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Drainage Reports - 05/30/2014
L I City of Ft. Collins prove lans Approved By. Date : 6: —- FINAL DRAINAGE AND EROSION CONTROL STUDY 1501 WEST ELIZABETH STREET Prepared for: Jim Hillhouse Hillhouse Architects Windsor, CO 80550 Prepared by: North Star Design, Inc. 700 Automation Drive, Unit I Windsor, Colorado 80550 (970)686-6939 April 4, 2014 Job Number 350-01 North Star design 700.Automation Drive, Unit I Windsor, CO 80550 Phone:970-686-6939 Fax:970-686-1188 April 4, 2014 Glen Schlueter City of Fort Collins Stormwater 700 Wood Street Fort Collins, CO 80522-0580 RE: Final Drainage and Erosion Control Study for 1501 West Elizabeth Street Dear Glen, I am pleased to submit for your review and approval, this Final Drainage and Erosion Control Study for 1501 West Elizabeth Street. I certify that this report for the drainage design was prepared in accordance With the Master Plan and the criteria in the City of Fort Collins Storm Drainage Manual. I appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. ii TABLE OF CONTENTS TABLEOF CONTENTS............................................................................................................... iii 1. GENERAL LOCATION AND DESCRIPTION 1.1 Location...................................................................................................................1 1.2 Description of Property ............................................................................................I 2. DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description..........................................................................................2 2.2 Sub -Basin Description.............................................................................................2 3.1 Regulations..............................................................................................................2 3.2 Development Criteria Reference and Constraints...................................................2 3.3 Hydrologic Criteria..................................................................................................3 3.4 Hydraulic Criteria....................................................................................................3 4. DRAINAGE FACILITY DESIGN 4.1 General Concept......................................................................................................3 4.2 Specific Flow Routing..............................................................................................4 4.3 Drainage Summary..................................................................................................4 5. STORMWATER MANAGEMENT CONTROLS 5.1 Written Analysis.....................................................................................................5 5.2 SWMP Contact Information...................................................................................6 5.3 Identification and location of all potential pollution sources..................................6 5.4 Best Management Practices (BMP's) for Stormwater Pollution Prevention ........... 7 5.5 BMP Implementation..............................................................................................:9 6. CONCLUSIONS 6.1 Compliance with Standards..................................................................................12 6.2 Drainage Concept..................................................................................................12 7. REFERENCES..................................................................................................................13 APPENDICES A Vicinity Map B Hydrologic Computations C Detention Pond Calculations D BMP Schedule and Cost Estimate E Floodplain Waiver F Excerpts from Other Reports iii 1. GENERAL LOCATION AND DESCRIPTION 1.1 Location The site is located on the Lot 20, Block 11 Fairview 9 h Filing in the Southeast '/4 of Section 15, Township 7 North, Range 68 West of the Sixth Principal Meridian, in the City of Fort Collins, Larimer County, Colorado. The address of the existing site is 1501 West Elizabeth Street. See the location map in Appendix A. The project is located on the south side of West Elizabeth Street between South Bryan Avenue and City Park Avenue. The project is bounded on all sides by existing commercial development. 1.2 Description of Property The entire site consists of approximately 1.46 acres of land. The land was previously developed with a c-store and car wash which were destroyed in a fire. The buildings have been removed from the site but some pavement and utilities currently remain on the site. These and all surface improvements will be removed with the redevelopment of this site. The site currently drains to a detention pond on the south portion of the site. Slopes on site range from approximately 1% to 2%. This site was located in the City regulatory 100 year Canal Importation Basin floodplain but was removed prior to the approval of this proposed redevelopment via the City Floodplain Waiver process. This project will include the development of a single building that has commercial, restaurant and retail uses on the main floor located in the north half of the site. There will be private drives, parking and landscaping on the remainder of the site. The site will have the required pervious pavement in the parking areas (as shown on the plan in Appendix A) and will provide detention storage under the parking lot with a combination of infiltration and collection in a system of perforated pipes. 2. DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description The proposed development lies within the Canal Importation Drainage Basin. The site is was previously located in a 100 year floodplain. With this proposed development, an application for a City Floodplain Waiver was approved to remove this site from the 100 year floodplain (refer to Appendix E for a copy of this approved waiver). The waiver was justified based on the information contained in the "As -Built Design Summary & Floodplain Modeling report for Canal Importation, Ponds and Outfall" by Ayres Associates dated February 2013. Since the property was removed from the floodplain by the waiver process, there will be no Chapter 10 compliance issues. 2.2 Sub -basin Description This site was included in the "Final Drainage Report for Diamond Shamrock Gas Station, Convenience Store and Car Wash, Lot 2 Fairview Shopping Center II" by Galloway, Romero & Associates dated February 6, 1989 and revised May 16, 1989. Portions of this report are included in the Appendix. 3. DRAINAGE DESIGN CRITERIA 3.1 Regulations This report was prepared to meet or exceed the "City of Fort Collins Storm Drainage Design Criteria Manual' specifications. Where applicable, the criteria established in the "Urban Storm Drainage Criteria Manual" (UDFCD), developed by the Denver Regional Council of Governments, has been used. 3.2 Development Criteria Reference and Constraints The runoff from this site has been routed to maintain the same general patterns as previously established. The site is restricted to a 2 year historic release rate with this development. The historic condition for this site is an undeveloped condition without consideration of the previous development condition. The runoff from the entirety of the site, including the entire proposed building, will be directed to the parking lot where the water will enter the under parking lot detention area via the proposed porous pavements 2 or via an inlet proposed near the southeast corner of the site. The runoff from the roof will be connected to the underground detention pipes without discharging to the surface pavement. The release rate for the detention pond has been calculated to be 0.45 cfs which is equivalent to the 2 year historic runoff rate for this site in an undeveloped condition. An orifice plate will be installed in the manhole on site to restrict the release rate to the 2 year historic rate. An overflow will also be provided in the manhole to allow overtopping of the plate if the orifice becomes plugged. The detention pond will release to the north into an existing storm manhole as the site previously has done. 3.3 Hydrologic Criteria Runoff coefficients calculations were prepared for the 2 and 10-year minor and 100-year major storm frequency utilizing the rational method. Detention is proposed on site under the parking lot with a release rate equal to the 2 year historic runoff rate. The amount of detention provided under the parking lot was based on an assumed porosity of the chosen aggregate of 0.4. Based on the results of the geotechnical report for the site (excerpts included in Appendix F), some of the site runoff is expected to infiltrate into the existing site soils and enter the groundwater table. 3.4 Hydraulic Criteria The onsite collection system is 4" or 6" perforated pipe which is collect in a larger pipe and conveyed to the outlet point with a restriction to the historic runoff rate. An inlet is located in the parking lot which will act as a collection point if the porous pavements cannot intercept all of the site runoff. Sizes for the inlet and pipes have not been calculated as the amount of runoff expected in these conveyances are difficult to predict. Stormwater will also infiltrate into the groundwater as indicated by the geotechnical report, portion of which are included in the appendix. 