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HomeMy WebLinkAboutDrainage Reports - 12/18/2003±n,al " �i'� 14;o, p{? DRAINAGE STUDY FOR KFC / TACO BELL RESTAURANT A PORTION OF LOT 6 OF MULBERRY AND LEMAY CROSSINGS FLING NO. 2 CITY OF FORT COLLINS, LARIlMIER COUNTY, COLORADO July 18, 2001 (Revised: December 11, 2001) (Revised: January 18, 2002) (Revised: September 10, 2002) (Revised: October 28, 2002) PREPARED FOR: ARCHITEKTON 398 SOUTH MILL AVENUE, SUITE 301 TEMPE, AZ 85281 (480)894-4637 PREPARED BY: HIGHLINE ENGINEERING AND SURVEYING COMPANY 9101 EAST KENYON AVENUE, SUITE 2500 DENVER, COLORADO 80237 (303) 889-0044/(303) 889-0012 fax DWG NO. 173 I. INTRODUCTION Mulberry and Lemay Crossings Filing No. 2 is a 15.5 acres office/retail development. The KFC/Taco Bell Pad Site is a portion of Lot 6 Mulberry and Lemay Crossings Filing No. 2 consisting of 1.09 acres. A Final Drainage Report for Mulberry and Lemay Crossings has been approved as prepared by Colorado Land Consultants, Inc., (CLC), revised July 25, 2000. Having all storm sewer, detention and other infrastructure currently under construction, this report identifies that the proposed improvements for the KFC/Taco Bell has been designed in accordance with the Final Drainage Report for Mulberry and Lemay Crossings. H. GENERAL LOCATION AND DESCRIPTION The project site consists of 1.09 acres is located at the northeast corner of East Magnolia Street and South Lemay Avenue. The proposed restaurant will face north toward East Magnolia Street. The interior shared private drive and parking of the shopping center are located north of the project site. The site is located within the southwest quarter of Section 7, Township 7 North, Range 68 West of the 6th Principal Meridian, City of Fort Collins, Larimer County, State of Colorado. Presently, Mulberry and Lemay Crossings Filing No. 2, including the KFC / Taco Bell site, is currently under construction. It is anticipated that all infrastructure will be in place prior to construction of the KFC / Taco Bell site. No plans currently exist to develop the remainder of lot 6, and it is anticipated that the developer of this area will be required to conform to the approved plans and designs for the overall shopping center prepared by CLC.. III. DRAINAGE BASIN AND SUB -BASINS The site lies within the Poudre River drainage basin. The Poudre River is located south and west of the KFC site. Contained within the appendix of this report, please find that Lot 6 of Mulberry and Lemay Crossings Filing No. 2 is located within a 100 year floodplain per FEMA Flood Insurance Rate Map Community Panel Number 080101 0179 E, Panel 179 of 278, (Revised to reflect LOMR dated December 22, 1999). The restaurant building Finished Floor Elevation is proposed at 4938.50, being 4.1 feet higher than the 100 year base flood elevation of 4934.4. The approved Final Drainage Report for Mulberry and Lemay Crossings depicts the subject site located within Sub -basins B-8 and B-9. 48-inch storm sewer with catch basins are depicted on the approved drainage plan approximately 110 feet east of the site being tributary to a detention pond located in sub -basin P2. The storm sewer is designed to intercept developed runoff from the minor storm event and a portion of the major storm event and continue conveyance to the detention pond in sub -basin P2. Runoff from the major storm 173MArg 2 event not intercepted by the storm sewer outfall will continue conveyance to the detention pond overland via paved parking and drives. The detention Pond in Sub -basin P2 is designed to attenuate developed runoff for both the 10 and 100 year storm event, and continue conveyance to the Poudre River. IV. DRAINAGE FACILITY DESIGN In accordance with the Final Drainage Report for Mulberry and Lemay Crossings, runoff for both the design and major storm events of the site will be conveyed overland within paved parking and drives north toward the 48-inch outfall tributary to the detention pond in sub - basin P2. A high point will be he to split and convey onsite developed runoff overland to both entrances onto the north shared drive as depicted on the approved drainage study. V. CONCLUSION The drainage facilities for a portion of lot 6 of Mulberry and Lemay Crossings Filing No. 2 were designed in accordance with the Final Drainage Report for Mulberry and Lemay Crossings and the City of Fort Collins Storm Drainage Criteria. Developed runoff will be conveyed overland to the approved outfall Tributary to the detention pond as shown on the approved report. Prepared by or under the direct supervision of Russell B. Hall, PE & PLS Colorado Registration No. 26715 173kfc.drg 3 REFERENCES " Final Drainage Analysis Mulberry and Lemay Crossings", prepared by Colorado Land Consultants, Inc., revised January 25, 2000. 173kfc.drg 4 EROSION CONTROL The purpose of this plan is to provide additional information and requirements for Erosion Control associated with Construction Activity". A. Site Description a) The proposed construction activity is development of A fast food restaurant with all relevant amenities including, but not limited to, streets, utilities, and drainage improvements. b) The anticipated sequence of construction is as follows : 1. Installation of perimeter erosion control measures 2. Site Clearing & Demolition 3. Overlot grading 4. Installation of temporary onsite erosion control measures 5. Utility Construction 6. Drainage improvements construction including erosion protection at outfall locations 7. Street, Parking, and Building Fine Grading (See Building Schedule) 8. Street curb, gutter, walk, and building 9. Street Paving 10. Sod and landscaping of open space areas, 11. Removal of erosion control appurtenances after site is stabilized. 173kfc.drg 5 Building Schedule 1. Foundation Excavation 2. Foundation Backfill 3. Above grade building construction 4. Domestic wet utility connection 5. Dry utility installation 6. Driveway / patio/ sidewalk installation 7. Precise lot grading 8. Reseeding and / or sodding per Landscape Plan c) The total area of the site is approximately 1.1 acres. The area of the site expected to undergo grading activities is approximately 1.1 acres not including public roadways. d) Runoff coefficients and soils data are identified in this Final Drainage Study. e) Little vegetation exists on this site consisting mainly of recently overlot graded bare ground covering approximately 95 % of the site. f) Potential pollution sources include equipment refueling and maintenance, grading operations, and concrete wash water. g) No significant non-stormwater components of runoff are anticipated. h) Receiving waters are initially minor tributaries and storm sewer outfalls to the Poudre River. B. Site Maps The maps, taken from the "Construction Plans for KFC//A&W at Mulberry and Lemay", include: Drainage Study & plan, Grading Plan, Erosion Control Plan. 173kfc.drg 6 C. Best Management Practices (BMP) for Stormwater Pollution Prevention a) Erosion and Sediment Control Structural practices : Overlot grading operations present the greatest opportunity for pollution of state waters. Due to the nature of the site, disturbed areas shall be contained by a perimeter silt fence which shall remain in place until non-structural ways 'and means are established. Upon completion of the overlot grading, surface runoff velocities shall be slowed by slope reduction, (The existing average slope across the pad site is approximately 1.4 percent, and some portions of the site are to be graded at 0.5 percent thus reducing velocity of surface runoff through the site). The grading improvements generally direct runoff to a central point of site release thereby permitting point source methods of pollution abatement management practices (For purposes of this report. "Point source methods of pollution abatement management practices" is defined as placement of"Structural Best Management Practices" or Structural BMP's at locations where surface runoff