No preview available
HomeMy WebLinkAboutDrainage Reports - 11/28/1995T OF Final roved FORT COLLDW ii�=a!e I FINAL DRAINAGE AND EROSION CONTROL STUDY FOR WILDWOOD TOWNHOMES FORT COLLINS, COLORADO ,If FINAL DRAINAGE AND EROSION CONTROL STUDY FOR WILDWOOD TOWN HOMES FORT COLLINS, COLORADO October 26, 1995 Prepared for: James Company 2919 Valmont Road, Suite 109 Boulder, Colorado 80301 Prepared by:. RBD, Inc. Engineering Consultants 209 South Meldrum Street Fort Collins, Colorado 80521 (970) 482-5922 RBD Job No. 607-006 INC. ' Engineering Consultants 209 S. Meldrum Fort Collins, Colorado 80521 303/482-5922 FAX:303/482-6368 -' October 26, 1995 Mr. Basil Harridan City of Fort Collins Utility Services, Stormwater ' 235 Matthews Fort Collins, Colorado 80522 ' RE: Final Drainage and Erosion Control Study for Wildwood Townhomes Dear Basil: ,' 1 11 We are pleased to submit to you, for your review and approval, this Final Drainage and Erosion Control Study for Wildwood Townhomes. All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. In response to the concerns voiced in the meeting on October 24, we have added a 5' curb cut in Timberwood that will intercept over half of the flows before they reach the eastmost entrance into the site. This should alleviate. the concerns regarding flows not "turning" into the site as intended. We appreciate your time and consideration in reviewing this submittal you have any questions. Respectfully, RBD Inc. Engineering Consultants P ared by: Patricia Kroetch Project Engineer Reviewed by: )Kevin Gingery, E. Project Manager Water Resources Please call if ' Denver303/458-5526 I. GENERAL LOCATION AND DESCRIPTION A. LOCATION 1 B. DESCRIPTION OF PROPERTY 1 H. DRAINAGE BASINS AND SUB -BASINS A. MAJOR.BASIN DESCRIPTION 1 B. SUB -BASIN DESCRIPTION 2 III. DRAINAGE DESIGN CRITERIA A. REGULATIONS 2 B. DEVELOPMENT CRITERIA REFERENCE, CONSTRAINTS, AND COMPARISON 2 C. HYDROLOGICAL CRITERIA 3 D. HYDRAULIC CRITERIA 3 E. VARIANCES FROM CRITERIA 3 IV. DRAINAGE FACILITY DESIGN A. GENERAL CONCEPT 3 B. SPECIFIC DETAILS 4 V. STORM WATER QUALITY A. GENERAL CONCEPT 5 VI. EROSION CONTROL A.' GENERAL CONCEPT 6 VII. CONCLUSIONS. A. COMPLIANCE WITH STANDARDS 6 B. DRAINAGE CONCEPT 6 C. STORMWATER QUALITY CONCEPT 7 D. EROSION CONTROL CONCEPT 7 REFERENCES 1 8 VICINITY MAP 1 HYDROLOGY CALCULATIONS 3 EXCERPTS FROM PREVIOUS DRAINAGE REPORTS 9 SWALE AND SIDEWALK CULVERT SIZING 16 DETENTION POND SIZING 24 EROSION CONTROL CALCULATIONS 33 CHARTS, TABLES & FIGURES 41 FINAL DRAINAGE AND EROSION CONTROL STUDY FOR WILDWOOD TOWN HOMES FORT COLLINS, COLORADO 1 I. GENERAL LOCATION AND DESCRIPTION 1 A. Location ' The Wildwood Townhomes Site is located in the southeast part of Fort Collins, South of Harmony Road and west of County Road 9. The site location can also be described as situated in the Northeast Quarter of Section 5, Township 6 North, Range 68 West of the 6th Principal Meridian, City of Fort Collins, Larimer County, Colorado. The project site is shown on the Vicinity Map in the Appendix. The Wildwood Townhomes development is bounded by undeveloped land (owned by Poudre Valley Hospital) on the west, Timberwood Drive on the ' south, Corbett Drive on the east, and Mountain Crest Hospital on the north. B. Description of Property The Wildwood Townhomes P.U.D. contains approximately 10.47 acres and is generally undeveloped at the present. The existing site is presently open ' ground covered with native grasses. The site topography generally slopes toward the southeast corner at approximately 1.4%. Runoff historically sheet flows to Corbett Drive and south to the Timberwood Junior High detention ' pond. There is currently a concrete irrigation ditch on the western edge of the project site. This ditch has been replaced by an 18" irrigation pipe west of the project site, as shown on the plans. The concrete irrigation ditch has ' therefore been abandoned and is scheduled to be removed with this construction. II. DRAINAGE BASINS AND SUB -BASINS ' A. Major Basin Description The project site is located in the McClellands Basin and is described in the report entitled McClellands Basin Master Drainage Plan, prepared by ' 1 Greenhorn and O'Mara, Inc., 1986 and is further described in the Amended Overall Drainage Study for Wild Wood Farm by RBD, 1992. A portion of the latter report is included in the appendix. B. Sub -Basin Description 1 Flows from the site, in a developed condition, were included as part of the drainage study for the adjacent Southeast Junior High Site, as prepared by ' RBD, Inc. A portion of that report is included in the Appendix. ' In the Amended Overall Drainage Study for Wild Wood Farm by RBD, Inc., the site is designated as a medium density residential/professional office with on -site detention. Further detailed in the drainage study for the adjacent Southeast Junior High Site, the Wildwood Townhomes Site flows were to be detained on -site with flows released onto Corbett Drive and conveyed south by curb and gutter to a low point in Corbett Drive where it will be intercepted by inlets. From there it will be conveyed to the Junior High detention pond, and bypassed through the Junior High School Detention Pond and released along with the detained developed flows from ' the Junior High Site. III. DRAINAGE DESIGN CRITERIA A. Regulations 1 The City of Fort Collins Storm Drainage Design Criteria is being used for the subject site. ' B. Development Criteria Reference, Constraints, and Comparison ' The criteria established the Amended Overall Drainage Study for Wild Wood Farm (dated June, 1992) and by the Final Drainage Report for the Southeast ' Junior High School (dated April, 1993), both prepared by RBD, Inc., will be used for this site. Densities and imperviousness are consistent with Basin C of the approved Amended ODP for Wild Wood Farm. Detention will be provided on the site and flows released at 0.2 cfs/acre in the 10 year event (2.1 cfs total) and 0.5 cfs/acre in the 100 year event (5.3 ' cfs total). Released flows will continue on Corbett Drive to a detention pond on the Junior High School site. This information is taken from the drainage report for the Southeast Junior High School. ' 2 ' Corbett Drive on the east boundary of the site is existing and Timberwood Drive on the south side of the site is existing for approximately 350 feet. As currently proposed, the