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Mr tl ...+p.e rwqup .M1Y )0 NP N.1 N MN.Y NM nWA.N �: p11 a'-s.P P+-Y. M Yn1YL NyPYp, a LPNYy N NY. a Iw11Y NY tlI !!4 Yl Y YMn !r .MMa Ml YNYIYM 4YtlIN IIMYtl �:I M 4 N.wY+ YWYN/ h M .aln1Y CN1 UTILITY I DTACATIOR CENTER OF CQGRABO 1-800-922-1987 ((AL 'HI9F5 MK N .MN4 OOf 1W T. GIIKC W OCJnR {UG L( YYYIC 6 WIW.OY.II I�ADf URIIQ Y L N.11 Ilh v] PRELIMINARY AtlN i FOR, cow wiIw y 1rL ATE 14. 100E 2 � worilill -TT QIIB AC- zo 49N3. O OW 100 ROW 5 a 50 25 0 50 100 z N Q N pN F UI SCALE: 1' w 50' a 1 a LEGEND O s a c � O N C O Q1 DESIGN PORT BASIN IDETHTRICATI N 00 Q RUNOFF COEMCENT (C5) AREA IN ACRES �- ROW DIRECTION NIBB P M M � BASN OWNUARY _ _ _ _ _ EXIS1NG PIPES ® PROPOSED STORY PIPE FLARED END SECRON PROPOSED NIET LOCATION Z Q E)a51111G 5' CONTOUR J a _. ..... .. ..._ .... _ EaSTM V CONTOUR J PROPOSED 5' CONTOUR Z 0 W H �4AM PROPOSED V CONTOUR ® 1� O SILT RMi cc O 01EI PROTECTIONZ O O® CMSTRUCTION ENTRANCE Q O NY "OSON BALES :3 WV OSO)YERT RUP in ^V ® RPRAP W Q Q UQ City of Fort Colinv. EolRllao UTIUTY PLAN APPROVAL APPROMD: 4r[ylr OW SHEET CHECKED Br: Ynl...l.r Wk, Dil. CHECKED BY: J 3 BlwwsI. INN. PN. CHECKED BY: PpY. ! Rgnllw pal. CHECKED BY, -- CHECKED BY oN. Horsetooth Road o�ye I G° Bighorn Road o\0 ° o °a j ° Y(U o Of a� i a o v 0 o E T c G° ° o 0 o ¢ Caribou Rod N •c Linton Elementary School i i a 0 I 0 J 0 elfP��c \� ) E I T 0 U Harmony Road APPROX SCALE 1"=1000' SHEET 1 OF 1 DATE: 06/14/02 North Star SCALE: 1 " = 1000' VICINITY MAP '1�- design, inc. DRAWN BY: TDS CARIBOU APARTMENTS Windsorr,Unit ,Colorado 80 50 Phone: 970-686-6939 JOB NO.: 168-01 Fax:970-686-1188 0 1 r 1 1 I I I I I APPENDIX A VICINITY MAP F41 I 7. REFERENCES 1. City of Fort Collins, "Storm Drainage Criteria Manual", (SDCM), dated March, 1986. 2. The Fox Meadows Basin Drainage Master Plan Update Baseline Hydrology Report by ICON Engineering dated January 31, 2002. 3. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria Manual", Volumes 1 and 2, dated March, 1969, and Volume 3 dated September, 1992. 10 1 6. CONCLUSIONS 1 6.1 Compliance with Standards IAll computations that have been completed within this report are in compliance with the City of Fort Collins Storm Drainage Design Criteria Manual. 1 6.2 Drainage Concept The proposed drainage concepts presented in this report and on the construction plans adequately provide for the detention and transmission of developed on -site runoff to the Iexisting storm system. The impact of the development of this site on existing downstream facilities is not substantial. Detention is being provided to meet ' requirements set by the conceptual review comments and Fox Meadows Basin Drainage Master Plan Update Baseline Hydrology Report. , by ICON engineering, INC dated January 31, 2002. ' If, at the time of constriction, groundwater is encountered, a Colorado Department of Health Construction Dewatcrin. Permit would be required. 1 6.3 Erosion Control Concept ' Since the site is greater than 5.0 acres, a NPDES permit is required. During construction, erosion control shall be maintained to minimize erosion on this site and transport of silt Idownstream. 1 9 1 5.2 Specific Details To limit the amount of silt leaving the site, several erosion control measures shall be implemented during construction. Silt fence shall be installed along the boundary of the site. Also, vehicle -tracking pads shall be installed at the entrances to control mud being tracked onto the existing pavement. During overlot grading, disturbed areas are to be kept in a roughened condition and watered to reduce wind erosion. Sediment traps in water quality ponds shall be implemented to minimize sediment transport to off site locations. 5.3 Dust Abatement During the performance of the xork required by these plans, the contractor shall carry out proper efficient measures where .•cr and as necessary to reduce dust nuisance, and to prevent dust nuisance, wluch has originated from his operations from damaging crops, orchards, cultivated fields and dwellings, or causing nuisance to persons. The Contractor will be held liable for any damage resulting from dust originating from his operations under these plans, on right-of-way or elsewhere. 5.4 Tracking Mud Wherever construction vehicles access routes intersect paved public roads, provisions Ishall be made to minimize the transport of sediment (mud) by runoff or vehicles tracking onto the paved surface. A stabilized construction entrance is required per the detail shown on the Detail Sheet with base material consisting of 6" coarse aggregate. The contractor will be responsible for clearing tracked mud on a daily basis. 