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HomeMy WebLinkAboutDrainage Reports - 02/13/2020M INOR A MENDMENT - D RAINAGE L ETTER P LATTE R IVER P OWER A UTHORITY HQ B UILDING E XPANSION F ORT C OLLINS , CO 1501 ACADEMY CT. STE 203 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com November 25, 2019 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Platte River Power Authority HQ Building Addition Fort Collins, CO Project Number: U16014 Dear Staff: United Civil Design Group, LLC is pleased to submit this Drainage Letter accompanying the Minor Amendment application for the Platte River Power Authority Building Addition site in Fort Collins, Colorado. In general, this letter serves to document the storm water impacts associated with the building addition and to confirm that the improvements conform to the previously approved drainage study for the project. SITE LOCATION AND PROJECT DESCRIPTION The Platte River Power Authority Headquarters Campus (referred herein as ”the site” or “the Campus”) is a parcel of land situated in the Southeast Quarter of Section 30, Township 7 North, Range 68 West of the 6th Principal Meridian to the City of Fort Collins, Larimer County, Colorado. More specifically, the site is located at the northwest corner of Horsetooth Road and Timberline Road and is bounded by East Horsetooth Road to the south, Timberline Road to the east, existing commercial property and Danfield Court to the north, and Union Pacific Railroad right-of-way to the west. The planned improvements to the site will consist of the following: The expansion of the south bar of the newly constructed headquarters building. The reconfiguration of previously designed Phase 2 improvements including hard surfaces adjacent to the building expansion, roof drain piping systems and the detention pond located east of the proposed expansion. The addition of an emergency access from Timberline Road to the headquarters building. PREVIOUS REPORTS AND BACKGROUND INFORMATION As mentioned, the drainage of the Platte River Power Authority Campus site was previously studied by United Civil with the report entitled, “Final Drainage Report – Platte River Power Authority HQ Campus”, and dated May 23, 2018. This report details the drainage design of site including requirements associated with detention, water quality and Low Impact Development. Revisions to this report required for the building addition are documented in the following sections of this letter. PROPOSED HYDROLOGY The building addition project does not alter overall drainage patterns for the campus and includes only minor revisions to the hydrology of two (2) basins as shown in previously approved drainage study. The basins altered with the project include Basin A1 and Basin C1. The table on the following page provides a summary of the proposed site characteristics relative to its previously approved design condition. City of Fort Collins Approved Plans Approved by: Date: Matt Simpson 02/13/2020 M INOR A MENDMENT - D RAINAGE L ETTER P LATTE R IVER P OWER A UTHORITY HQ B UILDING E XPANSION F ORT C OLLINS , CO 1501 ACADEMY CT. STE 203 | FORT COLLINS, CO 80524 | 970-530-4044 | www.unitedcivil.com COMPARISON SUMMARY TABLE PRPA Campus Previously Approved Design Proposed Design Overall Area (acre) 17.9 17.9 Roof (sf) 76,311 73,787 Asphalt (sf) 160,957 160,957 Concrete (sf) 116,895 125,366 Landscape (sf) 412,198 406,251 % Imperviousness 44.8% 45.5% Note that the overall roof area has decreased from the previous design due to the removal of 8,500 sf of future building previously assumed for the addition. The actual building addition area is currently set at approximately 5,800 sf. DETENTION POND CONVERSION Proposed site improvements include the expansion of the HQ building to the east and over a portion of the previously planned detention pond (Pond A1) in that area. As a result, the overall pond volume for the site has been slightly reduced. Additionally, due to the added impervious area, the volume required has slightly increased. The detention and water quality volumes for the ponds were both previously planned for future improvements so neither condition negatively impacts the overall storage or water quality volumes. The following table summarizes the revised detention pond design: Pond Designation Detention Volume Required (ac-ft) Detention Volume Provided (ac-ft) 100- year WSEL Pond Release Rate (cfs) WQCV Required (ac-ft) WQCV Provided (ac-ft) Water Quality WSEL Top of Pond Elevation Pond A1 2.43 2.71 4952.25 3.15 0.19 0.23 4949.50 4953.25 LOW IMPACT DEVELOPMENT (LID) The previously approved design for the campus met current City LID requirements by treating 75% of the newly added impervious area using a combination of LID techniques including underground water quality detention, bioswales and a wet pond. With the proposed addition, the newly added impervious area for the campus has been increased by approximately 2,800 sf from what was previously planned; all of which is located within Basin A1. The newly added impervious area for the expansion project is not being treated with LID techniques for the following reasons: 1. The added impervious area is located within Basin A1 which was previously designed without LID improvements. 2. The majority of the drainage basins for the site (13 of 16 basins) do already include LID treatment techniques. 3. Due to proximity of the proposed improvements to existing and proposed drainage features (the wet pond and detention pond) and the number of existing utilities in the area, the addition of new LID features adjacent to the improvements is highly constrained. This is particularly true for the additional roof area which is being piped from the roof directly to the detention pond. 4. Existing utilities and topography north of the addition further limit the ability to provide adequate bioretention or underground retention facilities and limit the ability to collect the required impervious area. Additionally, due to the proximity of the detention ponds, the elevation required to provide either type of system are limited as both require a minimum of 30”-36” to provide for an underdrain or the below ground facilities. 5. As the improvements are adjacent to the proposed extended detention and water quality pond, all of the proposed improvements will be treated via extended detention prior to being allowed to exit the site. 6. Due to the relatively small amount of added impervious area, the impact to the overall LID treatment percentage for the site is relatively small, decreasing from 75% to 73%. The added impervious area would require approximately 160 cf of added LID treatment assuming a 12-hour storage time. Refer to the LID Summary table in Appendix B for additional information and Appendix C for a copy of the Variance Request. A PPENDIX A H YDROLOGIC C ALCULATIONS Ru n o f f C o e f f i c i e n t s a n d % I m p e r v i o u s Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . C o m p o s i t e N R C S S o i l To t a l T o t a l Ro o f (1 ) As p h a l t Co n c r e t e (1 ) Gr a v e l (1 ) La w n s (1 ) Im p e r v i o u s n e s s T y p e C2 C10 0 %I = 9 0 % % I = 1 0 0 % % I = 9 0 % % I = 4 0 % % I = 2 % ( % I ) ac r e s s f sf s f s f s f s f EX 1 E X 1 3. 7 5 1 6 3 , 5 5 3 1 9 , 3 7 0 5 1 , 6 2 7 8 , 6 2 7 2 , 6 7 0 8 1 , 2 5 9 48 . 6 % C/ D 0 . 5 7 0 . 7 1 EX 2 E X 2 2. 3 8 1 0 3 , 4 8 5 2 , 8 8 3 2 2 , 0 3 3 7 , 5 0 6 1 , 7 6 7 6 9 , 2 9 6 32 . 3 % C/ D 0 . 4 4 0 . 5 5 EX 3 E X 3 2. 1 9 9 5 , 2 3 3 1 7 , 6 8 3 5 4 , 4 0 8 6 , 1 0 4 1 , 0 2 9 1 6 , 0 0 9 80 . 4 % C/ D 0 . 8 2 1 . 0 0 EX 4 E X 4 2. 3 3 1 0 1 , 3 2 5 9 , 0 1 2 5 , 2 0 8 4 , 3 1 6 8 1 0 8 1 , 9 7 9 18 . 9 % C/ D 0 . 3 4 0 . 4 2 EX 5 E X 5 1. 3 5 5 8 , 6 5 2 1 6 , 1 9 4 4 2 , 4 5 8 12 . 5 % C/ D 0 . 2 8 0 . 3 5 OS - 1 O S - 1 0. 3 1 1 3 , 4 0 9 9 2 8 3 4 3 3 , 3 3 1 8 , 8 0 7 20 . 5 % C/ D 0 . 3 5 0 . 4 3 OS - 2 A O S - 2 A 0. 3 3 1 4 , 3 0 2 2 , 5 3 9 1 , 1 7 7 1 0 , 5 8 6 26 . 6 % C/ D 0 . 3 9 0 . 4 9 OS - 2 B O S - 2 B 0. 9 3 4 0 , 3 1 0 2 6 , 5 6 8 6 , 2 2 8 7 , 5 1 4 80 . 2 % C/ D 0 . 8 1 1 . 0 0 OS - 3 O S - 3 2. 2 2 9 6 , 5 7 6 1 4 , 3 8 6 4 , 1 1 0 7 8 , 0 8 0 20 . 3 % C/ D 0 . 3 4 0 . 4 3 OS - 4 O S - 4 1. 2 8 5 5 , 8 4 6 3 8 , 6 8 2 2 , 0 6 1 1 5 , 1 0 3 73 . 1 % C/ D 0 . 7 5 0 . 9 3 OS - 5 O S - 5 0. 5 4 2 3 , 6 6 8 2 3 , 6 6 8 2. 0 % C/ D 0 . 2 0 0 . 2 5 17 . 5 9 7 6 6 , 3 6 1 4 8 , 9 4 8 2 1 6 , 3 7 9 4 0 , 4 7 2 2 5 , 8 0 1 4 3 4 , 7 6 1 4 1 . 2 % C / D 0 . 5 1 0 . 