site will not receive runoff from either of these existing streets. Approximately 800 feet of Timberwood Drive will be designed with this project. Flows from the north half of approximately 670 ' feet of Timberwood Drive will flow through the on site detention pond, but these flows were accounted for in the design of the Preston JHS detention pond (illustrated as Basin F in the drawing excerpt from the Amended ' Overall Drainage Study for Wild Wood Farm included in the appendix) and, therefore, will not be detained. ' C. Hydrological Criteria ' The Rational Method was used for determining surface runoff for the project site. The 10-year and 100-year storm event criteria, obtained by the City of ' Fort Collins, were used in calculating runoff values. These calculations and criteria are included in the Appendix. ' D. Hydraulic Criteria All hydraulic calculations within this report have been prepared in accordance with the City of Fort Collins Storm Drainage Criteria and are ' included in the Appendix. ' E. Variances from Criteria No variances from City of Fort Collins Storm Drainage Criteria are being ' sought for this project. ' IV. DRAINAGE FACILITY DESIGN ' A. General Concept The on -site runoff produced by the proposed Wildwood Townhomes ' development will flow into an on -site detention pond and will be released at a predetermined rate onto Corbett Drive. The released storm water will flow on Corbett to the existing detention pond on the Timberwood Junior High ' School site. Flows from Corbett Drive and Timberwood Drive will be allowed to flow undetained to the detention pond on the Junior High Site because the flows were accounted for in the design of the Junior High Detention Pond. ' The proposed drainage and grading plan is included in the back pocket of ' 3 this report. ' B. Specific Details The Wildwood Townhomes development has been broken down into 6 sub - basins. All of the sub -basins will drain into the detention pond located in the east corner of the site. Sub -basin 1 contains the west one-third of the site. This sub -basin flows to the westerly parking lot in the center of the sub -basin via small swales and ' then is directed, via curb and gutter, south into sub -basin 2. Sub -basin 2 contains a small area to the north of Timberwood Drive. Runoff from this sub -basin flows into sub -basin 2A. Sub -basin 2A contains the north half of Timberwood Drive and slopes to the ' east at 0.53%. Runoff from this sub -basin (including runoff from sub -basin 2) flows via curb and gutter to the east and into the easterly parking lot in sub -basin 3. These flows will be routed through the on -site detention pond, ' but will not be detained because they have been accounted for in the design of the Junior High Detention Pond. ' Sub -basin 3, contains the middle one-third of the site. The flows from this sub -basin drain to the easterly parking lot via small swales. These flows are then directed south via curb and gutter. These flows join the runoff from ' sub -basin 2 (including runoff from sub -basin 1) and flow to a 8' concrete sidewalk culvert in the southeast corner of the parking lot. The sidewalk culvert will pass the 10 year flows (from sub -basins 1, 2, 2A, and 3 flows ' total 14.3 cfs) and the 100 year flows (31.3 cfs) will flow over the sidewalk. Ponding will occur in the parking lot to approximately elevation 4941 but will ' not flow into Timberwood Drive. The sidewalk culvert empties into the detention pond in sub -basin 5 via a concrete trickle pan. ' Sub -basin 4 contains a grassed swale that runs along the north boundary of the site and flows into an 8" pipe which empties into sub -basin 5. This pipe is sized to carry 10 year and 100 year flows. ' Sub -basin 5 contains the on -site detention pond. Flows from all of the on - site sub -basins are directed to this sub -basin. Runoff from the south enters ' sub -basin 5 through an 8' concrete sidewalk culvert to a 4' trickle pan. The runoff will flow through 2-12" pipes before entering the detention pond. The 12" pipes are sized to carry low flows and major flows will flow over the ' pipes. Runoff from the north enters sub -basin 5 from an 8" pipe from sub- 1 4 7 basin 4 and a sidewalk culvert from a swale in sub -basin 5. These flows then enter the detention pond in a 4' trickle pan. ' The outlet for the pond is a concrete weir that has been designed to conform ' to the 10 year and 100 year release rates which are 0.2 cfs/acre for the 10 year storm event .(2.1 cfs plus runoff from sub -basin 2A totals an aggregate release rate of 3.5 cfs) and 0.5 cfs/acre (5.2 cfs plus runoff from sub -basin ' 2A totals and aggregate release rate of 8.3 cfs) for the 100 year event. The F.A.A. method was utilized to size the detention pond at the east corner ' of the site. The pond model for the 100 year event is included in the appendix. The pond provides 0.73 acre-feet of storage at a WSEL of 4940.00. The pond is to be built with approximately one foot of freeboard. Flows are carried via Corbett Drive to the detention pond on the Southeast Junior High School site. This pond has been sized to accept flows from the ' Wildwood Townhomes site at the release rates discussed above and also developed flows from Timberwood and Corbett Drives. ' V. STORM WATER QUALITY ' A. General Concept The water quality of storm water runoff must be addressed on all final design ' utility plans. The Wildwood Townhomes development is anticipating construction beginning in January of 1996. Best Management Practices for the treatment of storm water runoff have been incorporated into the design ' for this project. The Wildwood Townhomes site will maintain a grassed detention pond and Junior High Detention Pond will provide mechanisms for ' pollutants to settle out of the storm water runoff before being released downstream. All construction activities must comply with the State of Colorado permitting process for Storm water Discharges Associated with Construction Activity. A Colorado Department of Health NPDES Permit will be required before any construction grading can begin. ' 5 .1 VI. EROSION CONTROL A. General Concept The Wildwood Townhomes Site is in the Moderate Rainfall and Moderate ' Wind Erodibility Zones per the City of Fort Collins zone maps. The potential exists for erosion problems during construction, and after construction