is concentrated due to grading design. The Structural BMP's are designed to block or filter surface runoff which will mitigate erosion potential and allow pollutants to settle before exiting the site. See the Urban Storm Drainage Criteria Manual Volume 3 for further definitions). Surface areas remain denuded during utility construction, but the structural elements remain in place. Maintenance procedures shall be recorded by the developer's construction manager in a log book. Surface runoff from the site is tributary to an existing 48-inch storm sewer outfall with catch basins located approximately 110 feet east of the site being tributary to a detention pond located further south. Because the structural BMP's proposed on the KFC site cannot intercept 100 percent of sediment from erosion, a gravel filter will be constructed around the catch basin located to the east as shown on the Erosion Control Plan to further intercept sediment which is not intercepted upstream. 2. Non-structural Practices: Silt and sediment deposits shall be removed and spread evenly in open areas. Upon establishment of surface vegetation, structural erosion control measures shall then be removed whereby non-structural methodology shall be practiced. b) Materials Handling and Spill Prevention 173kfc.drg 7 Potential pollutant material brought onsite would be fuel for earth moving and trenching equipment. Berm shall be provided at the fueling site as a containment measure. There will be no permanent bulk fuel storage on this site. The Fire Protection District is equipped for spill cleanup. Any contaminated materials shall be properly disposed of. Other potential pollutant material includes concrete wash water. This shall be done in areas designed by the developer's construction manager and protected from runoff and, after hydration, buried in designated non -construction zones. Building materials are expensive and shall be protected by storage outside of runoff areas. This shall be performed by the materials owner to protect the inherent value and no additional measures will be taken. Waste building materials shall be collected by a reputable waste management company and transported to a legal waste disposal facility. Site inspections shall be performed weekly to assure onsite collection. No dedicated concrete or asphalt batch plants are proposed on the site. D. Final Stabilization and Long Term Stormwater Management After infrastructure construction is complete, runoff will be directed via onsite parking and drives to a detention pond and continued conveyance via storm sewer to the Poudre River. After completion of the buildings, pavement, and landscape by the builder, the owner shall maintain the property in good functioning order. The stormwater quality is then classified as urban runoff. E. Other Controls Offsite soil tracking is limited by the restriction of construction traffic to a single access and by a periodic street sweeping. Waste disposal shall be by means of a local waste management company. Implementation of the controls shall be by.the erosion control plan which is part of the contract documents. F. Inspection and Maintenance Maintenance procedures are outlined in the notes contained on the overlot grading and erosion control details. A log record noting all inspections and mitigation efforts shall be kept with the construction manager. 173kfc.drg 8 APPENDIX No Text No Text I DRAINAGE CRITERIA MANUAL TABLE 3-1 (42) / RECOMMENDED RUNOFF COEFFICIENTS AND PERCENT IMPERVIOUS LAND USE OR PERCENT FREQUENCY SURFACE CHARACTERISTICS IMPERVIOUS 2 5 10 100 Business: Commercial Areas 95 .87 .87 .88 .89 Neighborhood Areas 70 .60 .65-, .70 .80 Residential: Single -Family * .40 .45 .50 .60 Multi -Unit (detached) 50 .45 .50 .60, .70 Multi -Unit (attached) 70 .60 .66 .70 .80 1/2 Acre Lot or Larger * .30 .35 .40 AD Apartments 70 .65 .70 .76, .80 Industrial: Light Areas 80 .71 .72 .76 .82 Heavy Acres 90 .80 .80 .85 .90 Parks, Cemetaries: 7 010 - .10 .35 .60 Playgrounds: V 13 .15 ` Schools: 50 .45 .25 .50 .35 .60 .65 .70 - Railroad Yard Areas - 40 - .40 .45 .50 - .60 Undeveloped Areas: Historic'Flow, Analysis- 2 . (See "Lawns") Greenbelts, Agricultural Offsite Flow Analysis (when 45 .43 .47 .55 .65 land use not defined) Streets: Paved 100 .87 .88 ..90 .93 Gravel 13 .15 •-.25 .35 .65 Drive and Walks: 96 .87 .87 : .88 .89 Roofs: 90 .80 .85 .90 .90 Lawns, Sandy Soil 0 .00 .01. .05 .20 Lawns, Clayey Soil 0 :05 .10 .20 .40 1 OF RUNOFF . NOTE: These Rational Formula coefficients may not be valid for large basins. *See Figure 2-1 for percent impervious. 