5.5 Maintenance All temporary and permanent erosion and sediment control practices must be maintained and repaired as needed to assure continued performance of their intended function. Silt fences will require periodic r^placement. Maintenance is the responsibility of the contractor. 8 i I Sub -basin 16 is located in tl;e south portion of the site and includes a portion of a multi- unit structure 6, parking area, automobile storage structures G8, G9 and associated landscaping. Runoff from Sul. -basin 16 will flow to a curb cut located in the southeast portion of this sub -basin. F:ow will be conveyed to Pond 4 then overtop to the Timberline Sump. Sub -basin 17 is located in the south most portion of the site and includes the Club House, a portion of multi -unit str�!cture 6, the water quality ponds 2-4 and associated landscaping. This basin inc!Oes the ponds, outlet structure and is the area where the Timberline Sump volume wi'' ' increased. 1 4.3 Drainage Summary The storm conveyance system is a surface and sub -surface system and has been designed for minimal maintenance. The proposed storm sewer system (outlet structures, inlets, storm pipe, concrete pans an(l detention ponds) will be owned and maintained by the property owners. The existinc storm system shall be maintained, by the City of Fort Collins or other responsible parties. 4.4 Variance Requests No variances are being requested a: this time. 5. EROSION CONTROL 1 5.1 General Concept This site lies within the Moderate Rainfall and Wind Erodibility Zone per the City of Fort Collins Zone Maps. A potential crists for silt movement from the site to be transported into the existing ponds locate l to the north and south of the site. All erosion control measures necessary to minimi•..e sediment transport have been shown on the Erosion Control Plan. 7 I I I Sub -basin 10 is located in the c: st central portion of the site and includes the west half of multi -unit building 1. Runoff from Sub -basin 10 will flow west and will be captured by a swale located to the west of the multi -unit structure. This swale will flow south and discharge flow into the private street, Sub -basin 12. Sub -basin 11 is located in the central portion of the site and includes the south portion of the central parking area, half of multi -unit structure 4, associated automobile storage structures G2, G3 and adjaco!­ landscaping. Runoff from Sub -basin 11 will flow southeast then southwest and be conveyed by sheet flow and curb & gutter into an inlet located in a sump. Flow wi I l be conveyed to Pond 4 by Storm Sewer 4 then overtop to the Timberline Sump. Sub -basin 12 is located in the central portion of the site and includes the south portion of multi -unit structure 4, associat d landscaping, and the north half of the private road through the site. Runoff from � !b-basin 12 will flow to an inlet located at the sump on the private road in the central p&-t;on of the site. Flow will be conveyed to Pond 4 by Storm Sewer 4 then overtop to the Timberline Sump. Sub -basin 13 is located in the west central portion of the site and includes the southern portion of multi -unit structure parking area, automobile storage structure G5 & G6 and associated landscaping. Runof° from Sub -basin 13 will flow to an inlet located at the sump located in the southwest c-:rner of the parking area. Flow will be conveyed to Pond 2 by Storm Sewer 6 then overtop the Timberline Sump. Sub -basin 14 is located in the central portion of the site and includes north portions of multi -unit structures 5 & 6, parking area, associated landscaping, and the south half of the private road through the site. ?? unoff from Sub -basin 14 will flow to an inlet located at the sump on the private road i;i tl,e central portion of the site. Flow will be conveyed to Pond 4 by Storm Sewer 4 the, c- , ;-'op to the Timberline Sump. Sub -basin 15 is located in the sou Ili central portion of the site and includes the south half of multi -unit structure 5, p^rl<ing area and associated landscaping. Runoff from Sub - basin 15 will be conveyed by c:irb & gutter and concrete pans to an inlet located at the sump in the south portion e` t! :q sub -basin. Flow will be conveyed to Pond 3 by Storm Sewer 5 then overtop to the Ti,,-!,.,dine Sump. C J I Sub -basin 3 is located in the north central portion of the site and includes a portion of the southwest comer of multi -unit building 2 and associated