until ' the disturbed ground is revegetated or paved. It is anticipated that construction will begin in January of 1996. Calculations for erosion control performance standards were completed per the City of Fort Collins Erosion Control Reference Manual for Construction Sites and are included in the appendix. The construction on this site is divided into two phases, therefore, an erosion control performance standard was computed for each phase. The erosion control performance standard for Phase 1 is 78.9%. The effectiveness of the proposed erosion control ' plan for Phase 1 construction is 79.3%. The erosion control performance standard for Phase 2 was calculated to be 79.4%.The effectiveness of the proposed erosion control plan during the construction of Phase 2 is 79.5%. Therefore, the erosion control plan will meet the City of Fort Collins criteria. ' VII. CONCLUSIONS A. Compliance with Standards ' All computations that have been completed within this report are in compliance with the City of Fort Collins Erosion Control Reference Manual ' for Construction Sites and the Storm Drainage Design Criteria Manual. In addition, this design is also consistent with the McClellands Basin Master ' Plan and Southeast Junior High School report prepared by RBD. B. Drainage Concept ' The proposed drainage concepts presented in this report and on the construction plans adequately provide for the conveyance and release of ' developed on -site flows into the existing curb and gutter on Corbett Drive. The combination of on -site street capacities and the on -site minor swale system will provide for the 10 and 100 year developed flows to reach the ' proposed on -site detention facility. The existing detention pond downstream on the Timberwood Junior High School site has been designed and built to account for flows released from the Wildwood Townhomes site. ' b ' If groundwater is encountered at the time of construction, a Colorado Department of Health Construction Dewatering Permit will be required. C. Storm Water Quality Concept ' Because storm water quality has become a requirement, the proposed design has addressed this storm water aspect. A grass -lined detention pond will provide an opportunity for storm water pollutants to filter out of the storm water runoff before the runoff flows off site. The Junior High .Detention Pond will further allow pollutants to settle out prior to release downstream. ' D. Erosion Control Concept The proposed erosion control concepts adequately provide for the control of wind and rainfall erosion from the Wildwood Townhomes. Through the construction of the proposed erosion control concepts, the City of Fort ' Collins performance standard will be met. The proposed erosion control concepts presented in this report and shown on the erosion control plan are in compliance with the City of Fort Collins Erosion Control Criteria. 1 11 1 7 REFERENCES 1. Storm Drainage Design Criteria and Construction Standards, by the City of Fort Collins, Colorado, May 1984,-revised January 1991. 2. Erosion Control Reference Manual for Construction Sites, by the City of Fort Collins, Colorado, January 1991. 3. McClellands Basin Master Drainage Plan, by Greenhorn and O'Mara, Inc., 1986. 4. Master Drainage Study for Wildwood Farm, by RBD, Inc., July, 1988. 5. Amended Overall Drainage Study for the Wildwood Farm, Fort Collins, Colorado, by RBD, Inc., June, 1992. 6. Final .Drainage and Erosion Control Study for the Southeast Junior High School Site, prepared by RBD, Inc., April 1993. 8 I _••�I�U7/:1 u 1 t I VICINITY MAP 1 1 n I 1 I n HARMONY ROAD 0 MOUNTAIN CREST Q HOSPITAL O ry 0') W z Q O Ld m - TI M BE2bk! �F DRiv� O PROJECT PRESTON JUNIOR SI TE HIGH SCHOOL HIGH DJUNIOR ETENTION POND VICINITY MAP NOT TO SCALE 2 1 I 1 1 1 1 1 1 1 1 1 t 1 HYDROLOGY CALCULATIONS 3 1 Y o ao d 0 L N LO C 0 N N L L O O 0) O 03 U 0) N 0 a U (A aD L w -- 2 cn z U O L4 ❑ O a) 0 L N O y L Mr�Ln V- �l,- LO Cl_ COITI�(DMM � E V 666666 6 0= U v, 0)co(D LO LO 00) 0 Lo cc) co v m (o IT(0Nv.rnco LO `.Z O 0) d � .- M t7 (D a7 Ln Ln C IT s LO 00 (D cM 8 O LoMtiLoOL �- V E D0) _ — MOOLni� (D Q 1�-NM000M V 0 00 'i Q � 0 IT N co 0) co (D N 0 '.T Mt-- w N o m rioocYio � o Q N N N N N N N 7 0- .Z v 0 0 0 0 0 0 O a� a m o rnrnrnrnrnrn 000000 0 � U O_ E �N<ce) LO N -y N Q ui � � U) I L' H Z 0 I- Z W U Z O L.L O W (D 0 0 I 0 I N d 0 > LO Q i `) O O T• W O 1- �0 N N 0 L C I- U 0 �Y d U m W U w Q CL U QCM W � t cl V' r- O V; (O w E M LO � 0) LO N Z N L v U Z pi O LU 2 U NLU O�`- 3 n.D� w c5 O Q U a K U. U w to I` (O I,- CA N (0 V) } (O M(O(OMI�M CN CA W 0 v W W W I-- LO rl- PO (n 0 (n o O o � O O O C5 O (V O (n 000(11�0 Oo~0O C(0 VNM ZglM W J V I,-Il-N000)� W._._ (D cM T N E L v Z W M V 0 0 0 0 0 Co O O O O O O A o L NNNNNCA J W (n O N r,, c0 r- co o F- O uO CMOOV'LO N r N CO N Q Z LLJ Z J c0 MII- (n V'� I� M N (O V•I,-(0CO M QU O 0 0 0 C] 0 0 00 ON((00ITmr�cco C)< N Z w c N O M O O (h O U Q Q m (� W Cn� (n NNM V•(n 5 u Ln 0 U (` x U U) r U F- N LL !Y O LL Q Z z O F- Z W Z O U- w _2 F- N fl. O N N U')-00 L � 0 0 0 CA r C) W 0 Q U U to N 0 L c F- O 3 �Y CL Um w U 0 Q aU Y W E J Ln I— (D O (O (`M Ln M O Z w E N U v U UZ N H O w a F- N U W Ogg a � D a O > n J w U OQ a a U U w " fA .. ti (OtiON(0 Ln J.00 C6 1q'6(OLn1 V' .- E �- v O (M (D (D (M ti CM CN U n 0 U,JO � _j v LLI J O O O O O O ;a ^ ti LC)r�r�LnOL!) O O o 00 O O O C; N C7 J .� F- U) _ Ln 000(nI�- 0 cM r` ti (D � U) (D Z t` 00 M (D V N m �� W J OR T7rnoV•r�o Lli w N E Z W M V' 0 0 0 Cl 0 0 0 0 0 0 0 0 Q O o Lin N N N N N CN -7 J v W (n 002 O Lnr�ODr�000 F- O Ln (Y) 0 - 0 V' LO N N (M N Q F- Z ZJ 00 (Y)r�LOV•�r� U N N � (DItl(00 C) Q O O O O O O O (0N(�O pw U VN'M�� ZC. ON O CM00ce)0 - F Q. m (� m U) ar Cn0 I CO I CNN() V'Ln I I I I I .1 I � I I I } k � § m � � f § § § �§ /| � � | |! � � G\ k kk � 7 � ) ■ k ® 2� 4` 2!� � m wo 65 oo 2A \� �K�e @ § 2§— „ \ § ` §z= /§(, on— ■� | ! • S 9 n ! | ■ � £!� . � ( 3! S§!| 5 5! o! n;; ;;; ; 2;; �| ■;� . � . k£!© 3 - � ■ OEM §§` � I I I I I I I I p I H � I I I I I I I ¥ | k! |k , | � |� m !k� - aA m !` - ! § |z� ;2 �k} k k ° |)� kOF 0 ° m 30 G S!! 5 S ; ■r k§It 0 , Q!