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HomeMy WebLinkAboutDrainage Reports - 06/30/1999Fina! AwrnyM Repof U DRAINAGE INVESTIGATION for HEART OF THE ROCKIES CHRISTIAN CHURCH located on Lot l., Block 1 of Heart of the Rockies Second Subdivision, Fort Collins, Colorado Prepared for: ARCHITECTURE ONE 150 East 29th Street, Suite 200 Loveland, Colorado 80538 April 1998 Revised: June 29, 1999 Project No. GRD - 282 - 98 Prepared By: MESSNER Engineering. Inc. _ -150 East 29th Street, Suite 238 Loveland, Colorado 80538 Telephone: (9M 661"-2221 r .i [1 1 1 Engineering, Inc. Project No. GRD - 282 - 98 Revised: June 29, 1998 Mr. Alan Hauser, Architect ARCHITECTURE ONE, Architects and Planners,. P.C. 150 East 29th Street, Suite 200 Loveland,Colorado 80538 Dear Mr. Hauser, The enclosed revision to the report addresses concerns expressed. by the City. of Fort Collins staff and represents the results of the drainage investigation for the proposed Heart of the Rockies Christian Church, Fort. Collins,. Colorado. This investigation was based upon the proposed site development plans; existing reports and plans for other developments nearby; on -site observations; and available topographic information. The investigation was performed according to the criteria established in the City of Fort Collins"'Storm Drainage Design Criteria and Construction -Standards." Thank you for the opportunity to be of service. If you should have any questions, please feel free to contact this office. Respectfully Submitted, M E S S N EkMain eerine. Inc. Dennis R. Messner, President DRM/mkm ' Enclosures It Civil Engineering Consultants 150 E. 29th Street, Suite 238 Loveland, Colorado 80538 (970) 663-2221 TABLE OF CONTENTS Letter of Transmittal Table of Contents Scope Site Description Existing Conditions Proposed Development Erosion Control Conclusions and Recommendations References i ii 1 1 3 4 5 5 EXHIBITS Vicinity Map Existing Conditions Exhibit Proposed Conditions Exhibit Grading and Drainage Plan Calculations ii 1 SCOPE 1 11 1 1 11 The following report represents the results of a drainage investigation for the proposed facilities. including: structure, landscaped grounds, access drives and associated parking lot for the Heart of the Rockies Christian Church. The facility is to be located on Lot 1, Block 1 of the Heart of the Rockies Second Subdivision, Fort Collins, Colorado. The investigation was performed for Architecture One, Architects and Planners, P.C., the project architects. The purpose of this investigation is to determine the effects of the proposed facility on the area's existing drainage conditions and to determine the needed drainage improvements, if any. The conclusions and recommendations presented in this report are based upon the proposed site development plan; grading and drainage construction plans and reports for existing developments in the vicinity of the project site; on -site observations; and the available topographic information. The analysis was performed according to the City of Fort Collins' "Storm Drainage Design Criteria and Construction Standards." SITE DESCRIPTION The site is considered to be irregular in shape and contains approximately 11 acres. The site's maximum north -south dimension is approximately 640 feet and its maximum west -east dimension is approximately 880 feet. The site is located in the "FOSSIL CREEK DRAINAGE BASIN". The site is not located within a designated floodway or flood plain. EXISTING CONDITIONS The area surrounding the site is either developed or in the process of being developed. Brittany Street borders the