4. DRAINAGE FACILITY DESIGN 4.1 General Concept The runoff from this site will flow into the parking lot which will be constructed using 75% conventional materials (asphalt or concrete) and 25% porous pavement (concrete or 3 pavers). The runoff from the site will enter the subsurface material (3/4" poorly graded angular rock) via the porous pavements or via pipe from the roof drains. In a situation where the porous pavements are clogged, the runoff will flow to the proposed inlet in the southeast corner of the site and enter the subsurface material. A small amount of flow from the patio on the north is anticipated to enter West Elizabeth Street without detention. No offsite flows will enter this site. 4.2 Specific Flow Routing A summary of the drainage patterns within each basin is provided in the following paragraphs. Basin 1 encompasses the majority of the proposed development including the entire building, parking lot, private drives and the landscaping on the west side of the site. A majority of the runoff flows to the parking lot in the south half of the site which will convey the flows beneath the parking lot to the proposed detention pond: This detention pond will have a small release rate (0.45 cfs) which equate to the 2 year undeveloped runoff. The water quality extended detention is incorporated into the subsurface detention system. The detention system will have an overflow to the east along the private drive that extends into the adjacent property. This site is being developed under the City criterion that requires that 25% of the site pavements be pervious. This site has approximately 21,950 square feet of proposed parking lot pavement on site which is entirely within Basin 1. Of the 28,700 square feet, 25% of this area would equate to 5490 square feet of required pervious pavement and with this proposed development, approximately 5650 square feet of pervious pavements are being proposed and will be located in the parking spaces as shown on the grading and drainage plan. 4.3 Drainage Summary All runoff from this site and the adjacent sites will be safely conveyed via surface flow to the detention pond. The site will generally conform to the Canal Importation Master Drainage plan which this site is included in. 4 The City of Fort Collins will be responsible for maintenance of the existing storm drainage facilities located within the right-of-way. The drainage facilities located outside of the right of way (including the detention pond) will be maintained by the property owner. 5. STORMWATER MANAGEMENT CONTROLS 5.1 Written Analysis The soils on this site are classified by the USGS Soil Survey as Altvan-Santana Loams and are classified in the hydrologic group B. The soils are described as being well drained and having a moderately high to high ability to transmit water (0.6 to 2.0 inches per hour). The geotechnical report indicates that the soils on site have a porosity as high as 108 feet per day. The rainfall and wind erodibility is deemed to be moderate. The site is surrounded by developed sites including streets and paved areas. The construction shall utilize silt fence around the perimeter to control sediment transport from rainfall and from wind. The silt fence that is located in the proposed pavement areas will be removed prior to placing new pavement. Rock socks will be utilized in the existing curb to capture sediments that are not fully contained by the silt fence placement. The locations of the rock socks will be in the areas of concentrated flow such as the existing curb and on the existing concrete sidewalks. The site may also utilize a vehicle tracking control pad to minimize sediment from being tracked onto adjacent pavements. Sediment that is tracked will be removed and placed within the site or permanently disposed of offsite. A concrete washout will be used on site during the concrete placement. All hardened concrete will be disposed of offsite. These BMP's have not been located on the site map due to the fact that the site is very small and these BMP's will need to be placed by the contractor in locations that are most beneficial and will minimize disruption of adjacent traffic. Permanent erosion control consists of covering the soils with a building, concrete walks, concrete drives and sod. No soil will be left exposed to erosion after the construction is complete. Refer to the landscape plan for areas of and instructions for placement of sod and soil amendments required prior to placement of sod. 5 Refer to Appendix D for the timing of the construction phases and the sequential installation of all BMP phasing for this site. Refer to the end of Appendix D for the Erosion Control Surety calculations. 5.2 SWMP contact information Permit holder: Name: Address: Phone Number: Email Address: Appointed agent: Name: Address: Phone Number: Email Address: 5.3 Identification and location of all potential pollution sources ���cm is l P Potentiaollutant SourceActivrty ed S yxpm— Y}-H Potential Pollutant Generated 8, �w�A�� '1 t � . Applic`able to thmproject Disturbed Areas Sediment X Soil stockpiles Sediment X Travel to adjacent public streets Tracked sediment X Contaminated soils Sediment, chemicals Possible Loading and unloading chemicals Chemicals Unloading of building materials Trash, debris X Outdoor storage of chemicals Chemicals On site equipment maintenance Oil, grease On site equipment fueling Diesel, gasoline X Dust generating activities Particulates, sediment X Use of fertilizer, pesticides, herbicides Fertilizer, pesticides Use of detergents, solvents, oils Detergents, solvents, oil X Waste dumpsters, waste piles Chemicals,.trash, debris X 6 Concrete washout Concrete, sediment, wash water X On site equipment washing Detergents, oil On site asphalt batch plant Asphaltic cement, sediment On site concrete batch plant Cement, sediment Portable toilets Domestic sewage X 5.4 Best Management Practices (BMP's) for Stormwater Pollution Prevention Structural Practices for Erosion and Sediment Control Structural practices for the site will consist mainly of silt fence and rock sock filters and are described in detail in the following paragraphs. These BMP's are expected to change as the construction progresses and it is the responsibility of the contractor to ensure appropriate BMP's are in place and/or removed at the appropriate time in the construction sequence. All temporary and permanent erosion and sediment control practices must be maintained and repaired as needed to assure continued performance of their intended function. Silt fence and rock sock filters shall be in place prior to commencement of construction activities. During clearing and grubbing necessary for silt fence installation, all cleared material shall be placed on the uphill side so that if erosion occurs from the cleared material, the sediment will be trapped and not transported downstream. Rock socks shall be implemented in the existing curb line as shown on the Drainage & Erosion Control Plan. All BMP's shall be installed per the details shown on the construction plan set. Temporary & Permanent Structural BMP's: a. �IltruRturallBMP��� .. . Qpproximate location on�s1te� c x Apphable.to this Silt Fence Site perimeter, refer to site map X Straw bale dams Rock Socks At proposed sidewalk culverts, refer to site map X Earthen diversion dams Vegetated swales Sediment trap/pond Pipe slope drains Geogrid . Inlet/outlet protection Culverts Riprap F1 Erosion control mats Inlet protection At inlet on site. X Vehicle Tracking Control Pad At site entrances, refer to site map X Concrete Washout To be located by Contractor X Non -Structural Practices for Erosion and Sediment Control: Soils exposed during the earthwork phase and landscape prep phase shall be kept in a roughened condition by ripping or disking along land contours until mulch, vegetation, or other permanent erosion control is installed. No large amount of soils (in excess of 15 yards) will be allowed to be stock piled on site. Overburden from the utility pipe trenching will be piled adjacent to trenches upstream of sediment controls and will be replaced in the trenches within 72 hours. Excess excavated materials from the demolition and grading phases of the project that cannot be reused on site will be exported as it is excavated. This includes any asphalt pavement from the existing site that is to be removed. A vehicle tracking pad will be installed at a location most beneficial to the site construction as determined by the contractor. Vehicles will not be permitted in the excavated area if soil is muddy. Gravel sub base will be placed and compacted in the areas indicated for pavement following excavation. In the current pre construction state the site enables tracking of silt onto the adjacent streets during wet conditions. During construction activities the street will be monitored for foreign debris tracked out of the site and mechanical sweeping and clean up will be performed as needed. No area shall remain exposed by land disturbing activity for more than thirty (30) days before required temporary or permanent erosion control (e.g. seed/mulch, landscaping, etc.) is installed. Temporary & Permanent non-structural BMP's: A ' :•i..e.,'"4 �i t ''. � air _� Non Structural BMP MM.