� ) ~ K 2 Ci = ®- - © , e R n R,■ e a §§` m! � I 1 ' EXCEPTS FROM PREVIOUS DRAINAGE REPORTS 1 1 �^1 I I n 1 AMENDED OVERALL DRAINAGE STUDY FOR WILD WOOD FARM FORT COLLINS, COLORADO June 26, 1992 Prepared for: The Architects, Studio 117 E. Mountain Ave. Suite 200 Fort Collins, Colorado 80524 Prepared by: RBD, Inc. Engineering Consultants 2900 South College Avenue Fort Collins, Colorado 80525 (303) 226-4955 .RBD Job No. 330-003 m City of Fort Collins Storm Drainage Criteria. E. Variances from Criteria A variance is being sought for the outfall of storm water runoff from the upper portion of developed SWMM Basins 215 and 216 of the McClellands Basin Master Plan. IV. DRAINAGE FACILITY DESIGN A. General Concept As development occurs within the Wild Wood Farm site, the drainage concepts shown on the Overall Drainage Plan, in the back pocket of this report, should be followed. A detention pond is planned in the southeast corner of the 1994 Junior High School Site. An existing detention pond lies in the southeast corner of the Charter Hospital Site (Basin B) and discharges storm water onto Corbett Drive at the required staged release rate. As development occurs within the Wild Wood Farm, individual basins are to have on -site detention ponds with staged release rates to drain towards the McClellands Basin Drainageway located to the south of the Wild Wood Farm site. B. Specific Details A permanent detention pond exists at the southeast corner of the Charter Hospital site (Basin B) and discharges storm water onto Corbett Drive. A temporary detention pond exists at the end of existing Corbett Drive. Detained runoff leaving the two existing detention ponds currently drains east across the existing farm land to County Road 9. A detention pond is planned near the -southeast corner of the -Junior High School site (Basin D) at the southern end of Corbett Drive. This detention pond is intended to serve the 1994'Junior High School future Elementary School and future City of Fort Collins Park. Storage provided is based on the criteria of a release rate of 0.2 cfs/acre for the 1O.year storm and 0.5 rfs/acre for the 100 year storm.- Thison-site detention pond is sized to provide storage for the permanent sireeis n inuHU[ he Junioro' High School site, as well as theremainderof Corbett Drive from the Junior High School site to Harmony Road (Basin F . The existing detention facility for Charter Hospital contains a staged release mechanism for the 10 and 100 year storm events. The temporary pond at the south end of Corbett Drive can be eliminated as Corbett Drive is 3 11 p. RY, '•-r ,..vim..-.�'....+:c+..:a'�'u°I<. 'eT' ''ll �'r-' a tv ;7R w,.�,.+..�. �.{.�..1'=•�Y.-•b�1!(,.::.:YtT.`.Mi.-�']."� _N T a •> � � '•��,i WC1M2�1`A9M1M "+WM .W? v.2T'1 .MI`�t ' ralu <�•,,�_: 1,�...vr.,s_, — ---- HARMONY_R A _ }' r�-_•-,.�-` 'G N �• _ { t� 1 yL7 Yam' �C�+_ + `t. L .a�r� +v. �'T'i .4 ��4t� r 'll M1CA�IL�l:it•1Ep ')RKLGA7jpN LAYE2Al, �. YIP'Cp t I ��' °ice i w /,ny �/ •I 777 f:� a S n ut < z __.._---'--"'-' � �.i r .,ti :rF : ih� ti• 1� r :TJ_'�, Nr- � . ,, D --� _ .._,n .. .. •._. I 1 Xs. m� t✓i FI'. TJ fit. )jQ . J' �•� / D��.Tz-0 ---�'�- av . vs�s '�C } '.4Ylt,t, akr�r* a.��)M1t 71�Vi l.rj te.i " of �: �. Z ,Gos.lt{X ialr )tL+{ '+ lr .ASV""< T� ,'i�E.•.-_%�Z''L l `,. r l� { � ;�t �/z � r `� `r.a - • 1,a. ; 1, ., . 1...+} 1' i.�H hF .M1\�7'f • T�i� ..rt {,,j �, titi� J>A•. j,+f +T+^I�-" �t ::�r•i �e ..� 4.:\.o.w .... 7..4L:.1T:�5jY.Yhr<Y>4aRYCwE!•SLkJ'JM��,r. ' YQ� ,•.1�. +, ...; ti s ._.:>•:`... n+.,rit �....'� ..._.. _ _... FINAL DRAINAGE AND EROSION CONTROL STUDY FOR THE SOUTHEAST JUNIOR HIGH SCHOOL SITE FORT COLLINS, COLORADO April 9, 1993 Prepared for: Client: The Architects' Studio 117 E. Mountain Avenue Suite 100 Fort Collins, Colorado. 80524 Prepared by: RBD, Inc. Engineering Consultants 209 South Meldrum Fort Collins, Colorado 80525 (303) 482-5922 RBD Job No. 330-003 mi I ' D. 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 the appendix. E. Variances from Criteria ' No variances are being sought for the proposed project site. ' IV. DRAINAGE FACILITY DESIGN ' A. General Concept ' All on site runoff produced by the proposed development of the Southeast Junior High School site will flow southeasterly to a detention pond located at the southeast corner of the site. Also to be detained in the pond will be ' developed flows from the future Elementary School west of this project, and from the future City Park, which is southwest of this project. Detained developed staged released flows will be routed east to County Road 9, and ' then south to the McClellands Drainageway by a combination of open channels and pipe flow. ' Detained flows from the Charter Hospital Site and from the parcel between the Charter Hospital and the Junior High School site will be bypassed throuah the project detention pond and released along with the detained ' developed flows from this site. Detained developed flows from the Charter Hospital and the parcel to the south will be released onto Corbett Drive. From there it will flow south in the curb and gutter to a low point in Corbett ' Drive. where it will be intercepted by this developments storm sewer system and conveyed to the detention pond being built with this project. ' B. Specific Details This project has been broken into 15 sub -basins; Basins A through J, and ' 0-1 through 0-5. Basins A, C, E, and F represent the roof area of the proposed Junior High ' School. Runoff from the roof will be directed by gutters, downspouts, and underground piping to the proposed inlets and piping system conveying flows to the detention pond. 3 ' I I 14 Basins B, D, G, H, I, and J represent the remainder of the site and are composed of open space, access toads and parking lots, sports fields (permeable and impermeable surfaces), concrete sidewalks, and the detention pond. Developed runoff from these basins is conveyed to the Detention Pond by any combination of overland flows, open channels, curb and gutter, or storm sewer systems. Offsite Basin 0-1 represents the drainage basin containing the Charter Hospital Site and the parcel immediately south of the Charter Hospital and north of Preston Parkway. Detained flows (0.2 cfs/acre for the 10 year storm event and 0.5 cfs/acre for the 100 year event) will be released onto Corbett Drive and conveyed south by curb and gutter to the curb inlets at the southeast corner of the site, and bypassed through the Junior High School Offsite Basins &2 and 0-3 represent the future Elementary School site and the Future City Park. No construction is proposed on these parcels at this