6 4 No t e s : (1 ) R e c o m m e n d e d R u n o f f C o e f f i c i e n t V a l u e s f r o m F C S C M T a b l e R O - 1 1 . (2 ) C o m p o s i t e R u n o f f C o e f f i c i e n t i s b a s e d o n F C S C M e q u a t i o n R O - 8 a n d C o e f f i c i e n t A d j u s t m e n t f a c t o r s p e r T a b l e R O - 1 2 . Co m p o s i t e R u n o f f C o e f f i c i e n t s (2 ) Ar e a s Ex i s t i n g B a s i n s Ex i s t i n g T o t a l Da t e : 1 0 / 1 5 / 2 0 1 9 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s _ E E C . x l s m Ru n o f f C o e f f i c i e n t s a n d % I m p e r v i o u s Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . C o m p o s i t e N R C S S o i l To t a l T o t a l Ro o f (1 ) As p h a l t Co n c r e t e (1 ) Gr a v e l (1 ) La w n s (1 ) Im p e r v i o u s n e s s T y p e C2 C10 0 ac r e s s f %I = 9 0 % % I = 1 0 0 % % I = 9 0 % % I = 4 0 % % I = 2 % ( % I ) sf s f s f s f s f A- 1 A - 1 3. 3 3 1 4 5 , 1 8 2 8 , 5 0 5 - 2 2 , 5 1 2 - 1 1 4 , 1 6 5 20 . 8 % C/ D 0 . 3 6 0 . 4 5 A- 2 A - 2 0. 9 1 3 9 , 8 2 4 - 2 6 , 6 9 1 6 , 6 0 4 - 6 , 5 2 9 82 . 3 % C/ D 0 . 8 3 1 . 0 0 A- 3 A - 3 0. 3 7 1 6 , 2 4 2 1 6 , 2 4 2 - - - - 90 . 0 % C/ D 0 . 9 5 1 . 0 0 A- 4 A - 4 0. 5 7 2 4 , 6 8 1 3 , 1 9 9 1 6 , 7 3 9 1 , 8 7 3 - 2 , 8 7 0 86 . 5 % C/ D 0 . 8 6 1 . 0 0 A- 5 A - 5 0. 4 0 1 7 , 3 4 4 - 1 3 , 8 3 1 9 0 5 - 2 , 6 0 8 84 . 7 % C/ D 0 . 8 4 1 . 0 0 A- 6 A - 6 0. 5 1 2 2 , 2 9 4 1 1 7 - 1 2 , 8 4 4 - 9 , 3 3 3 53 . 2 % C/ D 0 . 6 4 0 . 8 0 A- 7 A - 7 0. 3 2 1 4 , 0 1 0 7 , 9 6 5 - 1 0 6 - 5 , 9 3 9 52 . 7 % C/ D 0 . 6 3 0 . 7 9 A- 8 A - 8 0. 2 1 9 , 0 9 7 3 , 3 0 8 3 , 2 3 1 - 2 , 5 5 8 65 . 3 % C/ D 0 . 7 4 0 . 9 2 A- 9 A - 9 0. 6 4 2 8 , 0 4 6 5 , 8 2 6 - 2 2 , 2 0 0 - 2 0 89 . 9 % C/ D 0 . 9 5 1 . 0 0 A- 1 0 A - 1 0 0. 6 8 2 9 , 5 0 4 5 , 8 7 2 - 2 2 , 5 2 1 - 1 , 1 1 1 86 . 7 % C/ D 0 . 9 2 1 . 0 0 A- 1 1 A - 1 1 0. 9 7 4 2 , 1 8 6 1 1 , 2 3 5 - 6 0 3 - 3 0 , 3 4 8 26 . 7 % C/ D 0 . 4 1 0 . 5 1 A- 1 2 A - 1 2 1. 1 5 5 0 , 0 2 0 - - 2 , 2 4 0 - 4 7 , 7 8 0 5. 9 % C/ D 0 . 2 3 0 . 2 9 A- 1 2 ( F u t u r e ) A - 1 2 ( F u t u r e ) 1. 1 5 5 0 , 0 2 0 - 4 4 , 9 0 0 - - 5 , 1 2 0 90 . 0 % C/ D 0 . 8 7 1 . 0 0 A- 1 3 A - 1 3 0. 2 6 1 1 , 5 1 7 1 1 , 5 1 7 - - - - 90 . 0 % C/ D 0 . 9 5 1 . 0 0 A- T O T A L A - T O T A L 10 . 3 3 4 4 9 , 9 4 7 7 3 , 7 8 7 5 7 , 2 6 1 9 5 , 6 3 9 - 2 2 3 , 2 6 0 47 . 6 % C / D 0 . 5 8 0 . 7 2 B- 1 B - 1 0. 4 2 1 8 , 4 8 6 - 5 , 9 0 7 4 , 2 1 8 - 8 , 3 6 1 53 . 4 % C/ D 0 . 6 1 0 . 7 6 B- 2 B - 2 1. 4 5 6 2 , 9 9 5 - 2 3 , 6 4 0 3 , 2 7 7 - 3 6 , 0 7 8 43 . 4 % C/ D 0 . 5 2 0 . 6 5 B- T O T A L B - T O T A L 1. 8 7 8 1 , 4 8 1 - 2 9 , 5 4 7 7 , 4 9 5 - 4 4 , 4 3 9 45 . 6 % C / D 0 . 5 4 0 . 6 8 C- 1 C - 1 1. 2 8 5 5 , 6 7 0 - 6 , 0 2 0 - 4 9 , 6 5 0 11 . 5 % C/ D 0 . 2 8 0 . 3 5 C- T O T A L C - T O T A L 1. 2 8 5 5 , 6 7 0 - - 6 , 0 2 0 - 4 9 , 6 5 0 11 . 5 % C / D 0 . 2 8 0 . 3 5 OS - 1 O S - 1 0. 6 8 2 9 , 5 3 3 2 9 , 5 3 3 2. 0 % C/ D 0 . 2 0 0 . 2 5 OS - 2 A O S - 2 A 0. 2 1 8 , 9 4 0 8 , 9 4 0 2. 0 % C/ D 0 . 2 0 0 . 2 5 OS - 2 B O S - 2 B 0. 9 3 4 0 , 3 1 0 2 6 , 5 6 8 6 , 2 2 8 7 , 5 1 4 80 . 2 % C/ D 0 . 8 1 1 . 0 0 OS - 3 O S - 3 0. 5 1 2 2 , 1 1 5 1 5 , 3 0 9 4 , 3 2 1 2 , 4 8 5 87 . 0 % C/ D 0 . 8 7 1 . 0 0 OS - 4 O S - 4 1. 2 6 5 4 , 6 9 7 3 2 , 2 7 2 5 , 6 6 4 1 6 , 7 6 1 68 . 9 % C/ D 0 . 7 2 0 . 9 0 OS - 5 O S - 5 0. 5 4 2 3 , 6 6 8 2 3 , 6 6 8 2. 0 % C/ D 0 . 2 0 0 . 2 5 OS - T O T A L O S - T O T A L 4. 1 2 1 7 9 , 2 6 3 - 7 4 , 1 4 9 1 6 , 2 1 3 - 8 8 , 9 0 1 50 . 5 % C / D 0 . 5 8 0 . 7 2 17 . 5 9 7 6 6 , 3 6 1 7 3 , 7 8 7 1 6 0 , 9 5 7 1 2 5 , 3 6 6 - 4 0 6 , 2 5 1 4 5 . 5 % C / D 0 . 5 5 0 . 6 9 No t e s : (1 ) R e c o m m e n d e d R u n o f f C o e f f i c i e n t V a l u e s f r o m F C S C M T a b l e R O - 1 1 . (2 ) C o m p o s i t e R u n o f f C o e f f i c i e n t i s b a s e d o n F C S C M e q u a t i o n R O - 8 a n d C o e f f i c i e n t A d j u s t m e n t f a c t o r s p e r T a b l e R O - 1 2 . (3 ) B a s i n B - 2 i n c l u d e s a p p r o x i m a t e l y 1 0 , 0 0 0 s f o f f u t u r e p a r k i n g a r e a . (4 ) B a s i n A - 1 2 ( F u t u r e ) i s i n c l u d e d f o r s t o r m s e w e r s i z i n g o n l y a n d i s n o t i n c l u d e d w i t h i n " A - T O T A L " a b o v e . D e t e n t i o n a n d L I D r e q u i r e m e n t s w i l l b e r e q u i r e d f o r B a s i n A - 1 2 w i t h f u t u r e d e v e l o p m e n t . Pr o p o s e d T o t a l Pr o p o s e d B a s i n s Ar e a s Co m p o s i t e R u n o f f C o e f f i c i e n t s (2 ) Da t e : 1 0 / 1 5 / 2 0 1 9 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s _ E E C . x l s m 2- Y e a r T i m e o f C o n c e n t r a t i o n Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a C(1 ) Le n g t h S l o p e ti(2 ) Le n g t h S l o p e C v Ve l o c i t y (3 ) tt(4 ) Ch e c k t c? To t a l L e n g t h tc(5 ) ac r e s f t % m i n f t % f p s m i n m i n U r b a n ? f t m i n m i n EX 1 E X 1 3 . 7 5 0. 5 7 35 3. 8 % 3. 8 39 0 2. 3 % 20 3. 0 2 . 1 5 . 9 Y e s 4 2 5 1 2 5. 9 EX 2 E X 2 2 . 3 8 0 . 4 4 2 7 5 0 . 6 % 2 4 . 2 1 9 0 1 . 0 % 7 0. 7 4 . 5 2 8 . 7 Y e s 4 6 5 1 3 12 . 6 EX 3 E X 3 2 . 1 9 0 . 8 2 2 0 1 . 2 % 2 . 2 4 1 5 1 . 0 % 2 0 2. 0 3 . 5 5 . 7 Y e s 4 3 5 1 2 5. 7 EX 4 E X 4 2 . 3 3 0 . 3 4 5 0 1 . 0 % 1 0 . 1 2 0 5 1 . 1 % 7 0. 7 4 . 7 1 4 . 7 Y e s 2 5 5 1 1 11 . 4 EX 5 E X 5 1 . 3 5 0 . 2 8 1 0 5 1 . 1 % 1 5 . 2 1 3 0 0 . 1 % 7 0. 2 9 . 3 2 4 . 5 Y e s 2 3 5 1 1 11 . 3 OS - 1 O S - 1 0 . 3 1 0 . 3 5 7 0 4 . 4 % 7 . 2 2 0 4 . 6 % 2 0 4. 3 0 . 1 7 . 3 Y e s 9 0 1 1 7. 3 OS - 2 A O S - 2 A 0 . 3 3 0 . 3 9 3 0 5 . 9 % 4 . 0 6 0 1 . 2 % 2 0 2. 2 0 . 5 4 . 5 Y e s 9 0 1 1 5. 0 OS - 2 B O S - 2 B 0 . 9 3 0 . 8 1 5 0 2 . 0 % 3 . 0 4 9 0 0 . 7 % 2 0 1. 6 5 . 1 8 . 1 Y e s 5 4 0 1 3 8. 1 OS - 3 O S - 3 2 . 2 2 0 . 3 4 3 0 1 0 . 0 % 3 . 6 6 1 0 0 . 4 % 7 0. 4 2 3 . 0 2 6 . 6 Y e s 6 4 0 1 4 13 . 6 OS - 4 O S - 4 1 . 2 8 0 . 7 5 6 0 5 . 0 % 3 . 0 2 5 0 1 . 1 % 2 0 2. 1 2 . 0 5 . 0 Y e s 3 1 0 1 2 5. 0 OS - 5 O S - 5 0 . 5 4 0 . 2 0 3 0 1 0 . 0 % 4 . 3 2 0 0 0 . 7 % 7 0. 6 5 . 7 1 0 . 0 Y e s 2 3 0 1 1 10 . 0 No t e s : (1 ) C = C x*C f (2 ) ti = [ 1 . 8 7 ( 1 . 1 - C xCf)L 1/ 2 ]/ S 1/ 3 , S = s l o p e i n % , L = l e n g t h o f o v e r l a n d f l o w ( 4 0 0 ' m a x ) (3 ) V= C vS0. 5 , S = w a t e r c o u r s e s l o p e i n f t / f t , U D F C D E q u a t i o n R O - 4 (4 ) tt=L / ( V * 6 0 s e c / m i n ) (5 ) tc c h e c k ( f o r u r b a n o r d e v e l o p e d a r e a s o n l y ) = t o t a l l e n g t h / 1 8 0 + 1 0 (6 ) mi n t c = 5 m i n Ex i s t i n g B a s i n s In i t i a l O v e r l a n d F l o w T i m e ( t i) Tr a v e l / C h a n n e l i z e d T i m e o f F l o w ( t t) ti+t t tc Ch e c k f o r U r b a n i z e d B a s i n s Fi n a l tc(6 ) Da t e : 1 0 / 1 5 / 2 0 1 9 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s _ E E C . x l s m 2- Y e a r T i m e o f C o n c e n t r a t i o n Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a C(1 ) Le n g t h S l o p e ti(2 ) Le n g t h S l o p e C v Ve l o c i t y (3 ) tt(4 ) Ch e c k t c? To t a l L e n g t h tc(5 ) ac r e s f t % m i n f t % f p s m i n m i n U r b a n ? f t m i n m i n A- 1 A - 1 3 . 3 3 0. 3 6 23 5 1. 5 % 18 . 6 46 5 0. 5 % 20 1. 4 5 . 5 2 4 . 0 Y e s 7 0 0 1 4 13 . 9 A- 2 A - 2 0 . 9 1 0 . 8 3 1 0 2 . 0 % 1 . 2 8 3 0 5 0 . 5 % 2 0 1. 4 3 . 6 4 . 9 Y e s 3 1 5 1 2 5. 0 A- 3 A - 3 0 . 3 7 0 . 9 5 5 0 1 2 . 5 % 0 . 8 6 1 5 3 0 . 0 % 2 0 11 . 0 0 . 0 0 . 9 Y e s 6 5 1 0 5. 0 A- 4 A - 4 0 . 5 7 0 . 8 6 3 6 2 . 0 % 2 . 1 2 2 4 2 2 . 0 % 2 0 2. 8 1 . 4 3 . 5 Y e s 2 7 8 1 2 5. 0 A- 5 A - 5 0 . 4 0 0 . 8 4 5 0 2 . 0 % 2 . 7 6 1 3 3 1 . 5 % 2 0 2. 4 0 . 9 3 . 7 Y e s 1 8 3 1 1 5. 0 A- 6 A - 6 0 . 5 1 0 . 6 4 1 7 2 . 0 % 2 . 8 5 1 2 3 2 . 0 % 2 0 2. 8 0 . 7 3 . 6 Y e s 1 4 0 1 1 5. 0 A- 7 A - 7 0 . 3 2 0 . 6 3 6 4 1 . 5 % 6 . 1 2 2 1 0 1 . 0 % 1 5 1. 5 2 . 3 8 . 5 Y e s 2 7 4 1 2 8. 5 A- 8 A - 8 0 . 2 1 0 . 7 4 1 5 2 . 0 % 2 . 0 8 5 0 2 . 0 % 2 0 2. 8 0 . 3 2 . 4 Y e s 6 5 1 0 5. 0 A- 9 A - 9 0 . 6 4 0 . 9 5 2 5 1 2 . 5 % 0 . 6 1 2 1 0 0 . 5 % 2 0 1. 4 2 . 5 3 . 1 Y e s 2 3 5 1 1 5. 0 A- 1 0 A - 1 0 0 . 6 8 0 . 9 2 6 3 4 . 0 % 1 . 6 7 2 0 0 1 . 5 % 2 0 2. 4 1 . 4 3 . 0 Y e s 2 6 3 1 1 5. 0 A- 1 1 A - 1 1 0 . 9 7 0 . 4 1 2 0 7 . 0 % 3 . 0 3 1 9 0 0 . 5 % 1 5 1. 1 3 . 0 6 . 0 Y e s 2 1 0 1 1 6. 0 A- 1 2 A - 1 2 1 . 1 5 0 . 2 3 2 0 7 . 0 % 3 . 8 1 2 0 5 0 . 5 % 1 5 1. 1 3 . 2 7 . 0 Y e s 2 2 5 1 1 7. 0 A- 1 2 ( F u t u r e ) A - 1 2 ( F u t u r e ) 1 . 1 5 0 . 8 7 1 0 2 . 0 % 1 . 0 7 2 0 5 2 . 0 % 2 0 2. 8 1 . 2 2 . 3 Y e s 2 1 5 1 1 5. 0 A- 1 3 A - 1 3 0 . 2 6 0 . 9 5 7 2 1 2 . 5 % 1 . 0 3 1 5 3 0 . 0 % 2 0 11 . 0 0 . 0 1 . 1 Y e s 8 7 1 0 5. 0 A- T O T A L A - T O T A L 1 0 . 3 3 0 . 5 8 5 1 1 . 5 % 6 . 