site along its western and northern boundaries. The area on the opposite side of Brittany Street is comprised of single-family residential subdivisions. The western most area is the Brittany Knolls First Filing and the eastern portion of the adjacent residential subdivision is the Brittany Knolls Second Filing. A portion of the surface run-off from this area flows to the south and east to Brittany Street. The drainage facilities that intercept and direct surface run-off from the area to the west and north are a combination of the Brittany Street street improvements and a piped storm drain system. The storm drain system begins at the intersection of Brittany Street and Courtney Circle and runs along Brittany Street easterly to Lemay Avenue. The storm drain pipe then runs north along the west side of Lemay Avenue approximately 650 feet until it discharges into the developed portion of the Fossil Creek drainage course that crosses Lemay Avenue at this point. 1 I [1 EXISTING CONDITIONS (continued) Lemay Avenue borders the site along its eastern boundary. The area on the opposite side of Lemay Avenue is comprised of residential developments known as Paragon Point. The run-off generated in the Paragon Point development that is opposite the site drains to the east toward the drainage course that flows from Northwest to Southeast through the Paragon Point. Trilby Road borders the site along its southern boundary. The area on the opposite side of Trilby Road is comprised of residential developments. The run-off generated in the development to the south of Trilby Road drains to a detention facility located at the southwest corner of Trilby Road and Lemay Avenue. The outfall from the detention facility is to the east along the south side of Trilby Road until it discharges into the natural drainage course located approximately 500 feet east of Lemay Avenue. The area located to the East of Lemay Avenue and South of Trilby Road drains toward the natural drainage course located to the east and away from the site. A moderate stand of grasses is the predominant ground cover on the site. Trees and shrubs have been established along Brittany Street to provide a landscaped boarder for the site. The ground surface generally slopes from West to East. The surface slopes of the site range from 4 % to 6 % over the majority of the site. The area immediately west of Lemay Avenue is the flattest area on the site. The slopes in this area range from 1% to 2%. A constructed drainage swale is situated at the eastern boundary of the site adjacent to Lemay Avenue. The swale intercepts surface run-off from the site. The intercepted run-off is directed northerly in the swale to a 21" diameter reinforced concrete pipe. The 21" pipe entrance is located approximately 25 feet south of Brittany Street and 30 feet west of Lemay Avenue. The run-off enters the 21" pipe through a manufactured flared end section that is situated so that the pipe invert matches the bottom of the swale. The 21" pipe continues northerly along the west side of Lemay Avenue for approximately 200 feet where it discharges into a 30" diameter pipe. The 30" pipe continues northerly for approximately 500 feet where it discharges into the existing Fossil Creek drainage course. The run-off that is generated on the streets adjacent to the site is directed on the existing pavement surface and along existing curb and gutter to the northeast corner of the site. A portion of the street flow generated along Brittany Street is intercepted by storm drain inlets situated along the southern curb line of Brittany Street. The inlets are a part of the storm drain pipe system that has been previously described. The surface run-off that reaches the northeast corner of the site flows northerly along the west curb line of Lemay Avenue for approximately 600 feet where it discharges into the existing drainage course. 