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Home My WebLink AboutLIND PROPERTY - OVERALL DEVELOPMENT PLAN - 39-94A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTLIND PROPERTY Appendix Jim Sell Design, Inc. JB2084 9/8/00 JFS Detention Pond Volume Calculations for Pond1.3 Pond 1 100-YR STORM O=CCflA C= 0.7 Cf= 1.25 A 52.2 AC Duration (min) 100 Yr. Intensity (in/hr) Developed Site runoff (cfs) Volume (cu-ft) Release Flow (cfs) Release Volume (cu-ft) Pond Detention Volume(100-yr) (cu-ft) Max Required Detention (twice 100-yr) Volume (ac-ft) 5 1 46 13703 5 1500 12203 10 1.14 52 31242 5 3000 28242 15 2.33 106 95780 5 4500 91280 20 2.23 102 122226 5 6000 116226 25 2.84 130 194576 5 7500 187076 30 5.49 251 451360 5 9000 442360 35 9.95 454 954379 5 10500 M94387.91M 40 4.12 188 451634 5 12000 439634 45 2.48 113 305840 5 13500 292340 50 1.46 67 200057 5 15000 185057 55 1.22 56 183888 5 16500 167388 60 1.06 48 174296 5 18000 156296 65 1 46 178133 5 19500 158633 70 0.95 43 182243 5 21000 161243 75 0.91 42 187039 5 22500 164539 80 0.87 40 190739 5 24000 166739 85 0.84 38 195672 5 25500 170172 90 0.81 37 199782 5 27000 172782 95 0.78 36 203071 5 28500 174571 100 0.75 34 205538 5 30000 175538 105 0.73 33 210059 5 31500 178559 110 0.71 32 214033 5 33000 161033 115 0.69 32 217459 5 1 34500 182959 120 0.67 31 220336 5 1 36000 184336 Pond 2 100-YR STORM O=CCfIA C= 0.7 Cf= 1.25 A 34.3 AC Duration (min) 100 Yr. Intensity (in/hr) Developed Site runoff (cfs) Volume (cu-ft) Release Flow (cfs) Release Volume (cu-ft) Pond Detention Volume(100-yr) (cu-ft) Max Required Detention (twice 100-yr) Volume (ac-ft) 5 1 30 9004 5 1500 7504 10 1.14 34 20529 5 3000 17529 15 2.33 70 62936 5 4500 58436 20 2.23 67 80313 5 6000 74313 25 2.84 85 127853 5 7500 120353 30 5.49 165 296584 5 9000 287584 35 9.95 299 627111 5 10500 M616611 26 40 4.12 124 296764 5 12000 284764 45 2.48 74 200964 5 13500 187464 50 1.46 44 131455 5 15000 116455 55 1.22 37 120830 5 16500 104330 60 1.06 32 114528 5 18000 96528 65 1 30 117049 5 19500 97549 70 0.95 29 119750 5 21000 98750 75 0.91 27 122901 5 22500 100401 80 0.87 26 125332 1 5 24000 101332 85 04 25 128574 5 25500 103074 90 0.81 "24 131275 5 27000 104275 95 0.78 23 133436 5 28500 104936 100 0.75 23 135056 5 30000 105056 105 0.73 22 138027 5 31500 106527 110 0.71 21 140639 5 33000 107639 115 0.69 21 142890 5 34500 108390 120 0.67 200 144780 5 36000 108780 Pond 3 100-YR STORM Q=CCOA C= 0.7 Cf= 1.25 A= 88.4 AC Duration (min) 100 Yr. Intensity (in/hr) Developed Site runoff (cfs) Volume (cu-ft) Release Flow (cfs) Release Volume (cu-ft) Pond Detention Volume(100-yr) (cu-ft) Max Required Detention (twice 100-yr) Volume (ac-ft) 5 1 77 23205 5 1500 21705 10 1.14 88 52907 5 3000 49907 15 2.33 180 162203 5 4500 157703 20 2.23 172 206989 5 6000 200989 25 2.84 220 329511 5 7500 322011 30 5.49 425 764373 5 9000 755373 35 9.95 770 1616228 5 10500 160572 .. 40 4.12 319 764837 5 12000 752837 45 2.48 192 517936 5 13500 504436 50 113 338793 5 15000 323793 55 94 311411 5 16500 294911 60 82 295168 5 18000 277168 65 77 301665 5 19500 282165 70 73 308627 5 21000 287627 75 446 70 316748 5 22500 294248 80 67 323014 5 24000 299014 85 65 331367 5 25500 305867 90 63 338329 5 27000 311329 95 60 343898 5 28500 315398 100 58 348075 5 30000 318075 0.73 56 355733 5 31500 4233 3242330.73 55 355733 5 31500 329462 M 0.69 53 368263 534500 333763 0.67 52 373136 5 36000 337136 FIGURE 2 LIND PROPERTY DRAINAGE BASIN DEUNEATION BASIN #. ACRES AND 1 RUNOFF COEIMCIENT 522 .7 FLOW ARROW J7 DETENTION POND O ME OTI No Text Conceptual Drainage Report Lind REFERENCES City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Storm Drainage Division, May 1984 Urban Storm Drainage Criteria Manual, Denver Regional Council of Governments, Dated 1969, Volumes 1, 2, & 3 Conceptual Drainage Report Lind INTRODUCTION This report is the presentation of results from a conceptual drainage evaluation for the Lind Property. An analysis of the overall drainage for the site and a mass balance model was created to determine the amount of storm water