1 0 9 8 5 0 . 4 % 2 0 1. 3 1 3 . 0 1 9 . 1 Y e s 1 0 3 6 1 6 1 5 . 8 B- 1 B - 1 0 . 4 2 0 . 6 1 7 0 2 . 0 % 6 . 0 9 4 0 2 . 0 % 2 0 2. 8 0 . 2 6 . 3 Y e s 1 1 0 1 1 6. 3 B- 2 B - 2 1 . 4 5 0 . 5 2 5 0 2 5 . 0 % 2 . 6 5 2 9 0 0 . 5 % 1 5 1. 1 4 . 6 7 . 2 Y e s 3 4 0 1 2 7. 2 B- T O T A L B - T O T A L 1 . 8 7 0 . 5 4 5 0 2 5 . 0 % 2 . 5 6 2 9 0 0 . 5 % 1 5 1. 1 4 . 6 7 . 1 Y e s 3 4 0 1 2 7 . 1 C- 1 C - 1 1 . 2 8 0 . 2 8 1 6 2 . 0 % 4 . 8 7 7 5 1 0 . 0 % 1 5 4. 7 0 . 3 5 . 1 Y e s 9 1 1 1 5. 1 C- T O T A L C - T O T A L 1 . 2 8 0 . 2 8 1 6 2 . 0 % 4 . 8 7 7 5 1 0 . 0 % 1 5 4. 7 0 . 3 5 . 1 Y e s 9 1 1 1 5 . 1 OS - 1 O S - 1 0 . 6 8 0 . 2 0 7 0 4 . 4 % 8 . 6 4 2 0 4 . 6 % 2 0 4. 3 0 . 1 8 . 7 Y e s 9 0 1 1 8. 7 OS - 2 A O S - 2 A 0 . 2 1 0 . 2 0 3 0 5 . 9 % 5 . 1 3 6 0 1 . 2 % 2 0 2. 2 0 . 5 5 . 6 Y e s 9 0 1 1 5. 6 OS - 2 B O S - 2 B 0 . 9 3 0 . 8 1 5 0 2 . 0 % 3 . 0 5 4 9 0 0 . 7 % 2 0 1. 6 5 . 1 8 . 1 Y e s 5 4 0 1 3 8. 1 OS - 3 O S - 3 0 . 5 1 0 . 8 7 1 4 0 1 . 5 % 4 . 5 3 1 6 5 0 . 7 % 2 0 1. 7 1 . 6 6 . 2 Y e s 3 0 5 1 2 6. 2 OS - 4 O S - 4 1 . 2 6 0 . 7 2 6 0 5 . 0 % 3 . 2 3 2 5 0 1 . 1 % 2 0 2. 1 2 . 0 5 . 2 Y e s 3 1 0 1 2 5. 2 OS - 5 O S - 5 0 . 5 4 0 . 2 0 3 0 1 0 . 0 % 4 . 3 1 2 0 0 0 . 7 % 7 0. 6 5 . 7 1 0 . 0 Y e s 2 3 0 1 1 10 . 0 No t e s : (1 ) C = C x*C f (2 ) ti = [ 1 . 8 7 ( 1 . 1 - C xCf)L 1/ 2 ]/ S 1/ 3 , S = s l o p e i n % , L = l e n g t h o f o v e r l a n d f l o w ( 4 0 0 ' m a x ) (3 ) V= C vS0. 5 , S = w a t e r c o u r s e s l o p e i n f t / f t , U D F C D E q u a t i o n R O - 4 (4 ) tt=L / ( V * 6 0 s e c / m i n ) (5 ) tc c h e c k ( f o r u r b a n o r d e v e l o p e d a r e a s o n l y ) = t o t a l l e n g t h / 1 8 0 + 1 0 (6 ) mi n t c = 5 m i n Pr o p o s e d B a s i n s In i t i a l O v e r l a n d F l o w T i m e ( t i) Tr a v e l / C h a n n e l i z e d T i m e o f F l o w ( t t) ti+t t tc Ch e c k f o r U r b a n i z e d B a s i n s Fi n a l tc(6 ) Da t e : 1 0 / 1 5 / 2 0 1 9 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s _ E E C . x l s m 10 0 - Y e a r T i m e o f C o n c e n t r a t i o n Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a C(1 ) Le n g t h S l o p e ti(2 ) Le n g t h S l o p e C v Ve l o c i t y (3 ) tt(4 ) Ch e c k t c? To t a l L e n g t h tc(5 ) ac r e s f t % m i n f t % f p s m i n m i n U r b a n ? f t m i n m i n EX 1 E X 1 3 . 7 5 0. 7 1 35 3. 8 % 2. 8 39 0 2. 3 % 20 3. 0 2 . 1 4 . 9 Y e s 4 2 5 1 2 5. 0 EX 2 E X 2 2 . 3 8 0 . 5 5 2 7 5 0 . 6 % 2 0 . 2 1 9 0 1 . 0 % 7 0. 7 4 . 5 2 4 . 7 Y e s 4 6 5 1 3 12 . 6 EX 3 E X 3 2 . 1 9 1. 0 0 20 1. 2 % 0. 8 41 5 1. 0 % 20 2. 0 3 . 5 4 . 2 Y e s 4 3 5 1 2 5. 0 EX 4 E X 4 2 . 3 3 0 . 4 2 5 0 1 . 0 % 8 . 9 2 0 5 1 . 1 % 7 0. 7 4 . 7 1 3 . 6 Y e s 2 5 5 1 1 11 . 4 EX 5 E X 5 1 . 3 5 0. 3 5 10 5 1. 1 % 13 . 9 13 0 0. 1 % 7 0. 2 9 . 3 2 3 . 2 Y e s 2 3 5 1 1 11 . 3 OS - 1 O S - 1 0 . 3 1 0. 4 3 70 4. 4 % 6. 4 20 4. 6 % 20 4. 3 0 . 1 6 . 5 Y e s 9 0 1 1 6. 5 OS - 2 A O S - 2 A 0 . 3 3 0 . 4 9 3 0 5 . 9 % 3 . 5 6 0 1 . 2 % 2 0 2. 2 0 . 5 3 . 9 Y e s 9 0 1 1 5. 0 OS - 2 B O S - 2 B 0 . 9 3 1. 0 0 50 2. 0 % 1. 1 49 0 0. 7 % 20 1. 6 5 . 1 6 . 1 Y e s 5 4 0 1 3 6. 1 OS - 3 O S - 3 2 . 2 2 0 . 4 3 3 0 1 0 . 0 % 3 . 2 6 1 0 0 . 4 % 7 0. 4 2 3 . 0 2 6 . 2 Y e s 6 4 0 1 4 13 . 6 OS - 4 O S - 4 1 . 2 8 0. 9 3 60 5. 0 % 1. 4 25 0 1. 1 % 20 2. 1 2 . 0 3 . 4 Y e s 3 1 0 1 2 5. 0 OS - 5 O S - 5 0 . 5 4 0 . 2 5 3 0 1 0 . 0 % 4 . 1 2 0 0 0 . 7 % 7 0. 6 5 . 7 9 . 8 Y e s 2 3 0 1 1 9. 8 No t e s : (1 ) C = C x*C f (2 ) ti = [ 1 . 8 7 ( 1 . 1 - C xCf)L 1/ 2 ]/ S 1/ 3 , S = s l o p e i n % , L = l e n g t h o f o v e r l a n d f l o w ( 4 0 0 ' m a x ) (3 ) V= C vS0. 5 , S = w a t e r c o u r s e s l o p e i n f t / f t , U D F C D E q u a t i o n R O - 4 (4 ) tt=L / ( V * 6 0 s e c / m i n ) (5 ) tc c h e c k ( f o r u r b a n o r d e v e l o p e d a r e a s o n l y ) = t o t a l l e n g t h / 1 8 0 + 1 0 (6 ) mi n t c = 5 m i n Ex i s t i n g B a s i n s ti+t t Fi n a l tc(6 ) tc Ch e c k f o r U r b a n i z e d B a s i n s In i t i a l O v e r l a n d F l o w T i m e ( t i) Tr a v e l / C h a n n e l i z e d T i m e o f F l o w ( t t) Da t e : 1 0 / 1 5 / 2 0 1 9 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s _ E E C . x l s m 10 0 - Y e a r T i m e o f C o n c e n t r a t i o n Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a C(1 ) Le n g t h S l o p e ti(2 ) Le n g t h S l o p e C v Ve l o c i t y (3 ) tt(4 ) Ch e c k t c? To t a l L e n g t h tc(5 ) ac r e s f t % m i n f t % f p s m i n m i n U r b a n ? f t m i n m i n A- 1 A - 1 3 . 3 3 0. 4 5 23 5 1. 5 % 16 . 3 46 5 0. 5 % 20 1. 4 5 . 5 2 1 . 8 Y e s 7 0 0 1 4 13 . 9 A- 2 A - 2 0 . 9 1 1 . 0 0 1 0 2 . 0 % 0 . 4 7 3 0 5 0 . 5 % 2 0 1. 4 3 . 6 4 . 1 Y e s 3 1 5 1 2 5. 0 A- 3 A - 3 0 . 3 7 1. 0 0 50 12 . 5 % 0. 5 7 15 30 . 0 % 20 11 . 0 0 . 0 0 . 6 Y e s 6 5 1 0 5. 0 A- 4 A - 4 0 . 5 7 1 . 0 0 3 6 2 . 0 % 0 . 8 9 2 4 2 2 . 0 % 2 0 2. 8 1 . 4 2 . 3 Y e s 2 7 8 1 2 5. 0 A- 5 A - 5 0 . 4 0 1. 0 0 50 2. 0 % 1. 0 5 13 3 1. 5 % 20 2. 4 0 . 9 2 . 0 Y e s 1 8 3 1 1 5. 0 A- 6 A - 6 0 . 5 1 0 . 8 0 1 7 2 . 0 % 1 . 8 7 1 2 3 2 . 0 % 2 0 2. 8 0 . 7 2 . 6 Y e s 1 4 0 1 1 5. 0 A- 7 A - 7 0 . 3 2 0. 7 9 64 1. 5 % 4. 0 6 21 0 1. 0 % 15 1. 5 2 . 3 6 . 4 Y e s 2 7 4 1 2 6. 4 A- 8 A - 8 0 . 2 1 0 . 9 2 1 5 2 . 0 % 1 . 0 1 5 0 2 . 0 % 2 0 2. 8 0 . 3 1 . 3 Y e s 6 5 1 0 5. 0 A- 9 A - 9 0 . 6 4 1. 0 0 25 12 . 5 % 0. 4 1 21 0 0. 5 % 20 1. 4 2 . 5 2 . 9 Y e s 2 3 5 1 1 5. 0 A- 1 0 A - 1 0 0 . 6 8 1 . 0 0 6 3 4 . 0 % 0 . 9 4 2 0 0 1 . 5 % 2 0 2. 4 1 . 4 2 . 3 Y e s 2 6 3 1 1 5. 0 A- 1 1 A - 1 1 0 . 9 7 0. 5 1 20 7. 0 % 2. 5 8 19 0 0. 5 % 15 1. 1 3 . 0 5 . 6 Y e s 2 1 0 1 1 5. 6 A- 1 2 A - 1 2 1 . 1 5 0 . 2 9 2 0 7 . 0 % 3 . 5 6 2 0 5 0 . 5 % 1 5 1. 1 3 . 2 6 . 8 Y e s 2 2 5 1 1 6. 8 A- 1 2 ( F u t u r e ) A - 1 2 ( F u t u r e ) 1 . 1 5 1. 0 0 10 2. 0 % 0. 4 7 20 5 2. 0 % 20 2. 8 1 . 2 1 . 7 Y e s 2 1 5 1 1 5. 0 A- 1 3 A - 1 3 0 . 2 6 1 . 0 0 7 2 1 2 . 5 % 0 . 6 9 1 5 3 0 . 0 % 2 0 11 . 0 0 . 0 0 . 7 Y e s 8 7 1 0 5. 0 A- T O T A L A - T O T A L 1 0 . 3 3 0. 7 2 51 1. 5 % 4. 4 1 98 5 0. 4 % 20 1. 3 1 3 . 0 1 7 . 4 Y e s 1 0 3 6 1 6 1 5 . 8 B- 1 B - 1 0 . 4 2 0. 7 6 70 2. 0 % 4. 1 9 40 2. 0 % 20 2. 8 0 . 2 4 . 4 Y e s 1 1 0 1 1 5. 0 B- 2 B - 2 1 . 4 5 0 . 6 5 5 0 2 5 . 0 % 2 . 0 5 2 9 0 0 . 5 % 1 5 1. 1 4 . 6 6 . 6 Y e s 3 4 0 1 2 6. 6 B- T O T A L B - T O T A L 1 . 8 7 0. 6 8 50 25 . 0 % 1. 9 4 29 0 0. 5 % 20 1. 4 3 . 4 5 . 4 Y e s 3 4 0 1 2 5 . 4 C- 1 C - 1 1 . 2 8 0. 3 5 16 2. 0 % 4. 4 5 75 10 . 0 % 15 4. 7 0 . 3 4 . 7 Y e s 9 1 1 1 5. 0 C- T O T A L C - T O T A L 1 . 2 8 0 . 3 5 1 6 2 . 0 % 4 . 4 5 7 5 1 0 . 0 % 1 5 4. 7 0 . 3 4 . 7 Y e s 9 1 1 1 5 . 0 OS - 1 O S - 1 0 . 6 8 0 . 2 5 7 0 4 . 4 % 8 . 1 6 2 0 4 . 6 % 2 0 4. 3 0 . 1 8 . 2 Y e s 9 0 1 1 8. 2 OS - 2 A O S - 2 A 0 . 2 1 0. 2 5 30 5. 9 % 4. 8 5 60 1. 2 % 20 2. 2 0 . 5 5 . 3 Y e s 9 0 1 1 5. 3 OS - 2 B O S - 2 B 0 . 9 3 1 . 0 0 5 0 2 . 0 % 1 . 0 5 4 9 0 0 . 7 % 2 0 1. 6 5 . 1 6 . 1 Y e s 5 4 0 1 3 6. 1 OS - 3 O S - 3 0 . 5 1 1. 0 0 14 0 1. 5 % 1. 9 4 16 5 0. 7 % 20 1. 7 1 . 6 3 . 6 Y e s 3 0 5 1 2 5. 0 OS - 4 O S - 4 1 . 2 6 0 . 9 0 6 0 5 . 0 % 1 . 7 0 2 5 0 1 . 1 % 2 0 2. 1 2 . 0 3 . 7 Y e s 3 1 0 1 2 5. 0 OS - 5 O S - 5 0 . 5 4 0. 2 5 30 10 . 0 % 4. 0 7 20 0 0. 7 % 7 0. 6 5 . 7 9 . 8 Y e s 2 3 0 1 1 9. 8 No t e s : (1 ) C = C x*C f (2 ) ti = [ 1 . 8 7 ( 1 . 1 - C xCf)L 1/ 2 ]/ S 1/ 3 , S = s l o p e i n % , L = l e n g t h o f o v e r l a n d f l o w ( 4 0 0 ' m a x ) (3 ) V= C vS0. 5 , S = w a t e r c o u r s e s l o p e i n f t / f t , U D F C D E q u a t i o n R O - 4 (4 ) tt=L / ( V * 6 0 s e c / m i n ) (5 ) tc c h e c k ( f o r u r b a n o r d e v e l o p e d a r e a s o n l y ) = t o t a l l e n g t h / 1 8 0 + 1 0 (6 ) mi n t c = 5 m i n Pr o p o s e d B a s i n s In i t i a l O v e r l a n d F l o w T i m e ( t i) Tr a v e l / C h a n n e l i z e d T i m e o f F l o w ( t t) ti+t t tc Ch e c k f o r U r b a n i z e d B a s i n s Fi n a l tc(6 ) Da t e : 1 0 / 1 5 / 2 0 1 9 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s _ E E C . x l s m Ra t i o n a l M e t h o d P e a k R u n o f f Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a 2 - y e a r 1 0 0 - y e a r ac r e tc tc C2 C10 0 I2 I10 0 Q2 Q10 0 mi n m i n i n / h r i n / h r c f s c f s EX 1 E X 1 3 . 7 5 6 5 0 . 5 7 0 . 7 1 2 . 6 7 9 . 9 5 5 . 7 1 2 6 . 6 2 EX 2 E X 2 2 . 3 8 1 3 1 3 0 . 4 4 0 . 5 5 1 . 9 8 6 . 9 2 2 . 0 7 9 . 0 4 EX 3 E X 3 2 . 1 9 6 5 0 . 8 2 1 . 0 0 2 . 6 7 9 . 9 5 4 . 7 8 2 1 . 7 5 EX 4 E X 4 2 . 3 3 1 1 1 1 0 . 3 4 0 . 4 2 2 . 1 3 7 . 4 2 1 . 6 8 7 . 3 3 EX 5 E X 5 1 . 3 5 1 1 1 1 0 . 2 8 0 . 3 5 2 . 1 3 7 . 4 2 0 . 8 1 3 . 5 3 OS - 1 O S - 1 0 . 