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Home My WebLink AboutDIAMOND SHAMROCK CORNER STORE #1100 PUD - PRELIMINARY - 14-89 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTrFINAL DRAINAGE REPORT • DIAMOND SHAMROCK GAS STATION, CONVENIENCE STORE AND CAR WASH LOT 2, FAIRVIEW SHOPPING CENTER II 1515 W. ELIZABETH STREET FORT COLLINS, COLORADO FEBRUARY 6, 1989 This drainage report has been based on and is in compliance with "Storm Drainage Design Criteria and Construction Standards" manual issued by the City of Fort Collins dated May, 1984. -.1, 5�z� Roge A. Barringer, P.E. Galloway, Romero & Associates Prepared For: Diamond Shamrock Refining And Marketing Company 520 E. 56th Avenue Denver, Colorado 80216 Attn: Ed Kress Prepared By: Galloway, Romero and Associates, Inc. • 12449 E. 39th Avenue Denver, Colorado 80239 Attn: Roger Barringer • FINAL DRAINAGE REPORT DIAMOND SHAMROCK GAS STATION, CONVENIENCE STORE AND CAR WASH LOT 2, FAIRVIEW SHOPPING CENTER II 1515 W. ELIZABETH ST. FORT COLLINS, COLORADO FEBRUARY 6, 1989 General Location and Description The site is located on the south side of Elizabeth Street, just west of Shields and contains 1.465 acres. It is part of Fairview Shopping Center with existing stores on either side and vacant property to the south. Planned for this site is a Diamond Shamrock gasoline station, convenience store and car wash. Drainage Design Criteria • This drainage study has been prepared using the Rational Method since the site is relatively small and less than 200 acres. Calculations have been performed for the 2, 10 and 100 year storms. Flows offsite have been limited to historic rates. Drainage Facility Design The site has been divided into two subbasins: A and B. Subbasin A contains 1.304 acres and has again been subdivided into Al and A2. Subbasin Al contains 0.793 acres and includes most of the landscaping, about half the paving and the car wash. Subbasin A2 contains 0.511 acres which includes the remainder of the paving, the store and some landscaping to the north. Subbasin B contains 0.161 acres and includes the remainder of the landscaping to the north and east. Runoff will be as follows: runoff from subbasin Al (2 yr: 1.56 cfs, 100 yr: 4.56 cfs) will be captured in a trench drain at the southeast access point, and directed through PVC pipe into a detention pond (maximum volume: 4500 cu. ft.) at the south side of the site. Runoff from subbasin A2 (2 yr: 1.26 cfs, 100 yr: 3.67 cfs) will also be captured by a trench drain, at the • northeast access, and directed to the same detention pond. This flow will not include car wash discharge which will be routed into a sand trap located within the car wash building, and then into the sanitary sewer. Detained water from the pond will then be released through a restricting orifice and 12 inch pipe at a 100 year rate of 1.35 cfs. Discharge will be into an existing storm sewer to the north of the site. Runoff from subbasin B (2 yr: 0.21 cfs, 100 yr: 0.61 cfs) will be nominal since the subbasin is mostly grass covered, and will be directed offsite to the north and east. Total runoff after detention will be 2.74 cfs for the 100 year event which is less than the historical value of 2.76 cfs. The buried fuel tanks, to be located to the east of the 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 accompanying plan is in compliance with the City of Fort Collins