detention required to detain the 100-year storm. GENERAL LOCATION AND DESCRIPTION The Lind Property, located in the City of Fort Collins in Larimer County and is approximately 172 acres in size (see Figure 1). The property lies within the west half of Section 29, Township 8 North, Range 68 West. The site is bounded on the west by the proposed Richard's Lake Development and County Road #11, on the south by County Road 52 and on the north and west by the No. 8 ditch. The proposed development would consist of single and multi -family residential, a neighborhood center, neighborhood park and commercial uses. The property is in the LMN-Low Density Mixed -Use Neighborhood Zoning District. The area has a semi -arid climate and has an approximate mean annual precipitation of 13 inches. The land is currently a mix of agriculture and native grasses and weeds. HISTORIC CONDITIONS 1 Off -site flows on the Lind Property are considered to be insignificant. The flows are captured by the No. 8 ditch on the north and east boundary and by County Road 11 and 52 on the west and south boundaries. The terrain on the Lind Property terrain generally slopes to the southeast, with a pocket in the north portion that slopes to the west and a low ridge running parallel to the No. 8 ditch. The Lind Property is within the ELCO water district and the Boxelder sanitation district. DRAINAGE PLAN DEVELOPMENT The proposed drainage plan for this site consists of overland and gutter flow. The runoff will move across landscaped yards and parking lots as sheet flow, concentrating at the proposed streets. The runoff will be transported by gutter flow to inlets and piped to on -site detention ponds. Three sub -basins have been delineated in order to analyze the detention pond. See Figure 2. for developed basin delineation and Appendix A for the 100-year runoff quantities. The expected allowable discharge from the Lind Property into the No. 8 ditch is 5 cfs. This 5 cfs flow will not be allowed to leave the site within the first 48 hours after each storm event (as stipulated by the Windsor Reservoir and Canal Company). POND ANALYSIS The required detention volume for the three on -site ponds (see Figure2) was calculated by mass balance. This detention volume will need to be calculated using twice the 100-yr storm values (as stipulated by the Windsor Reservoir and Canal Company). It was determined that Pond 1 will need to detain approximately 43.4 ac-ft, Pond 2 will need approximately 28 ac-ft and Pond 3 will need approximately 74 ac-ft of water detention. Refer to Appendix A for calculations. ENGINEER'S CERTIFICATION BLOCK I hereby certify that this report (plan) for the Conceptual Drainage Letter Report for Lind Property ODP was prepared by me (or under my direct supervision) in accordance with the provisions of City of Fort Collins Storm Drainage Design Criteria and Construction Standards Manual for the owners thereof. Registered Professional Engineer State of Colorado No. September 11, 2000 Mr. Basil Harridan City of Fort Collins Storm Water Utilities Department P. O. Box 580 Fort Collins, Colorado 80522-0580 RE: LIND PROPERTY ODP Dear Mr. Hamdan, Please refer to our enclosed "Conceptual Drainage Letter Report for Lind Property ODP." This report was prepared to meet requirements for the Overall Drainage Report as specified in the City of Fort Collins Development Manual. The report has been prepared to be in accordance with the City of Fort Collins Storm Drainage Criteria Manual. Included herein is a project description, historic and developed conditions, and a detention storage analysis. Please call if you have any questions regarding this report. We thank you for your time and consideration in reviewing this drainage report submittal. Sincerely, JIM SELL DESIGN, INC. es Crawford, P.E. Director of Engineering CC: file Enclosure o�pp0• RE��sW G� v �o• 31480 d CONCEPTUAL DRAINAGE LETTER REPORT FOR LIND PROPERTY ODP Centex Homes, Inc. Fort Collins, Colorado 9250 East Costilla Ave. Suite 110 Englewood, CO 80112 Attn. Steve Hanson