2 I I ' EXISTING CONDITIONS (continued) ' The existing street flow capacity has been reviewed under previous drainage investigation studies for this area. In particular, refer to "Supplemental to the Final Drainage Study for Brittany Knolls P.U.D. Filing 2" prepared by Lidstone - Anderson, Inc. dated May ' 1992. PROPOSED DEVELOPMENT The foot -print area for the proposed structure will be approximately 7,100 square feet. The proposed paved area is to be approximately 20,315 square feet of walkways, access drive and parking lot. The balance of the site will be a combination of intense landscaping around the structure and drought tolerant grasses in the undeveloped open area. ' The proposed grading and drainage plan is designed to be able to conform with the ' existing slope and grades as closely as possible. Virtually all of the improved .site area will drain onto Lots 1 and 2 of the Heart of the Rockies Second Subdivision and will not impact the surrounding area. The run-off from the proposed structure and parking area is ' to be routed to a shallow grassed settling basin and then discharge into the existing swale located adjacent to Lemay Avenue. The settling basin is recommended in order to allow suspended solids to settle out of the run-off during minor storm low flow events. This may cause short term ponding and will require some additional maintenance, but should not be a nuisance situation. The previous drainage investigations for the Brittany Knolls subdivisions have established that due to the site's proximity to the major storm ' outfall and that there is available capacity within the existing storm drain pipe, on -site detention is not recommended. Future expansion of the facility may require that ' incorporation of on -site detention is incorporated with the added site development due to the limited capacity of the existing facilities. ' The site has been considered as two sub -basins. Sub -basin "A" contains all of the area that will drain from the site into the existing 21" diameter pipe located at the Northeast corner of the site. Sub -basin "A" has been further divided into three points of ' concentration in order to identify flow rates for design purposes. Sub -basin °B" is that portion of the site that contains the surrounding streets. the run-off generated on the streets and the minor adjacent landscaped area is routed to the East and North as previously outlined in the Existing Conditions. 1 3 .1 ' EROSION CONTROL ' The "Soil Survey of Larimer County Area, Colorado" prepared by the U.S. Department of Agriculture, Soil Conservation Service, indicates that the surface soils consist of a Tassel sandy loam. ' The "Soil Survey" identifies the run-off potential as medium to rapid, the hazard of water ' erosion as severe and the hazard of wind erosion as moderate. Erosion control considerations have been made based upon the short term, i. e., during ' construction activities and the long term, through the life of the facility. The long term measures incorporated to eliminate erosion are 'the proposed methods and materials to be used to provide a surface covering for the driveways, parking areas, walkways and the ' landscaped open areas. The structure and hard surfaced areas will also provide a deterrent to erosion. The landscape plantings and re -seeding of any disturbed open area ' will provide a combination of plantings and ground covers to deter erosion. The short term erosion control method to be incorporated into the construction ' requirements for the project is the placing of a "Straw Bale Filter" at the proposed settling basin outlet and "Silt Fence" at the downhill perimeter of the site. These have been specified in order to prevent debris and sediment from flowing from the site onto the ' adjacent property and into the pond. Wind erosion control measures have not been recommended for the site. The site area is relatively small and will be open and subject to wind action for an extremely short time. The building foundations, slabs and gravel surfacing will effectively act as a deterrent to wind erosion. 4. 11 ' CONCLUSIONS AND RECOMMENDATIONS ' 1. The proposed development will retain the existing drainage patterns. 2. The site is located in the FOSSIL CREEK DRAINAGE BASIN. The site is not located within a designated floodway or flood plain. ' 3. Water quality measures such as the proposed settling basin will help to prevent suspended solids in the storm run-off from entering the receiving drainage course. ' The run-off from the site will be partially detained to the extent that the existing drainage swale located at the eastern border of the site will act to slow the rate of flow as it is discharged into the existing 21" storm drain outfall pipe. 1 4. 1 1 All development is to be performed in accordance with City of Collins' "Storm Drainage Design Criteria and Construction Standards". 5. The City of Fort Collins' Standards for temporary and permanent erosion control measures are recommended to be incorporated with the construction activities. Specifically, measures should be taken to control and prevent mud and debris from being washed or tracked onto the adjacent streets and into the existing storm drain system. The grading and drainage plan indicates that "Straw Bale Filter" and "Silt Fence" are to be used to prevent this. The completed construction of the structure and pavement along with the installation of landscaping will provide the means to control erosion over the life of the project site. REFERENCES: 1. City of Fort Collins "Storm Drainage Design Criteria and Construction Standards", dated May, 1984 and revised 1997. 2. "Final Drainage Report for Brittany Knolls Filing No. 1, Phase 1 West of Brittany Street", prepared by: JR Engineering, Ltd., dated August 1994. 3. "Final Drainage Report for Brittany Knolls Filing No. 2", prepared by: TST, Inc. Consulting Engineers, dated May 1992. 4. "Supplemental to the Final Drainage Report for Brittany Knolls P.U.D.Filing 2", prepared by: Lidstone -Anderson, Inc., dated May 1992. E Engineering, Inc. Project No. GRD - 282 - 98 June 11, 1999 Basil Y. Harridan, P. E. Stormwater Utility City of Fort Collins 700 Vine Street Fort Collins, Colorado 80522 - 0580 Re: Heart of the Rockies Christian Church, Fort Collins, Colorado Dear Mr. Hamdan, My opinion of cost for the temporary erosion control measures to be utilized during the project construction period is: 1. Silt Fence 1,350 L.F. @ $1.42/L.F. _ $1,917.00 2. Straw Bale Dike 10 Each @ $63.00/Each = $ 630.00 3. Vehicle Tracking Pad Lump Sum = $ 535.00 4. Seeding 44,380 S.F. @ $0.0125/S.F. 554.75 TOTAL $3,636.75 With the required 150% contingency factor, the cost is (1.5 x $3,636.75) _ $5,455.13 The estimated cost to re -seed the entire site is: 1. Seeding 469,625 S.F. @ $0.0125/S.F. _ $5,870.31 Therefore, since the amount of surety is to be the greater of the two estimated costs, the amount to be secured is $5,870.31. If you should have any questions or desire additional information, please feel free to contact this office. MESSMER EAkineering, Inc. R. Messner, President Civil Engineering Consultants 150 E. 29th Street, Suite 238 Loveland, Colorado 80538 (970) 663-2221 i 1 1 1 1 1 1 1 1 1- 1 �� 1 1 1 1 I 1 1 1 [1 1 1 _. 