5-1-84 DRAINAGE CRITERIA MANUAL RUNOFF 50 30 t— 20 -f- 1 11, Ia Q o � III I' c ICI r� I� @ 'n ►� `' I I I I I I I I I ?� I I Qr I 1 I 1 I I I I I' I 1 I I I• I I I I I 1.1 I I I F I I I I I I I I I I I I I 1 1 I I I I I IL I I Yi I I I I I I I I 11 .2 ,3 .5 1 1 ►1� 2 3 5 10 20 VELOCITY IN FEET PER SECOND Figure 3-3 ESTIMATE OF AVERAGE FLOW VELOCITY FOR USE WITH THE RATIONAL FORMULA. ` MOST FREQUENTLY OCCURRING "UNDEVELOPED" LAND SURFACES IN THE DENVER REGION. REFERENCE:: "Urban Hydrology For Small Watersheds" Technical Release No. 55, USDA, SCS Jan. 1975. 5-1-84 URBAN DRAINAGE & FLOOD CONTROL DISTRICT No Text City of Fort Calling Rainfall Intensk"uratlon.F for using the Ralioml Liethod y Table (5 fdnutes - 30 Nnules) Figure 3-1a eo•d City of Fort Collins Rainfall Intensity -Duration -Frequency Table for using the Rational Method (31 minutes - 60 minutes) Figure 3.1b Duration (minutes) 2-year Intensity r 10-year Intensity i 100-year Intensify IrJhr 31.00 1.27 2.16 4.42 32.00 1.24 2.12 4.33 33.00 1.22 2.08 4.24 34.00 1.19 2.04 4.16 35.00 1.17 2.00 4.08 36.00 1.15 1.96 4.01 37.00 1.13 1.93 3.93 38.00 1.11 1.59 3.87 39.00 1.09 1.56 3.80 40.00 1.07 1.83 3.74 41.00 1.05 1.80 3.68 42.00 1.04 1.77 3.62 43.00 1.02 1.74 3.56 44.00 1.01 1.72 3.51 45.00 0.99 1.69 3.46 46.00 0.96 1.67 3.41 47.00 0.96 1.64 3.36 48.00 0.95 1.62 3.31 49.00 0.94 1.60 3.27 50.00 0.92 1.58 3.23 51.00 0.91 1.56 3.18 52.00 0.90 1.54 3.14 53.00 0.89 1.52 3.10 54.00 0.88 1.50 3.07 65.00 0.87 1.48 3.03 50.00 0.86 1.47 2.99 57.00 0.95 1.45 2.96 55.00 0.64 1.43 2.92 59.00 0.83 1.42 2.89 60.00 0.82 1.40 2.86 Vold Aan:&n AA-ft7_Bnw J O n Z co 0 1 w N a c � H cc Z ui LL 0 Z 0 Q V C Q 0 U W � � m ~ � W m H J G � m U N C) ��11■111■■ ■�u���nn ��J�IIIYII U z C z 7z w w z 0 z W U 0 0 acr r[1 u z W a } z w m o o' a Q aE W J c W Yn O Q O� p G � O. PY E C Y Y� O J �. V W M Ix 2 z .. fn 3 W O u Q w Z? ~L w 8 i au 22 ('r 3 0 O J V Z V O Z O U C �W LL o u ICI Z Z o �— z c � �K W " a V hl rJ Ci HE C E� IN W O to m ai — ►r o` c `o O O u q o i Q u r y t N Y Q ai �} o o 0 E vP Q •� o Y _o _ N O O u 'N E d •� `c a - o u' oa = o N cA � dJ N tv N g.t1 � In O cQ per. r � T T T r CP O s CC,) p o O r_ 1 Y uA � Y X X X Nj M ul •V I g, (� c r � r- N O Q r N o fl -IN-IM EFFECTIVENESS CALCULATIONS ---------------------------------------------------- PROJECT: KFCG/1'PAC 0 Q;ILL, COMPLETED BY: E,4j ---------------- STANDARD FORM B DATE: y OZ Erosion Control C-Factor P-Factor Method ------------ Value Value Comment ------------- 501D G-?-ASS ------------ 0101 ---------- ----------- 1'00 �ON�S/WKLYS o,o %. 1,do C-r-AVc(. flCa)t //0 0 D/ &0 5/`7- f-'"CE ' /,00 O, 5V MAJOR BASIN i- -PS-- IW `SUB BASIN i-K-- AREA (Ac) CALCULATIONS -------------------------------------- C - FAC TOE. ©►51 E FF: [' (0151) (o," 00 =C9,796 =79.8�I., i i i i ---------------------------------- )I/SF-B:1989 RAINFALL PERFORMANCE STANDARD EVALUATION --------------------------------------------------------------------- PROJECT: K rc I7 AC.0 SF- LL- STANDARD FORM A COMPLETED DEVELOPED SUBBASIN K BY: ,-/-f- DATE:. 9 L - --------------------------------------------------------- ERODIBILITYI Asb I Lsb I Ssb Lb I Sb I PS ZONE I (ac) I (ft) I(%) I (feet) I 1() ----------- I ------- I ------- ►------- I ------- I ------- I------- MoDECA-t-F-1 1,0 1 350 1 0,7S13.50 10,75" 174ibS ------------------------------------------- -------------------------- DI/SF-A:1969