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Home My WebLink AboutDrainage Reports - 06/17/1996FINAL DRAINAGE STUDY FOR LOT 3, REPLAT NO. I OF COUNTRY CLUB CORNERS THIRD FILING, P.U.D. POUDRE VALLEY HOSPITAL COMMUNITY HEALTHCARE CENTER Prepared For. Poudre Valley Hospital 1024 South Lemay Avenue Fort Collins, CO 80524-3998 April3, 1996 Project No. PVAL -6B2C-0 1 -217 CONSULTING ENGINEER Landmark Engineering Ltd. 3521 West Eisenhower Boulevard Loveland, Colorado 80537 17 1 CERTIFICATION 1 I hereby certify that this Final Drainage Study for Lot 3, Replat No. 1 of Country Club Corners Third Filing P.U.D., Poudre Valley Hospital Community Healthcare Center was prepared by me or under my direct supervision in accordance with 1 the provisions of the City of Fort Collins Storm Drainage Criteria for the Owners thereof. Patrick M. Mestos Colo. P.E. 73886 TABLE OF CONTENTS PAGE NO. INTRODUCTION ............................................. 1 SITE DESCRIPTION ........................................... 1 DRAINAGE IMPACT .......................................... 2 Flood Plain Phase 2 Drainage Phase 1 Interim Drainage APPENDIX Drainage Exhibit Phase 1 Interim Drainage Computations Final Drainage Study Country Club Corners P.U.D. Amended Final Drainage Study Country Club Corners P.U.D. I 1 I H I I, I, I, I II FINAL DRAINAGE STUDY FOR LOT 3, REPLAT NO. i OF COUNTRY CLUB CORNERS THIRD FILING P.U.D. POUDRE VALLEY HOSPITAL COMMUNITY HEALTHCARE CENTER INTRODUCTION The Poudre Valley Hospital Community Healthcare Center lies on Lot 3 Replat No. ] of Country Club Corners Third Filing P.U.D. The Lot 3 replot is a part of Lot 9 of Country Club Corners Third Filing, a Planned Unit Development. A Final Drainage Study and an Amended Final Drainage Study has been prepared and approved for the Country Club Corners Third Filing P.U.D. development. Copies of the final drainage studies are included in the Appendix. The purpose of this drainage study is to evaluate and present the drainage impacts from the healthcare center on the approved final drainage studies. In the evaluation, a site description of the healthcare project will be presented and its relationship to the Country Club Corners Third Filing P.U.D. development. The drainage impact will present the changes to the developed flow conditions and proposed improvements to resolve the impact of the drainage flow condition. SITE DESCRIPTION The healthcare center is a 8737 sq, ft. one story building. It lies on the North side of Bristlecone Drive and immediately on the East side of the West access to the Country Club Corners development. The lot is 36932 sq. ft. of which 77,760 sq. ft. is driveway access, parking and two landscaped median islands. The ground cover around the building and the setback frontage along Bristlecone Drive will be turfed and landscaped. The building pad area between the healthcare center and the East access to the Country Club Development will be regraded and reseeded with drought tolerant non -irrigated turf. II I I J With respect to drainage, the Country Club Corners Phase 1 interim development is under construction and very near complete. The healthcare center is a continuation and a part of the Phase 1 - interim development. DRAINAGE IMPACT Flood Plain The healthcare center lies in the 100-Year floodplain fringe of the Dry Creek drainage basin. (Dry Creek Drainagewoy Planning; January, 1980, Gingery Associates, inc.) The flood plain and applicable water surface cross-section (Section 26, 27, 28) are shown on the Drainage Exhibit. The 100-Year surface elevation at Cross -Section 27 which is through the healthcare center is at 4975.9. The finished floor elevation of the healthcare center is at 4979.0. Phase 2 Drainage The Phase 2 Drainage improvements are based on the Country Club Corners full development, Country Club Corners is being constructed in "phases" in which the healthcare center is a part of the phased construction. The Drainage Plan Phase 1 Interim improvements for the phased construction are now complete. The major drainage component of the Drainage Plan Phase 2 improvements yet remaining is the outfoll storm drain system in Bristlecone Drive. The healthcare center will not have a drainage impact on the Drainage Plan Phase 2 improvements. The impact is limited to the Phase 1 Interim drainage improvements as presented in the next subsection. Phase 1 - Interim Droinoae The healthcare center impacts the developed flow conditions from the A and C subbasins. The B and D subbasins are not impacted because the healthcare center is not in the contributory areas. The impact is primarily due to a higher C- factor with the times of concentration and contributory areas remaining essentially the some. The C subbasins are contributory to Bristlecone Drive and the A subboins are contributory to the Phase 1 Interim detention pond. A summary of the 100-Year developed Phase 1 runoff with the healthcare center is as follows: Q in Street Q in Pipe Q700 Subbosins cfs cfs As 0.00 5.99' 65,76 Bs 7.90 78.40 26.30 Cs 74.37 " 0.00 74.37 Totals 22.21 24.39 106.37 Restricted release from detention based on Release Rate = 25.00 cfs (Ex. 30" SD capacity) - 0.67 cfs.