- v « ¢war s 3`a v. t �� Approximate locatiomon stet $ xs farm Apphcabtefo�this Surface roughening Entire site X Soil stockpile height limit (less than 10') Perimeter vegetative buffer West boundary of site X Minimization of site disturbance Mulch Seed & mulch stockpiles after 30 days Stockpile toe protection (silt fence, wattles or ditch) Preservation & protection of existing vegetation & trees West boundary of site X 8 Good site housekeeping (routine cleanup of trash & constr debris) Entire Site X Sweeping & scraping of hardscape On and off site pavements X areas Heavy equip staged on site, properly maintained & inspected daily (no Staging area X onsite maintenance) 5.5 BMP Implementation 1) Phased BMP Implementation BMP's are expected to change as the construction progresses and it is the responsibility of the contractor to ensure appropriate BMP's are in place and/or removed at the appropriate time in the construction sequence. A construction sequence schedule has been included on the Drainage & Erosion Control Plan and included in the construction plans for this site. All BMP's shall be inspected and repaired or replaced as required to satisfy the conditions of he Stormwater Discharge Permit. All BMP's must be maintained and repaired as needed to. assure continued performance of their intended function. Refer to Appendix D for BMP Implementation Schedule Refer to Appendix D for BMP Estimated Costs 9 2 Materials Handling and S ill Prevention: �Matenals�Handlmg�&'Spitler Approximate location on 51 e - A Iicable to this KPrevenhon Portable toilets, anchored & Contractor to determine X located away from drainages Fuel storage located in bulk tanks with secondary containment & spill kit Mobile fueling performed at least 200 feet away from drainages & Contractor to determine X fully attended Fertilizers, form oil, solvents, cleaners, detergent stored in 55 gal Contractor to determine X or smaller containers, kept in storage units Dumpsters containing used chemicals containers & liquid Contractor to determine X wastes kept covered Equipment cleaning (on site) uses no detergents & flows to onsite retention basin In case of a release of fuel or other chemicals, absorbent booms or earthen berms will be immediately Location of spill X constructed to contain the spill & prevent runoff to adjacent surface waters MSDS sheets for onsite chemicals will be kept at the construction Contractor to determine X trailer to facilitate spill response & cleanup 3) Dedicated Asphalt or Concrete Batch Plant: Not proposed with this development 4) Vehicle Tracking Pad: Vehicle tracking control pad shall be installed wherever construction vehicle access routes intersect paved public roads. Vehicle tracking control pads shall be installed to minimize the transport of sediment (mud) by runoff or vehicles tracking onto the paved surface. Any mud tracked to public roads shall be removed on a daily basis and after any significant storm that causes sediment to be transported. It is unlawful to track sediment/mud onto public streets and may be enforced by the City of Fort Collins, by the State of Colorado or by the EPA. 10 5) Waste Management and Disposal: Portable toilets will be anchored & periodically maintained by waste management company. Dumpsters on site will be covered & periodically emptied by waste management company. Concrete waste will be allowed to harden and then will be removed from site. No washing activities will occur on site. Location of the concrete washout is shown on the site map. The washout will be sufficiently deep to accommodate all anticipated concrete truck wash water. Waste concrete will be allowed to harden and be removed from site periodically as the washout reaches 50% of its capacity. Truck wash water will not be allowed to reach the curb & gutter or any other water course. 6) Groundwater and Stormwater Dewatering: No groundwater was encountered during soils exploration therefore ground water is not anticipated to be an issue. If groundwater is encountered a groundwater discharge permit shall be obtained and a detailed report shall be completed describing the location and the .route of where pumped groundwater will be conveyed and the measures taken to prevent the transport of any pollutants to downstream waters. 7) Inspection & Maintenance: It is required that routine site inspections are performed to effectively address maintenance and repair of Best Management Practices (BMP's). The site inspections are to performed by the contractor or an inspector designated by the administrator at a minimum of once every fourteen (14) calendar days on active construction sites and after any significant. storm event (an event causing runoff). As part of the site inspections the inspector is required to keep documentation of all inspections and BMP maintenance, including an updated Site Map indicating new BMP's or the removal of BMP's since the previous inspection. Any maintenance, repair, or necessary installation of BMP's that are noted during the inspection must be completed within seven (7) calendar days from the date of the inspection. In 6. CONCLUSIONS 6.1 Compliance with Standards All computations that.have been completed within this report are in compliance with the City of Fort Collins Storm Drainage Design Criteria Manual and the Canal Importation Master Drainage Plan. The site was removed from the City regulatory 100 year Canal Importation Basin floodplain by the waiver process which was justified based on the information contained in the "As -Built Design Summary & Floodplain Modeling report for Canal Importation Ponds and Outfall" by Ayres Associates dated February 2013. Since the property was removed from the floodplain, there will be no Chapter 10 compliance issues. 6.2 Drainage Concept The proposed drainage concepts presented in this report and on the construction plans adequately provide for conveyance of runoff to the detention areas. Conveyance elements have been designed to pass required flows and to minimize future maintenance. If, at the time of construction, groundwater is encountered, a Colorado Department of Health Construction Dewatering Permit would be required. 12 7. REFERENCES City of Fort Collins, "Storm Drainage Criteria Manual", (SDCM), dated March, 1986. 2. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria Manual", Volumes 1 and 2, dated March, 1969, and Volume 3 dated September, 1992. 13 APPENDIX A VICINITY MAP a a z U IS FOOT MUDDPLAN BO kdower Al t _ /)ll ( r PS t ,� W ' W cc 13 U i W�rJIII�I Q a FLOOOPLAN NOTES t. PORTIONS 0E THIS %IOECT NERE LOCATED IN THE OTY REQRATtltY 100-IEAR CANAL IYPORTAnpl BASIN EL000PLAIN BUT THE STE NAS BEEN REYOL£D NA THE ROCOPLAIN WAIVER PROCESS BASED ON I.FMMAYM CDNTMNED IN THE 'AS -BUILT DESIGN SUMMARY A rLOCOPLNN YODELING REPORT FOR CAN.U. IMPORTATION PONDS AND WTFALL' BY AYRES ASSOCIATES DAM EEBWANY 9011 t ONAPTER 10 REQUIREMENTS Or MY YUMCPAL CODE NO LONGER APPLY. 2. INFORMATION SHOW IS BASED ON THE CURRENT EEEECTLE YODEL YIP BY ANDERSON CONSULTING ENQNEERS DAM 3001. WEST ELIZABETH STREET ■ R O p _ �_ : I l I 11, LLi i / t.2B 0.8 II n .I r{ i ROLE KNOT TIED N70 {� IRLLCROIOUNO lxPNG . DOES NOT ptMN ONTO PYOWG LOT NNOT IFD onto ERONOlM1 PIPING. NOT DRYN ONTO PNaONG LOT _ 9 Ewo9a cPIlR0. NOTES, 1) The City Slormwaler Deportment erosion control inspector must be notified at I...1 24 hour. prior to any construction on this site. ED 2) All required Sups shall be im.t.1led prior to any land disturbing activity 7 N (stockpiling stripping. grading, etc). All of required erosion contra measures most y o cO be installed at the appropriate: time in the construction sequence as indicated in the I m m Co approved project %chitlins, construction plans, and erosion control report. DO 1 m 3) Pre -disturbance vegetation moll be protected and retained wherever b C o ct � apossible.qu;r Removal existing sh di disturbance of existing vegetation .hall be vegetation limited the area required rb oil O^ m shortest Ior 'vnmatliate construction operations, and for the aM1ortesl practical period of lime. c Q•C O U rQ 4) All soils exposed during Iona disturbing octivity (stripping, grading, utility ono rr^�^' 3 N m A Lot; 20 10 0 20 40 installations, stockpiling. filling, etc.) shall be kept in a roughened condition by Q U C ripping or disking along land contours untl mulch, vegetation, or other permanent is installed. No r�s a) C gCC ,0 Ed •D erosion control soils in areas outside project street riyyhis of way SCALE: 1' - 20' shall remain exposed by land disturbing octivity for more than thirty (30) do, , � r S D. w before required temporary or permanent erosion control (e.g. seed/mulch, •v. landscaping, etc) is installed, unless otherwise approved by `O the Slormwaler Department. '">e 5) The properly must be watered and maintained at oll times during consbuciion octivities so as to prevent wind -caused erosion. All land disturbing activities sM1oll be -immediately discontinued when fugitive dust Impacts adjacent properties, oe determined by the City Engineering Department. 8) All temporary (structural) erosion contra measures most be inspected and w • repaired or reconstructed as necessary after each runoff event and every 14 days in • Order to assure continued performance of their intended function. All retained O sediments, particularly those on paved roadway surfaces, sM1oll be removed and disposed of in a manner and location 50 as not to cause their release into any Y m drainogewvy. 7) No Boll stockpile shall exceed ten (10) feel in height. All soil stockpiles shall be protected from sediment transport by surface roughening, watering, and perimeter ell fencing. Any soil stockpile remaining otter 30 days Shall be seeded and mulched. 8) City Ordinance prohibits the tracking, dropping, or depositing of sails or any other material onto city streak by or from any vehicle. My inadvertent deposited material shall be cleaned Immediately by the controctor. Z O N Of - LEGEND 9LT FENCE To K N PLAEC MA NG DE-WCQN A OLENLOT GRADING. REYOIE MOOR TO Mitsui NSTA ATIFN t PAIN OPERATIONS IONS 1 iP #<#f# � t L O "• }• 1 .. a 2 • t 1 t ' {? s TT NQ o f I REPM*TO OET SHEET For MINCERMEIea 1 ? PAr KTExnII1 KrA4 } � rv(- � �l "`L� Yr i[ ( �iir}�.