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HomeMy WebLinkAboutHAMPSHIRE POND EAST PUD PRELIMINARY AND FINAL - 44 93C - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT• A f Ilk 5l00l�unlcipal 1I �b 35' /heldo 506�� �. �...... ... 9��� y: ...... 1.f1�[8 M R ., yl ... T ,; 0 \ o 11 ■ o o_ • II N92 Tri P Park wo ti = f'44 ,+ / n ` "/, n' �•; y RAD STI ' S •��• •073 = ,�� ...��� UNIVE I'CY• 4 i' �'4re 4491 y; a IL w�lloup baps �. i s ?'1 �..• • 1 /` /, 1:1 Il - Z o o o 5065 , 5056/% 5 ' ..7........ u o 11R O • Ld o ark_-- ,, p 0 LL h9 I JDrake //89 s 5090 J DRAKE ROAD •1 GOo• 50_43' - `-- il 11 o f • :II i; i.. ^ It Rm y momtsm J > I High,Sch )• I- �� 2I I Park_.—;! �_! --- ------ I 1 �! /488 5119 . �L o \ 3Z30- ^\ J ¢ J. r10`G Pit 127 ST -!"HORS' 'TH ROAD 50e2 505 I, - W ¢ I Trailer Parks ``� � y.,l � .� ,r � 13. O I_ � � of r i ha � .i• 2 Gravel I!I / i 3;. �' ri =:134 _ -- -- --- _— 13�-- J Mc ellands• Storm Drainage and Erosion Control Report For Hampshire Pond East Page 2 EROSION CONTROL Hampshire Pond East is located in a moderate wind erodibility zone and in a high rainfall erodibility zone. Sediment filters, and a silt fence shall be used to sediment control and reseeding and mulching shall be done to control erosion. Rip rap shall be placed at pipe outlets. All erosion control procedures shall comply with City of Fort Collins Criteria STORM DRAINAGE AND EROSION CONTROL REPORT FOR HAMPSHIRE POND EAST EXISTING SITE AND DRAINAGE CONDITIONS Hampshire Pond East will be 26 townhouse lots on 2.87 acres located on the extension of Water Blossom Drive to the east of the existing Hampshire Pond Subdivision. .The site slopes to the southeast on approximately a 2 percent slope. There is some natural vegetation on the site. The runoff from the site is into Spring Creek which is located about 300 feet to the southeast. Drake Road lies along the north side of the site and curb, walk and pavement are existing. The runoff in the south gutter of Drake Road is east towards Taft Hill Road. The only offsite runoff is from Basin D6 of the Hampshire Pond Subdivision. This offshe basin is 0.37 acres and the runoff quantities are Q2 = 0.37 c.f.s. and Q,00 = 1.38 c.f.s.. DEVELOPED CONDITIONS DRAINAGE Hampshire Pond East will be developed by extending Water Blossom Lane about 300 feet to the east to end in a cul-de-sac. Runoff from this cul-de-sac will be picked up in a catch basin and piped east and south to an existing ponding area. This existing ponding area was constructed by the Hampshire Pond Subdivision as a temporary holding and settling basin until the proposed regional detention pond is constructed in the future. This existing pond which is constructed on City property has an outlet into Spring Creek. We propose to not change the existing pond outlet or release rate, but to enlarge the pond enough to hold the entire 100 year runoffvolume from Hampshire Pond East. This will require a volume of 27097 cubic feet. Storm runoff from Hampshire Pond East will be carried through the subdivision by street gutters, concrete pans and pipes to the southeast comer of the site. Flows from the southeast comer of the site will be carried to the detention pond in an open ditch. When the future regional detention pond is constructed, flows from this southeast comer will go directly into the ponding area. A copy ofthe drainage and erosion control plan for Hampshire Pond which was prepared by Northern Engineering Services is included with this report. On this plan we have shown the proposed pond enlargement and also the Hampshire Pond East development with the swale to the enlarged ponding area. This ponding configuration is temporary and will be completely changed by the future Taft Hill Regional Pond. STEWART$,LSSOCWES Consulting Engineers and Surveyors August 21, 1995 Mr. Basil Hamdan Stormwater Utility City of Fort Collins P.O. Box 580 Fort Collins, CO 80522 Dear Basil: The following drainage report has been prepared for Hampshire Pond East, which an extension to the east of Water Blossom Lane from the existing Hampshire Pond Subdivision. The site is located on the south side of West Drake Road and a few hundred feet west of South Taft Hill Road. The site is located in the Spring Creek Basin. The site slopes to the southeast and historic runoff is over land about 300 feet to Spring Creek. The following drainage report complies with City of Fort Collins Criteria, except that we request a variance from the criteria to leave the runoff from the Drake Road right-of-way in the south flow lime as it now exists. There is negligible runoff from this site into the Drake Road right-of-way. Sincerely, f/�^�-~-� Phillip I. Ro inson, P.E. & L.S. Vice President rsc 4502 enclosures Mn James H. Stewart and Associates. Inc. 103 S. Meldrum Street P.O. Box 429 Ft. Collins, CO 80522 303/482-9331 Fax 303/482-9382 STORM DRAINAGE AND EROSION CONTROL REPORT FOR HAMPSHIRE POND EAST PREPARED FOR BRET LARIMER PREPARED BY STEWART & ASSOCIATES, INC. 103 SOUTH MELDRUM STREET FORT COLLINS, COLORADO 80521 970/482-9331 AUGUST 21,1995