landscaping. Runoff from Sub - basin 3 will flow into an area inlet located at a sump. Flow will be conveyed east to Pond 1. Sub -basin 4 is located in the north central portion of the site and includes the north half of multi -unit building 2. Runoff from Sub -basin 4 will flow north and will be captured by the multi -units roof drainage system and discharge into a 12" PVC. This system discharges captured flow east in:o Pond 1. Sub -basin 5 is located in the north central portion of the site and includes a portion the south half of multi -unit building 2. Runoff from Sub -basin 5 will flow south and will be captured by a swale located to t!ie south of the multi -unit structure. This swale will flow east and discharge flow into Ponc! 1. Sub -basin 6 is located in the north central portion of the site and includes the north portion of the central parking area, associated automobile storage structures G2 and G3 and adjacent landscaping. Runoff from Sub -basin 6 will flow northeast and will be conveyed by curb & gutter into Pond 1. Sub -basin 7 is located in the northeast portion of the site and includes the proposed north Water Quality and Detention Pond (Pond 1), the north portion of a multi -unit building 1 along with adjacent landscaping. Flow from Sub -basin 7 will be discharged into an existing storm sewer system lo,.-!ted in the northeast corner of the site at a 2-yr historic release rate of 2.0 cfs. Sub -basin 7 accepts flow from Sub -basins 1 through 9. Sub -basin 8 is located in the e^.st portion of the site and includes a portion the west half of Timberline Road. Runoff fn um Sub -basin 8 will flow north to an on -grade inlet and captured flow will be conveyer! ,orthwest to Pond 1. Sub -basin 9 is located in the e,.st central portion of the site and includes the east half of multi -unit building 1. Runof.` f::>m Sub -basin 9 will flow east and will be captured by a swale located to the east of the multi -unit structure. This swale will flow north and discharge flow into Pond 1. F Iflow, concrete pans, curb & gutt--r and a series of inlets to water quality facilities, which ' overtop to the existing Timberl nc Sump regional facility. See Appendix C for detailed water quality calculations. The Fox Meadows Basin Drainage Master Plan Update Baseline Hydrology Report, by ICON Engineering, Inc. dated January 31, 2002, accounted for developed conditions for the Caribou Apartments site. The report shows that the release rate from the Timberline Sump is the same with exist::-;.,• and developed conditions (77 cfs). Based on this information, it is proposed that t: site not provide on -site detention to the 2 year historic rate as discussed in the Conceptual Review Comments. On -site grading to increase the detention volume of the Timberline Sump has been provided and calculations show that approximately 0.7 acre-feet of additional detention below the 100 year water surface elevation (4952.5) is achieved. This is the only additional detention volume (o t, , r than the regional pond) provided on the south. 4.2 Specific Flow Routing A summary of the drainage pats;ems within each basin is provided in the following paragraphs. For more specific de'ails seethe calculations located in Appendix B of this report. Sub -basin 1 is located in the corthwest corner of the site and includes a portion of northeast half of multi -unit building 3, adjacent automobile storage structure G4, associated drive areas and a portion of the landscaped area. Runoff from Sub -basin 1 will flow to an inlet and will be convc� ed east to Pond 1. Sub-basin-2 is located in the northwest portion of the site and includes a portion of the private road and adjacent sides :;1;; to the west. Runoff from Sub -basin 2 will flow north to an on -grade inlet and captur,x' 'low will be conveyed east to Pond 1. 4 r� 1. I I C 0 u I 0 ft even though the Master Plan shows that none is required. If the water surface elevation were allowed to increase by approximately OX; the detention facility volume would increase by approximately 1.0 acre-ft. This information is based on the stage/storage data in the Master Plan. Modifying the design pond depth may require modification of the outlet structure to maintain the design discharge of 77 cfs. Runoff from the site was calculated based on the rainfall criteria adopted by the City of Fort Collins on March 26, 1999. The streets and associated drainage systems surrounding the site are existing 3.3 Hydrologic Criteria Runoff computations were prepared for the 2-year minor and 100-year major storm frequency utilizing the rational method. All hydrologic calculations associated with the basins are included in Appendix B of this report. Standard Form 8 (SF-8) provides time of concentration calculations for all sub - basins. Standard Form 9 (SF-9) provides a summary of the design flows for all Sub - basins and Design Points associated with this site. 3.4 Hydraulic Criteria All hydraulic calculations within this report have been prepared in accordance with the City of Fort Collins Drainage Criteria and are also included in Appendix B of this report. 