended for flood insurance rating purposes only and should not be used as the sole source of flood elevation information. Accordingly, flood elevation data presented in the FIS report should be utilized in conjunction with the FIRM for purposes of construction and/or floodplain management. Coastal Base Flood Elevations shown on this map apply only landward of 0.0' North American Vertical Datum of 1988 (NAVD 88). Users of this FIRM should be aware that coastal flood elevations are also provided in the Summary of Stillwater Elevations table in the Flood Insurance Study report for this jurisdiction. Elevations shown in the Summary of Stillwater Elevations table should be used for construction and/or floodplain management purposes when they are higher than the elevations shown on this FIRM. Boundaries of the floodways were computed at cross sections and interpolated between cross sections. The floodways were based on hydraulic considerations with regard to requirements of the National Flood Insurance Program. Floodway widths and other pertinent floodway data are provided in the Flood Insurance Study report for this jurisdiction. Certain areas not in control structures. the Flood Insurance for this jurisdiction. Special Flood Hazard Areas may be protected by flood Refer to Section 2.4 "Flood Protection Measures" of Study report for information on flood control structures The projection used in the preparation of this map was Colorado State Plane north zone (FIPSZONE 0501). The horizontal datum was NAD83, GRS1980 spheroid. Differences in datum, spheroid, projection or State Plane zones used in the production of FIRMs for adjacent jurisdictions may result in slight positional differences in map features across jurisdiction boundaries. These differences do not affect the accuracy of the FIRM. Flood elevations on this map are referenced to the North American Vertical Datum of 1988. These flood elevations must be compared to structure and ground elevations referenced to the same vertical datum. For information regarding conversion between the National Geodetic Vertical Datum of 1929 and the North American Vertical Datum of 1988, visit the National Geodetic Survey website at http://www.ngs.noaa.gov/ or contact the National Geodetic Survey at the following address: NGS Information Services NOAA, N/NGS12 National Geodetic Survey SSMC-3, #9202 1315 East-West Highway Silver Spring, MD 20910-3282 To obtain current elevation, description, and/or location information for bench marks shown on this map, please contact the Information Services Branch of the National Geodetic Survey at (301) 713-3242, or visit its website at http://www. ngs. noaa.gov/. Base map information on this FIRM was provided by the Larimer County GIS and Mapping Department. Additional input was provided by the City of Fort Collins Geographic Information Services Division. These data are current as of 2010. Design Procedure Form: Runoff Reduction UD-BMP (Version 3.07, March 2018) Sheet 1 of 1 Designer: EJK Company: JVA, Inc. Date: October 11, 2023 Project: FC 9/11 Memorial Location: Fort Collins SITE INFORMATION (User Input in Blue Cells) WQCV Rainfall Depth 0.82 inches Depth of Average Runoff Producing Storm, ds = 0.82 inches (for Watersheds Outside of the Denver Region, Figure 3-1 in USDCM Vol. 3) Area Ar Downstream Design Pc Downstream BMP DCI, UI. RP, SP, HSG, HSG� HSG C/I Average Slope of RPA UTA:RPA Intertace Wid Type UTA:RPA �aID A1 int ID 1 Type None a (ft�) a (i(�) 6,500 1 (ft�) 1Q000 a i�) _ a(%) 0% 3(%) 100% )(%) 0% (ft/ft) 0.020 th (it) 50.00 CALCULATED RUNOFF RESULTS ArealD At