1 1 1 1 11 1 1 Q c �- t,$ Mom. �� --st n c—j poAr _ _ -_.\` ' : `"•:'-. - _ ___ __ ` M strew S °� •I mcke St. •.v' _ - _ 7 c __ am�� 3 _ . .. c p pu.°L°rr� r PORT ER �-r i. �•�� Tu RE v7 TO4 ick • - r. h s _� Ot .. s Nvn Nn ran Na pr ^ 7r - Ce - 8@ ae u4100Q� JY' Pwim"nr Ct ^r ->" r- CA ," '. r �µ_., � �- c ,�.�_.. q "✓a•sirai ^`�• Tx fi_ � -�'� = 0 5 •' ry -^��. ¢ V �. ♦ .._ _. x ♦ ✓ta•<+i,c"-- �N^.r�: ��� B .a1.w•� - Clin.°L. i-i.-"'._`r`1 Slreei 31 Elm . _+..:_ "�� ,t,.-� ��,.'�`-'+S+ Q_ -r '� a °L: c° >•�....� ,�.,c� 8 _.'I E Tr Jbv ad � �v Roof •` 34 ��. rory Orne i r . � Rrk Or o a y'-'1 cA�..c.-r, .....)� � -.,-.� L Pi+ner lk Y U�•v.'/3�'''''•a.r+`„`�.---tea BarCsSwd; -:�.. E. ^'?�' �. �. KVu%r!h„� �'�" .'x-T+.,•ni .�„'� ° g enf '}i yn�i +iv+► . _ a "T' -> i `1'= �� � >�,�,:= ass 'r, r."rm En.• 'i ?r `F.:e`!-� .Y. 3'. ' i " Y T�•�+ � :. ' T:c �e� ;.•✓ � »�ti pvrok>d .cr. � - :yi „' l ..c lr�.--- .44 n-. +n�_- -.w,. fa._ ../ �ry� ♦�. au�iu Las .a :i �F jam_ -� '�b. s,. �'T_. '^"".•_ ..a� .•i Ta i. ;� �� r� a Som 'c•' � ryr,b�e�^.r1uy. : ma's ..if• S i'�•wr---r �. se°T '_4 �,�, v. fi .•• +.:••-r.-r `� -�' - �.L t -_ .�� .S± sx`- are!• 'itia-.d!_iF i T•'.•i M `_ .a�_77 VICINITY MAP for HEART OF THE ROCKIES CI3RISTIAN CHURCH FORT COLLINS, COLORADO Property Description: Lot 1, Block 1 of Heart of the Rockies Second Subdivision, Fort Coffins, Colorado 11 f 25 100 o 50 150 1' — 100' T� z � o� �A A OMO A z o 8 P W U Ww� .Qo p+ U W 04 E- O W G4 w z� aE a�w DATE: FEB. 19.1999 SCALE: AS NOTED DRAWN: M.S,R, CHKD: D.R.M. Project No. GRG-2B2-9B SHEET 1 of 2 25 100 mmommoll O 50 150 1. _ ILoa. tr \ l \ I dr Indgei -� Sw I 2.95 cc: t 1o.s1 ac. i cc. # i #1+#2+#3 Basi'A� I I I Basin 'A' \ \\ �e ing sin 7 1 ` ` 1 .26 a� Basi \ A I' I A i 6.4 ���III/ ,ll 11 ��l11 !I ►,��il I T— — -- \ 77 i i m z om © E-` O Um NW W ow [—i a w W H U I x H w E. � Qo z z E. ar4 w -J J U H F- DATE, FES.19.1999 SCALE: AS NOTED DRAWN: M.S.R. CHKD: D.R.M. Project No. GRG-282-98 SHEET 2 of 2 � � ����it1���CL�� 1 [1 1 DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project No: GRD-282-98 Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Date: Apr. 22, 1998 Location: Lott, Blki, Heart of the Rockies 2nd Subd., Fort Collins, CO By: D.R.M. Rev. 2/19/99 The site is located in the "Fossil Creek" Drainage Basin. RATIONAL METHOD Runoff Coefficients, "C" RATIONAL METHOD City of Fort Collins S.D.D.C.&C.S. (Table 3-3) Frequency Adjustment Factors Land Use Description "C" Building/Roofs 0.95 Drives and Walks 0.95 Gravel Surfaced 0.50 Undeveloped Open Areas 0.20 Grassed Landscaped Areas 0.15 Storm Return Period ears Freq. Factor Cf 2 1.00 5 1.00 10 1.00 100 1.25 EXISTING CONDITIONS: Existing Onsite Area Draining to Swale at East side of Site - Area'A' ' Building/Roof Area = 0 Sq.Ft. Street, Driveway and Walks Area = 1,065 Sq.Ft. 1 Gravel Surfaced Landscape Area = 0 Sq.Ft. ' Undeveloped Open Areas Area = 467,605 Sq.Ft. Landscaped Areas Area = 0 Sq.Ft. ' TOTAL SITE AREA Area = 468,670 Sq.Ft. = 10.76 Acres Avg. C = [(0.95 x 0)+(0.95 x 1,065)+(0.50 x 0)+(0.20 x 467,605)+(0.15 x 0)] / 468,670 1 Avg. "C" = 0.20 Time of Concentration ' Travel Time Overland, To, considered as sheet flow across site from West to East L = 600 ft. Elev. Diff.