��y_,_,�� ?S ✓��T a .(4,f��, 'ffil - ----------- ------ ------------------ ------------ - — ----Y- PAVO15 IMS W POFwOIG ' = i PAWNS CALL UTILITY N0T1na71ON CENTER OF COLORADO 1.800-922-1987 (811) ,c&ly.2-BUSNESS DAYS IN ADVANCE BEFORE YOU No. MADE. OR EXCAVATE I'M THE YANKING O l RWWNB YEMEM UIWYIE& METING PIPES O Z .905 — EASTUNG 5' CONTOp t r I______________ ' EnSTNG. 1' CONTOUR —e905 PROPOSED 5- Carl PRCP05E3 V CONTOIR 'a O N Y 0. 0 Y m .. Q K9Gx PONT 10 N N _ b . s Z BASINTFMA O.M 0.9 10 YN Pull COEmoENT AREA N AMES y a ai U n c 9I rn - b a 3 a ' saw aREcnW NA NN s0 we BASIN MILINDARY •_ ® —SF SF— SILT FLIIO O U O O OD REGi`- - YEHILIE TRA(%wc PAD uoa 313a8 O'b' ®0 a CDINCRETE wA91wT AREA , RS ROCK SOM CNPL wtcr PRoncnw CONSTRUCTION SE6UENCE CONSTWICTION," �r _ere®eeeeee SIZE -------- -- --- -------- ------------ 000===00 MEW ------------ - - ------------ ------------ ------------ mm W W G Non z as d " a-1 w Z _z o N co 0 uI Li CL� a =O Li 0 LO r Z _¢ Q O City of Fort Collins. Colorado UTILITY PLAN APPROVAL APPROVED: C11y Engn.r Drlr SHEET CHECKED BY: wale a woaldal. umb D.I. CHECKED BY: am.elelnlii Uty D.I.Del. CHECKED By. POV a low, ten Dwx CHECKED BY: S OF J irelle Engilem pet. -No. -- 350-01 CHECKED -BY: -- — Jab D.I. PERMEABLE PAVER SECTION PER DETAIL THIS AASHTO 07 AGGREGATE. 03RMACTOR TO PRONDE T.OP. ELEV TOP Cf SWEET OR STANDARD PAKMENT b BASE L[RIfICA11pi 10 NORTH STAR DESIGN k CITY PAVEMENT EIEVAnON CWRSE SECTION MR cEOTECNNICAL REPORT STMYWATER Cf A MRRWAI POROSITY Of 0.1 (COMPACTED) P%OR'TO PLACWG .1 MATERIAL OR SITE. 1 30 NIL PIC VIER AT )r' -LOCATIONS SHOWN ON PLAN �W RO•a .- IR Aa,E—� a� Mp i PEAFmSNOPE SOE RIDGE %PEN A SOCK ELEIIATEVI.nON MV.%PE INVERT Yl M CLEVAnaV SUBd1ADE UNDER PARKING LOT DETENTION DETAIL 1 1 I 1 ' 1 26 V b' SOLD PVC AT 2% I ) 1 1E ENW ROO, DRAIN TO 1 I I ARC�� ARCH FOR OnAN� I CONECTOI MTAA. LOv..1al 1/I I TIE FROR � DRAWN TTO FORD LINEA mv�N h 1 I PExmARn PK R[ru To PER BETNL I 1 ARCH FOR ROOT Ofl", PE 1 ( CORRECTION DETAL C Pvc Rut T.C.P. Fw31aA jA T I' T 1T Nw]IA w If 6' SOYD PLC AT 2 R FROM ROOT, DRNN 1 PEWORATEO PVC. PETER 1 ARCH FOR ROOF DRNI/M CONErna MIN ROOF GRAN O _PEN DETAIL. FI aOAMOFE ROT•NI m , F- L pp6'm•tAO r L IFPE rm SpDI Al F" 10 5 0 10 20 SCALE: 1- . to' n If a- SAID PK AT 1 111��Ci Itlu Il Il rl '.L 7 J I( CJ ;1 n _I :i 'y O C- TREE CONCRETE CINB - PERMEABIE WTERLOO(R1O PAYERS PER DETAa THIS SHEETLANDSCAPE SVRFACNG PER PLAN TIME PIT NTH PLANTING SCa BEDDING STORE PER DETAL NIS SE CONCRETE alREI II 11 . .. n o n Nv.N.l ROOF' ORYI SLOPE TO I IBIe IBJ'tL DRAW PER IETAI. RT PLAM zTO I � / SLOPE TO MIN TRAIN m 0Rm RorAWI[ I zz L '_' S A • .Pki."M:.lI' ADW SOIL MDER = _ SOD YY `1 IN. DIA. PERFORATED PIPE 1 ( TT...O.P: 39.21 TOP..mp3 1,114. %RARPED WITH WASHED AGGREGATE AND Nv.3161 "GRADE NOTE: FILTER FABRIC DRAIN TO STORY SEWER 4Ewu7 ROOT BARRIER MAY BE REQUIRED INSIDE — — OF CONCRETE CELLAR DEPENDING ON'TREE SPECIES CONSULT ABORIST FOR TNIS APPLICATION. J ` ' PIT WITH PERMEABLE INTERLOCKING a u E (\TREE \ /CONCRETE PAVEMENT (SECTION X-X) ( 1 t 1 I L r REFER TO Vmin RAN I'm I R"`%`A DR ON THIS PmTlm ? 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LI t, f .. ! r" LI ', ri I .I �t 1 IROFE RUC 1 ,I I r 1 '- { i-' r H rJ -( IJ iJ1j-1I I Iflp 7rl fJ '' ! .C1111 L j L I L. , i 1 _ ..{- �L— ----------------------------- -------------------- PmD UNG---------- POPE DET/y -r____- - ill STALL RATim STON -1 MAxx= R/ OY,a RATE XG V 12- ON Norm SOL SEE DETAIL PK DIED AT p SHEET ]. ass SOIL RR1-39.50 Fw1Eo 1 a P a' PERT,GRAIED E N I.Ox SLOE SOIX AT I IS6 ME Y T I[ RATED CIEMOIT RRwa1N �Nvlx•PK caw AT a3R SOPE 'In. a 3uw 1r.1• MEsn TOP.-X.n I I QXANO`W.31T) N I I NI 27:3 V IT, PK - CYW AT a52 SOS TAP..36.31 . sFabDE f]Ew31.20 I 1 SnI7A CCIONATKN INLET GRATE.311.1e Nv.]1111 V 1- SOD AS AT ass ' - J 1 SIP ®b TRKi% / RATED pEAlali T.O.P. / / Rlv-SI.m"'.05 I - - - - - - - - - - - - ------------ - - - - - II I� laa tf P 1 PUFmArm;M13 TO Or _-- 1 wm s001 a D.0 1RmrnGND 4� �TENnTA li it � N m paWm U 3 0�� C o m "- �i 3' aacm o .0 `a a I \r i Q. f- a INIC.o Alt IN Z Li Z W W O CO UJ H � 0 a �4 OEl �.DYlI15 0�1ra 1tYm lnl�y WIIstR1aCRGv ORAaS � D-S4 I 0 � r Z - - City of Fort Collins, Colorado - UTILITY PLAN APPROVAL - APPROVED: SHEET pIY Enynw Oel. ' CHECKED BY: unuy 001.. w /U- CHECKED BY: CALL RSi—.1.NOTIFICATION Si—.1. mNry not. CENTER OF COLORADO 1-800-922-1987 (811) CHECKED BY: Pp4. M RW.eIiOn D•I• S DAYS N ADVANCE bLL 2i= CHECKED BY: 6 OF 9 Y(RI OQ Ow. m CRCAVAIE irellk Enamv Dole FOR T RK C T,m ORE .E.M c nI IRIpERmONp YEYan YnLIPES CHECKED RY; 350-01 D,,, APPENDIX B HYDROLOGIC COMPUTATIONS N 7 O K W a 0 N F Z W U LL LL W O U LL LL O Z C C y E E o Y O o o w W d' m a ao tl! _O L e d a E m LL LL LL Q LL z W (I N N N y Q O O y U W IL Q ULU w m ❑ Q y Z � Q J Y J Q Q w 3 W O o y Q Q y w ;w x y it v y a. aQ= N Owe o O O K O Q w w m oaq y J Q LU O N N rQ Z 9 O V C � m m y Q m O U w O m NL. Q d yy O c a y N U J m U O a m 4U 0 y m C L UM � y 2 U m !E {p !Eo a j w 0.6 O O d y N m a— c 2 E n 2 m o E n n o Q U Q c Q y Q c U m U W dn uU U a nm. c m U � U W , a d � N o o [al 3 o r U _ _ c 7 ° m '-N 0] O 00. m 00 O O N NJ ° O_FF U p F O E II U K r z O z Z W U z O U LL iD W F- Rio mco y� ccSO oEO E U m N j Ov t 0 0 c Z on x z z O 2 zz O F Qh to O K 0 4 .A aUC1 C C E m y o a o m i Q O m � W m G. I IL a J c U. z � w + U o E = W Iv UN 2 J U Q FN J LL W C O v o Z E c o Z Q S U K al � rn o 0 Z O W (7 l0 O � O O w O g F J p o 07 N O w L J � elf W F O a Q � v Z Q J L a R $ W"��v O J U N m J F U o 0 Z U m N N O N 0 O m a` c Q Z O Z y to m U o Q m x m � m rn Z F u fq c2 ZIn n_ w O x oa } O z O F z z W U 2 O v LL O cW C_ F c a N E E Y 0 o Q > rL O O W m � i a J Q U C a m O Z � Q o C m m U = W IU U N ... Z U Q J F m J LL J W C D P p 8 Z E N O U R• O —y�N o N 0 N R^ z of W � W Oac � o 0 W N C m YI W � I--O Q ^ ^ o O o r 0 n U N Z JL W ' v J v U N o J Q H U o Z ✓J m N o m c N U N N N Q �°. a H Z 0 Z N u 2 m m m N 7 Z F u N 0 Z N W O x LL LL O Z D Q W (L oQ OW Z CW N G J Q Z O N� LL 0 O -c U C > O m0 MID oU c Q to o c Z on rn Y � Q c L d E n W m o d m m � N N N � O a J � Q U o Q' w d O Y � Q C � C U y d 0 N 42 a o v O N V 1� O C N U. U. C v O £ N Z D F W U N ONO Q U f0 N N c N � � H � � _ 7 2 U) C o m C o N 0 oa w d L) U LL 0 E O w Vl ,may- L N U C U C �- m m N N m N U C m — f6 NCL C C N L " (G U II II ` II 0 < N a LL LL O z D Y . uj IL n Q O w s� L- o W J Q z O .0 0) Y � c Q c E m W o 0 m > m N w O a a J O H o_ O w f- 0 � O W W U > 0 O } Q rn c U � o oa U � Cy C ri a LL c w .E o O z 7 I- U W 0 (� N N N m � U o 0 � N N = U N U_ 'C y n � _ U N 'p m oa L) U LL a E O w � N w L G1 v U �1 .L (0 m y U a Y O (0 C n c6 O II II ` II C3 U '_' ¢ 0 0 2 0 s d a W Lo N r Y � Q c E d W o 0 Of d d o a a J O Q o y rn a0 f O O U N N O O y W U � O 0 } y c Q me V d 0 o w rn cq v U N N v L O � W C aD O; LLLL O n ui z 7 ly F- LU U N o0 a G « U o Q U (0 N N C U 7 N � C o 0 O O Q APPENDIX C DETENTION POND CALCULATIONS. C 100-YEAR DETENTION VOLUME REQUIRED UNDER PARKING LOT DETENTION POND FAA METHOD LOCATION: . 1501 West Elizabeth PROJECT NO: 350-01 COMPUTATIONS BY: PPK DATE: 1/28/2014 Equations: A trib. To pond = 1.28 acre QD = CIA C100 = 1.00 Vi = T C I A= T QD Developed C A= 1.3 acre Vo =K QPo T QPo = 0.45 cfs S=Vi -Vo K= 0.9 Rainfall intensity from City of Fort Collins IDF Curve Storm Duration, T (min) Rainfall Intensity, i (in/hr) QD (cfs) Vol. In Vi (ft) Vol. Out Vo (ft) Storage S (ft) Storage S (ac-ft) 5 9.95 12.7 3821 0 3821 0.088 10 7.72 9.9 5929 0 5929 0.136 20 5.60 7.2 8602 243 8359 0.192 30 4.52 5.8 10414 486 9928 0.228 40 3.74 4.8 11489 729 10760 0.247 50 3.23 4.1 12403 972 11431 0.262 60 2.86 3.7 13179 1215 11964 0.275 70 2.62 3.4 14085 1458 12627 0.290 80 2.38 3.0 14623 1701 12922 0.297 90 2.22 2.8 15345 1944 13401 1 0.308 100 2.05 2.6 15744 2187 13557 0.311 110 1.93 2.5 16305 2430 13875 0.319 120 1.80 2.3 16589 2673 13916 0.319 130 1.60 2.0 15974 2916 13058 0.300 140 1.40 1.8 15053 3159 11894 0.273 150 1.20 1.5 13824 1 3402 10422 0.239 160 1.15 1.5 14131 3645 10486 0.241 170 1 1.10 1.4 14362 3888 10474 0.240 180 1 1.05 1.3 14515 4131 10384 0.238 Required Storage Volume: 13916 W 0.319 acre-ft WATER QUALITY CALCULATIONS LOCATION: PROJECT NO: COMPUTATIONS BY DATE: 1501 West Elizabeth J50-01 PPK 1/28/2014 Use 24-hour brim -full volume drain time for extended detention basin Required Storage = a ' ( 0.91 ' 13 -1.19 ' IZ + 0.78 - 1 ) Water Quality Capture Volume = WQCV = (required storage/12)"(tributary drainage area) SUB BASIN Trib. area (ac) % Imperv. Req. Storage (in. of runoff) from Fig. SQ-2 WQCV (ac-ft) req. vol WQCV •1.2 (ac-ft) DN,Q (ft) req. area/row from Fig. EDB-3 (in2/row) POND 3 1.28 80 0.33 0.035 0.042 1.00 0.381 WQ outlet sizing for pond 1 FromiFigure 5, for 314 in. hole diameter Area of hole = 0.442 in # of columns = 1 Area provided/row = 0.442 in Area Required/row = 0.381 in Use 1 columns of 314" diam holes LOCATION: PROJECT NO: COMPUTATIONS BY: DATE: STAGE -STORAGE TABLE 100-YEAR 1501 West Elizabeth 350-01 PPK 1/28/2014 POND 1 Extended Water Quality Volume Required = 106 year WSEL Spillway Elevation 100 yr Detention Volume Required = Total 100 yr Volume Required = With 0.40 porosity 0.042 0.105 ac ft 0.319 0.799 ac ft 0.361 0.904 ac ft Stage (ft) Surface Area W) Incremental Storage (ac-ft) Total Storage (ac-ft) 5033.47 0 5034.50 13,888 0.109 0.109 5035 20,630 