4. DRAINAGE FACILITY DESIGN 4.1 General Concept The runoff from the north side of the ridge will be conveyed north by via overland sheet flow, concrete pans, curb & gutter and a series of inlets to the proposed detention pond. The flow will be detained in the proposed north detention pond and released at the 2-year historic rate. The runoff from the south side of the ridge will be conveyed south by via overland sheet 3 1 3. 2.2 Sub -basin Description Sub -basins are described thoroughly in Section 4.2. DRAINAGE DESIGN CRITERIA 3.1 Regulations This report was prepared to meet or exceed the "City of Fort Collins Storm Drainage Design Criteria Manual' specifications. Where applicable, the criteria established in the "Urban Storm Drainage Criteria Manual" (UDFCD), 1984, developed by the Denver Regional Council of Governments, has been used. 3.2 Development Criteria Reference and Constraints ' Detention is proposed for this site is in two locations. The northern pond is restricted to the calculated 2-yr historic release rate of 2.0 cfs. The southern pond is restricted to ' 1.5 cfs. Water quality measures will be provided in the form of extended detention and are included in the detention volume requirements on the north. Independent water quality ponds are provided on the south. There is an existing regional detention facility to the south of the site. The Fox Meadows Basin Drainage Master Plan Update Baseline Hydrology Report, by ICON Engineering, Inc. dated January 31, 2002, accounted for developed conditions for the Caribou ' Apartments site. The report shows that the release rate from the Timberline Sump is the same with existing and developed conditions (77 cfs). Based on this information, it is 1 proposed that this site not provide on -site detention to the 2 year historic rate as discussed in the Conceptual Review Comments. 1 On -site grading to increase the detention volume of the Timberline Sump has been provided and calculations show that approximately 0.7 acre-feet of additional detention ' below the 100 year water surface elevation (4952.5) is achieved. ' Calculations show that the detention volume that would be required to provide for the 2 year historic release from the site 1.7 acre-ft. The proposed design has provided 0.7 acre- 1 2 1 1 1 1. 1 1 t n 0 1 0 1 1 I 1 1 Ll u 1 GENERAL LOCATION AND DESCRIPTION 1.1 Location This site is located in a tract of land in the Southwest Quarter of Section 31, Township 7 North, Range 68 West of the Sixth Principal Meridian, in the City of Fort Collins, County of Larimer, State of Colorado. See the location map in Appendix A. The project is located south of Caribou Road and west of South Timberline Road. These streets bound the site to the north and east, the Timberline Sump (regional wetlands detention facility) to the south and public storage units are located to the west. 1.2 Description of Property The entire project consists of approximately 11.0 acres of land. The land is currently partially developed with a single-family home and an outbuilding that will be removed with this development. The topography of this site consists of a ridge in the central portion running east and west. This ridge splits the flows with approximately 4.25 acres draining to the southwest (into ,the Timberline Sump) and the remaining 6.75 acres draining to the northeast. Slopes range from 3.0% to 5.0%. The project will consist of six multi -family residential buildings, a clubhouse facility and 11 detached automobile storage structures with associated drives and parking areas. The site will access from the existing Caribou Road and Timberline Road. 2. DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description The proposed development lies within the Fox Meadows Basin Master Drainage Basin. The site is included in the area covered by the Fox Meadows Basin Drainage Master Plan Update Baseline Hydrology Report, by ICON Engineering, INC dated January 31, 2002. Portions of this report are