= 4940 - 4913 = 27.00 ft. ' Slope, S = 27 / 600 = 4.50 % ' To 2 = 1.87(1.1-CCf)L1"2'(S'13) =1.87(1.1-(0.20x1.00))(600'"2) / (4.50'rJ) = 24.92 minutes To ioo= 1.87(1.1-CCf)L'2 / (S'rJ) =1.87(1.1-(0.20x1.25))(60019 / (4.501/3) = 23.53 minutes ' 1 Page 1 of 11 1 1 1 1 1 1 1 DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project No: GRD-282-98 Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Date: Apr. 22, 1998 Location: Lott, BIk1, Heart of the Rockies 2nd Subd., Fort Collins, CO By: D.R.M. Rev. 2/19/99 EXISTING CONDITIONS: (continued) Travel Time in Swale:, Ts L = 390 ft. Elev. Diff.= 4908 - 4905 = 3.00 ft. Slope, S = 3 / 390 = 0.77 % From Figure 3 - 2 @ Watercourse Slope, S = 0.8 % Flow Velocity = 1.4 ft. / sec. Ts = 390 / (1.4 x 60) = 4.64 minutes Tc 2 = To + Ts = 24.97 + 4.64 = 29.57 minutes Tc ioo = To + Ts = 23.58 + 4.64 = 28.17 minutes Rainfall Intensities based upon 30 minute Time of Concentration, Tc: 12 = 1.45 in./hr. I100 = 4.15 in./hr. AREA'A' Q = CIACf Q2 = 0.20 x 1.45 x 10.76 x 1.00 = 3.15 c.f.s. Qloo = 0.20 x 4.15 x 10.76 x 1.25 = 11.26 c.f.s. Existing Adjacent Street Area Draining to Northeast Comer of Site - Area 'B' Building/Roof Area = 0 Sq.Ft. Street, Driveway and Walks Area = 96,200 Sq.Ft. Gravel Surfaced Landscape Area = 0 Sq.Ft. Undeveloped Open Areas Area = 38,855 Sq.Ft. Landscaped Areas Area = 0 Sq.Ft. TOTAL SITE AREA Area = 135,055 Sq.Ft. = 3.10 Acres Avg. C = [(0.95 x 0)+(0.95 x 96,200)+(0.50 x 0)+(0.20 x 38,855)+(0.15 x 0)]] / 135,055 Avg. "C" = 0.73 Travel Time in Street, Ts: Elev. Diff.= 4941 - 4907 = 34.00 ft. L = 1430 ft. Slope, S = 34 / 1430 = 2.38 % From Figure 3 - 2 @ Watercourse Slope, S = 2.4 % Flow Velocity = 3.15 ft. / sec. Page 2 of 11 ' DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Project No: Date: GRD-282-98 Apr. 22, 1998 Location: Lott, BIk1, Heart of the Rockies 2nd Subd., Fort Collins, CO By: D.R.M. Rev. 2/19/99 ' EXISTING CONDITIONS: (continued) Ts = 1,430 / (3.15 x 80) = 7.57 minutes Travel Time in urbanized condition: / 180 + 10 = 1250/180 + 10 = 17.94 minutes USE 7.5 minutes as Tc 12 = 2.80 in./hr. I100 = 7.85 in./hr. ' AREA'B' Q = CIACf Q2= 0.73 x 2.80 x 3.10 x 1.00 = 6.37 c.f.s. ' Qfoo = 0.73 x 7.85 x 3.10 x 1.25 = 22.34 c.f.s. PROPOSED CONDITIONS: Onsite Area Draining to Inlet at Northeast side of Parking Lot - D. P. #1 Building/Roof Area = 3,705 Sq.Ft. Street, Driveway and Walks Area = 54,285 Sq.Ft. ' Gravel Surfaced Landscape Area = 0 Sq.Ft. Undeveloped Open Areas Area = 0 Sq.Ft. ' Landscaped Areas Area = 23,550 Sq.Ft. TOTAL SITE AREA Area = 81,540 Sq.Ft. = 1.87 Acres ' Avg. C = 3,705)+(0.95 54,285)+(0.50 0)+(0.20 0)+(0.15 23,550)1 / 81,540 [(0.95 x x x x x ' Avg. "C" = 0.72 Time of Concentration ' Travel Time Overland, To, considered as sheet flow across landscaped area at West side of site. L = 40 ft. Elev. DIM= 4940 - 4938 = 2.00 ft. ' Slope, S = 2 / 40 = 5.00 % ' To 2 = 1.87(1.1-CCOLIn(Sf/3) =1.87(1.1-(0.15x1.00))(4012)( 51/3) = 6.57 minutes To loo = 1.87(1.1-CCf)L�/2S1f3 =1.87(1.1-(0.15x1.25))(401/2)(511) = 6.31 minutes ' Travel Time Overland, To, considered as sheet flow across paved area at West side of site. L = 60 ft. Elev. Diff.= 4938 - 4935 = 3.00 ft. ' Slope, S = 3 / 60 = 5.00 1 Page 3 of 11 I 1 1 1 DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project No: GRD-282-98 Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Date: Apr. 22, 1998 Location: Lott, BIk1, Heart of the Rockies 2nd Subd., Fort Collins, CO By: D.R.M. Rev. 3/28/99 PROPOSED CONDITIONS: (continued) To 2 = 1.87(1.1-CCf)Lfn / (Sf�3)=1.87(1.1-(0.95 x 1.00)(60f12) / (5lr3) = 1.27 minutes To too= 1.87(1.1-M)1-1n / (S19=1.87(1.1 - 1.00) (6019 / (5' ) = 0.85 minutes Travel Time in Street, Ts: Elev. Diff.