0.242 .0.242 5036 1 0,630 0.474 0.715 5036.40 20,630 0.189 0.905 5037 20,630 0.284 1.189 A Detention Pond Outlet Sizing 100-YEAR LOCATION: 1501 West Elizabeth PROJECT NO: 350-01 COMPUTATIONS BY: PPK DATE: 1/28/2014 Submerged Orifice Outlet: release rate is described by the orifice equation, Q. = CA sgrt( 2g(h-E,)) where Qo = orifice outflow (cfs) Ca = orifice discharge coefficient g = gravitational acceleration = 32.2 ft/s A. = effective area of the orifice (ft`) Eo = greater of geometric center elevation of the orifice or d/s HGL (ft) h = water surface elevation (ft) QMU = outlet pipe dia = D = Invert elev. = Ea = h= Co = 0.45 cfs 12.0 in 5033.47 ft 5033:61 ft 5036.00 ft - 100 yr WSEL 0.6 solve for effective area of orifice using the orifice equation A. = 0.060 ft` 8.7 in` orifice dia. = d = 3.33 in Check orifice discharge coefficient using Figure 5-21 (Hydraulic Engineering) d / D = 0.28 kinematic viscosity, v = 1.22E-05 ftZ/s Reynolds no. = Red = 4Q/(pdv) = 1.69E+05 Co = (K in figure) = 0.6 check Use d = Ao = Qa = Detention.xls 3.300 in 0.059 ft ` = 8.55 in ` 0.44 cfs APPENDIX D BMP SCHEDULE &. COST ESTIMATE ED CONSTRUCTION SEQUENCE PROJECT: 1501 W ELIZABETH (UPTOWN PLAZA) DATE: 4/4/14 CONSTRUCTION PHASE (MONTH) 1 2 3 4 5 6 7 8 9 110 1 it 12 DEMOLITION GRADING (INCLUDES OVERLOT) OVERLOT UNDERGROUND DETENTION WO POND SWALES, DRAINAGEWAYS, STREAMS PIPELINE INSTALLATION INCLUDES OFFSITE) WATER SAINITARY SEWER STORM SEWER CONCRETE INSTALLATION (INCLUDES OFFSITE) AREA INLETS CURB INLETS CURB AND GUTTER PAVEMENT INSTALLTATION FINE GRADING BASE COURSE INSTALL PAVEMENT BEST MANAGEMENT PRACTICES STRUCTURAL SILT FENCE BARRIERS CONTOUR FURROWS (RIPPING/DISKING) INLET PROTECTION VEHICLE TRACKING PADS FLOW BARRIERS WATTLES, ETC) CONCRETE WASHOUT ROCK SOCKS BARE SOIL PREPARATION TERRACING RIPRAP VEGETATIVE TEMPORARY SEED PLANTING MULCHING SEALANT PERMANENT SEED PLANTING SOD INSTALLATION NETTING/BLANKETS/MATS SEDIMENT/EROSION CONTROL BEST MANAGEMENT PRACTICES (BMPs) COST OPINION SPREADSHEET 1501 West Elizabeth (Uptown Plaza) Item No. BMP ID Unit Installation Unit Cost Quantity Cost 1 Check Dam CDR LF $0.00 2 Check Dam (Reinforced) CDR LF $0.00 3 Concrete Washout Area CWA EA $1,200.00 1 $1,200.00 4 Construction Fence CF LF $0.00 5 Construction Markers CM LF $0.00 6 Culvert Inlet Filter CIF LF $0.00 7 Dewatering DW EA $0.00 8 Diversion Ditch (Unlined) DD LF $0.00 9 Diversion Ditch (ECM or plastic) DD LF $0.00 10 . Sediment/Erosion Control Matting ECM SY $0.00 11 _ Inlet Protection IP LF $10.00 16 $160.00 12 , Reinforced Rock Berm RRB LF $0.00 13 Sediment Basin(') SB LF $0.00 14 Sediment Control Log (Wattle) SCL LF $0.00 15 Seeding and Mulching SM AC $0.00 16 Silt Fence SF LF $3.00 885 $2,655.00 17 Rock Sock RS LF $10.00 35 $350.00 18 Stabilized Staging Area SSA SY $0.00 19 Surface Roughening SR AC $0.00 20 Temporary Stream Crossing TSC EA $0.00 21 Topsoil (6-inch Lift) TSL AC $0.00 22 VehicleTrackin ControllZl VTC EA $1,500.00 1 $1,500.00 Subtotal Maintenance & replacements (50%) #1 Erosion control amount TOTAL #2 Reseeding Erosion control escrow (greater of #1 & #2) AC $1,200 $5,865.00 $2,932.50 $8,797.50 < —'COMPARE 1.28� $1,536.00 <---- $8,797.50 <--- HIGHER COST APPENDIX E FLOODPLAIN WAIVER Q.. of F6rtC' MEMORANDUM DATE: November 1, 2013 Utilities electric • stonnwater - wastewater • water 700 Wood Street Po Box 580 Fort Collins. CO 80522 970.221.6700 970.221.6619 — fax 970.224.6003 — Too uH1Xes@fcgov.=n fcgov.com/uUHtles TO: Brian Janonis, Utilities Executive Director FROM: Mark Taylor, Civil Engineer I I A* Ken Sampley, Stormwater and Floodplain Program Managerr�/C, RE: Floodplain waiver request for 1501 West Elizabeth Street PURPOSE/EXECUTIVE SUMMARY A proposed redevelopment (mixed use with multi -family over commercial) project at 1501 W Elizabeth Street can benefit from a City floodplain waiver. The project is located in the Canal Importation Basin Floodplain and downstream of the capital improvements associated with the Canal.lmportation Ponds and Ouffall Project (CIPO) project. The CiPO project has completely removed this property from the 100-year floodplain. The effect of these improvements on flood hazard mapping, as studied and documented in February, 2013 by Ayres Associates, have not been adopted into the Stormwater Master Plan by City Council. Your review and/or approval of the waiver is requested to allow the development to move forward with the benefit of more accurate flood risk information, consistent with the standards of Section 10-144 of Chapter 10 of City Municipal Code. This will remove requirements to elevate mixed -use residential structures in the Cityflood fringe currently outlined in Sections 10-37 and 10-140. BACKGROUND A proposal to construct a new 2-story mixed use building with multi -family residential on the second floor and commercial use on the first floor is in the process of being reviewed by City staff. The previous structure, formerly operated as service station/convenience store, has been demolished. A portion of the property is within the flood fringe of the City -regulated 100-year Canal Importation Basin floodplain, as shown in Attachment B. The current effective hydraulic model on West Elizabeth Street was established by Anderson Consulting Engineers as part of the Canal Importation Basin Master Plan, in 2001. The City contracted with Ayres Associates to update the hydraulics and hydrology in the Canal Importation Basin following the completion of the CIPO improvements. The updated hydraulic model, which was completed in February, 2013, has been reviewed and accepted by City staff, but has not been adopted by City Council at this time. REQUEST The developer of 1501 W. Elizabeth Street has requested that the City grant a floodplain waiver, included as Attachment A, so that the most up-to=date hydraulic data may be used, which completely removes the property from the 100-year floodplain and enables the development to FortCollins be completed without elevating or floodproofing per the floodplain standards of Chapter 10 of City Municipal Code. CURRENT EFFECTIVE HYDRAULIC MODEL — 2001 Attachment B is Plate 8 of the 100-year floodplain in the Elizabeth Street/Constitution Avenue Flow Path, and shows the BFE and the HEC-RAS cross -sections along Elizabeth Street. 1501 W. Elizabeth St. has been highlighted and cross -hatched, and as can be seen, a portion of the property is in the current effective floodplain. POST PROJECT (CIPO) HYDRAULIC MODEL — 2013 Attachment C is Plate 8 of the 100-year floodplain in the Elizabeth Street Channel Flow Path, and shows the BFE and the HEC-RAS cross -sections that remain along the Elizabeth Street flow path, after updating the hydraulic model to reflect the improvements made as part of the CIPO project. 1501 W. Elizabeth St. has been highlighted and cross -hatched. Please note that the entire lot has been completely removed from the 100-year post project floodplain. FLOODPLAIN DOCUMENTATION In addition to the attachments, the following documents are available for review and inspection in the Stormwater Master Planning and Floodplain Administration office: • "Volume III, Technical Appendix E, F Canal Importation Basin Master Drainage Plan"; Anderson Consulting Engineers; May 11, 2001 • "As -Built Design Summary and Floodplain Modeling Report for Canal Importation Ponds and Outfall Project (C1PO)"; Ayres Associates; February, 2013 APPLICABLE CODE • 10-140(1) —new mixed -use construction is permitted in the flood fringe of a City basin, as long as the standards of 10-37 or 10-38 are satisfied. • 10-37(c)(3)(a) — new structures must be elevated eighteen inches above the base flood elevation. WAIVER AUTHORITY • 10-144 — The General Manager may waive floodplain requirements if he is satisfied that there is sufficient degree of certainty that the property will be removed from the floodplain as a result of a City funded capital project. The construction of the project and the hydraulic analysis are complete and accepted by City staff and awaiting adoption by City Council. FLOODPLAIN WAIVER Stormwater staff recommends that the floodplain waiver be approved. If there are any questions, or if additional information is needed, please contact Stormwater staff. cc: Jon Haukaas, Water Engineering and Field Operations Manager Brian Varrella, Floodplain Administrator 2. City Floodplain Waiver Form Attachment A (Based on City of Fort Collins Code, Section 10-114 or 10-144) Section A Property information 't— a_ a`.:a-.k .,...s�.:.:xE.rsz•'-.`'--"-". c bi-...w..-.a+.r. *n...gx. : Y,.. _ a ...�....'3,.... Property address or legal description 1501 West Elizabeth Street, Parcel 97154-40-001 Applicant name Patricia Kroetch, P.E. Phone 970-686-6939 Applicant address 700 Automation Dr., Windsor, CO 80550 tft Section B Proposed Project Information) a:f ��,+--.�e*• .-. 'r ;. _e -+r n.= -k 3 t.IC-v��v,.