(Burger King) - 78.40 cfs = 5.99 cfs Includes Poudre Valley Hospital Healthcare Center and the Proposed Big O Tire on Lot 2, Replot No. 1 of Country Club Corners Third Filing, P.U.D. The total IX -Year runoff from Country Club Comers Phase 1 including the healthcare center and the proposed Big O Tires is 49.47 cfs. Bristlecone Direct Runoff 22.21 cfs Bristlecone Existing 30" SD 24.39 cfs Willox Direct Runoff 2.81 cfs Total 49.41 cfs There is sufficient capacity in the existing Bristlecone Drive street section to accommodate the Phase 1 release rate shown as follows: 3 I Bristlecone Drive street section capacity Less direct release to Bristlecone Drive Less offsite contributory area to Bristlecone Dr. Unused street capacity 43.22 cfs - 22.21 cfs - 7.55 cfs 13.46 cfs As shown above, the release rate from the existing Phase 1 interim detention pond will remain the some (5.99 cfs). The volume of the Phase i Interim detention pond will also remain the some (2.05 a.f) and is based on the full developed condition of the contributory areas. The location of the detention pond will remain the some that is between the East and West access to the Country Club Corners site in the center of Lot 9. The inlet and outlet piping will also remain the some. The parking lot necessary for the healthcare center encroaches into the Southwest corner of the existing Phase i Interim detention pond. To maintain the required volume, the North perimeter of the existing detention pond has expanded and depth increases slightly from 3.42 ft. to 4.75 ft. The 100-Year HWL is now at on elevation of 4974.20 which is essentially equivalent to the flowline elevation of SD junction Box #6 (4974.78). Referencing the Utility Plans for the Phase 1 Interim work for Country Club Corners, the heodloss in the inlet piping to next upstream inlet (Inlet #3) results in the HGL below the flowline elevation of Inlet #3. The orifice plate in the outlet pipe controlling the release rate will be modified for the increase water depth. The Drainage Exhibit and computations for the healthcare center drainage impacts are in the Appendix. 4 I I 1 APPENDIX DRAINAGE EXHIBIT I I I APPENDIX ' Phase I Interim Drainage Computations Q Q 0 z Fn w 0 cc Q z w 0- 2 } w Q z Q C) CE 0 INS 111111111111�11 HIM 111111 1111111111:INN III HIM 11111 �II��111111�1 � 11111111JIR11111111111 �III�11111l11l1�11 NINE 111�l.�1111III 111 �II��III�11111�1� 1111111�1811111111111 �01�111111�11g1 1111l.Ii11A11111111111 ®11�1111111111111111111 I1111111111 IlIs 11l11 1111111111111111111111 ®111111111111111 11 �1 1110111111111111111 �II��II�i11�11111111111� 11�1111111111 �II�I�IC�111111N11111�11111 1111111111 �61�111�111111�11�1�11111��1111111111 ®OI�A�1��11111�1111111111111111111111 �OIl��1�11L1111�1@1111@111:1111111111 OIEIIC111�11111111111111111 Nil 1111 ®01�111lilllllllllllllll III lllll • ®01�111111111111111111111 HIM 111 ®Ol11 MEN 1111111111111111 ®01►111�1111111111111111111111111 ®O 11111l1�1111111III 11111MEN 111 a� m LL Q 0 Z CD co w ICE } Q Z; J ' w CC a 2. w co ci w z. o o; m L O LL 2 CE 0 LL J Q U n- F- �11101111111l 111111111111111111111 �111!lIIIIIIIII�1�l1111111111111111111 � . �111l1�IIIIIIII�i��1111111111111111111 �IIIIII�i111111�1��1111111111111111111 �Illl�l�illll�lillllllllllllllllllllll �Illlll�lllll�llllilllllllllllllllllll . ®111111111111111�11111111111111111111 1111�IIIIIIIli1�11111111111111111111 �6111EIIIIIIIIIIIIIIIIIIIIIIIIn11111 111111 " 111111 i 1111111111111111111111 �111111i1111�1ilellli1111111�11111111 �111111" ill0 iilllll�i11111=111111111 . � �11111111111�1@Illll�illlllllllllllll �111111111 A�11i111111i111111L�11111111 = �0111!l11111l1111111:111111111111111 n0®111si11 �IlAlllellllllllllllllllli .. 011lllllli�llllllllllllellllllllllll - �Olellllllllllllllllli11111111111111 �0101111111��11111111111�111111111111 �01�11111111�111111111111!!1111111111 �OI�IA I�I�II Ia111A111111A11111111111 .: ` y Z) m u Q Q 0 Z CD W 0 } z� J , W cr d 2. 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