storm drainage requirements, and provides sufficient drainage control to mitigate any effects to downstream sites. Sufficient detention has been provided onsite to reduce total developed runoff to the historic rate. • • A P P E N D I X • • -.VICINITY MAP .... I mmx • RUNOFF CALCULATIONS RATIONAL METHOD PROJECT: DIAMOND SHAMROCK - 1515 W ELIZABETH MUNICIPALITY: CITY FORT COLLINS DATE: 06-Feb-89 INPUT STORM FREQUENCY SELECTION: 2,5,100 (1); 2,10,100 (2); 5,10,100 (3) SELECTION ==—> 2 .................................................................................................... LAND AREAS ; RUNOFF COEFFICIENTS HIST EXIST DEVEL. 2y l0y 100y IMP. GRASS 57511 NA 22124 0.20 0.20 0.20 0 PAVING 6290 NA 39326 ; 0.95 0.95 0.95 100 ROOFS 0 NA 2351 ; 0.95 0.95 0.95 90 SOILS 0 NA 0 ; 0.00 0.00 0.00 0 TOTALS (SQ FT) 63801 NA 63801 ; • (ACRES) 1.465 NA .................................................................................................... 1.465 ; HISTORIC EXISTING DEVELOPED SHEET FLOW LENGTH WATERCOURSE (L) 240 NA 233 ft < site plan SLOPE WATERCOURSE (S) 1.67 NA 1.72 % < site plan CHANNEL FLOW C100 0.34 NA 0.86 < calc from below LENGTH CHANNEL (Lc) = 0.00 0.00 58.00 ft SLOPE CHANNEL (Sc) = 0.00 0.00 0.01 % VELOCITY IN CHANNEL (Vc) 0.00 0.00 4.66 fps < velocity curves CALCULATIONS RUNOFF COEFFICIENTS (SUM C*A/SUM A) STORM FREQUENCY HIST EXIST DEVE L 2y 0.27 NA 0.69 10y 0. NA 0.69 100y = C(1.25) = 0 0.34 34 - - NA - - 0.8686 - 10 10 I* CALCULATED RUNOFF HIST -------------------------------------------------------- INITIAL TIME (Ti) (sheet flow) LENGTH WATERCOURSE (L) 240 SLOPE WATERCOURSE (S) 1.67 C100 = 0.34 a) Ti = 1.87(1.1-C100)(L".5)/(S".33) 18.50 b) Ti = L/180 + 10 = N/A USE Ti = 18.50 TRAVEL TIME (Tt) (channel flow) LENGTH CHA,`NEL (Lc) = 0.00 SLOPE CHANNEL (Sc) = 0.00 RUNOFF VELOCITY (Vc) = 0.00 Tt = Lc/Vc(60) = 0.00 TIME OF CONCENTRATION (Tc) Tc = Ti + Tt = 18.50 USE 18 RAINFALL INTENSITY (I) - from time -intensity -duration curves 12 1.95 I10 3.42 I100 5.50 2 YEAR STORM: A 1.465 C 0.27 1 1.95 RUNOFF (Q) = A*C*I 0.78 10 YEAR STORM: ------------------------------------------------------------ A 1.465 C 0.27 1 3.42 ----------------------------------------------- RUNOFF (Q) = A*C*I 1.37 100 YEAR STORM: ------------------------------------------------------------- A 1.465 C 0.34 1 5.50 ------------------------------------------------------ RUNOFF (Q) = A*C*I 2.76 EXIST ------------------------------------- DEVEL UNITS NA 233 ft NA 1.72 % NA 0.86 NA 5.56 min NA 11.29 min NA 5.56 min 0.00 58.00 ft 0.00 0.01 % 0.00 4.66 fps 0.00 0.21 min NA 5.87 min NA 6 min NA 3.00 in/hr NA 5.25 in/hr NA 8.75 in/hr NA 1.465 acres NA 0.69 NA 3.00 in/hr NA 3.03 cfs NA 1.465 acres NA 0.69 NA 5.25 in/hr NA 5.31 cfs NA 1.465 acres NA 0.86 NA 8.75 in/hr NA 11.05 cfs 0 REQUIRED DETENTION VOLUME TIME MIN SEC I100 A -------------------------------- 0 0 NA 1.46 5 300 NA 1.46 10 600 NA 1.46 15 900 5.95 1.46 20 1200 5.18 1.46 25 1500 4.60 1.46 30 1800 4.17 1.46 35 2100 3.80 1.46 40 2400 3.50 1.46 45 2700 3.24 1.46 50 3000 3.00 1.46 55 3300 2.79 1.46 60 3600 2.60 1.46 0 D E V E L O P E D HISTORIC REQ'D C100 Q100 VOLUME Q100 VOLUME DET'N 0.86 NA NA 2.76 0 NA 0.B6 NA NA 2.76 828 NA 0.86 NA NA 2.76 1655 NA O.B6 7.52 6754 2.76 2483 4281 0.86 6.54 7852 2.76 3310 4542 0.86 5.81 8716 2.76 4138 4578 0.86 5.27 9481 2.76 4965 4516 0.86 4.80 10080 2.76 5793 4287 0.86 4.42 10610 2.76 