�x..s..c- k _ '"' r�wuZaw • Description of proposed project (check all that apply):❑d new construction ❑ addition ❑remodel ❑redevelopment ❑accessory structure ❑✓ fill Qexcavation change of use❑other (Attach additional descriptions and drawings as necessary.) Current use (check one):❑residentialznon-residential ❑mixed -use ❑vacant ground • Proposed use (check one): ❑residential ❑✓ non-residential ❑ mixed -use ❑other • If non-residential or mixed -use, describe use in more detail: Commercial use • Foundation type (check one): 21slab on grade ❑ basement❑crawl space [I enclosed area above grade - -, ,. ,mom, ,,, s� ,� a s.ta� -�` 5� a> , 35 Section C Waiver Information • Base flood elevation (100-year flood level): 5041.911 NGVR (City) N/A (FEMA) • Regulatory flood protection elevation: N/A • Floodplain designation: ❑FEMA ❑✓ City Floodplain name: Canal Importation Floodway:❑yes ❑✓ no • Proposed lowest floor elevation (refer toCity code lo-37(d)):N/A (attach drawing) • Nat ate of capital project that will remove property from floodplain: CIPO • Section(s) of City Code for which a waiver is being requested: 10-139(1) and 10-37(C)(3)(a) • What is the waiver request? Request to use post-CIPO construction hydrologic and hydraulic in to remove the parcel from the floodplain and from the standards of Chapter 10 of City Code. The applicant hereby certifies that the above information, along with the attached plans and project descriptions, are correct.The applicant agrees to comply with the provisions of the zoning ordinance, building code, all other applicable sections of City Code, Land Use Code, City Plan and all other laws and ordinances affecting the construction and occupancy of the proposed building. The applicant understands that if this waiver is approved the structure and its occupants may be more susceptible to flood damage and, if in a FEMA floodplain, the cost of flood insurance may increase for the property. The applicant understands that new structures that are constructed pursuant to this waiver and upon completion of the relevant capital project are determined to not have been re�11ved fro the floodway or flood fringe as anticipated at the time of said waiver and will be deemed to be non-confonni ru spnd fu u activities and development shall be subject to the requirements of Chapter 10 of City Code as the same would a ly to any co g structure. Signature of Capital project Notice to Proceed date: Expected capital project completion date: 7E Technical analysis for capital project: Capital project will completely remove property from floodplain (check one) ja yes ❑ no 0 unsure 7 Notes: ai V OWaiver. ❑ approved 0 denied kC'T►i lUtrilitiesGeneral Manager: floo*lainWalverform 1106 li Pi: 1= 1 D ml co 0 go mi A G t .;�, z vpr� g a 4 z -15 • I `� �_ L� .�,-y � � o rip � � g I'F~- Imo- ,'6+•.' a I• Z m �'•!'• r � .J LIE cn Ate. _ x rf[ �. +•" ��i �� r rJr�f'-- �lr •it � , 1 fl¢po `{y .rrw j { Jr l �/!. + - L�,A,rh _.1 - 4 l ( •�. 11j aie � w ..:'rdd" 'L- (gyp ' %�1 2 �'' !C 6^ --'^ r •�'R11� �Y•..-'ii- �.t.�. :.. _: �j � 10 _�__t�. � :._-- •.,.per—.-.:" � T I. %'-w° i •,~• I•;"i'"t. 't ',yj�'� ,ty m C7TY � -T.J.�r - p •j.Lljll T Ia .f t'.:3�: _ .'` 1 `..,,>, -T ^-I lk r7 A JI �'` -'1•.' - ! i I' AA ••J -+„� ` - L sx I SFr CBS NO f� 2 S••W s r.11 +1 $ n JIB z 1 a du IV � i ? � " v� � �rY � '� "'i � � �'L--•+ � � W � 1 {� alb �r � `1,i�F t 5 r ? •/ -x + __ .��e'-Y �/��Mf a x._: v� I ,_ .� 1— _ _ _e.._ -_ •� lr.�i1 l• .^' _ _ _- � LDS STR.�_E �..•... z�A C �ON!Tf3�7.R6�i ref$ � - ➢i :7 APPENDIX F EXCERPTS FROM OTHER REPORTS F Geotechnical Engineering Report Uptown Plaza 1501 West Elizabeth Street Fort Collins, Colorado July 24, 2013 Terracon Project No. 20135023 Prepared for: D.K. Investments, Inc. Windsor, Colorado Prepared by: Terracon Consultants, Inc. Fort Collins, Colorado Geotechnical Engineering Report 1%rracon Uptown Plaza s Fort Collins, Colorado July 24, 2013 a Terracon Project No. 20135023 i , Elevation of Depth to groundwater a Depth to groundwater a t Bonn ,Number °1 groundwater 8 days `" �.� �9 a while dnlhng; ft��� �� day after dnlling; OiR 1 6 2.5 5,035.8 2 6 i 6.1 5,032.6 3 13.5 4.9 5,034.9 4 6 3.2 5,035.7 5 Not encountered 3.8 5,034.5 6 Not encountered 3.5 5,035.9 DP-1 Not encountered -- -- DP-2 2.7 j -- These observations represent groundwater conditions at the time of the field exploration, and may not be indicative of other times or at other locations. Groundwater levels can be expected to fluctuate with varying seasonal and weather conditions, and other factors. Groundwater level fluctuations occur due to seasonal variations in amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels duing construction or at other times in the life of the structure may be higher or lower than the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project. Fluctuations in groundwater levels can best be determined by implementation of a groundwater monitoring plan. Such a plan would include installation of groundwater piezometers, and periodic measurement of groundwater levels over a sufficient period of time. 4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION 4.1 Geotechnical Considerations Based on subsurface conditions encountered in the borings, the site appears suitable for the proposed construction from a geotechnical point of view provided certain precautions and design and construction recommendations described in this report are followed. We have identified geotechnical conditions that could impact design and construction of the proposed structure, pavements, and other site improvements. 4.1.1 Existing, Undocumented Fill As previously noted, existing undocumented fill was encountered to depths up to about 4 feet in the borings drilled at the site. Deeper fills may be present on the site where buried tanks were removed during demolition of the gas station previously occupying the site. We do not recommend supporting shallow spread footing foundations or floor slabs on the existing fill Responsive a Resourceful a Reliable 4 Geotechnical Engineering Report Uptown Plaza ® Fort Collins, Colorado July 24, 2013 a Terracon Project No. 20135023 1rerracon should refer to ACI 302 for procedures and cautions regarding the use and placement of a vapor retarder. ® Other design and construction considerations, as outlined in the ACI Design Manual, Section 302.1 R are recommended. 4.5.2 Floor Systems -Construction Considerations Movements of slabs -on -grade using the recommendations discussed in previous sections of this report will likely be reduced and tend to be more uniform. The estimates discussed above assume that the other recommendations in this report are followed. Additional movement could occur should the subsurface soils become wetted to significant depths, which could result in potential excessive movement causing uneven floor slabs and severe cracking. This could be due to over watering of landscaping, poor drainage, improperly functioning drain systems, and/or broken utility lines. Therefore, it is imperative that the recommendations presented in this report be followed. 4.6 Hydraulic Conductivity Testing Two (2) hydraulic conductivity borings, presented as Exhibits A-10 and A-11, and designated as Boring DP-1 and DP-2,, were performed to depths of approximately 3 feet below existing site grades. Logs of the borings along with'a Boring Location Plan (Exhibit A-2) are included in Appendix A. 4.6.1 Hydraulic Conductivity — Field Investigation We understand a carwash building previously occupying the site was demolished and removed prior to our field investigation. During our field investigation, two (2) field hydraulic conductivity test borings were completed to a depth of approximately 3 feet below existing.site grades. The field hydraulic conductivity test borings were completed in areas of the site planned for permeable pavements. One of the field hydraulic conductivity test borings (DP-1) was completed in the area where the car wash building previously occupied the site. The second field hydraulic conductivity test boring (DP-2) was completed in the area of the site where we believe an existing detention area is present. Field hydraulic conductivity test boring DP-1 was drilled with a CME-45 truck mounted drill rig with 4-inch outer diameter solid -stem augers. Field hydraulic conductivity test boring DP-2 was completed with a 3Y4-inch hand auger. During the drilling operations, lithologic logs of the borings were recorded by the field engineer. Slotted PVC pipe was placed in each of the field hydraulic conductivity test holes full -depth and the annulus surrounding the slotted PVC pipe was filled with clean filter sand. The borings were then saturated with water and left to stabilize overnight. The soils encountered in DP-1 were visually classified in the field and consisted of existing fill materials comprised of lean clay with sand and gravel. The existing fill was slightly moist to Responsive o Resourceful o Reliable 17 Geotechnical Engineering Report lr�rracon Uptown Plaza a Fort Collins, Colorado July 24, 2013 a Terracon Project No. 20135023 moist. The soils encountered in DP-2 were also visually classified in the field and consisted of native sandy lean clay. The soils encountered in DP-2 were very moist to wet. Groundwater was not encountered in field hydraulic conductivity test boring DP-1. Groundwater was encountered infield hydraulic conductivity test boring DP-2 at a depth of approximately 2.7 feet below existing site grade while drilling. During delayed groundwater measurements taken in other borings completed on the site, groundwater was measured in Boring No. 5 (located near hydraulic conductivity test boring DP-2) at a depth of approximately 3.8 feet below the existing ground surface. The groundwater levels measured in our borings at the time of our field study were used when calculating the field hydraulic conductivity at this site. 4.6.2 Hydraulic Conductivity - Discussion The field hydraulic conductivity testing performed as part of our study was developed by the U.S. Bureau of Reclamation and was referred to as the well permeameter method. The field hydraulic conductivity tests were performed by adding water to the test holes to