3 1 7 6 0 . 3 5 0 . 4 3 2 . 5 2 9 . 9 5 0 . 2 7 1 . 3 2 OS - 2 A O S - 2 A 0 . 3 3 5 5 0 . 3 9 0 . 4 9 2 . 8 5 9 . 9 5 0 . 3 7 1 . 6 1 OS - 2 B O S - 2 B 0 . 9 3 8 6 0 . 8 1 1 . 0 0 2 . 4 0 9 . 3 1 1 . 8 0 8 . 6 2 OS - 3 O S - 3 2 . 2 2 1 4 1 4 0 . 3 4 0 . 4 3 1 . 9 2 6 . 7 1 1 . 4 6 6 . 3 9 OS - 4 O S - 4 1 . 2 8 5 5 0 . 7 5 0 . 9 3 2 . 8 5 9 . 9 5 2 . 7 3 1 1 . 9 1 OS - 5 O S - 5 0 . 5 4 1 0 1 0 0 . 2 0 0 . 2 5 2 . 2 1 7 . 7 2 0 . 2 4 1 . 0 5 21 . 9 3 9 9 . 1 8 Ex i s t i n g B a s i n s T o t a l s Pe a k D i s c h a r g e Ra i n f a l l I n t e n s i t y Ru n o f f C o e f f i c i e n t s Da t e : 1 0 / 1 5 / 2 0 1 9 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s _ E E C . x l s m Ra t i o n a l M e t h o d P e a k R u n o f f Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a 2 - y e a r 1 0 0 - y e a r ac r e tc tc C2 C10 0 I2 I10 0 Q2 Q10 0 mi n m i n i n / h r i n / h r c f s c f s A- 1 A - 1 3 . 3 3 1 4 . 0 1 4 . 0 0 . 3 6 0 . 4 5 1 . 9 2 6 . 7 1 2 . 3 1 1 0 . 0 7 A- 2 A - 2 0 . 9 1 5 . 0 5 . 0 0 . 8 3 1 . 0 0 2 . 8 5 9 . 9 5 2 . 1 5 9 . 1 0 A- 3 A - 3 0 . 3 7 5 . 0 5 . 0 0 . 9 5 1 . 0 0 2 . 8 5 9 . 9 5 1 . 0 1 3 . 7 1 A- 4 A - 4 0 . 5 7 5 . 0 5 . 0 0 . 8 6 1 . 0 0 2 . 8 5 9 . 9 5 1 . 3 9 5 . 6 4 A- 5 A - 5 0 . 4 0 5 . 0 5 . 0 0 . 8 4 1 . 0 0 2 . 8 5 9 . 9 5 0 . 9 5 3 . 9 6 A- 6 A - 6 0 . 5 1 5 . 0 5 . 0 0 . 6 4 0 . 8 0 2 . 8 5 9 . 9 5 0 . 9 3 4 . 0 5 A- 7 A - 7 0 . 3 2 8 . 0 6 . 0 0 . 6 3 0 . 7 9 2 . 4 0 9 . 3 1 0 . 4 9 2 . 3 7 A- 8 A - 8 0 . 2 1 5 . 0 5 . 0 0 . 7 4 0 . 9 2 2 . 8 5 9 . 9 5 0 . 4 4 1 . 9 2 A- 9 A - 9 0 . 6 4 5 . 0 5 . 0 0 . 9 5 1 . 0 0 2 . 8 5 9 . 9 5 1 . 7 4 6 . 4 1 A- 1 0 A - 1 0 0 . 6 8 5 . 0 5 . 0 0 . 9 2 1 . 0 0 2 . 8 5 9 . 9 5 1 . 7 8 6 . 7 4 A- 1 1 A - 1 1 0 . 9 7 6 . 0 6 . 0 0 . 4 1 0 . 5 1 2 . 6 7 9 . 3 1 1 . 0 6 4 . 6 3 A- 1 2 A - 1 2 1 . 1 5 7 . 0 7 . 0 0 . 2 3 0 . 2 9 2 . 5 2 8 . 8 0 0 . 6 8 2 . 9 5 A- 1 2 ( F u t u r e ) A - 1 2 ( F u t u r e ) 1 . 1 5 5 . 0 5 . 0 0 . 8 7 1 . 0 0 2 . 8 5 9 . 9 5 2 . 8 6 1 1 . 4 3 A- 1 3 A - 1 3 0 . 2 6 5 . 0 5 . 0 0 . 9 5 1 . 0 0 2 . 8 5 9 . 9 5 0 . 7 2 2 . 6 3 A- T O T A L A - T O T A L 1 0 . 3 3 1 6 . 0 1 6 . 0 0 . 5 8 0 . 7 2 1 . 8 1 6 . 3 0 1 0 . 8 0 4 7 . 0 0 B- 1 B - 1 0 . 4 2 6 . 0 5 . 0 0 . 6 1 0 . 7 6 2 . 6 7 9 . 9 5 0 . 6 9 3 . 2 2 B- 2 B - 2 1 . 4 5 7 . 0 7 . 0 0 . 5 2 0 . 6 5 2 . 5 2 8 . 8 0 1 . 9 0 8 . 2 8 B- T O T A L B - T O T A L 1 . 8 7 7 . 0 5 . 0 0 . 5 4 0 . 6 8 2 . 5 2 9 . 9 5 2 . 5 5 1 2 . 5 9 C- 1 C - 1 1 . 2 8 5 . 0 5 . 0 0 . 2 8 0 . 3 5 2 . 8 5 9 . 9 5 1 . 0 2 4 . 4 7 C- T O T A L C - T O T A L 1 . 2 8 5 . 0 5 . 0 0 . 2 8 0 . 3 5 2 . 8 5 9 . 9 5 1 . 0 2 4 . 4 7 OS - 1 O S - 1 0 . 6 8 9 . 0 8 . 0 0 . 2 0 0 . 2 5 2 . 3 0 8 . 3 8 0 . 3 1 1 . 4 2 OS - 2 A O S - 2 A 0 . 2 1 6 . 0 5 . 0 0 . 2 0 0 . 2 5 2 . 6 7 9 . 9 5 0 . 1 1 0 . 5 1 OS - 2 B O S - 2 B 0 . 9 3 8 . 0 6 . 0 0 . 8 1 1 . 0 0 2 . 4 0 9 . 3 1 1 . 8 0 8 . 6 2 OS - 3 O S - 3 0 . 5 1 6 . 0 5 . 0 0 . 8 7 1 . 0 0 2 . 6 7 9 . 9 5 1 . 1 7 5 . 0 5 OS - 4 O S - 4 1 . 2 6 5 . 0 5 . 0 0 . 7 2 0 . 9 0 2 . 8 5 9 . 9 5 2 . 5 8 1 1 . 2 5 OS - 5 O S - 5 0 . 5 4 1 0 . 0 1 0 . 0 0 . 2 0 0 . 2 5 2 . 2 1 7 . 7 2 0 . 2 4 1 . 0 5 25 . 4 7 1 0 8 . 0 3 To t a l s Pr o p o s e d B a s i n s Ru n o f f C o e f f i c i e n t s R a i n f a l l I n t e n s i t y P e a k D i s c h a r g e Da t e : 1 0 / 1 5 / 2 0 1 9 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s _ E E C . x l s m A PPENDIX B D ETENTION AND W ATER Q UALITY C ALCULATIONS Dention Pond Volume (FAA Method) Platte River Power Authority Campus, Fort Collins, CO POND ID:POND A1 100 Year Storm Into Detention Facility Area =580,678 square feet Area =13.33 acres C 100 = 0.73 Q 100 = 59.59 cfs (Total flows from Basins A and B) Release Rate Out of Pond Q OUT = 3.15 cfs Unit Flow =0.24 cfs/acre T C =15.8 minutes Notes: 1. Release Rate limited by the existing 12" outfall capacity in Timberline Road. 2. Pond area includes all of Basins A, B and OS-2 but excludes "Basin A-12 (Future)". Detention Volume Calculations Rainfall Rainfall Inflow Rate Inflow Volume Adjustment Average Outflow Volume Required Duration (T) Intensity (I) Qin 100*Area*I Vi=(Qin*T*60) Factor Outflow Rate Vo=Qav*T *60 Storage Volume m= 0.5(1 + Tc/T) Qav = m*Qout Vs=Vi-Vo min in/hr cfs ft 3 cfs ft 3 ft 3 5 9.95 96.5 28,962 1.00 3.15 945 28,017 10 7.72 74.9 44,943 1.00 3.15 1,890 43,053 15 6.52 63.3 56,935 1.00 3.15 2,835 54,100 20 5.60 54.3 65,202 1.00 3.15 3,780 61,422 25 4.98 48.3 72,479 1.00 3.15 4,725 67,754 30 4.52 43.9 78,941 1.00 3.15 5,670 73,271 35 4.08 39.6 83,132 1.00 3.15 6,615 76,517 40 3.74 36.3 87,091 1.00 3.15 7,560 79,531 45 3.46 33.6 90,642 1.00 3.15 8,505 82,137 50 3.23 31.3 94,019 1.00 3.15 9,450 84,569 55 3.03 29.4 97,017 1.00 3.15 10,395 86,622 60 2.86 27.7 99,898 1.00 3.15 11,340 88,558 70 2.59 25.1 105,545 1.00 3.15 13,230 92,315 80 2.38 23.1 110,843 1.00 3.15 15,120 95,723 90 2.21 21.4 115,791 1.00 3.15 17,010 98,781 100 2.06 20.0 119,925 1.00 3.15 18,900 101,025 110 1.94 18.8 124,233 1.00 3.15 20,790 103,443 120 1.84 17.9 128,541 1.00 3.15 22,680 105,861 Required Detention Volume V 100 = 105,861 cubic feet V 100 = 2.43 acre-ft Date: 10/15/2019 P:\U16014 - PRPA Campus\Reports\Drainage\Calculations\U16014-Drain Calcs_EEC.xlsm Wa t e r Q u a l i t y Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Re q u i r e d O n s i t e W a t e r Q u a l i t y C a p t u r e V o l u m e Ba s i n A r e a A r e a I m p e r v i o u s n e s s W a t e r s h e d W Q C V * (E x t e n d e d D e t e n t i o n ) (s f ) ( a c r e s ) ( % ) ( i n c h e s ) ( c f ) A- T O T A L 4 4 9 , 9 4 7 1 0 . 3 2 9 48 % 0. 2 0 8, 9 9 1 B- T O T A L 8 1 , 4 8 1 1 . 8 7 1 46 % 0. 1 9 1, 5 8 6 C- T O T A L 5 5 , 6 7 0 1 . 2 7 8 12 % 0. 0 8 42 0 OS - 2 T O T A L 4 9 , 2 5 0 1 . 1 3 1 66 % 0. 2 6 1, 2 7 1 TO T A L R E Q U I R E D 6 3 6 , 3 4 8 1 4 . 6 0 9 46 % 0. 1 9 12 , 3 8 2 Le s s W Q P r o v i d e d b y U n d e r g r o u n d D e t e n t i o n 3, 7 8 2 Le s s W Q P r o v i d e d i n W e t P o n d 42 0 To t a l W Q P r o v i d e d i n P o n d A 8 , 1 8 0 * b a s e d o n 4 0 h r s t o r a g e a n d a d d i t i o n a l 2 0 % f o r e x t e n d e d d e t e n t i o n De s i g n e d W a t e r Q u a l i t y P l a t e P a r a m e t e r s Ba s i n W Q C V W Q C V A r e a R e q u i r e d D i a m t e r o f S p a c e N o . o f N o . o f Pr o v i d e d D e p t h p e r W Q P l a t e R o w W Q H o l e b e t w e e n r o w s ( i n . ) C o l u m n s R o w s (c f ) ( f t ) ( i n 2) (i n ) ( i n ) Po n d A 1 1 0 , 4 0 9 1 . 5 0 0 . 9 2 2 3 / 4 4 2 5 Da t e : 1 0 / 1 5 / 2 0 1 9 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s _ E E C . x l s m Lo w I m p a c t D e v e l o p m e n t S u m m a r y Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n P r o p o s e d Im p e r v i o u s A r e a LI D T r e a t m e n t A r e a T r e a t e d % o f S i t e Tr e a t e d (s f ) ( a c r e s ) ( s f ) ( % ) A- 1 2 7 , 8 1 1 No n e (1 ) - 0% A- 2 3 3 , 2 9 5 No n e - 0% A- 3 1 6 , 2 4 2 Un d e r g r o u n d W a t e r Q u a l i t y 1 6 , 2 4 2 6% A- 4 2 1 , 8 1 1 Un d e r g r o u n d W a t e r Q u a l i t y 2 1 , 8 1 1 8% A- 5 1 4 , 7 3 6 Un d e r g r o u n d W a t e r Q u a l i t y 1 4 , 7 3 6 6% A- 6 1 2 , 9 6 1 Un d e r g r o u n d W a t e r Q u a l i t y 1 2 , 9 6 1 5% A- 7 8 , 0 7 1 Un d e r g r o u n d W a t e r Q u a l i t y 8 , 0 7 1 3% A- 8 6 , 5 3 9 Un d e r g r o u n d W a t e r Q u a l i t y 6 , 5 3 9 2% A- 9 2 8 , 0 2 6 Un d e r g r o u n d W a t e r Q u a l i t y 2 8 , 0 2 6 11 % A- 1 0 2 8 , 3 9 3 Un d e r g r o u n d W a t e r Q u a l i t y 2 8 , 3 9 3 11 % A- 1 1 1 1 , 8 3 8 Un d e r g r o u n d W a t e r Q u a l i t y 1 1 , 8 3 8 4% A- 1 2 2 , 2 4 0 Un d e r g r o u n d W a t e r Q u a l i t y 2 , 2 4 0 1% A- 1 3 1 1 , 5 1 7 No n e - 0% B- 1 1 0 , 1 2 5 Bi o s w a l e 1 0 , 1 2 5 4% B- 2 2 6 , 9 1 7 Bi o s w a l e (3 ) 26 , 9 1 7 10 % C- 1 6 , 0 2 0 We t P o n d 6 , 0 2 0 2% To t a l S i t e 26 6 , 5 4 2 1 9 3 , 9 1 8 73 % (1 ) B a s i n A - 1 e x c l u d e s a p p r o x i m a t e l y 3 , 2 0 0 s f o f b u i l d i n g a n d c o n c r e t e a r e a t h a t e x i s t e d p r i o r t o t h e c a m p u s r e d e v e l o p m e n t . (2 ) B a s i n A - 1 2 F u t u r e w i l l b e r e q u i r e d t o p r o v i d e L I D t r e a t m e n t a t t i m e o f f u t u r e d e v e l o p m e n t (3 ) B a s i n B - 2 i n c l u d e s 1 0 , 0 0 0 s f o f f u t u r e t r e a t e d a r e a b y t h e f u t u r e e x t e n s i o n o f t h e p r o p o s e d b i o s w a l e Lo w I m p a c t D e v e l o p m e n t ( L I D ) T r e a t e d A r e a s Ca l c u l a t i o n s b y : K R B Da t e : 1 0 / 1 5 / 2 0 1 9 