included in Appendix E. This report addressed existing & future hydrology in this area. This site is in basins 340 & 345 of the ICON report. I 1 TABLE OF CONTENTS TABLEOF CONTENTS.............................................................................................................................iii 1. GENERAL LOCATION AND DESCRIPTION 1.1 Location...............................................................................................................................1 1.2 Description of Property ........................................................................................................1 2. DRAINAGE BASINS AND SUB -BASINS 2.1 Major Basin Description......................................................................................................1 2.2 Sub -Basin Description.........................................................................................................2 3. DRAINAGE DESIGN CRITERIA 3.1 Regulations..........................................................................................................................2 3.2 Development Criteria Reference and Constraints................................................................2 3.3 Hydrologic Criteria..............................................................................................................3 3.4 Hydraulic Criteria................................................................................................................3 ' 4. DRAINAGE FACILITY DESIGN 4.1 General Concept..................................................................................................................3 4.2 Specific Flow ' Routing.........................................................................................................4 4.3 Drainage Summary .............................................................................................................. 4.4 Variance Requests...............................................................................................................7 ' ' 5. EROSION CONTROL 5.1 General Concept..................................................................................................................7 5.2 Specific Details....................................................................................................................8 5.3 Dust Abatement.........:.........................................................................................................8 5.4 Tracking Mud...................................................................................................................... 5.5 Maintenance........................................................................................................................ 8 8 t6. ' CONCLUSIONS 6.1 Compliance with Standards............................................................................................:...9 6.2 Drainage Concept................................................................................................................9 6.3 Water Quality and Erosion Control Concept.......................................................................9 7. REFERENCES..................................................................................................:............................10 APPENDICES A Vicinity Map B Hydrologic & Hydraulic Computations C Detention and Water Quality Calculations ® D Erosion Control Calculations I� E Figures and Tables F Excerpts from Previous Reports 1 iii n North Star �-�Anw., design, inc, June 14, 2002 Basil Hamdan City of Fort Collins Stormwater 700 Wood Street Fort Collins, CO 80522-0580 RE: Final Drainage Report for Caribou Apartments Dear Basil, I am pleased to submit for your review and approval, this Final Drainage & Erosion Control Report for Caribou Apartments. I certify that this report for the drainage design of Caribou Apartments was prepared in accordance with the criteria in the City of Fort Collins Storm Drainage Manual. I appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. Prepared by: Troy Spraker, E.I.T. Reviewed by: Michael Oberlander, RE, L.SV%0-19io�n North Star Design, Inc. ii 700 Automation Drive, Unit I Windsor, Colorado 80550 970-686-6939 Phone 970-686-1188 Fax ' FINAL DRAINAGE AND EROSION CONTROL REPORT CARIBOU APARTMENTS Prepared for: Hendricks Communities, LLC ' 1165 South Pennsylvania St. Suite 100 - Denver, CO 80210 Prepared by: North Star Design, Inc. 700 Automation Drive, Unit I Windsor, Colorado 80550 Ph# (970) 686-6939 Fax# (970) 686-1188 June 14, 2002 Job Number 168-0l I I