maintain a constant water level (constant head test). The calculated hydraulic conductivity value for field hydraulic conductivity test holes DP-1 and DP-2 were 3 feet per day (ft/day) and 108 ft/day, respectively. The calculated value for DP-1 is within the expected ranges for the soil types encountered in our borings and is considered to be a representative value. The calculated value for DP-2 is much higher than the expected ranges for the soil types (upper clays) encountered in our borings. However, a layer of clean to silty gravel with sand was encountered in some of the other borings completed at this site at a depth of approximately 6 feet below existing site grades. It is likely the gravel layer extends below most of the site and would be expected near the bottom of DP-2. We believe the comparatively higher field hydraulic conductivity value measured in DP-2 is due to the higher flow rates that occur as water flows into the gravel layer below the -site. The test results and schematics of the field hydraulic conductivity test hole details, Exhibit B-7 and B-8, are included in Appendix B. The field hydraulic conductivity test results and soils encountered in our borings completed at the site indicate infiltration of storm water retained in a reservoir below permeable pavements into the soils underlying this site will be favorable for the design of permeable pavements. However, shallow groundwater conditions may limit the allowable depth of the retention area below permeable pavements. The slotted PVC pipe was left in place for future groundwater readings. 4.7 Pavements 4.7.1 Pavements — Conventional Subgrade Preparation On most project sites, the site grading is accomplished relatively early in the construction phase. Fills are typically placed and compacted in a uniform manner. However as construction proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, or rainfall/snow melt. As a result, the pavement subgrade may not be suitable for pavement construction and corrective action will be required. The subgrade should be carefully Responsive a Resourceful a Reliable 18 Geotechnical Engineering Report Uptown Plaza ■ Fort Collins, Colorado Irerracon July 24, 2013 ■ Terracon Project No. 20135023 evaluated at the time of pavement construction for signs of disturbance or instability. We recommend the pavement subgrade be thoroughly proofrolled with a loaded tandem -axle dump truck prior to final grading and paving. All pavement areas should be moisture conditioned and properly compacted to the recommendations in this. report immediately prior to paving. 4.7.2 Pavements — Permeable Pavement Subgrade Preparation Unlike conventional pavements, permeable pavement subgrades are not compacted. When preparing the subgrade for permeable pavements, care should be taken to excavate the required reservoir storage volume without disturbing the underlying soils. Groundwater was encountered at depths of about 3.5 and 3.7 feet below existing site grades in the portion of the site planned for permeable pavements. Shallow groundwater conditions will limit the thickness of the rock reservoir layer used to store the storm water runoff. Shallow groundwater will.also reduce infiltration rates as the water stored within the rock reservoir layer infiltrates into the groundwater. 4.7.2 Pavements — Design Recommendations Design of pavements for the project have been based on the procedures outlined in the 1993 Guideline for Design of Pavement Structures prepared by the American Association of State Highway and Transportation Officials (AASHTO) and the Larimer County Urban Area Street Standards (LCUASS). A sample of the fill materials selected for swell -consolidation testing exhibited no movement when wetted under an applied pressure of 200 psf which is less than the maximum 2 percent criteria established for determining if swell -mitigation procedures in the pavement sections are required per LCUASS standards. Therefore, we do not believe swell -mitigation of the subgrade materials prior to pavement operations is necessary. Traffic patterns and anticipated loading conditions were not available at the time that this report was prepared. However, we anticipate that the new parking areas (i.e., light -duty) will be primarily used by personal vehicles (cars and pick-up trucks). Delivery trucks and refuse disposal vehicles will be expected in the drive lanes and loading areas (i.e., medium -duty). A maximum of 10 trucks per week were considered developing our recommendations. If heavier traffic loading is expected, Terracon should be provided with the information and allowed to review these pavement sections. Rigid pavement design is based on an evaluation of the Modulus of Subgrade Reaction of the soils (k-value), the Modulus of Rupture of the concrete, and other factors previously described. A Modulus of Subgrade Reaction of 200 pci, and a Modulus of Rupture of 600 psi, were used for pavement concrete. The rigid pavement thickness was determined on the basis of the AASHTO design equation. Recommended minimum pavement sections are provided in the table below. Responsive o Resourceful a Reliable 19 Geotechnical Engineering Report Uptown Plaza s Fort Collins, Colorado July 24, 2013 ■ Terracon Project No. 20135023 Conventional Pavements lrerracon 3A tMIR� Recommended�PavementThickness(inches), r r i'a affcsArea� Alternative Asphaltic s 4 ' Concrete Aggregate; Bas`e''Course �Poruand Cement Concrete Automobile Parking A 3 4 7 B - - 5 5 (light duty) Drive Lanes A 4 6 - 10 and Loading Areas (heavy duty) B 4 5 9 Permeable Pavements - * Recommended Pavement.Thicknesst(mches)� Traffic Ur Permeable r Altatrveporous "Asphalt �Rermeatile7 Concrete Interlocking ConcreteEwAgg[egate Pavement Base Course Total a .� fit, (PICP) , A. 3 - 6 9 Automobile B - 6 3 9 Parking C - Typically 3 % 3 6'/a Terracon recommends the design and construction of permeable pavements should be completed by a specialty contractor who has demonstrated experience with placing, compacting, finishing, edging, jointing, curing, and protecting permeable pavements. There are several choices for base course depending upon which type of permeable pavement is chosen. Terracon recommends constructing perimeter curbing around permeable pavements and between conventional and permeable pavements to reduce infiltration of water below moisture sensitive subgrades. Where rigid pavements are used, portland cement concrete should be produced from an approved mix design with the following minimum properties: Propeitiesr M111OLMIC" '.Al 44 ,s, :Value , Compressive strength 4,000 psi (mimum) Cement type Type I or II cement Entrained air content (°/a) 5 to 8 Concrete.aggregate ASTM C33 and CDOT Section 703 Responsive a Resourceful a Reliable 20 Geotechnical Engineering Report l��rr�con Uptown Plaza n Fort Collins, Colorado July 24, 2013 ■ Terracon Project No. 20135023 Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes from the time the water is added to the mix. Longitudinal and transverse joints should be provided as needed in concrete pavements for expansion/contraction and isolation per ACI 325. The location and extent of joints should be based upon the final pavement geometry. Joints should be sealed to prevent entry of foreign material and doweled where necessary for load transfer. Although not required for structural support, a minimum 4-inch thick aggregate base course layer is recommended for the PCC pavements in heavy-duty areas to help reduce the potential for slab curl, shrinkage cracking, and subgrade "pumping" through joints. Proper joint spacing will also be required for PCC pavements to prevent excessive slab curling and shrinkage cracking. All joints should be sealed to prevent entry of foreign material and dowelled where necessary for load transfer. For areas subject to concentrated and repetitive loading conditions such as dumpster pads, truck delivery docks and ingress/egress aprons, we recommend using a portland cement concrete pavement with a thickness of at least 6 inches underlain by at least 4 inches of granular base. Prior to placement of the granular base the areas should be thoroughly proofrolled. For dumpster pads, the concrete pavement area should be large enough to support the container and tipping axle of the refuse truck. Pavement performance is affected by its surroundings. In addition to providing preventive maintenance, the civil engineer should consider the following recommendations in the design and layout of pavements: • Site grades should slope a minimum of 2 percent away from the pavements; • The subgrade and the pavement surface have a minimum 2 percent slope to promote proper surface drainage; © Consider appropriate edge drainage and pavement under drain systems; m Install pavement drainage surrounding areas anticipated for frequent wetting; o Install joint sealant and seal cracks immediately; o Seal all landscaped areas in, or adjacent to pavements to reduce moisture migration to subgrade soils; and o Placing compacted, low permeability backfill against the exterior side of curb and gutter. 4.7.3 Pavements — Maintenance Preventative maintenance should be planned and provided for an ongoing pavement management program in order to enhance future pavement performance. Preventive maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first priority when implementing a planned pavement maintenance program and provides the highest return on investment for pavements. Responsive o Resourceful a Reliable 21 Geotechnical Engineering Report 1r�rrC7�on Uptown Plaza a Fort Collins, Colorado July 24, 2013 a Terracon Project No. 20135023 Permeable pavements require periodic inspection and cleaning. Consideration should be given to installing signage to restrict heavily loaded vehicles (i.e. trash trucks, delivery trucks, etc.) from driving on permeable pavement areas. Also, maintenance of permeable pavements should be completed by properly trained workers. 