time. The Detention Pond associated with this project will detain developed flows from these two areas. Runoff from these undisturbed areas will be routed to the Detention Pond. Offsite Basin 0-4 and 0-5 represent Corbett Drive and Preston Parkway. Developed runoff from these two public roads will be detained in the I detention pond associated with this project. The detention pond to be built for this project will contain approximately 7.72 ac.ft. of storage capacity. Only 4.22 ac.ft. of storage is required for detention; the additional 3.5 ac. ft. of volume is being provided for the future storage of irrigation water for the school. A staged release outlet structure will be built in phase 2 construction, possibly in April 1993, with a calculated release rate of 0.2 cfs/acre for the 10 year and 0.5 cfs/acre for the 100 year events. An emergency overflow structure will also be built into the pond. Irrigation water will be provided for by a lateral from Harmony Road that use to supply irrigation water for this area. A pipe and headwall will be built on the lateral and the irrigation water will be piped to the swale which runs from the softball fields to the detention pond. A backup water supply tap has been included in the domestic water supply system. dPhase 1 construction will consist of overlot grading, the construction of Corbett Drive and Preston Parkway, the installation of the water and sanitary sewer, and the storm sewer and curb inlets at the south end of Corbett IP Drive. Prior to overlot grading, the detention pond as shown will be constructed to act as a temporary siltation basin. During the overlot grading process, the entire 7.72 ac.ft. of volume will be excavated, and the pond will 4 j5 d 7 1 t 1 1 L 1 SWALE AND SIDEWALK CULVERT SIZING 16 I RBD INC. ENGINEERING CONSULTANTS CHANNEL RATING INFORMATION WILDWOOD SWALE A -A STA ELEV 0.00 2.00 10.00 0.00 25.00 1.00 35.00 1.20 N VALUE SLOPE (ft/ft) ----------------------- 0.060 0.0200 ELEVATION AREA VELOCITY DISCHARGE FROUDE (feet) --------- (sq ft) ------- (fps) -------- (cfs) NO. --------- ------ 0.10 0.1 0.5 0.05 0.37 0.20 0.4 0.8 0.30 CJ�o p��� 0.42 0.30 0.9 1.0 0.89 ,�Q�oo-� bcfs 0.45 0.40 1.6 1.2 1.92 0.47 0.50 2.5 1.4 3.47 0.49 0.60 3.6 1.6 5.65 0.50 0.70 4.9 1.7 8.52 0.52 0.80 6.4 1.9 12.16 0.53 0.90 8.1 2.1 16.64 0.54 1.00 10.0 2.2 26.39 0.55 I-7 RBD INC. ENGINEERING CONSULTANTS CHANNEL RATING INFORMATION WILDWOOD SWALE B-B STA ELEV 0.00 3.33 10.00 0.33 12.00 0.00 14.00 0.33 24.00 3.33 W VALUE SLOPE (ft/ft) ----------------------- 0.030 0.0050 ELEVATION AREA VELOCITY (feet) (sq ft) (fps) DISCHARGE FROUDE (cfs) NO. 0.20 0.2 0.8 0.18 0.42 0.40 1.0 1.2 1.19 0.47 0.60 2.0 1.7 3.36 0.51 0.80 3.3 2.1 6.73 0.53 1.00 4.8 2.4 Qp_ K3cF5,11.47 0.55 1.20 6.7 2.7 17.73 0.57 1.40 8.8 2.9 Q _ 31,2 > 5.64 i0O 0.58 1.60 11.1 3.2 35.37 0.59 1.80 13.7 3.4 47.04 0.60 2.00 16.6 3.7 60.78 0.61 2.20 19.8 3.9 76.74 0.62 2.40 23.2 4.1 95.02 0.63 2.60 26.9 4.3 115.77 0.64 2.80 30.9 4.5 139.09 0.65 3.00 35.1 4.7 165.11 0.65 3.20 39.6 4.9 193.94 0.66 i r-- 1 1 0 r- L ------------------------------------------------------------------------------ UDINLET: INLET HYDARULICS AND SIZING DEVELOPED BY DR. JAMES GUO, CIVIL ENG DEPT. U OF COLORADO AT DENVER SUPPORTED BY METRO DENVER CITIES/COUNTIES AND UD&FCD ------------------------------------------------------------------------------ USER:KEVIN GINGERY-RDB INC FT. COLLINS COLORADO .............................. ON DATE 10-25-1995 AT TIME 16:45:35 *** PROJECT TITLE: WILDWOOD TOWNHOMES *** CURB OPENING INLET HYDRAULICS AND SIZING: INLET ID NUMBER: TR(C.KIx Ci AM WO_ ON T IMBiE:ei,J b tD2. :5rA 12--t70 , INLET HYDRAULICS: IN A SUMP. GIVEN INLET DESIGN INFORMATION: GIVEN CURB OPENING LENGTH (ft)= 5.00 HEIGHT OF CURB OPENING (in)= 6.00 INCLINED THROAT ANGLE (degree)= 0.00 LATERAL WIDTH OF DEPRESSION (ft)= 2.00 SUMP DEPTH (ft)= 0.00 Note: The sump depth is additional depth to STREET GEOMETRIES: STREET LONGITUDINAL SLOPE ($) = 0.80 STREET CROSS SLOPE ($) = 4.00 STREET MANNING N = 0.016 GUTTER DEPRESSION (inch)= 2.00 GUTTER WIDTH (ft) = 2.00 STREET FLOW HYDRAULICS: WATER SPREAD ON STREET (ft) = 14.22 GUTTER FLOW DEPTH (ft) = 0.74 FLOW VELOCITY ON STREET (fps)= 4.51 FLOW CROSS SECTION AREA (sq ft)= 4.21 GRATE CLOGGING FACTOR (o)= 50.00 CURB OPENNING CLOGGING FACTOR(%)= 10.00 INLET INTERCEPTION CAPACITY: flow depth. IDEAL INTERCEPTION CAPACITY (cfs)= 11.53 BY FAA HEC-12 METHOD: DESIGN FLOW (cfs)= 19.10 FLOW INTERCEPTED (Cfs)= 10.37 CARRY-OVER FLOW (cfs)= 8 73�-- BY DENVER UDFCD METHOD: DESIGN FLOW (cfs)= 19.10 FLOW INTERCEPTED (Cfs)= 10.37 CARRY-OVER FLOW (cfs)= 8.73 19 UDINLET: INLET HYDARULICS AND SIZING DEVELOPED BY DR. JAMES GUO, CIVIL ENG DEPT. U OF COLORADO AT DENVER SUPPORTED BY METRO DENVER CITIES/COUNTIES AND UD&FCD ----------------------- ---------------------------------------------- SER:KEVIN GINGERY-RDB INC FT. COLLINS COLORADO.............................. ON DATE 10-25-1995 AT TIME 16:51:44 I** PROJECT TITLE: WILDWOOD TOWNHOMES *** CURB OPENING INLET HYDRAULICS AND SIZING: tINLET ID NUMBER: gg ZOA- EAST EhITEANCE (►'j-TO pg2KJWji , LC5T o>rF TlnagEZWOD-ID DRY ' INLET HYDRAULICS: IN A SUMP. GIVEN INLET DESIGN INFORMATION: GIVEN CURB OPENING LENGTH (ft)= 12.50 HEIGHT OF CURB OPENING (in)= 6.00 INCLINED THROAT ANGLE (degree)= 0.00 ' LATERAL WIDTH OF DEPRESSION (ft)= 2.00 SUMP DEPTH (ft)= 0.00 Note: The sump depth is additional depth to flow depth. ' STREET GEOMETRIES: STREET LONGITUDINAL SLOPE (%) = 0.40 STREET CROSS SLOPE M = 4.00 STREET MANNING N = 0.016 ' GUTTER DEPRESSION (inch)= 2.00 GUTTER WIDTH (ft) = 2.00 STREET FLOW HYDRAULICS: ' WATER SPREAD ON STREET (ft) = 11.88 GUTTER FLOW DEPTH (ft) = 0.64 FLOW VELOCITY ON STREET (fps)= 2.89 FLOW CROSS SECTION AREA (sq ft)= 2.99 GRATE CLOGGING FACTOR (%)= 50.00 CURB OPENNING CLOGGING FACTOR(%)= 10.00 ' INLET INTERCEPTION CAPACITY: IDEAL INTERCEPTION CAPACITY (cfs)= 19.03 BY FAA HEC-12 METHOD: DESIGN FLOW (cfs)= 8.70, FLOW INTERCEPTED (cfs)= 8.70' CARRY-OVER FLOW (cfs)= 0.00 ' BY DENVER UDFCD METHOD: DESIGN FLOW (cfs)= FLOW INTERCEPTED (cfs)= 8.70 8.70 CARRY-OVER FLOW (cfs)= 0.00 1 ----------------------------------------------------------------------------- UDINLET: INLET HYDARULICS AND SIZING DEVELOPED BY DR. JAMES GUO, CIVIL ENG DEPT. U OF COLORADO AT DENVER SUPPORTED BY METRO DENVER CITIES/COUNTIES AND UD&FCD -------------------------------------------- 7--------------------------------- tSER:KEVIN GINGERY-RDB INC FT. COLLINS COLORADO.............................. N DATE 09-01-1995 .AT TIME 11:11:41 ** WILDWOOD INLET 30 (iv -year) PROJECT TITLE: *** CURB OPENING INLET HYDRAULICS AND SIZING: ' INLET ID NUMBER: 30 INLET HYDRAULICS: IN A SUMP. GIVEN INLET DESIGN INFORMATION: GIVEN CURB OPENING LENGTH (ft)= 8.00 HEIGHT OF CURB OPENING (in)= 6.00 INCLINED THROAT ANGLE (degree)= 45.00 ' LATERAL WIDTH OF DEPRESSION (ft)= 2.00 SUMP DEPTH (ft)= 0.20 Note: The sump depth is additional depth to flow depth. ' STREET GEOMETRIES: ' STREET LONGITUDINAL SLOPE (%) STREET CROSS SLOPE (%) = 0.57 2.00 STREET MANNING N 0.016 GUTTER DEPRESSION (inch)= 2.00 ' GUTTER WIDTH (ft) = 1.50 STREET FLOW HYDRAULICS: WATER SPREAD ON STREET (ft) = 21.06 GUTTER FLOW DEPTH (ft) = 0.59 FLOW VELOCITY ON STREET (fps)= 3.10 ' FLOW CROSS SECTION AREA (sq ft)= 4.59 GRATE CLOGGING FACTOR (%)= 50.00 CURB OPENNING CLOGGING FACTOR(%)= 10.00 ' INLET INTERCEPTION CAPACITY: IDEAL INTERCEPTION CAPACITY (cfs)= 16.81 ' BY FAA HEC-12 METHOD: DESIGN FLOW FLOW INTERCEPTED (cfs)= (cfs)= 14.30 �-1��r 14.30' CARRY-OVER FLOW (cfs)= 0.00 BY DENVER UDFCD METHOD: DESIGN FLOW (cfs)= 14.30 ' FLOW INTERCEPTED (cfs)= 14.30 CARRY-OVER FLOW (cfs)= 0.00 C I ZI I t---------------------------------------------------------------------------- UDINLET: INLET HYDARULICS AND SIZING DEVELOPED BY DR. JAMES GUO, CIVIL ENG DEPT. U OF COLORADO AT DENVER SUPPORTED BY METRO DENVER CITIES/COUNTIES AND UD&FCD ------------------------------------------------------------------------ CSER:KEVIN GINGERY-RDB INC FT. COLLINS COLORADO.............................. DATE 08-31-1995 AT TIME 16:59:00 I** PROJECT TITLE: WILDWOOD INLET (100- gear ) *** CURB OPENING INLET HYDRAULICS AND SIZING: INLET ID NUMBER: 30 INLET HYDRAULICS: IN A SUMP. ' GIVEN INLET DESIGN INFORMATION: ' GIVEN CURB OPENING LENGTH (ft)= 8.00 HEIGHT OF CURB OPENING (in)= 6.00 ' INCLINED THROAT ANGLE (degree)= LATERAL WIDTH OF DEPRESSION (ft)= 45.00 2.00 SUMP DEPTH (ft)= 0.20 Note: The sump depth is additional depth to flow depth. ' STREET GEOMETRIES: STREET LONGITUDINAL SLOPE (t) = 0.57 ' STREET CROSS SLOPE M = 2.00 STREET MANNING N = 0.016 GUTTER DEPRESSION (inch)= 2.00 ' GUTTER WIDTH (ft) = 1.50 STREET FLOW HYDRAULICS: ' WATER SPREAD ON STREET (ft) = 28.75 GUTTER FLOW DEPTH (ft) = 0.74 ' FLOW VELOCITY ON STREET (fps)= FLOW CROSS SECTION AREA (sq ft)= 3.74 8.42 GRATE CLOGGING FACTOR M = 50.00 CURB OPENNING CLOGGING FACTOR(%)= 10.00 ' INLET INTERCEPTION CAPACITY: IDEAL INTERCEPTION CAPACITY (cfs)= 18.81 _ BY FAA HEC-12 METHOD: DESIGN FLOW (cfs)= 31.30-4 ' FLOW INTERCEPTED (cfs)= 16.93 CARRY-OVER FLOW (cfs)= 14.37 BY DENVER UDFCD METHOD: DESIGN FLOW (cfs)= 31.30 ' FLOW INTERCEPTED (cfs)= 16.93 CARRY-OVER FLOW (cfs)= 14.37 ' 22 1 1 ' RBD INC. ENGINEERING CONSULTANTS WEIR SECTION FLOW DATA ' WILDWOOD TOWNHOMES FLOW OVER SIDEWALK AT DESIGN POINT 30 ' WEIR COEF. ' 3.000 STA ELEV ' 0 0 41.71 101.0 41.14 140.0 40.77 154.0 40.95 170.0 41.19 1 ELEVATION DISCHARGE ' (feet)_ _(cfs) _ _- 40.77 0.00 ' 40.87 0.61 40.97 3.54 41.07 9.91 — I4.3C 5 @ EL' 4%1.09 Q1O0 41.17 20.55 y :Lout S o vt�P- S I opvA Lv- F02 600 a. , ' M Ax oar H CA= 1 ' Z 3 1 DETENTION POND SIZING r 1 29- 1 DETENTION POND SIZING BY FAA METHOD DEVELOPED BY JAMES C.Y. GUO, PHD, P.E. DEPARTMENT OF CIVIL ENGINEERING UNIVERSITY OF COLORADO AT DENVER EXECUTED ON 09-05-1995 AT TIME 08:19:08 tPROJECT TITLE: TYPE IN THE PROJECT TITLE **** DRAINAGE BASIN DESCRIPTION BASIN ID NUMBER = 5.00 BASIN AREA (acre)= 10.26 RUNOFF COEF = 0.55 ' *****DESIGN RAINFALL STATISTICS DESIGN RETURN PERIOD (YEARS) = 10.00 ' INTENSITY(IN/H R)-DURATION(IvM TABLE IS GIVEN DURATION 5 10 20 30 40 50 60 80 100 120 150 180 ' INTENSITY. 5.6 4.4 3.2 2.6 2.2 1.9 1.6 1.3 1.1 0.9 0.8 0.6 ' ***** POND OUTFLOW CHARACTERISTICS: MAXIMUM ALLOWABLE RELEASE RATE ='3.5 CFS ' OUTFLOW ADJUSTMENT FACTOR = .95 AVERAGE RELEASE RATE = 3.325 CFS ' AVERAGE RELEASE RATE = MAXIMUM RELEASE RATE * ADJUSTMENT FACTOR. ***** COMPUTATION OF POND SIZE ----------------------------------------------------- RAINFALL RAINFALL INFLOW OUTFLOW REQUIRED ' DURATION INTENSITY VOLUME VOLUME STORAGE MINUTE INCH/HR ACRE -FT ACRE -FT ACRE -FT 0.00 0.00 0.00 0.00 0.00 ' 5.00 5.60 0.22 0.02 0.20 10.00 4.40 0.34 0.05 0.30 15.00 3.81 0.45 0.07 0.38 20.00 3.22 0.50 0.09 0.41 25.00 2.91 0.57 0.11 0.46 30.00 2.60 0.61 0.14 0.47 ' 35.00 2.39 0.66 0.16 0.50 ' 25 40.00 2.18 0.68 0.18 0.50 45.00 2.02 0.71 0.21 0.50 50.00 1.85 0.72 0.23 0.30 55.00 1.74 0.75 0.25 0.50 60.00 1.62 0.76 0.27 0.49 65.00 1.54 0.78 0.30 0.49 70.00 1.46 0.80 0.32 0.48 75.00 1.38 0.81 0.34 0.47 ----------------------------------------------------- THE REQUIRED POND SIZE _ .5045704 ACRE -FT --eC- -10 geov- THE RAINFALL DURATION FOR THE ABOVE POND STORAGE= 45 MINUTES 26 DETENTION POND SIZING BY FAA METHOD ' DEVELOPED BY JAMES C.Y. GUO, PHD, P.E. DEPARTMENT OF CIVIL ENGINEERING UNIVERSITY OF COLORADO AT DENVER ' EXECUTED ON 09-01-1995 AT TIME 09:11:38 ' PROJECT TITLE: WILDWOOD DETENTION POND DRAINAGE BASIN DESCRIPTION ' BASIN ID NUMBER = 5.00 BASIN AREA (acre)= 10.26 RUNOFF COEF = 0.55 ' ***** DESIGN RAINFALL STATISTICS DESIGN RETURN PERIOD (YEARS) = 100.00 ' INTENSITY(INMR)-DURATION(MIN) TABLE IS GIVEN DURATION 5 10 20 30 40 50 60 80 100 120 150 180 ' INTENSITY 9.0 7.2 5.2 4.2 3.5 3.0 2.6 2.1 1.7 1.5 1.2 1.0 ***** POND OUTFLOW CHARACTERISTICS: MAXIMUM ALLOWABLE RELEASE RATE = 8.3 CFS ' OUTFLOW ADJUSTMENT FACTOR = .95 AVERAGE RELEASE RATE = 7.885 CFS ' AVERAGE RELEASE RATE = MAXIMUM RELEASE RATE * ADJUSTMENT FACTOR. ***** COMPUTATION OF POND SIZE ----------------------------------------------------- RAINFALL RAINFALL INFLOW OUTFLOW REQUIRED DURATION INTENSITY VOLUME VOLUME STORAGE MINUTE INCH&M ACRE -FT ACRE -FT ACRE -FT 0.00 0.00 0.00 0.00 0.00 ' 5.00 9.00 0.35 0.05 0.30 10.00 7.20 0.56 0.11 0.46 15.00 6.19 0.73 0.16 0.56 20.00 5.18 0.81 0.22 0.59 ' 25.00 4.68 0.92 0.27 0.64 30.00 4.17 0.98 0.33 0.65 35.00 3.84 1.05 0.38 0.67 ' ' 27 ' 40.00 3.50 1.10 0.43 0.66 45.00 3.25 1.15 0.49 0.66 ' 10.00 3.00 1.18 0.54 0.63 55.00 2.80 1.21 0.60 0.61 60.00 2.61 1.23 0.65 0.58 65.00 2.47 1.26 0.71 0.55 ----------------------------------------------------- THE REQUIRED POND SIZE _ .6718576 ACRE -FT 100 ' THE RAINFALL DURATION FOR TIM ABOVE POND STORAGE= 35 MINUTES fl [] r 1 23 ' RBD, Inc., Engineering Consultants Wildwood Townhomes Detention Pond Area -Capacity Ratinq Curve ' Cumulative Elev Area Area Storage (ft) ( ------------------ -- (ac) (ac-ft) ----- --- ' 4937.5 0 4938.0 1,917 4939.0 15,682 4940.0 291011 4941.0 40,685 1 ' j 0.8 c0 CU 0.6 00.4 CU (n 0.2 0 ' 4937 ' Area m Capacity MIffiIIII:1 ---------------------- V = d/6"(A+4ABm+B) 0.00 0 0.04 0.01 @ _ 4-9 39, f, 3 0.36 0.211- 0.67 0.73"� v 00 = 0 (07 AL- PTO wst-L = 49 39.1 iz 0.93 1.53 4938 4939 4940 4941 Stage (ft elevation) w v�- U w U lQ d M A ' 29 05-Sep-95 RBD INC. ENGINEERING CONSULTANTS WEIR SECTION FLOW DATA WILDWOOD TOWNHOMES WEIR OUTLET WEIR COEF 3.000 STA ELEV 0.0 41.00 0.0 39.63 2.2 39.63 2.2 37.47 2.6 37.47 2.6 39.63 4.8 39.63 4.8 41.00 ELEVATION DISCHARGE (feet) (cfs) --------- 37.47 --------- 0.00 37.67 0.09 37.87 0.27 38.07 0.49 38.27 0.75 38.47 1.05 38.67 1.38 38.87 1.74 39.07 2.13 39.27 2.54 39.47 2.97 39.67 3.53 39.87 5.46 40.07 8.25 40.27 11.68 40.47 15.62 40.67 20.01 40.87 24.81 Program uses weir equation Q = CLH'n ED STORM DRAINAGE DESIGN AND TECHNICAL.CRITERIAI TABLE ',401 1 WEIR FLOW COEFFICIENTS SHAPE Sharp.Crested ' ' Projection Ratio (H/P = 0.4) Projection Ratio (H/P = 2.0) ' Broad Crested W/Sharp U/S Corner W/Rounded U/S Corner 1 Triangular Section A) Vertical U/S Slope 1:1 D/S Slope ' A:1-D15-S1gpe 10:1 D/S Slope ' B) 1:1 U/S Slope 1:1 D/S Slope 3:1 D/S Slope Trapezoidal Section i:l U/S St(,pe, 2:; "'/S Slope Road Crossings 'r Gravel., Paved 1 t y Y •. o� • Y J �Y ' c �o COEFFICIENT 3.4 4.0 2.6 3.1 3.8 3.2 2.9 3.8 3.5 3.4 3.0 3.1 COMMENTS HNC 1.0 H> 1.0 Minimum Value Critical Depth • M,.(L w ,u,YL"t"t w SCHEMATIC H>0.7 Hf H> 0.7 H> 0.7 uu s o/s H>0.5 r H >0' S Ws o/s u/s a/s H>1.0 H:;-1.0 . , i ADJUSTMENT FOR TAILWATER D! te: NOV 11 S 4 ''isFF Rr- t ii c•:: ' Book lU111t)tifly, 1701 ve51ly'11 la�J��ld11 Va0i5I uuacoU u. �)i: i.'i an.. 117r i 6 RBD, Inc., Engineering Consultants Wildwood Townhomes 607-006 Detention Pond Capacity -Discharge Rating Curve Elevation Storage (ft) (ac-ft) 4937.47 0.00 4938.00 0.01 4938.50 0.11 4939.00 0.21 4939.50 0.47 4940.00 0.73 4940.50 1.13 4941.00 1.53 Weir Q (cfs) 0.00 0.41 1.10 1.99 3.05 7.27 of= g,3cfs @ 4940. 06 16.28co 27.33 Storage: See Area -Capacity Rating Curve. Weir Q: See outflow weir rating curve. 20 T 15 �L 0 L 10 5 0 4937 4937.5 4938 4938.5 4939 4939.5 4940 4940.5 Stage (ft et) --a- Discharge , capacity 3Z 26-Oct-95 EROSION CONTROL CALCULATIONS n RBD, Inc. RAINFALL PERFORMANCE STANDARD EVALUATION ltFm_nna PROJECT: Wildwood Townhomes (AHASEI) STANDARD FORM CALCULATED BY: PPK DATE: 07/21/95 DEVELOPE ERODIBILIT Asb Lsb Ssb Lb Sb PS SUBBASIN ZONE (ac) (ft % ft 1 moderate 3.11 530 1.3 2 moderate 1.06 670 0.7 3 moderate 3.33 622 0.9 4 moderate 2.46 663 1.4 0-1 moderate 0.68 480 0.8 Total 10.64 600 1.1 78.9 Wftl IT112 WWWW[_W9151AL\ ][ Nl ► h Lb = sum(AiLi)/sum(Ai) = (3.11 x 530 +... + 0.68 x 480)/ 10.64 600 ft Sb = sum(AiSi)/sum(Ai) = (3.11 x 1.25 +... + 0.68 x 0.80)/ 10.64 1.1 % PS (during construction) = 78.9 (from Table 8A) PS (after construction) = 78.9/0.85 = 92.8 M RBD, Inc. RAINFALL PERFORMANCE STANDARD EVALUATION 4607-006 PROJECT: Wildwood Townhomes (PHAn>E Z) STANDARD FORM CALCULATED BY: PPK DATE: 07/21/95 DEVELOPE ERODIBILIT Asb Lsb Ssb Lb Sb PS SUBBASIN ZONE ac ft % ft 1 moderate 3.11 605 1.0 2 moderate 1.06 670 0.7 3 moderate 3.33 622 0.9 4 moderate 2.46 883 1.4 0-1 moderate 0.68 480 0.8 Total 10.64 673 1.0 79.4 EXAMPLE CALCULATIONS Lb = sum(AiLi)/sum(Ai) = (3.11 x 605 +... + 0.68 x 480)/ 10.64 673 ft Sb = sum(AiSi)/sum(Ai) = (3.11 x 1.00 + ... + 0.68 x 0.80)/ 10.64 1.0 % PS (during construction) = 79.4 (from Table 8A) PS (after construction) = 79.4/0.85 = 93.5 35 u RBD, Inc. EFFECTIVENESS CALCULATIONS PINT KITIIT..^ PROJECT: Wildwood Townhomes STANDARD FORM B CALCULATED BY: PPK DATE: 07/21/95 Erosion Control C-Facto P-Facto Comment Number Method Value Value 4 Sediment/Basin Trap 1 0.5 installed at beginning of construction 5 Straw Bale Barrier 1 0.8 placed at swales 6 Gravel Filter 1 0.8 placed at inlets 8 Silt Fence Barrier 1 0.5 placed at outlets 9 Asphalt/Concrete Pavement 0.01 1 19 Established Grass Ground Cover- 100% 0.02 1 existing and undisturbed 38 Gravel Mulch 0.05 1 used on Timberwood Drive 39 Hay or Straw Dry Mulch (1-5% slope) 0.06 1 apply in detention pond area SUB PS AREA BASIN % ac Site 78.9 10.64 SUB SUB AREA Practice C"A P'A Remarks BASIN AREA ac DURING CONSTRUCTION (PHASE 1) 1 Total 3.11 Grassed Cover 3.11 19 0.06 3.11 Established Grass Ground Cover- 100% Remain. 0.00 5 0.00 0.00 Straw Bale Barrier 2 Total 1.06 Grassed Cover 0.70 19 0.01 0.70 Established Grass Ground Cover - 100% Impervious 0.15 9 0.00 0.15 Asphalt/Concrete Pavement Remain. 0.21 8 0.21 0.11 Silt Fence Barrier 3 Total 3.33 Grassed Cover 0.60 19 0.01 0.60 Established Grass Ground Cover - 100% Remain. 2.73 4 2.73 1.37 SedimenUBasin Trap 4 Total 2.46 Grassed Cover 0.30 19 0.01 0.30 Established Grass Ground Cover - 100% Remain. 2.16 39 0.13 2.16 Hay or Straw Dry Mulch (1-5% slope) 0-1 Total 0.68 Impervious 0.35 9 0.00 0.35 Asphalt/Concrete Pavement Remain. 0.33 39 0.02 0.33 Hay or Straw Dry Mulch (1-5% slope) Cnet = 13.11 x0.02+,,,+0.33x0.06]/0.68 = 0.30 Pnet = 0.8x[3.11 x1.00+„ +0.33x1.00]/0.68 0.69 EFF = (1-C`P)100 = (1-0.30'0.69)100 = 79.34 > 78.9 (PS) Assume paving not constructed within 6 weeks; use gravel inlet filters at aA-efes c0nGPG1c 61de in ets & silt fence at swales & downstream perimeters. r2 I.L. cu/VCvT G RBD, Inc. 1 1 1 1 EFFECTNENESS CALCULATIONS "i:3�ffid�b: PROJECT: Wildwood Townhomes STANDARD FORM B CALCULATED BY: PPK DATE: 07/21/95 Erosion Control C-Facto P-Factor Comment Number Method Value Value 4 Sediment/Basin Trap 1 0.5 installed at beginning of construction 5 Straw Bale Barrier 1 0.8 placed at swales 8 Silt Fence Barrier 1 0.5 placed at outlets 9 Asphalt/Concrete Pavement 0.01 1 20 Sod Grass 0.01 1 placed in Phase 1 38 Gravel Mulch 0.05 1 used on Timberwood Or and west p. lot 39 Hay or Straw Dry Mulch (1-5% slope) 0.06 1 apply in detention pond area SUB PS AREA BASIN % ac Site 79.4 10.64 SUB SUB AREA Practice C'A P'A Remarks BASIN AREA ac DURING CONSTRUCTION (PHASE 2) 1 Total 3.11 Impervious 0.00 9 0.00 0.00 Asphalt/Concrete Pavement Area to be paved 0.93 38 0.05 .. 0.93 Gravel Mulch Remain. 2.18 4 2.18 1.09 Sediment/Basin Trap 2 Total 1.06 Sod Cover 0.20 20 0.00 0.20 Sod Grass Impervious 0.35 9 0.00 0.35 AsphalUConcrete Pavement Remain. 