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s _ E E C . x l s m STAGE STORAGE TABLE ELEV AREA (sq. ft.) DEPTH (ft) AVG END INC. VOL. (cu. ft.) AVG END TOTAL VOL. (cu. ft.) CONIC INC. VOL. (cu. ft.) CONIC TOTAL VOL. (cu. ft.) 4,948.200 188.23 N/A N/A 0.00 N/A 0.00 4,948.400 1,037.66 0.200 122.59 122.59 111.19 111.19 4,948.600 2,931.58 0.200 396.92 519.51 380.89 492.08 4,948.800 5,765.90 0.200 869.75 1389.26 853.92 1346.00 4,949.000 9,301.26 0.200 1506.72 2895.98 1492.69 2838.70 4,949.200 12,888.17 0.200 2218.94 5114.92 2209.21 5047.91 4,949.400 16,487.21 0.200 2937.54 8052.46 2930.16 7978.07 4,949.600 20,423.50 0.200 3691.07 11743.53 3684.05 11662.13 4,949.800 23,793.84 0.200 4421.73 16165.26 4417.45 16079.57 4,950.000 26,925.84 0.200 5071.97 21237.23 5068.74 21148.31 4,950.200 29,934.56 0.200 5686.04 26923.27 5683.39 26831.70 4,950.400 32,392.72 0.200 6232.73 33156.00 6231.11 33062.81 4,950.600 34,097.07 0.200 6648.98 39804.98 6648.25 39711.06 4,950.800 35,422.51 0.200 6951.96 46756.93 6951.54 46662.60 4,951.000 36,392.35 0.200 7181.49 53938.42 7181.27 53843.87 4,951.200 37,318.53 0.200 7371.09 61309.51 7370.89 61214.76 4,951.400 38,267.07 0.200 7558.56 68868.07 7558.36 68773.12 4,951.600 39,241.04 0.200 7750.81 76618.88 7750.61 76523.73 4,951.800 40,246.81 0.200 7948.78 84567.66 7948.57 84472.30 4,952.000 41,385.33 0.200 8163.21 92730.88 8162.95 92635.25 4,952.200 42,668.52 0.200 8405.38 101136.26 8405.06 101040.31 4,952.400 42,816.19 0.200 8548.47 109684.73 8548.47 109588.77 103,177 cf @ 4952.25 24,764 cf @ 4952.25 136,451 cf total volume (2.96 ac-ft) 2.43 ac-ft required for detention (2.71 ac-ft provided) 0.19 ac-ft required for water quality (0.24 ac-ft provided) SMALL POND ELEV AREA (sq. ft.) DEPTH (ft) AVG END INC. VOL. (cu. ft.) AVG END TOTAL VOL. (cu. ft.) CONIC INC. VOL. (cu. ft.) CONIC TOTAL VOL. (cu. ft.) 4,949.000 1.33 N/A N/A 0.00 N/A 0.00 4,949.200 192.84 0.200 19.42 19.42 14.01 14.01 4,949.400 1,025.70 0.200 121.85 141.27 110.89 124.90 4,949.600 2,391.16 0.200 341.69 482.96 332.20 457.09 4,949.800 4,180.67 0.200 657.18 1140.14 648.90 1106.00 4,950.000 5,923.45 0.200 1010.41 2150.55 1005.36 2111.36 4,950.200 7,238.27 0.200 1316.17 3466.72 1313.98 3425.34 4,950.400 8,208.17 0.200 1544.64 5011.37 1543.63 4968.97 4,950.600 8,963.94 0.200 1717.21 6728.58 1716.66 6685.62 4,950.800 9,577.86 0.200 1854.18 8582.76 1853.84 8539.47 4,951.000 10,109.16 0.200 1968.70 10551.46 1968.46 10507.93 4,951.200 10,580.66 0.200 2068.98 12620.44 2068.80 12576.73 4,951.400 11,001.73 0.200 2158.24 14778.68 2158.10 14734.83 4,951.600 11,381.33 0.200 2238.31 17016.99 2238.20 16973.03 4,951.800 11,742.83 0.200 2312.42 19329.40 2312.32 19285.35 4,952.000 12,110.39 0.200 2385.32 21714.73 2385.23 21670.58 4,952.200 12,484.28 0.200 2459.47 24174.19 2459.37 24129.96 4,952.400 12,864.71 0.200 2534.90 26709.09 2534.80 26664.76 4,952.600 13,251.46 0.200 2611.62 29320.71 2611.52 29276.28 4,952.800 13,645.14 0.200 2689.66 32010.37 2689.56 31965.85 A PPENDIX C R EFERENCED M ATERIALS 1501 Academy Ct. Ste. 203 Fort Collins, Colorado 80524 (970) 530-4044 Final Drainage Report Platte River Power Authority HQ Campus Fort Collins, CO Prepared for: Platte River Power Authority 2000 East Horsetooth Road Fort Collins, CO 80525 May 23, 2018 APPENDIX A Hydrology Computations Ru n o f f C o e f f i c i e n t s a n d % I m p e r v i o u s Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . C o m p o s i t e N R C S S o i l To t a l T o t a l Ro o f (1 ) As p h a l t Co n c r e t e (1 ) Gr a v e l (1 ) La w n s (1 ) Im p e r v i o u s n e s s T y p e C2 C10 0 %I = 9 0 % % I = 1 0 0 % % I = 9 0 % % I = 4 0 % % I = 2 % ( % I ) ac r e s s f sf s f s f s f s f EX 1 E X 1 3. 7 5 1 6 3 , 5 5 3 1 9 , 3 7 0 5 1 , 6 2 7 8 , 6 2 7 2 , 6 7 0 8 1 , 2 5 9 48 . 6 % C/ D 0 . 5 7 0 . 7 1 EX 2 E X 2 2. 3 8 1 0 3 , 4 8 5 2 , 8 8 3 2 2 , 0 3 3 7 , 5 0 6 1 , 7 6 7 6 9 , 2 9 6 32 . 3 % C/ D 0 . 4 4 0 . 5 5 EX 3 E X 3 2. 1 9 9 5 , 2 3 3 1 7 , 6 8 3 5 4 , 4 0 8 6 , 1 0 4 1 , 0 2 9 1 6 , 0 0 9 80 . 4 % C/ D 0 . 8 2 1 . 0 0 EX 4 E X 4 2. 3 3 1 0 1 , 3 2 5 9 , 0 1 2 5 , 2 0 8 4 , 3 1 6 8 1 0 8 1 , 9 7 9 18 . 9 % C/ D 0 . 3 4 0 . 4 2 EX 5 E X 5 1. 3 5 5 8 , 6 5 2 1 6 , 1 9 4 4 2 , 4 5 8 12 . 5 % C/ D 0 . 2 8 0 . 3 5 OS - 1 O S - 1 0. 3 1 1 3 , 4 0 9 9 2 8 3 4 3 3 , 3 3 1 8 , 8 0 7 20 . 5 % C/ D 0 . 3 5 0 . 4 3 OS - 2 A O S - 2 A 0. 3 3 1 4 , 3 0 2 2 , 5 3 9 1 , 1 7 7 1 0 , 5 8 6 26 . 6 % C/ D 0 . 3 9 0 . 4 9 OS - 2 B O S - 2 B 0. 9 3 4 0 , 3 1 0 2 6 , 5 6 8 6 , 2 2 8 7 , 5 1 4 80 . 2 % C/ D 0 . 8 1 1 . 0 0 OS - 3 O S - 3 2. 2 2 9 6 , 5 7 6 1 4 , 3 8 6 4 , 1 1 0 7 8 , 0 8 0 20 . 3 % C/ D 0 . 3 4 0 . 4 3 OS - 4 O S - 4 1. 2 8 5 5 , 8 4 6 3 8 , 6 8 2 2 , 0 6 1 1 5 , 1 0 3 73 . 1 % C/ D 0 . 7 5 0 . 9 3 OS - 5 O S - 5 0. 5 4 2 3 , 6 6 8 2 3 , 6 6 8 2. 0 % C/ D 0 . 2 0 0 . 2 5 17 . 5 9 7 6 6 , 3 6 1 4 8 , 9 4 8 2 1 6 , 3 7 9 4 0 , 4 7 2 2 5 , 8 0 1 4 3 4 , 7 6 1 4 1 . 2 % C / D 0 . 5 1 0 . 6 4 No t e s : (1 ) R e c o m m e n d e d R u n o f f C o e f f i c i e n t V a l u e s f r o m F C S C M T a b l e R O - 1 1 . (2 ) C o m p o s i t e R u n o f f C o e f f i c i e n t i s b a s e d o n F C S C M e q u a t i o n R O - 8 a n d C o e f f i c i e n t A d j u s t m e n t f a c t o r s p e r T a b l e R O - 1 2 . Co m p o s i t e R u n o f f C o e f f i c i e n t s (2 ) Ar e a s Ex i s t i n g B a s i n s Ex i s t i n g T o t a l Da t e : 4 / 9 / 2 0 1 8 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s . x l s m Ru n o f f C o e f f i c i e n t s a n d % I m p e r v i o u s Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . C o m p o s i t e N R C S S o i l To t a l T o t a l Ro o f (1 ) As p h a l t Co n c r e t e (1 ) Gr a v e l (1 ) La w n s (1 ) Im p e r v i o u s n e s s T y p e C2 C10 0 ac r e s s f %I = 9 0 % % I = 1 0 0 % % I = 9 0 % % I = 4 0 % % I = 2 % ( % I ) sf s f s f s f s f A- 1 A - 1 3. 3 4 1 4 5 , 5 9 4 1 1 , 0 2 9 - 1 1 , 4 1 0 - 1 2 3 , 1 5 5 15 . 6 % C/ D 0 . 3 2 0 . 3 9 A- 2 A - 2 0. 9 1 3 9 , 8 2 4 - 2 6 , 6 9 1 6 , 6 0 4 - 6 , 5 2 9 82 . 3 % C/ D 0 . 8 3 1 . 0 0 A- 3 A - 3 0. 3 7 1 6 , 2 4 2 1 6 , 2 4 2 - - - - 90 . 0 % C/ D 0 . 9 5 1 . 0 0 A- 4 A - 4 0. 5 7 2 4 , 6 8 1 3 , 1 9 9 1 6 , 7 3 9 1 , 8 7 3 - 2 , 8 7 0 86 . 5 % C/ D 0 . 8 6 1 . 0 0 A- 5 A - 5 0. 4 0 1 7 , 3 4 4 - 1 3 , 8 3 1 9 0 5 - 2 , 6 0 8 84 . 7 % C/ D 0 . 8 4 1 . 0 0 A- 6 A - 6 0. 5 1 2 2 , 2 9 4 1 1 7 - 1 2 , 8 4 4 - 9 , 3 3 3 53 . 2 % C/ D 0 . 6 4 0 . 8 0 A- 7 A - 7 0. 3 2 1 4 , 0 1 0 7 , 9 6 5 - 1 0 6 - 5 , 9 3 9 52 . 7 % C/ D 0 . 6 3 0 . 7 9 A- 8 A - 8 0. 2 1 9 , 0 9 7 3 , 3 0 8 3 , 2 3 1 - 2 , 5 5 8 65 . 3 % C/ D 0 . 7 4 0 . 9 2 A- 9 A - 9 0. 6 4 2 8 , 0 4 6 5 , 8 2 6 - 2 2 , 2 0 0 - 2 0 89 . 9 % C/ D 0 . 9 5 1 . 0 0 A- 1 0 A - 1 0 0. 6 8 2 9 , 5 0 4 5 , 8 7 2 - 2 2 , 5 2 1 - 1 , 1 1 1 86 . 7 % C/ D 0 . 9 2 1 . 0 0 A- 1 1 A - 1 1 0. 9 7 4 2 , 1 8 6 1 1 , 2 3 5 - 6 0 3 - 3 0 , 3 4 8 26 . 7 % C/ D 0 . 4 1 0 . 5 1 A- 1 2 A - 1 2 1. 1 5 5 0 , 0 2 0 - - 2 , 2 4 0 - 4 7 , 7 8 0 5. 9 % C/ D 0 . 2 3 0 . 2 9 A- 1 2 ( F u t u r e ) A - 1 2 ( F u t u r e ) 1. 1 5 5 0 , 0 2 0 - 4 4 , 9 0 0 - - 5 , 1 2 0 90 . 0 % C/ D 0 . 8 7 1 . 0 0 A- 1 3 A - 1 3 0. 2 6 1 1 , 5 1 7 1 1 , 5 1 7 - - - - 90 . 0 % C/ D 0 . 9 5 1 . 0 0 A- T O T A L A - T O T A L 10 . 3 4 4 5 0 , 3 5 9 7 6 , 3 1 1 5 7 , 2 6 1 8 4 , 5 3 7 - 2 3 2 , 2 5 1 45 . 9 % C / D 0 . 5 6 0 . 7 0 B- 1 B - 1 0. 4 2 1 8 , 4 8 6 - 5 , 9 0 7 4 , 2 1 8 - 8 , 3 6 1 53 . 4 % C/ D 0 . 6 1 0 . 7 6 B- 2 B - 2 1. 4 5 6 2 , 9 9 5 - 2 3 , 6 4 0 3 , 2 7 7 - 3 6 , 0 7 8 43 . 4 % C/ D 0 . 5 2 0 . 6 5 B- T O T A L B - T O T A L 1. 8 7 8 1 , 4 8 1 - 2 9 , 5 4 7 7 , 4 9 5 - 4 4 , 4 3 9 45 . 6 % C / D 0 . 5 4 0 . 6 8 C- 1 C - 1 1. 2 7 5 5 , 2 5 8 - - 8 , 6 5 1 - 4 6 , 6 0 7 15 . 8 % C/ D 0 . 3 2 0 . 4 0 C- T O T A L C - T O T A L 1. 2 7 5 5 , 2 5 8 - - 8 , 6 5 1 - 4 6 , 6 0 7 15 . 8 % C / D 0 . 3 2 0 . 4 0 OS - 1 O S - 1 0. 6 8 2 9 , 5 3 3 2 9 , 5 3 3 2. 0 % C/ D 0 . 2 0 0 . 2 5 OS - 2 A O S - 2 A 0. 2 1 8 , 9 4 0 8 , 9 4 0 2. 0 % C/ D 0 . 2 0 0 . 2 5 OS - 2 B O S - 2 B 0. 9 3 4 0 , 3 1 0 2 6 , 5 6 8 6 , 2 2 8 7 , 5 1 4 80 . 2 % C/ D 0 . 8 1 1 . 0 0 OS - 3 O S - 3 0. 5 1 2 2 , 1 1 5 1 5 , 3 0 9 4 , 3 2 1 2 , 4 8 5 87 . 0 % C/ D 0 . 8 7 1 . 0 0 OS - 4 O S - 4 1. 2 6 5 4 , 6 9 7 3 2 , 2 7 2 5 , 6 6 4 1 6 , 7 6 1 68 . 9 % C/ D 0 . 7 2 0 . 9 0 OS - 5 O S - 5 0. 5 4 2 3 , 6 6 8 2 3 , 6 6 8 2. 0 % C/ D 0 . 2 0 0 . 2 5 OS - T O T A L O S - T O T A L 4. 1 2 1 7 9 , 2 6 3 - 7 4 , 1 4 9 1 6 , 2 1 3 - 8 8 , 9 0 1 50 . 5 % C / D 0 . 5 8 0 . 7 2 17 . 5 9 7 6 6 , 3 6 1 7 6 , 3 1 1 1 6 0 , 9 5 7 1 1 6 , 8 9 5 - 4 1 2 , 1 9 8 4 4 . 8 % C / D 0 . 5 5 0 . 