5.0 GENERAL COMMENTS Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide observation and testing services during grading, excavation, foundation construction and other earth -related construction phases of the project. The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concemed about the potential for such contamination or pollution, other studies should be undertaken. This report has been prepared for the exclusive use of our client for speck application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as described in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing. Responsive 13 Resourceful a Reliable 22 APPENDIX A FIELD EXPLORATION g , I —7 U 1 9� 164 5UILDINq I- V-49E i LEVEL I 5F,&CE FIN#.-Jct,� r`r 0 EAT. &Wftl '0 WAL� 1P u WAT W 3 I iETEK 0 04F \'1AY o; §L :Z 4 �' F�N > 5xt'aTtq Acc4st E'NE'q T t241 e--'EPW 01K6 WED ..�. ---J ___—_ — — MEW }hnL TF4LJ�5181) r j W�' DIP 2 41 -Wa. t its. LEGEND it APPROXIMATE SCALE I + Approximate Boring Location DP-1 -# Approximate Field Hydraulic Conductivity Location 01 20' 40' DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT Zk Approximate Location of Temporary Benchmark INTENDED FOR CONSTRUCTION PURPOSES (Top Man Hole Lid -Elevation 5,041.2') ftjKtManager. EDEI ftjeaNa. 20135023 BORING LOCATION PLAN EXHIBIT Raven By: BCJ Scale: 1'=40' 1rerracon Uptown Plaza Check By: ED13 FileNam: Comultin, Enginmrs & Scientists 1501 West Elizabeth Street A-2 App-ed By: EDB Dam: 6120/2013 Fu. " w U Fort Collins, Colorado C C F 0 `v c u C BORING LOG NO. DP-1 Page 1 of 1 PROJECT: Uptown Plaza CLIENT: D.K. Investments, Inc. Windsor, Colorado SITE: 1501 West Elizabeth Street Fort Collins, Colorado (7 LOCATION See Exhibit A-2 �m W ATTERBERG O w F E e e F ri LIMBS z o Latitude: 40.573953' Longitude: -105.103496' Q w F ur w Z LL w ca w a ca w ¢ 3 3 ¢ w Approximate Surface Elev: 5038.95 (Ft.) +/- o a rn Lu W < rn i O w LL-PL-PI it 30 m U 3 i DEPTH EL VATIO Ft. FI - I FAN QI AY with SAND and GRAVIFI, brown to dark brown 3.0 5036+/ Boring Terminated at 3 Feet i i I i i i i i i i i Stratification lines are approximate. In -situ, the transition may be gradual. Advancement Method: flinch solid -stem flight augers See Exhibit A-3 for description of field Notes: procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and Abandonment Method: Slotted PVC pipe with filter sand pack. abbreviations. WATER LEVEL OBSERVATIONS Boring Started: 6/20/2013 Boring Completed: 6r20/2013 No free wafer observed while drilling. �errac®n 1901 Sharp Point Drive, Suite C Drill Rig: CME-45 Driller. Odell Drilling, Inc. . Fort Collins, Colorado jProject No.: 20135023 Exhibit: A-10 BORING LOG NO. DP-2 Page 1 of 1 PROJECT: Uptown Plaza CLIENT: D.K. Investments, Inc. Windsor, Colorado SITE: 1501 West Elizabeth Street Fort Collins, Colorado cv LOCATION See Edvbil A-2 J m z W 2r e c ATTERBERG LIMITS w U Latitude: 40.573829° Longitude:-105.103103' V w >O - Q a Lu t_ vow E rn o _ .� w Z Q. W w w ¢ y 3 z o W LL-PL-PI O Approximate Surface Elev: 5034.85 (Ft.) +/- p ¢ xe LL O 3 w 3 O U) U a DEPTHON Ft rn SANDY LEAN CLAY, dark brown 3.0 5032+/ Boring Terminated at 3 Feet 3 9 J J C 1 ) i i i ) i 1 i Stratification lines are approximate. l"tu, the transition may be gradual. Advancement Method: See Exhibit A-3 for description of field Notes: 3-inch hand auger procedures. See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and Abandonment Method: Slotted PVC pipe with filter sand pack. abbreviations. WATER LEVEL OBSERVATIONS �" �erra 1901 Sharp Point Drive, Suite C Boring Started: 6/20/2013 Boring Completed: 6f20/2013 While drilling Drill Rig: Hand auger Driller. Bryce Johnson Fort Collins, Colorado Project No.: 20135023 Exhibit: A-11 M Prepared :For: `Diamond Shamrock ,Ref ining- And..Marke.ting Company 520 E. 56th Avenue Denver, Colorado 80226 Attn: Ed Kress Prepared By: Galloway, Romero and Associates, Inc. 12449 E..39th Avenue Denver, Colorado '80239- Attn: Roger Barringer ` 1 1 LK� I REVISED MAY. .3.989 .......................... ........................................ General Location -and Description Drainage Design Criteria. This drainage study has be,en prepared using- `the, Rational Method since the site is less than 200 acres. Calculations . have been performed for the -21 1 and 100 year storms. Developed f 167 .from the site has:beenlimited to. the. two year -historic rate. Drainage Facility Design,: The site has been divideA.,,in-ta five subbas ins: A, C;, D;, E, and F. All subbasins.,6x6eDt I or F, drain. to detention ponds located in three ,areas on 'ther,,, site. Total release has been limitedto the two,.year historic, I rate'... -Su�bbasins A, C and encompass almost all the paved area of the,. site in addition to -the store. and ' canopy, - subbas in E contains thecar and 4nost of the lain . dscaping including the. -large' . � detention pond to the. south, and subbasin F represents the .r.emaidd er., or mostly landscaped fringes to the north and east of the perty- -According,to city requirements, the south half of Elizabet.h, 4ni A Ti Street should be included in our report. However, we. are _ .: requesting a variance from .City requirements since this roadway l was constructed before this PUD was assembled, and therefore has already been incorporated into other studys. Additionally -we -` feel that in making the drainage work for this .site, without:the additional street area, we have already maximized detention. Runoff will be .as follows: runoff from subbasin A (10yr.-, 1.06 cfi, 10:0 yr 1.80 cfs) will be detained in a detention, pond (645 cu £t) located in the paved drive on the north side -then will discharge at a reduced rate O.e c£s) into a second pond' located in the landscaped area to the south. Runoff from subbasin C (10 yr: 1.31 cfs, 100 yr: 2.21 cfs) will be detasned,x.. by ar pond (1019 cu ft) again located in a drive, and also will also:: discharge at a reduced rate 0:.5 cfs) intothe south detention pond. Runoff from subbas will not be detained -but will be directed to a trench drain at the southeast entrance and in turn into the south pond Flow from D into the pond will be 0 70..,cfs for" the 10 yr"storm and. 18 £or the 100 yr storm. _-L Since.' the south pond is locat within subbasin E', runoff from,::subbas,in E (10 yr 0 .30 c`fs, 100 yr: 0_. 571cf,s") too will be ' detained in" this pond. Spillage a p pills e f.rom the c wash will, not be directed': into. the -sanitary ,;system, but will be: routed through trench drains and into the ;pond3 i Tota.l.10.0 yr flow into the.' south. pond will be 3.10.:cfs,_ Pond.voldme will be.`699"4 'cu. ft. Disclia'rge will be through a: 3 3:/I'6 anch orifice which .."wi-11 allow a 100 yr release of 0-.42 cfs:. This flow' will b'e channeled into an existing 12" storm - _ sewer` on West Elizabeth the capacity of which is 4.07 cfs r _Runoff from subbasin F will flow undetained`.from the site :at e re ItaS C- a. 100 yr ?rate of .0.35"cfs,. Total 100 yr developed, 10. :".will which. compares favorably with the. two year historic rate of;D`.cfs. Flow from the"east landscaped area onto the adjacent site to the east will be 087 x 20 x 4.00 = .67 cfs- (AxCxI) for the, 10 year.,storm and '0.87 x .25 x 6.40 = .14 cfs for the 100. This represents. a substantial reduction from the existing since the; his"unofficial copy was downloaded on Aug-19 2013 fromihe C�ty7o , Colhns'PubheRecords Webs�te http //citydocs.fegov:com - - - or additional inforioationpi an official ,copy,.please,contact City_of Foit Collins=Utli'ties 700-Wood Street PortCollins; CO 80524 USA.:. entire. site currently discharges onto this -adjacent site. The east half of -the .private drive -to the west of the ,site has been incorporated into this study, however flow from the.:west - half has already been incorporated into the drainage pattern` of, the existing Taco Bell site. It makes little sense to alter this condition. Both buildings have been set the minimum required distance above the 100 yr floodplain. Studys performed by the City.of. Fort Collins indicate .that a 100 year flow of about 24`0 cfs,pass the site to the south. Water surface -elevation of ::this floodwater -has been calculated to be about 38.5 ft., thus the buildings have been placed at 4.1.0, a full le inches above the floodwaters. The buried fuel tanks, to be located to the east of"'the I Al proposed convenience store, will be anchored to concrete deadmen placed'.at :the bottom of the tank farm excavation. The anchorage, ' for these tanks will be designed to, withstand all buoyancy loads..: Conclusions This design and. the accompanyi-ng: plan is in. compliance .with the City of Fort Collins storm drainage requirements, and prov:ides..sufficient "drainage control to mitigate any effects: to downstream sites. Sufficient detention has been provided onsite. to reduce total 1,00 yr developed runoff to the 2-yr historic, rate. hisunofHcial copy was downloaded on Aug 19 2073 from the City of,Fort Collins Public Recoil Website!�:http Ki'M, ocs fcgov`com - ._ ..z _. .. 1 cFa . —.. ;" ,.,,, onadditional-information:otan�ofHaahcopy"�pleasecontact C,tytofTo Collins I9hlities.700�1N+ood Street+FontCollins; CO &0524,,USA.,,.