0.51 38 0.03 0.51 Gravel Mulch 3 Total 3.33 Impervious 1.63 9 0.02 1.63 Asphalt/Concrete Pavement Sod Cover 1.14 20 0.01 1.14 Sod Grass Remain. 0.56 4 0.56 0.28 Sediment/BasinTrap 4 Total 2.46 Impervious 0.38 9 0.00 0.38 Asphalt/ConcretePavement Sod Cover 1.78 20 0.02 1.78 Sod Grass Remain. 0.30 4 0.30 0.15 Sediment/Basin Trap 0-1 Total 0.68 Impervious 0.53 9 0.01 0.53 Asphalt/Concrete Pavement Remain. 0.15 39 0.01 0.15 Hay or Straw Dry Mulch (1-5% slope) Cnet = 10.004.01+„ +0.15x0.061/0.68 = 0.30 Pnet = 0.8x[0.00x1.00+,,,+0.15xl.00]/0.68 = 0.69 EFF = (1-C"P)100 = (1-0.30-0.69)100 = 79.50 > 79.4 (PS) Assume paving not constructed within 6 weeks; use gravel inlet filters at eN area Lp7C`CfC SIC�e� inlets & silt fence at swales & downstream perimeters. 37 ' RBD, Inc. ' EFFECTIVENESS CALCULATIONS ' #607-006 1 PROJECT: Wildwood Townhomes STANDARD FORM B CALCULATED BY: PPK DATE: 07/21/95 Erosion Control C-Facto P-Facto Comment Number Method Value Value 9 Asphalt/Concrete Pavement 0.01 1 paved and constructed 14 Established Grass Ground Cover - 50% 0.08 1 SUB PS AREA BASIN % ac Site 93.5 10.64 SUB SUB AREA Practice C " A P' A Remarks BASIN AREA ac AFTER CONSTRUCTION 1 Total 3.11 Impervious 1.73 9 0.02 1.73 Asphalt/Concrete Pavement Remain. 1.38 14 0.11 1.38 Established Grass Ground Cover - 50% 2 Total 1.06 Impervious 0.50 9 0.01 0.50 Asphalt/Concrete Pavement Remain. 0.56 14 0.04 0.56 Established Grass Ground Cover-50% 3 Total 3.33 Impervious 1.85 9 0.02 1.85 Asphalt/Concrete Pavement Remain. 1.48 14 0.12 1.48 Established Grass Ground Cover-50% 4 Total 2.46 Impervious 0.38 9 0.00 0.38 Asphalt/Concrete Pavement Remain. 2.08 14 0.17 2.08 Established Grass Ground Cover- 50% 0-1 Total 0.68 Impervious 0.53 9 0.01 0.53 Asphalt/Concrete Pavement Remain. 0.15 14 0.01 0.15 Established Grass Ground Cover-50% C net = [1.73x0.01 +.. +0.53x0.01 ]/0.68 = 0.05 Pnet = [1.73x1.00+...+0.53x1.00]/0.68 = 1.00 EFF = (1-C-P)100 = (1-0.05-1.00)100 = 95.28 > 93.5 (PS) • RBD, Inc. CALCULATED BY: , PPK EROSION CONTROL CONSTRUCTION SEQUENCE SEQUENCE FOR 1995 ONLY Indicate by use of a bar line or symbols when erosion control measures will be installed. Major modifications to an approved schedule may require submitting a new schedule for approval by the City Engineer. YEAR( 96 'STRUCTURES: INSTALLED BY VEGETATION/MULCHING CONTRACTOR ' DATE SUBMITTED MAINTAINED BY APPROVED BY CITY OF FORT COLLINS ON 39 u IRBD, Inc. 1 I t 1 1 EROSION CONTROL COST ESTIMATE PROJECT: Wildwood Townhomes #607-006 PREPARED BY: PPK DATE: 10/24/95 CITY RESEEDING COST Unit Total Method Quantity Unit Cost Cost Notes Reseed/mulch 10.64 ac $500 $5,320 See Note 1. Subtotal $5,320 Contingency 50% $2,660 Total $7,980 EROSION CONTROL MEASURES Unit Total Number Method Quantity Unit Cost Cost Notes 8 Silt Fence Barrier 1170 LF $3 $3,510 4 Sediment/Basin Trap 1 ea $150 $150 5 Straw Bale Barrier 3 ea $150 $450 38 Gravel Mulch 1.44 ac $1,350 $1,944 39 Hay or Straw Dry Mulch (1-5% slope) 0.33 ac $500 $165 Subtotal $6,219 Contingency 50% $3,110 Total $9,329 Total Secudty $9,329 ' Notes: 1. A<1 ac=$1300/ac; A=1-10 ac=$650/ac; A>10 ac=$500/ac. 1 L r I CHARTS, TABLES, AND FIGURES 0 0 1 7 L I L 41 I No Text DRAINAGE CRITERIA MANUAL RUNOFF 5C 3C t- 20 Z W U W 10 Z W a O 5 N W cc 3 O U 2 cc W F- WOMEN iAj ii i i UM MEoil �1111//����• .2 .3 .5 1 2 3 5 10 20 VELOCITY IN FEET PER SECOND FIGURE 3-2. ESTIMATE OF AVERAGE FLOW VELOCITY FOR USE WITH THE RATIONAL FORMULA. *MOST FREQUENTLY OCCURRING°UNDEVELQPED" LAND SURFACES IN THE DENVER REGION. REFERENCE: "Urban Hydrology For Small Watersheds" Technical Release No. 55, USDA, SCS Jan. 1975. 5-1-84 43 URBAN DRAINAGE & FLOOD CONTROL DISTRICT - DRCOG 0 0 4 4J a� O O w O 0 w O a w c� V C.) R' 14 4J � � � N M 0 3 O o c4- V w V N N o O m O z C's \ o 00 (D Nt NON O 00 CO d- N 00 m rn rn rn 6 o DO DO 00 00 o 0 0 0 0 0 0 0 0 -4ua-cu4mfpv Moulnp WO ' Calculations for Curb Capacities and Velocities Major and Minor Storms 'per City of Fort Collins Storm Drainage Design Criteria RESIDENTIAL w/ 61, Vertical curb and gutter Prepared by: R8D, Inc. 0 is for one side of the road only November 23, 1993 ' V is based on theoretical capacities Area = 3.37 sq.ft. Area = 18.495 sq.ft. 'Minor Storm : Major Storm Slope Red. • Minor • C V Major • G V (X). :Factor : X : (cfs) (fps) : X : (cfs) (fps) '0.40 0.50 : 129.87 : 4.11 2.31 . 647.33 20.47 : 1.41 . 0.50 : 0.65 129.87 : 5.97 : 2.59 : 64733 • 29.75 1.58 : 0.60 : 0.80 : 129.87 : 8.05 2.83 : 647.33 : 40.11 1.73 : �- '0.70 : 0.80 : 129.87 : 8.69 3.06 : 647.33 43.33 : 1.87 : 0.80 : 0.80 : 129.87 : 9.29 3.27 : 647.33 : 46.32 2.00 : 0.90 0.80 : 129.87 : 9.86 3.47 : 647.33 : 49.13 2.12 : 1.00 0.80 : 129.87 : 10.39 3.66 : 647.33 : 51.79 2.24 : 1.25 0.80 : 129.87 : 11.62 4.09 : 647.33 : 57.90 2.50 : 1.50 0.80 : 129.87 : 12.72 : 4.48 : 647.33 : 63.43 : 2.74 : 1.75 0.80 : 129.87 : 13.74 4.84 : 647.33 : 68.51 2.96 : 2.00 0.80 : 129.87 : 14.69 5.17 : 647.33 : 73.24r. 3.16 : 2.25 : 0.78 : 129.87 : 15.19 5.49 : 647.33 : 75.74 : 3.35 : 2.50 : 0.76 : 129.87 : 15.61 5.78 : 647.33 : 77.79 : 3.53 : '2.75 : 0.74 : 129.87 : 15.94 6.07 : 647.33 : 79.44 : 3.71 : 3.00 0.72 : 129.87 : 16.20 6.34 : 647.33 : 80.73 : 3.87 : 3.25 0.69 : 129.87 : 16.15 : 6.60 : 647.33 : 80.52 : 4.03 : 3.50 0.66 : 129.87 : 16.04 : 6.84 : 647.33 : 79.93 : 4.18 : '3.75 0.63 : 129.87 : 15.84 : 7.08 : 647.33 : 78.97 : 4.33 : 4.00 0.60 : 129.87 : 15.58 : 7.32 : 647.33 : 77.68 : 4.47 : 4.25 0.58 : 129.87 : 15.53 : 7.54 : 647.33 : 77.40 : 4.61 : '4.50 0.54 : 129.87 : 14.88 : 7.76 : 647.33 : 74.15 : 4.74 : 4.75 0.52 : 129.87 : 14.72 : 7.97 : 647.33 : 73.36 : 4.87 : 5.00 0.49 : 129.87 : 14.23 : 8.18 : 647.33 : 70.93 : 5.00 : 5.25 : 0.46 : 129.87 : 13.69 : 8.38 : 647.33 : 68.23 : 5.12 : 5.50 : 0.44 : 129.87 : 13.40 : 8.58 : 647.33 : 66.80 : 5.24 : 5.75 : 0.42 : 129.87 : 13.08 : 8.77 : 647.33 : 65.19 : 5.36 : 6.00 : 0.40 : 129.87 : 12.72 : 8.96 : 647.33 : 63.43 : 5.48 : 1 1 4-5 No Text RWINC Engineering Consultants CLIENT` 17"l 011—H T:7C>1> C-1 = 1 3 -�l JOBNO. PROJECT CALCULATIONS FOR Or"'I ^p MADE BY Eb(2- DATE CHECKED BY_ DATE —SHEET— OF — - - it _LJ! T- L-T- i i T ;If 7 T if I U + V 7 L7 7 f T 1-7 r C>V. E=—� J--- -:- A P FE-JI 4- ir -7, ­17 4 A . . . . . . . . . . . LI. f fit!' 4 .7- T H I t 4 m..4-4 - + 4 L 4 c"', ..... ..... ..... ----- - ........ • . .. . .. .... I ,q7