6 8 No t e s : (1 ) R e c o m m e n d e d R u n o f f C o e f f i c i e n t V a l u e s f r o m F C S C M T a b l e R O - 1 1 . (2 ) C o m p o s i t e R u n o f f C o e f f i c i e n t i s b a s e d o n F C S C M e q u a t i o n R O - 8 a n d C o e f f i c i e n t A d j u s t m e n t f a c t o r s p e r T a b l e R O - 1 2 . (3 ) B a s i n A - 1 i n c l u d e s a p p r o x i m a t e l y 8 , 5 0 0 s f o f f u t u r e b u i l d i n g . B a s i n B - 2 i n c l u d e s a p p r o x i m a t e l y 1 0 , 0 0 0 s f o f f u t u r e p a r k i n g a r e a . (4 ) B a s i n A - 1 2 ( F u t u r e ) i s i n c l u d e d f o r s t o r m s e w e r s i z i n g o n l y a n d i s n o t i n c l u d e d w i t h i n " A - T O T A L " a b o v e . D e t e n t i o n a n d L I D r e q u i r e m e n t s w i l l b e r e q u i r e d f o r B a s i n A - 1 2 w i t h f u t u r e d e v e l o p m e n t . Pr o p o s e d T o t a l Pr o p o s e d B a s i n s Ar e a s Co m p o s i t e R u n o f f C o e f f i c i e n t s (2 ) Da t e : 4 / 9 / 2 0 1 8 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s . x l s m 2- Y e a r T i m e o f C o n c e n t r a t i o n Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a C(1 ) Le n g t h S l o p e ti(2 ) Le n g t h S l o p e C v Ve l o c i t y (3 ) tt(4 ) Ch e c k t c? To t a l L e n g t h tc(5 ) ac r e s f t % m i n f t % f p s m i n m i n U r b a n ? f t m i n m i n EX 1 E X 1 3 . 7 5 0. 5 7 35 3. 8 % 3. 8 39 0 2. 3 % 20 3. 0 2 . 1 5 . 9 Y e s 4 2 5 1 2 5. 9 EX 2 E X 2 2 . 3 8 0 . 4 4 2 7 5 0 . 6 % 2 4 . 2 1 9 0 1 . 0 % 7 0. 7 4 . 5 2 8 . 7 Y e s 4 6 5 1 3 12 . 6 EX 3 E X 3 2 . 1 9 0 . 8 2 2 0 1 . 2 % 2 . 2 4 1 5 1 . 0 % 2 0 2. 0 3 . 5 5 . 7 Y e s 4 3 5 1 2 5. 7 EX 4 E X 4 2 . 3 3 0 . 3 4 5 0 1 . 0 % 1 0 . 1 2 0 5 1 . 1 % 7 0. 7 4 . 7 1 4 . 7 Y e s 2 5 5 1 1 11 . 4 EX 5 E X 5 1 . 3 5 0 . 2 8 1 0 5 1 . 1 % 1 5 . 2 1 3 0 0 . 1 % 7 0. 2 9 . 3 2 4 . 5 Y e s 2 3 5 1 1 11 . 3 OS - 1 O S - 1 0 . 3 1 0 . 3 5 7 0 4 . 4 % 7 . 2 2 0 4 . 6 % 2 0 4. 3 0 . 1 7 . 3 Y e s 9 0 1 1 7. 3 OS - 2 A O S - 2 A 0 . 3 3 0 . 3 9 3 0 5 . 9 % 4 . 0 6 0 1 . 2 % 2 0 2. 2 0 . 5 4 . 5 Y e s 9 0 1 1 5. 0 OS - 2 B O S - 2 B 0 . 9 3 0 . 8 1 5 0 2 . 0 % 3 . 0 4 9 0 0 . 7 % 2 0 1. 6 5 . 1 8 . 1 Y e s 5 4 0 1 3 8. 1 OS - 3 O S - 3 2 . 2 2 0 . 3 4 3 0 1 0 . 0 % 3 . 6 6 1 0 0 . 4 % 7 0. 4 2 3 . 0 2 6 . 6 Y e s 6 4 0 1 4 13 . 6 OS - 4 O S - 4 1 . 2 8 0 . 7 5 6 0 5 . 0 % 3 . 0 2 5 0 1 . 1 % 2 0 2. 1 2 . 0 5 . 0 Y e s 3 1 0 1 2 5. 0 OS - 5 O S - 5 0 . 5 4 0 . 2 0 3 0 1 0 . 0 % 4 . 3 2 0 0 0 . 7 % 7 0. 6 5 . 7 1 0 . 0 Y e s 2 3 0 1 1 10 . 0 No t e s : (1 ) C = C x*C f (2 ) ti = [ 1 . 8 7 ( 1 . 1 - C xCf)L 1/ 2 ]/ S 1/ 3 , S = s l o p e i n % , L = l e n g t h o f o v e r l a n d f l o w ( 4 0 0 ' m a x ) (3 ) V= C vS0. 5 , S = w a t e r c o u r s e s l o p e i n f t / f t , U D F C D E q u a t i o n R O - 4 (4 ) tt=L / ( V * 6 0 s e c / m i n ) (5 ) tc c h e c k ( f o r u r b a n o r d e v e l o p e d a r e a s o n l y ) = t o t a l l e n g t h / 1 8 0 + 1 0 (6 ) mi n t c = 5 m i n Ex i s t i n g B a s i n s In i t i a l O v e r l a n d F l o w T i m e ( t i) Tr a v e l / C h a n n e l i z e d T i m e o f F l o w ( t t) ti+t t tc Ch e c k f o r U r b a n i z e d B a s i n s Fi n a l tc(6 ) Da t e : 4 / 9 / 2 0 1 8 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s . x l s m 2- Y e a r T i m e o f C o n c e n t r a t i o n Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a C(1 ) Le n g t h S l o p e ti(2 ) Le n g t h S l o p e C v Ve l o c i t y (3 ) tt(4 ) Ch e c k t c? To t a l L e n g t h tc(5 ) ac r e s f t % m i n f t % f p s m i n m i n U r b a n ? f t m i n m i n A- 1 A - 1 3 . 3 4 0. 3 2 23 5 1. 5 % 19 . 7 46 5 0. 5 % 20 1. 4 5 . 5 2 5 . 2 Y e s 7 0 0 1 4 13 . 9 A- 2 A - 2 0 . 9 1 0 . 8 3 1 0 2 . 0 % 1 . 2 8 3 0 5 0 . 5 % 2 0 1. 4 3 . 6 4 . 9 Y e s 3 1 5 1 2 5. 0 A- 3 A - 3 0 . 3 7 0 . 9 5 5 0 1 2 . 5 % 0 . 8 6 1 5 3 0 . 0 % 2 0 11 . 0 0 . 0 0 . 9 Y e s 6 5 1 0 5. 0 A- 4 A - 4 0 . 5 7 0 . 8 6 3 6 2 . 0 % 2 . 1 2 2 4 2 2 . 0 % 2 0 2. 8 1 . 4 3 . 5 Y e s 2 7 8 1 2 5. 0 A- 5 A - 5 0 . 4 0 0 . 8 4 5 0 2 . 0 % 2 . 7 6 1 3 3 1 . 5 % 2 0 2. 4 0 . 9 3 . 7 Y e s 1 8 3 1 1 5. 0 A- 6 A - 6 0 . 5 1 0 . 6 4 1 7 2 . 0 % 2 . 8 5 1 2 3 2 . 0 % 2 0 2. 8 0 . 7 3 . 6 Y e s 1 4 0 1 1 5. 0 A- 7 A - 7 0 . 3 2 0 . 6 3 6 4 1 . 5 % 6 . 1 2 2 1 0 1 . 0 % 1 5 1. 5 2 . 3 8 . 5 Y e s 2 7 4 1 2 8. 5 A- 8 A - 8 0 . 2 1 0 . 7 4 1 5 2 . 0 % 2 . 0 8 5 0 2 . 0 % 2 0 2. 8 0 . 3 2 . 4 Y e s 6 5 1 0 5. 0 A- 9 A - 9 0 . 6 4 0 . 9 5 2 5 1 2 . 5 % 0 . 6 1 2 1 0 0 . 5 % 2 0 1. 4 2 . 5 3 . 1 Y e s 2 3 5 1 1 5. 0 A- 1 0 A - 1 0 0 . 6 8 0 . 9 2 6 3 4 . 0 % 1 . 6 7 2 0 0 1 . 5 % 2 0 2. 4 1 . 4 3 . 0 Y e s 2 6 3 1 1 5. 0 A- 1 1 A - 1 1 0 . 9 7 0 . 4 1 2 0 7 . 0 % 3 . 0 3 1 9 0 0 . 5 % 1 5 1. 1 3 . 0 6 . 0 Y e s 2 1 0 1 1 6. 0 A- 1 2 A - 1 2 1 . 1 5 0 . 2 3 2 0 7 . 0 % 3 . 8 1 2 0 5 0 . 5 % 1 5 1. 1 3 . 2 7 . 0 Y e s 2 2 5 1 1 7. 0 A- 1 2 ( F u t u r e ) A - 1 2 ( F u t u r e ) 1 . 1 5 0 . 8 7 1 0 2 . 0 % 1 . 0 7 2 0 5 2 . 0 % 2 0 2. 8 1 . 2 2 . 3 Y e s 2 1 5 1 1 5. 0 A- 1 3 A - 1 3 0 . 2 6 0 . 9 5 7 2 1 2 . 5 % 1 . 0 3 1 5 3 0 . 0 % 2 0 11 . 0 0 . 0 1 . 1 Y e s 8 7 1 0 5. 0 A- T O T A L A - T O T A L 1 0 . 3 4 0 . 5 6 5 1 1 . 5 % 6 . 2 7 9 8 5 0 . 4 % 2 0 1. 3 1 3 . 0 1 9 . 2 Y e s 1 0 3 6 1 6 1 5 . 8 B- 1 B - 1 0 . 4 2 0 . 6 1 7 0 2 . 0 % 6 . 0 9 4 0 2 . 0 % 2 0 2. 8 0 . 2 6 . 3 Y e s 1 1 0 1 1 6. 3 B- 2 B - 2 1 . 4 5 0 . 5 2 5 0 2 5 . 0 % 2 . 6 5 2 9 0 0 . 5 % 1 5 1. 1 4 . 6 7 . 2 Y e s 3 4 0 1 2 7. 2 B- T O T A L B - T O T A L 1 . 8 7 0 . 5 4 5 0 2 5 . 0 % 2 . 5 6 2 9 0 0 . 5 % 1 5 1. 1 4 . 6 7 . 1 Y e s 3 4 0 1 2 7 . 1 C- 1 C - 1 1 . 2 7 0 . 3 2 1 6 2 . 0 % 4 . 6 6 7 5 1 0 . 0 % 1 5 4. 7 0 . 3 4 . 9 Y e s 9 1 1 1 5. 0 C- T O T A L C - T O T A L 1 . 2 7 0 . 3 2 1 6 2 . 0 % 4 . 6 6 7 5 1 0 . 0 % 1 5 4. 7 0 . 3 4 . 9 Y e s 9 1 1 1 5 . 0 OS - 1 O S - 1 0 . 6 8 0 . 2 0 7 0 4 . 4 % 8 . 6 4 2 0 4 . 6 % 2 0 4. 3 0 . 1 8 . 7 Y e s 9 0 1 1 8. 7 OS - 2 A O S - 2 A 0 . 2 1 0 . 2 0 3 0 5 . 9 % 5 . 1 3 6 0 1 . 2 % 2 0 2. 2 0 . 5 5 . 6 Y e s 9 0 1 1 5. 6 OS - 2 B O S - 2 B 0 . 9 3 0 . 8 1 5 0 2 . 0 % 3 . 0 5 4 9 0 0 . 7 % 2 0 1. 6 5 . 1 8 . 1 Y e s 5 4 0 1 3 8. 1 OS - 3 O S - 3 0 . 5 1 0 . 8 7 1 4 0 1 . 5 % 4 . 5 3 1 6 5 0 . 7 % 2 0 1. 7 1 . 6 6 . 2 Y e s 3 0 5 1 2 6. 2 OS - 4 O S - 4 1 . 2 6 0 . 7 2 6 0 5 . 0 % 3 . 2 3 2 5 0 1 . 1 % 2 0 2. 1 2 . 0 5 . 2 Y e s 3 1 0 1 2 5. 2 OS - 5 O S - 5 0 . 5 4 0 . 2 0 3 0 1 0 . 0 % 4 . 3 1 2 0 0 0 . 7 % 7 0. 6 5 . 7 1 0 . 0 Y e s 2 3 0 1 1 10 . 0 No t e s : (1 ) C = C x*C f (2 ) ti = [ 1 . 8 7 ( 1 . 1 - C xCf)L 1/ 2 ]/ S 1/ 3 , S = s l o p e i n % , L = l e n g t h o f o v e r l a n d f l o w ( 4 0 0 ' m a x ) (3 ) V= C vS0. 5 , S = w a t e r c o u r s e s l o p e i n f t / f t , U D F C D E q u a t i o n R O - 4 (4 ) tt=L / ( V * 6 0 s e c / m i n ) (5 ) tc c h e c k ( f o r u r b a n o r d e v e l o p e d a r e a s o n l y ) = t o t a l l e n g t h / 1 8 0 + 1 0 (6 ) mi n t c = 5 m i n Pr o p o s e d B a s i n s In i t i a l O v e r l a n d F l o w T i m e ( t i) Tr a v e l / C h a n n e l i z e d T i m e o f F l o w ( t t) ti+t t tc Ch e c k f o r U r b a n i z e d B a s i n s Fi n a l tc(6 ) Da t e : 4 / 9 / 2 0 1 8 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s . x l s m 10 0 - Y e a r T i m e o f C o n c e n t r a t i o n Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a C(1 ) Le n g t h S l o p e ti(2 ) Le n g t h S l o p e C v Ve l o c i t y (3 ) tt(4 ) Ch e c k t c? To t a l L e n g t h tc(5 ) ac r e s f t % m i n f t % f p s m i n m i n U r b a n ? f t m i n m i n EX 1 E X 1 3 . 7 5 0. 7 1 35 3. 8 % 2. 8 39 0 2. 3 % 20 3. 0 2 . 1 4 . 9 Y e s 4 2 5 1 2 5. 0 EX 2 E X 2 2 . 3 8 0 . 5 5 2 7 5 0 . 6 % 2 0 . 2 1 9 0 1 . 0 % 7 0. 7 4 . 5 2 4 . 7 Y e s 4 6 5 1 3 12 . 6 EX 3 E X 3 2 . 1 9 1. 0 0 20 1. 2 % 0. 8 41 5 1. 0 % 20 2. 0 3 . 5 4 . 2 Y e s 4 3 5 1 2 5. 0 EX 4 E X 4 2 . 3 3 0 . 4 2 5 0 1 . 0 % 8 . 9 2 0 5 1 . 1 % 7 0. 7 4 . 7 1 3 . 6 Y e s 2 5 5 1 1 11 . 4 EX 5 E X 5 1 . 3 5 0. 3 5 10 5 1. 1 % 13 . 9 13 0 0. 1 % 7 0. 2 9 . 3 2 3 . 2 Y e s 2 3 5 1 1 11 . 3 OS - 1 O S - 1 0 . 3 1 0. 4 3 70 4. 4 % 6. 4 20 4. 6 % 20 4. 3 0 . 1 6 . 5 Y e s 9 0 1 1 6. 5 OS - 2 A O S - 2 A 0 . 3 3 0 . 4 9 3 0 5 . 9 % 3 . 5 6 0 1 . 2 % 2 0 2. 2 0 . 5 3 . 9 Y e s 9 0 1 1 5. 0 OS - 2 B O S - 2 B 0 . 9 3 1. 0 0 50 2. 0 % 1. 1 49 0 0. 7 % 20 1. 6 5 . 1 6 . 1 Y e s 5 4 0 1 3 6. 1 OS - 3 O S - 3 2 . 2 2 0 . 4 3 3 0 1 0 . 0 % 3 . 2 6 1 0 0 . 4 % 7 0. 4 2 3 . 0 2 6 . 2 Y e s 6 4 0 1 4 13 . 6 OS - 4 O S - 4 1 . 2 8 0. 9 3 60 5. 0 % 1. 4 25 0 1. 1 % 20 2. 1 2 . 0 3 . 4 Y e s 3 1 0 1 2 5. 0 OS - 5 O S - 5 0 . 5 4 0 . 2 5 3 0 1 0 . 0 % 4 . 1 2 0 0 0 . 7 % 7 0. 6 5 . 7 9 . 8 Y e s 2 3 0 1 1 9. 8 No t e s : (1 ) C = C x*C f (2 ) ti = [ 1 . 8 7 ( 1 . 