UTA:RPAArea(ft�) 16,500 L / W Ratio 6.60 UTA / Area 0.3939 Runoff (in) 0.00 Runoff (ft') 0 Runoff Reduction (ft') 390 CALCULATED WQCV RESULTS ArealD AI WQCV (ft') 516 WQCV Redudian (ft') 516 WQCV Reduction ( % ) 100 % Untreated WQCV (ft') 0 CALCULATED DESI< Downstream Desi9n Poir DCIA UTA RPA SPA Total Area Total Impervious Area WQCV WQCV Reduction WQCV Reduction Untreated WQCV CALCULATED SITE RESULTS (sums results from all columns in worksheet) Total Area (fl�) 16,500 Total Impervious Area (ft�) 6,500 WQCV (ft') 516 WQCV Reduction (ft') 516 WQW Reduction (%) 100% Untreated WQCV (9t') 0 JVA Incorporated Job Name: CoFC 9/t t Memorial 1319 Spruce Street Job Number. 3768c Sti Boulder, CO 80302 Date� 10/11/23 Concrete D Ph:(303)444 1951 By: EJK CoFC 9/11 Memorial Historic Runoff Coefficient & Time of Concentration Calculations Location: Fort Collins Minor Design Storm: 2 Major Design Storm� 100 Soil Type: C/D Landsca Landscapir I(%)= 100 % 96 % 90 % 13 % 13 % 50 % 0% 0% I(%) Runofl Coeffs Initial Overland Time (ti) Travel Time (t,) x 60) APa�ed �s�ao�ce �s�aPe Upper Basin Design Add�esroo A�oor Pgra�ei Aqyyna Aan.wrt %�Totai ATotal �mp most Slope t, Length Slope so-eeia soU (croson� C2 C5 C10 C100 Type of Lend Surface k Name Point (sf) °° �sf) (s� �� s� �s� (sf) (sf) �sf) (a°� (%) Length (%) (min) (ft) (%) H1 1 183 9,198 9,381 022 1.9% 0.02 0.12 021 0.51 200 3.4% 16.9 ShortPastureand _ 0 0.00 0 0.00 0 0.00 0 0.00 TOTALSITE 0 183 0 0 0 0 9,198 0 9,381 022 19% Time of Basin Design Arocai Name Point Conc C2 CS C10 C100 2 5 10 100 Arpcai (sf) Q2 Q5 Q10 Q100 (tcj (ac) H1 1 11.1 OA2 0.12 021 0.51 2.12 0.00 3.62 Z39 9,381 022 0.01 0.00 0.17 0.81 0 0 0 0.00 0 0 0 0.00 0 0 0 0.00 0 0 0 0.00 TOTAL SITE 9,381 022 0.01 0.00 0.17 0.81 Paved areas & shallow Z aved swales Paved areas & shallow z aved swales Paved areas & shallow Z aved swales Paved areas & shallow „ 3768c - JVA Cfvil Rational Calculations Histonc JVA Incorporated 1319 Spruce Street Boulder, CO 80302 Ph: (303j 444 1951 CoFC 9/11 Memorial Composite Runoff Coefficient Calculations Location' Fort Collins Minor Design Storm' 2 Major Design Storm: 100 Soil Type: C/D Job Name: CoFC 9/11 Memorial Job Number: 3768c Date: 10/11 /23 By: EJK I� StreetsPaved 100% ConcreteDriveslWalks 96% Roaf 90% Gravei 13% Landscaping(Bsoip 0% Landscaping (C/D solp 0% Playground 13% ArtificialTurt 50% C2 C5 C10 C100 0.87 0.88 0.90 0.93 �.87 0.87 �.88 0.89 0.80 0.85 0.90 0.90 0.15 025 0.35 0.65 0.00 0.10 0.20 0.50 0.05 0.10 0.20 0.40 0.15 0.25 0.35 0,65 0.45 0.50 0.60 0.70 Basin Desi n Data I(%j= 100% 96% 90% 13% 13% 50% 0% 0% I(%) RunoffCoeff's easin Desi n APaved Aar�vesic A� A A Aa P`�scaPe �B A�scaPe A A Im 9 oof gravel prygnd rt.turt Tota1 Tota1 p C2 C5 C10 C100 Name Point s�reets (sf) (sf) (sf) (sf) (sf) saq �ciosmp (sf) (ac) (�) �s� ono (sf) (sf) A1 1 4,236 1,981 3,164 9,381 022 46.1 % 0.42 0.48 0.54 0.71 TOTAL SITE 0 4,236 0 1,981 0 0 3,164 0 9,381 022 46.1% 0.42 0.48 0.54 071 3768c - JVA Civil Rational Calculations Basin Data Page 2 of 4 JVA Incorporated Job Name: CoFC 9/11 Memorial 1319 Spruce Street Job Number: 3768c Boulder, CO 80302 Date: 10/11/23 Ph:(303)4441951 By: EJK CoFC 9/11 Memorial Time of Concentration Calculations Location' Fort Collins Minor Design Storm_ 2 Major Design Storm: 100 Soil Type: C/D Sub-Basin Data Initial Overland Time (t;) Travel Time (t�) t� Comp tc Urbanized Check t� t,=Length/(Velocity x 60) ON Final Upper Time of Basin Design Aro�ai most t; Length Velocity t� Total t� (L/180) Min Name Point ac C5 Length Slope (%) min (ft Slope (%) Type of Land Surface C� f S Conc ( ) ( ) ) ( p ) (min) ti + t = � Length (ft) +10 (min) t� (fq A1 1 022 0.48 200 3.4 % 10.7 Paved areas & shallow 20 0.0 0.0 10.7 200 11.1 10.7 aved swales 3768c - JVA Civil Rational Calculations Basin Data Page 3 of 4 JVA Incorporated 1319 Spruce Street Boulder, CO 80302 Ph: (303) 444 1951 CoFC 9/11 Memorial Design Storm : 100 Year Job Name: CoFC 9/11 Memorial Job Number: 3768c Date: 10/ 11 /23 By: EJK Developed Storm Runoff Calculations Point Hour Rainfali (P�) : 2.86 Direct Runoff Total Runoff Inlets Pi e a � c � . E o o a� �- > �n a� °' °1 ^ 3 m` z°' � v � ci � � � ,.., �- u o N nl � �a o o fl- ; c � � '^ f° in -' � � d. � O C (0 L N L Vl � N d N t �m �a`�i � � � ¢ � � o c U � v °' � cc9i 9 a a�i a o n w m � m o ¢ � .� c� C7 � E W d � o o� O a o d u� a � �� A1 1 0.22 OJ1 10J0 0.15 7.51 1.14 10]0 0.15 7.51 1.14 3768c - JVA Civil Rational Calculations Q100 Stormwater Alternative ComplianceNariance Application City of Fort Collins Water Utilities Engineering Engineer Name Cody Gratny, P.E. Phone 303-444-1951 Street Address 213 Linden Street, Suite 200 City Fort Collins Owner Name City of Fort Collins Street Address 215 N Mason City Fort Collins State CO Zip 80524 Phone 970-416-2260 State CO Zip 80522 Project Name 9�11 Memorial at Spring Park Project/Application Number from Development Review (i.e. FDP123456) Legal description and/or address of property 2100 Matthews Street, Fort Collins, CO 80524 Description of Project Renovation of existing park area to install memorial monument in concrete plaza with signs. Existing Use (check one): �' residential �� non-residential �' mixed-use � vacant ground Proposed Use (check one): �" residential C� non-residential �� mixed-use � other If non-residential or mixed use, describe in detail Park Property State the requirement from which alternative compliance/variance is sought. (Please include applicable Drainage Criteria Manual volume, chapter and section.) Alternative to Quantity Detention ("Beat the Peak"), FC Stormwater Criteria Manual, Ch. 6, 2.5 What hardship prevents this site from meeting the requirement? The project site does not currently provide detention as it is within Spring Creek 100-yr Floodplain and Floodway. The project involves adding minimal impervious areas within less than 10,000 SF of disturbed area. Attach separate sheet if necessary What alternative is proposed for the site? We are proposing to add some impervious to the site (�4000 sf of concrete), but the runoff from this portion of the site will beat the peak for the Spring Creek. See attached Drainage Memo for details. Attach separate sheet if necessary 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. Digitally signed by Greg Oakes Greg Oakes DN CN=GregOakes,OU=UsarsandGmups OU=ParkPianning, OU=CPRE, DC=cs, oo-�aY, oo-r�9o�, oo-�om 10/13/2023 Signature of owner: oate�o23.,0.,3,328:3o-osoo Date: The engineer hereby certifies that the above information, along with the reference plans and project descriptions is correct. Signature of engineer: �°'�9 � Date: ioii3i2o23 :\\\\\\\\�� RE • /ST /��i ; �,�•' F.GR�'.F�% '�0 opy '9>,.�� " 45 .3 �: __ �� T• � /13/2��3 \�`�� // /�s,.••�...•• C� �Q �� S � �NA L �N��\�� PE STAMP Date complete application submitted: 10/13/23 Date of approval/denial: 10/18/23 Variance: � approved � denied Staffjustification/notes/conditions: New impervious area is disconnected and flows cross landscape area before entering Spring Creek for water quality. The site is adjacent to Spring Creek so beat the peak is appropriate. HeidiHansen .:"' :� ^`.•.' "'....`•..".°`"". Approved by: �,.._........,wa. Entered in UtilityFile Database? �yes �no