6620 3990 0.86 4.09 11050 2.76 744E 3602 0.86 3.79 11368 2.76 8275 3093 0.86 3.52 11630 2.76 9103 2527 0.86 3.28 11623 2.76 9931 1892 REQUIRED DETENTION = 4578 mmx � 0 S U B B A S I N CALCULATIONS INPUT .ul SUBBASINS: Al A2 A tot B E F GRASS 13474 3800 17274 4850 0 0 PAVING 20285 16886 37171 2155 0 0 ROOFS 784 1567 2351 0 0 0 SOILS 0 0 0 0 0 0 TOTALS (SQ FT) 34543 22253 56796 7005 0 0 (ACRES) 0.793 0.511 1.304 0.161 0.000 0.000 TOTAL SITE AREA (ac) 1.465 CALCULATIONS • RUNOFF COEFFICIENTS (SUM C*A/SUM A) STORM FREQUENCY Al A2 A tot B E F 2y 0.66 0.82 0.72 0.43 BRR ERR l0y 0.66 0.82 0.72 0.43 ERR ERR 100y 0.66 0.82 0.72 0.43 ERR BRR C Al • • CALCULATED RUNOFF Al A2 A tot B E F UNITS TIME OF CONCENTRATION (Tc) (overall site) USE 5.87 5.87 5.87 5.87 5.87 5.87 min RAINFALL INTENSITY (I) - from time -intensity -duration curves 12 3.00 3.00 3.00 3.00 3.00 3.00 in/hr I10 5.25 5.25 5.25 5.25 5.25 5.25 in/hr I100 8.75 8.75 8.75 8.75 8.75 8.75 in/hr 2 YEAR STORM: A 0.793 0.511 1.304 0.161 0.000 0.000 acres C 0.66 0.82 0.72 0.43 ERR ERR 1 3.00 3.00 3.00 3.00 3.00 3.00 in/hr RUNOFF (Q) = A*C*I 1.56 1.26 2.82 0.21 ERR ERR cfs 10 YEAR STORM: A 0.793 0.511 1.304 0.161 0.000 0.000 acres C 0.66 0.82 0.72 0.43 ERR ERR 1 5.25 5.25 5.25 5.25 5.25 5.25 in/hr RUNOFF (Q) = A*C*I 100 YEAR STORM: A C I 2.74 2.20 4.94 0.36 ERR ERR cfs 0.793 0.511 1.304 0.161 0.000 0.000 0.66 0.82 0.72 0.43 ERR ERR 8.75 8.75 8.75 ---------- 8.75 8.75 8.75 acres in/hr ------------------- RUNOFF (Q) = A*C*I 4.56 3.67 8.24 0.61 ERR ERR cfs DETENTION POND DESIGN SUBBASIN SUBBASIN AREA POND MAX. ORIFICE POND SLOPE PIPE 10. AREA RATIO AREA DEPTH HEAD(h) VOLUME PIPE(s) N. Al 34543 0.541 0 0.0 0.00 0 0.000 0.000 A2 22253 0.349 0 0.0 0.0 0 0.000 0.000 A tot 56796 0.890 4600 3.0 3.0 4600 0.005 0.013 B 7005 0.110 0 0.0 0.0 0 0.000 0.000 E 0 0.000 0 0.0 0.0 0 0.000 0.000 F 0 0.000 0 0.0 0.0 0 0.000 0.000 TOTALS 63801 1.000 4600 4600 • • • ALLOWABLE RELEASE RATE COMPUTATION ------- —----------------------- — SUBBASIN A -------------------------------------------------------------------------------- AREA RATIO = 0.B9 TIME TOT DEV AREA DEV VOL REQ'D MIN SEC VOLUME RATIO BASIN DET'N DIFF RELEASE ------------------------------------------------------------------------ 0 0 NA 0.89 NA 4600 NA NA 5 300 NA 0.39 NA 4600 NA NA 10 600 NA 0.89 NA 4600 NA NA 15 900 6764 0.89 6021 4600 1421 1.579 20 1200 7852 0.89 6990 4600 2390 1.991 25 1500 8716 0.89 7759 4600 3159 2.106 30 1800 9481 0.89 8440 4600 3840 2.133 35 2100 10080 0.89 8973 4600 4373 2.082 40 2400 10610 0.89 9445 4600 4845 2.019 45 2700 11050 0.89 9837 4600 5237 1.940 50 3000 11368 0.89 10120 4600 5520 1.840 55 3300 11630 0.89 10353 4600 5753 1.743 60 3600 11823 0.89 10525 4600 5925 1.646 MAXIMUM REQUIRED RELEASE RATE = 2.133 ORIFICE SIZE USE "Cd" = 0.62 REQUIRED AREA = Q / Cd*(29h)".5 35.65 sq in CIRCULAR: 6.74 inches diameter SOUARS: 5.97 inches square PIPS SIZE -------------------- Q = 2.941(s".5)(r-2.67) / n Q = 2.133 cfs slope (s) = 0.005 n = 0.013 r = 0.47 ft diameter (min) = 11.28 inches • 1� • RELEASE SUMMARY -------------- SUBBASIN A B TOTAL REQUIRED PIPE SIZES RELEASE UNITS 2.13 cfs 0.61 cfs 2.74 cfs --------------- 2.76 cfs Q = 2.941(s".5)(r"2.67) / n Al A2 units Q = 8.236 3.674 cfs slope (s) = 0.010 0.010 length = 58.00 96.00 n = 0.013 0.013 r = 0.68 0.51 ft diameter (min) = 16.43 12.14 in use: 18.00 12.00 in velocity = 4.66 4.68 fps No Text