1 - C xCf)L 1/ 2 ]/ S 1/ 3 , S = s l o p e i n % , L = l e n g t h o f o v e r l a n d f l o w ( 4 0 0 ' m a x ) (3 ) V= C vS0. 5 , S = w a t e r c o u r s e s l o p e i n f t / f t , U D F C D E q u a t i o n R O - 4 (4 ) tt=L / ( V * 6 0 s e c / m i n ) (5 ) tc c h e c k ( f o r u r b a n o r d e v e l o p e d a r e a s o n l y ) = t o t a l l e n g t h / 1 8 0 + 1 0 (6 ) mi n t c = 5 m i n Ex i s t i n g B a s i n s ti+t t Fi n a l tc(6 ) tc Ch e c k f o r U r b a n i z e d B a s i n s In i t i a l O v e r l a n d F l o w T i m e ( t i) Tr a v e l / C h a n n e l i z e d T i m e o f F l o w ( t t) Da t e : 4 / 9 / 2 0 1 8 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s . x l s m 10 0 - Y e a r T i m e o f C o n c e n t r a t i o n Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a C(1 ) Le n g t h S l o p e ti(2 ) Le n g t h S l o p e C v Ve l o c i t y (3 ) tt(4 ) Ch e c k t c? To t a l L e n g t h tc(5 ) ac r e s f t % m i n f t % f p s m i n m i n U r b a n ? f t m i n m i n A- 1 A - 1 3 . 3 4 0. 3 9 23 5 1. 5 % 17 . 7 46 5 0. 5 % 20 1. 4 5 . 5 2 3 . 2 Y e s 7 0 0 1 4 13 . 9 A- 2 A - 2 0 . 9 1 1 . 0 0 1 0 2 . 0 % 0 . 4 7 3 0 5 0 . 5 % 2 0 1. 4 3 . 6 4 . 1 Y e s 3 1 5 1 2 5. 0 A- 3 A - 3 0 . 3 7 1. 0 0 50 12 . 5 % 0. 5 7 15 30 . 0 % 20 11 . 0 0 . 0 0 . 6 Y e s 6 5 1 0 5. 0 A- 4 A - 4 0 . 5 7 1 . 0 0 3 6 2 . 0 % 0 . 8 9 2 4 2 2 . 0 % 2 0 2. 8 1 . 4 2 . 3 Y e s 2 7 8 1 2 5. 0 A- 5 A - 5 0 . 4 0 1. 0 0 50 2. 0 % 1. 0 5 13 3 1. 5 % 20 2. 4 0 . 9 2 . 0 Y e s 1 8 3 1 1 5. 0 A- 6 A - 6 0 . 5 1 0 . 8 0 1 7 2 . 0 % 1 . 8 7 1 2 3 2 . 0 % 2 0 2. 8 0 . 7 2 . 6 Y e s 1 4 0 1 1 5. 0 A- 7 A - 7 0 . 3 2 0. 7 9 64 1. 5 % 4. 0 6 21 0 1. 0 % 15 1. 5 2 . 3 6 . 4 Y e s 2 7 4 1 2 6. 4 A- 8 A - 8 0 . 2 1 0 . 9 2 1 5 2 . 0 % 1 . 0 1 5 0 2 . 0 % 2 0 2. 8 0 . 3 1 . 3 Y e s 6 5 1 0 5. 0 A- 9 A - 9 0 . 6 4 1. 0 0 25 12 . 5 % 0. 4 1 21 0 0. 5 % 20 1. 4 2 . 5 2 . 9 Y e s 2 3 5 1 1 5. 0 A- 1 0 A - 1 0 0 . 6 8 1 . 0 0 6 3 4 . 0 % 0 . 9 4 2 0 0 1 . 5 % 2 0 2. 4 1 . 4 2 . 3 Y e s 2 6 3 1 1 5. 0 A- 1 1 A - 1 1 0 . 9 7 0. 5 1 20 7. 0 % 2. 5 8 19 0 0. 5 % 15 1. 1 3 . 0 5 . 6 Y e s 2 1 0 1 1 5. 6 A- 1 2 A - 1 2 1 . 1 5 0 . 2 9 2 0 7 . 0 % 3 . 5 6 2 0 5 0 . 5 % 1 5 1. 1 3 . 2 6 . 8 Y e s 2 2 5 1 1 6. 8 A- 1 2 ( F u t u r e ) A - 1 2 ( F u t u r e ) 1 . 1 5 1. 0 0 10 2. 0 % 0. 4 7 20 5 2. 0 % 20 2. 8 1 . 2 1 . 7 Y e s 2 1 5 1 1 5. 0 A- 1 3 A - 1 3 0 . 2 6 1 . 0 0 7 2 1 2 . 5 % 0 . 6 9 1 5 3 0 . 0 % 2 0 11 . 0 0 . 0 0 . 7 Y e s 8 7 1 0 5. 0 A- T O T A L A - T O T A L 1 0 . 3 4 0. 7 0 51 1. 5 % 4. 6 3 98 5 0. 4 % 20 1. 3 1 3 . 0 1 7 . 6 Y e s 1 0 3 6 1 6 1 5 . 8 B- 1 B - 1 0 . 4 2 0. 7 6 70 2. 0 % 4. 1 9 40 2. 0 % 20 2. 8 0 . 2 4 . 4 Y e s 1 1 0 1 1 5. 0 B- 2 B - 2 1 . 4 5 0 . 6 5 5 0 2 5 . 0 % 2 . 0 5 2 9 0 0 . 5 % 1 5 1. 1 4 . 6 6 . 6 Y e s 3 4 0 1 2 6. 6 B- T O T A L B - T O T A L 1 . 8 7 0. 6 8 50 25 . 0 % 1. 9 4 29 0 0. 5 % 20 1. 4 3 . 4 5 . 4 Y e s 3 4 0 1 2 5 . 4 C- 1 C - 1 1 . 2 7 0. 4 0 16 2. 0 % 4. 1 8 75 10 . 0 % 15 4. 7 0 . 3 4 . 4 Y e s 9 1 1 1 5. 0 C- T O T A L C - T O T A L 1 . 2 7 0 . 4 0 1 6 2 . 0 % 4 . 1 8 7 5 1 0 . 0 % 1 5 4. 7 0 . 3 4 . 4 Y e s 9 1 1 1 5 . 0 OS - 1 O S - 1 0 . 6 8 0 . 2 5 7 0 4 . 4 % 8 . 1 6 2 0 4 . 6 % 2 0 4. 3 0 . 1 8 . 2 Y e s 9 0 1 1 8. 2 OS - 2 A O S - 2 A 0 . 2 1 0. 2 5 30 5. 9 % 4. 8 5 60 1. 2 % 20 2. 2 0 . 5 5 . 3 Y e s 9 0 1 1 5. 3 OS - 2 B O S - 2 B 0 . 9 3 1 . 0 0 5 0 2 . 0 % 1 . 0 5 4 9 0 0 . 7 % 2 0 1. 6 5 . 1 6 . 1 Y e s 5 4 0 1 3 6. 1 OS - 3 O S - 3 0 . 5 1 1. 0 0 14 0 1. 5 % 1. 9 4 16 5 0. 7 % 20 1. 7 1 . 6 3 . 6 Y e s 3 0 5 1 2 5. 0 OS - 4 O S - 4 1 . 2 6 0 . 9 0 6 0 5 . 0 % 1 . 7 0 2 5 0 1 . 1 % 2 0 2. 1 2 . 0 3 . 7 Y e s 3 1 0 1 2 5. 0 OS - 5 O S - 5 0 . 5 4 0. 2 5 30 10 . 0 % 4. 0 7 20 0 0. 7 % 7 0. 6 5 . 7 9 . 8 Y e s 2 3 0 1 1 9. 8 No t e s : (1 ) C = C x*C f (2 ) ti = [ 1 . 8 7 ( 1 . 1 - C xCf)L 1/ 2 ]/ S 1/ 3 , S = s l o p e i n % , L = l e n g t h o f o v e r l a n d f l o w ( 4 0 0 ' m a x ) (3 ) V= C vS0. 5 , S = w a t e r c o u r s e s l o p e i n f t / f t , U D F C D E q u a t i o n R O - 4 (4 ) tt=L / ( V * 6 0 s e c / m i n ) (5 ) tc c h e c k ( f o r u r b a n o r d e v e l o p e d a r e a s o n l y ) = t o t a l l e n g t h / 1 8 0 + 1 0 (6 ) mi n t c = 5 m i n Pr o p o s e d B a s i n s In i t i a l O v e r l a n d F l o w T i m e ( t i) Tr a v e l / C h a n n e l i z e d T i m e o f F l o w ( t t) ti+t t tc Ch e c k f o r U r b a n i z e d B a s i n s Fi n a l tc(6 ) Da t e : 4 / 9 / 2 0 1 8 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s . x l s m Ra t i o n a l M e t h o d P e a k R u n o f f Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a 2 - y e a r 1 0 0 - y e a r ac r e tc tc C2 C10 0 I2 I10 0 Q2 Q10 0 mi n m i n i n / h r i n / h r c f s c f s EX 1 E X 1 3 . 7 5 6 5 0 . 5 7 0 . 7 1 2 . 6 7 9 . 9 5 5 . 7 1 2 6 . 6 2 EX 2 E X 2 2 . 3 8 1 3 1 3 0 . 4 4 0 . 5 5 1 . 9 8 6 . 9 2 2 . 0 7 9 . 0 4 EX 3 E X 3 2 . 1 9 6 5 0 . 8 2 1 . 0 0 2 . 6 7 9 . 9 5 4 . 7 8 2 1 . 7 5 EX 4 E X 4 2 . 3 3 1 1 1 1 0 . 3 4 0 . 4 2 2 . 1 3 7 . 4 2 1 . 6 8 7 . 3 3 EX 5 E X 5 1 . 3 5 1 1 1 1 0 . 2 8 0 . 3 5 2 . 1 3 7 . 4 2 0 . 8 1 3 . 5 3 OS - 1 O S - 1 0 . 3 1 7 6 0 . 3 5 0 . 4 3 2 . 5 2 9 . 9 5 0 . 2 7 1 . 3 2 OS - 2 A O S - 2 A 0 . 3 3 5 5 0 . 3 9 0 . 4 9 2 . 8 5 9 . 9 5 0 . 3 7 1 . 6 1 OS - 2 B O S - 2 B 0 . 9 3 8 6 0 . 8 1 1 . 0 0 2 . 4 0 9 . 3 1 1 . 8 0 8 . 6 2 OS - 3 O S - 3 2 . 2 2 1 4 1 4 0 . 3 4 0 . 4 3 1 . 9 2 6 . 7 1 1 . 4 6 6 . 3 9 OS - 4 O S - 4 1 . 2 8 5 5 0 . 7 5 0 . 9 3 2 . 8 5 9 . 9 5 2 . 7 3 1 1 . 9 1 OS - 5 O S - 5 0 . 5 4 1 0 1 0 0 . 2 0 0 . 2 5 2 . 2 1 7 . 7 2 0 . 2 4 1 . 0 5 21 . 9 3 9 9 . 1 8 Ex i s t i n g B a s i n s T o t a l s Pe a k D i s c h a r g e Ra i n f a l l I n t e n s i t y Ru n o f f C o e f f i c i e n t s Da t e : 4 / 9 / 2 0 1 8 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s . x l s m Ra t i o n a l M e t h o d P e a k R u n o f f Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n D e s i g n P t . A r e a 2 - y e a r 1 0 0 - y e a r ac r e tc tc C2 C10 0 I2 I10 0 Q2 Q10 0 mi n m i n i n / h r i n / h r c f s c f s A- 1 A - 1 3 . 3 4 1 4 . 0 1 4 . 0 0 . 3 2 0 . 3 9 1 . 9 2 6 . 7 1 2 . 0 3 8 . 8 5 A- 2 A - 2 0 . 9 1 5 . 0 5 . 0 0 . 8 3 1 . 0 0 2 . 8 5 9 . 9 5 2 . 1 5 9 . 1 0 A- 3 A - 3 0 . 3 7 5 . 0 5 . 0 0 . 9 5 1 . 0 0 2 . 8 5 9 . 9 5 1 . 0 1 3 . 7 1 A- 4 A - 4 0 . 5 7 5 . 0 5 . 0 0 . 8 6 1 . 0 0 2 . 8 5 9 . 9 5 1 . 3 9 5 . 6 4 A- 5 A - 5 0 . 4 0 5 . 0 5 . 0 0 . 8 4 1 . 0 0 2 . 8 5 9 . 9 5 0 . 9 5 3 . 9 6 A- 6 A - 6 0 . 5 1 5 . 0 5 . 0 0 . 6 4 0 . 8 0 2 . 8 5 9 . 9 5 0 . 9 3 4 . 0 5 A- 7 A - 7 0 . 3 2 8 . 0 6 . 0 0 . 6 3 0 . 7 9 2 . 4 0 9 . 3 1 0 . 4 9 2 . 3 7 A- 8 A - 8 0 . 2 1 5 . 0 5 . 0 0 . 7 4 0 . 9 2 2 . 8 5 9 . 9 5 0 . 4 4 1 . 9 2 A- 9 A - 9 0 . 6 4 5 . 0 5 . 0 0 . 9 5 1 . 0 0 2 . 8 5 9 . 9 5 1 . 7 4 6 . 4 1 A- 1 0 A - 1 0 0 . 6 8 5 . 0 5 . 0 0 . 9 2 1 . 0 0 2 . 8 5 9 . 9 5 1 . 7 8 6 . 7 4 A- 1 1 A - 1 1 0 . 9 7 6 . 0 6 . 0 0 . 4 1 0 . 5 1 2 . 6 7 9 . 3 1 1 . 0 6 4 . 6 3 A- 1 2 A - 1 2 1 . 1 5 7 . 0 7 . 0 0 . 2 3 0 . 2 9 2 . 5 2 8 . 8 0 0 . 6 8 2 . 9 5 A- 1 2 ( F u t u r e ) A - 1 2 ( F u t u r e ) 1 . 1 5 5 . 0 5 . 0 0 . 8 7 1 . 0 0 2 . 8 5 9 . 9 5 2 . 8 6 1 1 . 4 3 A- 1 3 A - 1 3 0 . 2 6 5 . 0 5 . 0 0 . 9 5 1 . 0 0 2 . 8 5 9 . 9 5 0 . 7 2 2 . 6 3 A- T O T A L A - T O T A L 1 0 . 3 4 1 6 . 0 1 6 . 0 0 . 5 6 0 . 7 0 1 . 8 1 6 . 3 0 1 0 . 5 4 4 5 . 8 6 B- 1 B - 1 0 . 4 2 6 . 0 5 . 0 0 . 6 1 0 . 7 6 2 . 6 7 9 . 9 5 0 . 6 9 3 . 2 2 B- 2 B - 2 1 . 4 5 7 . 0 7 . 0 0 . 5 2 0 . 6 5 2 . 5 2 8 . 8 0 1 . 9 0 8 . 2 8 B- T O T A L B - T O T A L 1 . 8 7 7 . 0 5 . 0 0 . 5 4 0 . 6 8 2 . 5 2 9 . 9 5 2 . 5 5 1 2 . 5 9 C- 1 C - 1 1 . 2 7 5 . 0 5 . 0 0 . 3 2 0 . 4 0 2 . 8 5 9 . 9 5 1 . 1 5 5 . 0 1 C- T O T A L C - T O T A L 1 . 2 7 5 . 0 5 . 0 0 . 3 2 0 . 4 0 2 . 8 5 9 . 9 5 1 . 1 5 5 . 0 1 OS - 1 O S - 1 0 . 6 8 9 . 0 8 . 0 0 . 2 0 0 . 2 5 2 . 3 0 8 . 3 8 0 . 3 1 1 . 4 2 OS - 2 A O S - 2 A 0 . 2 1 6 . 0 5 . 0 0 . 2 0 0 . 2 5 2 . 6 7 9 . 9 5 0 . 1 1 0 . 5 1 OS - 2 B O S - 2 B 0 . 9 3 8 . 0 6 . 0 0 . 8 1 1 . 0 0 2 . 4 0 9 . 3 1 1 . 8 0 8 . 6 2 OS - 3 O S - 3 0 . 5 1 6 . 0 5 . 0 0 . 8 7 1 . 0 0 2 . 6 7 9 . 9 5 1 . 1 7 5 . 0 5 OS - 4 O S - 4 1 . 2 6 5 . 0 5 . 0 0 . 7 2 0 . 9 0 2 . 8 5 9 . 9 5 2 . 5 8 1 1 . 2 5 OS - 5 O S - 5 0 . 5 4 1 0 . 0 1 0 . 0 0 . 2 0 0 . 2 5 2 . 2 1 7 . 7 2 0 . 2 4 1 . 0 5 25 . 3 1 1 0 7 . 3 5 To t a l s Pr o p o s e d B a s i n s Ru n o f f C o e f f i c i e n t s R a i n f a l l I n t e n s i t y P e a k D i s c h a r g e Da t e : 4 / 9 / 2 0 1 8 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s . x l s m APPENDIX B Detention and Water Quality Calculations Dention Pond Volume (FAA Method) Platte River Power Authority Campus, Fort Collins, CO POND ID:POND A1 100 Year Storm Into Detention Facility Area =581,090 square feet Area =13.34 acres C 100 = 0.71 Q 100 = 58.44 cfs (Total flows from Basins A and B) Release Rate Out of Pond Q OUT = 3.15 cfs Unit Flow =0.24 cfs/acre T C =15.8 minutes Notes: 1. Release Rate limited by the existing 12" outfall capacity in Timberline Road. 2. Pond area includes all of Basins A, B and OS-2 but excludes "Basin A-12 (Future)". Detention Volume Calculations Rainfall Rainfall Inflow Rate Inflow Volume Adjustment Average Outflow Volume Required Duration (T) Intensity (I) Qin 100*Area*I Vi=(Qin*T*60) Factor Outflow Rate Vo=Qav*T *60 Storage Volume m= 0.5(1 + Tc/T) Qav = m*Qout Vs=Vi-Vo min in/hr cfs ft 3 cfs ft 3 ft 3 5 9.95 94.7 28,418 1.00 3.15 945 27,473 10 7.72 73.5 44,098 1.00 3.15 1,890 42,208 15 6.52 62.1 55,866 1.00 3.15 2,835 53,031 20 5.60 53.3 63,977 1.00 3.15 3,780 60,197 25 4.98 47.4 71,117 1.00 3.15 4,725 66,392 30 4.52 43.0 77,458 1.00 3.15 5,670 71,788 35 4.08 38.8 81,571 1.00 3.15 6,615 74,956 40 3.74 35.6 85,455 1.00 3.15 7,560 77,895 45 3.46 32.9 88,939 1.00 3.15 8,505 80,434 50 3.23 30.8 92,253 1.00 3.15 9,450 82,803 55 3.03 28.8 95,194 1.00 3.15 10,395 84,799 60 2.86 27.2 98,022 1.00 3.15 11,340 86,682 70 2.59 24.7 103,563 1.00 3.15 13,230 90,333 80 2.38 22.7 108,761 1.00 3.15 15,120 93,641 90 2.21 21.0 113,616 1.00 3.15 17,010 96,606 100 2.06 19.6 117,672 1.00 3.15 18,900 98,772 110 1.94 18.5 121,899 1.00 3.15 20,790 101,109 120 1.84 17.5 126,126 1.00 3.15 22,680 103,446 Required Detention Volume V 100 = 103,446 cubic feet V 100 = 2.37 acre-ft Date: 4/9/2018 P:\U16014 - PRPA Campus\Reports\Drainage\Calculations\U16014-Drain Calcs.xlsm STAGE STORAGE TABLE - POND A1 NORTH ELEV AREA (sq. ft.) DEPTH (ft) AVG END INC. VOL. (cu. ft.) AVG END TOTAL VOL. (cu. ft.) CONIC INC. VOL. (cu. ft.) CONIC TOTAL VOL. (cu. ft.) 4,948.200 137.56 N/A N/A 0.00 N/A 0.00 4,948.400 1,094.72 0.200 123.23 123.23 108.02 108.02 4,948.600 3,133.91 0.200 422.86 546.09 405.39 513.41 4,948.800 6,000.79 0.200 913.47 1459.56 898.09 1411.50 4,949.000 9,570.39 0.200 1557.12 3016.68 1543.30 2954.79 4,949.200 13,193.81 0.200 2276.42 5293.10 2266.75 5221.54 4,949.400 16,829.99 0.200 3002.38 8295.48 2995.01 8216.55 4,949.600 20,811.40 0.200 3764.14 12059.62 3757.10 11973.65 4,949.800 24,256.08 0.200 4506.75 16566.36 4502.35 16476.00 4,950.000 27,457.60 0.200 5171.37 21737.73 5168.06 21644.07 4,950.200 30,539.89 0.200 5799.75 27537.48 5797.02 27441.08 4,950.400 33,087.44 0.200 6362.73 33900.21 6361.03 33802.12 4,950.600 34,901.34 0.200 6798.88 40699.09 6798.07 40600.19 4,950.800 36,320.29 0.200 7122.16 47821.26 7121.69 47721.88 4,951.000 37,391.61 0.200 7371.19 55192.45 7370.93 55092.81 4,951.200 38,356.39 0.200 7574.80 62767.25 7574.59 62667.41 4,951.400 39,341.32 0.200 7769.77 70537.02 7769.56 70436.97 4,951.600 40,353.45 0.200 7969.48 78506.49 7969.26 78406.23 4,951.800 41,397.19 0.200 8175.06 86681.56 8174.84 86581.07 4,952.000 42,572.75 0.200 8396.99 95078.55 8396.72 94977.79 4,952.200 43,891.77 0.200 8646.45 103725.00 8646.12 103623.91 4,952.400 45,220.87 0.200 8911.26 112636.27 8910.93 112534.84 STAGE STORAGE TABLE - POND A1 SOUTH ELEV AREA (sq. ft.) DEPTH (ft) AVG END INC. VOL. (cu. ft.) AVG END TOTAL VOL. (cu. ft.) CONIC INC. VOL. (cu. ft.) CONIC TOTAL VOL. (cu. ft.) 4,949.000 1.34 N/A N/A 0.00 N/A 0.00 4,949.200 237.76 0.200 23.91 23.91 17.13 17.13 4,949.400 1,075.80 0.200 131.36 155.27 121.29 138.41 4,949.600 2,508.89 0.200 358.47 513.74 348.51 486.92 4,949.800 4,404.37 0.200 691.33 1205.06 682.50 1169.42 4,950.000 6,253.35 0.200 1065.77 2270.83 1060.38 2229.80 4,950.200 7,637.64 0.200 1389.10 3659.93 1386.79 3616.59 4,950.400 8,940.94 0.200 1657.86 5317.79 1656.15 5272.74 4,950.600 10,218.98 0.200 1915.99 7233.78 1914.57 7187.31 4,950.800 11,462.58 0.200 2168.16 9401.94 2166.97 9354.28 4,951.000 12,663.01 0.200 2412.56 11814.50 2411.56 11765.84 4,951.200 13,750.96 0.200 2641.40 14455.89 2640.65 14406.49 4,951.400 14,634.78 0.200 2838.57 17294.47 2838.12 17244.60 4,951.600 15,276.37 0.200 2991.12 20285.58 2990.89 20235.49 4,951.800 15,698.81 0.200 3097.52 23383.10 3097.42 23332.91 4,952.000 16,080.80 0.200 3177.96 26561.06 3177.89 26510.80 4,952.200 16,467.22 0.200 3254.80 29815.86 3254.73 29765.52 4,952.400 16,858.99 0.200 3332.62 33148.49 3332.54 33098.07 4,952.600 17,256.19 0.200 3411.52 36560.00 3411.44 36509.51 4,952.800 17,658.48 0.200 3491.47 40051.47 3491.39 40000.90 105,852 cf @ 4952.25 30,599 cf @ 4952.25 136,451 cf total volume (3.13 ac-ft) 2.37 ac-ft required for detention (2.89 ac-ft provided) 0.18 ac-ft required for water quality (0.24 ac-ft provided) Wa t e r Q u a l i t y Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Re q u i r e d O n s i t e W a t e r Q u a l i t y C a p t u r e V o l u m e Ba s i n A r e a A r e a I m p e r v i o u s n e s s W a t e r s h e d W Q C V * (E x t e n d e d D e t e n t i o n ) (s f ) ( a c r e s ) ( % ) ( i n c h e s ) ( c f ) A- T O T A L 4 5 0 , 3 5 9 1 0 . 3 3 9 46 % 0. 2 0 8, 7 9 5 B- T O T A L 8 1 , 4 8 1 1 . 8 7 1 46 % 0. 1 9 1, 5 8 6 C- T O T A L 5 5 , 2 5 8 1 . 2 6 9 16 % 0. 1 0 53 6 OS - 2 T O T A L 4 9 , 2 5 0 1 . 1 3 1 66 % 0. 2 6 1, 2 7 1 TO T A L R E Q U I R E D 6 3 6 , 3 4 8 1 4 . 6 0 9 45 % 0. 1 9 12 , 2 4 5 Le s s W Q P r o v i d e d b y U n d e r g r o u n d D e t e n t i o n 3, 7 8 2 Le s s W Q P r o v i d e d i n W e t P o n d 53 6 To t a l W Q P r o v i d e d i n P o n d A 7 , 9 2 6 * b a s e d o n 4 0 h r s t o r a g e a n d a d d i t i o n a l 2 0 % f o r e x t e n d e d d e t e n t i o n De s i g n e d W a t e r Q u a l i t y P l a t e P a r a m e t e r s Ba s i n W Q C V W Q C V A r e a R e q u i r e d D i a m t e r o f S p a c e N o . o f N o . o f Pr o v i d e d D e p t h p e r W Q P l a t e R o w W Q H o l e b e t w e e n r o w s ( i n . ) C o l u m n s R o w s (c f ) ( f t ) ( i n 2) (i n ) ( i n ) Po n d A 1 1 0 , 4 0 9 1 . 5 0 0 . 9 2 2 3 / 4 4 2 5 Da t e : 4 / 9 / 2 0 1 8 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s . x l s m Lo w I m p a c t D e v e l o p m e n t S u m m a r y Pl a t t e R i v e r P o w e r A u t h o r i t y C a m p u s , F o r t C o l l i n s , C O Ba s i n P r o p o s e d Im p e r v i o u s A r e a LI D T r e a t m e n t A r e a T r e a t e d % o f S i t e Tr e a t e d (s f ) ( a c r e s ) ( s f ) ( % ) A- 1 2 2 , 4 3 9 No n e (1 ) - 0% A- 2 3 3 , 2 9 5 No n e - 0% A- 3 1 6 , 2 4 2 Un d e r g r o u n d W a t e r Q u a l i t y 1 6 , 2 4 2 6% A- 4 2 1 , 8 1 1 Un d e r g r o u n d W a t e r Q u a l i t y 2 1 , 8 1 1 8% A- 5 1 4 , 7 3 6 Un d e r g r o u n d W a t e r Q u a l i t y 1 4 , 7 3 6 6% A- 6 1 2 , 9 6 1 Un d e r g r o u n d W a t e r Q u a l i t y 1 2 , 9 6 1 5% A- 7 8 , 0 7 1 Un d e r g r o u n d W a t e r Q u a l i t y 8 , 0 7 1 3% A- 8 6 , 5 3 9 Un d e r g r o u n d W a t e r Q u a l i t y 6 , 5 3 9 2% A- 9 2 8 , 0 2 6 Un d e r g r o u n d W a t e r Q u a l i t y 2 8 , 0 2 6 11 % A- 1 0 2 8 , 3 9 3 Un d e r g r o u n d W a t e r Q u a l i t y 2 8 , 3 9 3 11 % A- 1 1 1 1 , 8 3 8 Un d e r g r o u n d W a t e r Q u a l i t y 1 1 , 8 3 8 4% A- 1 2 2 , 2 4 0 Un d e r g r o u n d W a t e r Q u a l i t y 2 , 2 4 0 1% A- 1 3 1 1 , 5 1 7 No n e - 0% B- 1 1 0 , 1 2 5 Bi o s w a l e 1 0 , 1 2 5 4% B- 2 2 6 , 9 1 7 Bi o s w a l e (3 ) 26 , 9 1 7 10 % C- 1 8 , 6 5 1 We t P o n d 8 , 6 5 1 3% To t a l S i t e 26 3 , 8 0 1 1 9 6 , 5 5 0 75 % (1 ) B a s i n A - 1 i n c l u d e s a p p r o x i m a t e l y 8 , 5 0 0 s f o f f u t u r e b u i l d i n g a r e a n o t b e i n g t r e a t e d (2 ) B a s i n A - 1 2 F u t u r e w i l l b e r e q u i r e d t o p r o v i d e L I D t r e a t m e n t a t t i m e o f f u t u r e d e v e l o p m e n t (3 ) B a s i n B - 2 i n c l u d e s 1 0 , 0 0 0 s f o f f u t u r e t r e a t e d a r e a b y t h e f u t u r e e x t e n s i o n o f t h e p r o p o s e d b i o s w a l e Lo w I m p a c t D e v e l o p m e n t ( L I D ) T r e a t e d A r e a s Ca l c u l a t i o n s b y : K R B Da t e : 4 / 9 / 2 0 1 8 P: \ U 1 6 0 1 4 - P R P A C a m p u s \ R e p o r t s \ D r a i n a g e \ C a l c u l a t i o n s \ U 1 6 0 1 4 - D r a i n C a l c s . x l s m A PPENDIX D D RAINAGE E XHIBIT SOUTH TIMBERLINE ROAD UNION PACIFIC RAILROAD MAINTENANCE SHOP / TRUCK WASH SUBSTATION GARAGE FLEET PARKING GARAGE A FLEET PARKING GARAGE B PLATTE RIVER POWER AUTHORITY05/23/18 PLATTE RIVER POWER AUTHORITY HQ DRAINAGE PLAN PREPARED FOR:DATE SUBMITTED: The engineer preparing these plans will not be responsible for, or liable for, unauthorized changes to or uses of these plans. All changes to the plans must be in writing and must be approved by the preparer of these plans.