= 4935 - 4927 = 8.00 ft. L = 380 ft. Slope, S = 8 / 380 = 2.11 % From Figure 3 - 2 @ Watercourse Slope, S = 2.1 % Flow Velocity = 2.85 ft. / sec. Ts = 380 / (2.85 x 60) = 2.22 minutes Tc2 = 6.57 + 1.27 + 2.22 = 10.06 minutes Tcfoo = 6.31 + 0.85 + 2.22 = 9.38 minutes Flow time in urban condition: T = L / 180 + 10 = 480/180 + 10 = 12.67 minutes ' Rainfall Intensities based upon 10 minute Time of Concentration, Tc: 12 = 2.50 in./hr. 1100 = ' AREA'A' - D.P. #1 Q2 = 0.72 x 2.50 x 1.87 x 1.00 = Qloo=0.72x7.15x1.87x1.25 = 1 1 1 1 Proposed Onsite Area Draining to Northeast Comer of Site - D. P. #2 Building/Roof Area = 3,470 Sq.Ft. Street, Driveway and Walks Area = 1,210 Sq.Ft. Gravel Surfaced Landscape Area = 0 Sq.Ft. 7.15 in./hr. 3.36 c.f.s. 12.03 c.f.s. Undeveloped Open Areas Area = 148,380 Sq.Ft. Landscaped Areas Area = 11,450 Sq.Ft. TOTAL SITE AREA Area = 164,510 Sq.Ft. = 3.78 Acres Avg. C = [(0.95 x 3470)+(0.95 x 1210)+(0.50 x 0)+(0.20 x 148380)+(0.15 x 11450)) / 164510 Avg. "C" = 0.22 Page 4 of 11 1 DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project No: GRD-282-98 Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Date: Apr. 22, 1998 Location: Lott, BIk1, Heart of the Rockies 2nd Subd., Fort Collins, CO By: D.R.M. Rev. 3/28/99 PROPOSED CONDITIONS: (continued) Travel Time in Swale, Ts: Elev. Diff.= 4923.7 - 4909.0 = 14.70 ft. L = 350 ft. Slope, S = 14.7 / 350 = 4.20 % From Figure 3 - 2 @ Watercourse Slope, S = 4.2 % Flow Velocity = 3.1 ft. / sec. Ts = 350 / (3.1 x 60) = 1.88 minutes Time of Concentration = Tc#1 + T pipe + T swale Tc = 10 + 1.88 = 11.88 minutes Therefore, USE 12 minutes as Tc 12 = 2.30 in./hr. I100 = 6.60 in./hr. AREA'A' -D.P. #2 Q2 = 0.22 x 2.30 x 3.78 x 1.00 = 1.89 c.f.s. Qioo = 0.22 x 6.60 x 3.78 x 1.25 = 6.79 c.f.s. AREA 'A' - D.P. #1 + D.P. #2 CA@D.P.#1 + CA@D.P.#2 = (0.72 x 1.87) + (0.22 x 3.78) = 2.18 ac. Q2=2.18x2.30x1.00= 5.01 c.f.s. Qioo = 2.18 x 6.60 x 1.25 = 17.99 c.f.s. Undeveloped portion of onsite area Draining to Northeast Comer of Site - D.P. #3 Building/Roof Area = 0 Sq.Ft. Street, Driveway and Walks Area = 0 Sq.Ft. Gravel Surfaced Landscape Area = 0 Sq.Ft. Undeveloped Open Areas Area = 229,125 Sq.Ft. Landscaped Areas Area = 0 Sq.Ft. TOTAL SITE AREA Area = 229,125 Sq.Ft. = 5.26 Acres Avg. C = [(0.95 x 0)+(0.95 x 0)+(0.50 x 0)+(0.20 x 229,125)+(0.15 x 0)] / 229,125 Avg. "C"= 0.20 Page 5 of 11 I 1 DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project No: GRD-282-98 Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Date: Apr. 22, 1998 Location: Lott, Blkl, Heart of the Rockies 2nd Subd., Fort Collins, CO By: D.R.M. Rev. 2/19/99 PROPOSED CONDITIONS: (continued) Time of Concentration Travel Time Overland, To, considered as sheet flow across landscaped area at West side of site. L = 400 ft. Elev. Diff.= 4941 - 4922 = 19.00 ft. Slope, S = 22 / 400 = 4.75 % To 2 = 1.87(1.1-CCf)L1rz / (S1/3)=1.87(1.1-(020 x 1.00))(4001r2) / (4.75113) = 21.14 minutes To ioo = 1.87(1.1-CCf)LIrz / (S1/3)=1.87(1.1-(20 x 1.25))(4001/2) / (4.7519 = 20.30 minutes Travel Time, Ts: Elev. Diff.= 4922 - 4911 = 11.00 ft. L = 300 ft. Slope, S = 11 / 300 = 3.67 % From Figure 3 - 2 @ Watercourse Slope, S = 3.7 % Flow Velocity = 1.4 ft. / sec. Ts = 300/ (1.4 x 60) = 3.57 minutes Travel Time, Ts: Elev. Diff.= 4911 - 4909 = 2.00 ft. L = 100 ft. Slope, S = 2 / 100 = 2.00 % From Figure 3 - 2 @ Watercourse Slope, S = 2.0 % Flow Velocity = 1 ft. / sec. Ts = 100/ (1.0 x 60) = 1.67 minutes Travel Time, Ts: Elev. Diff.= 4909 - 4906.6 = 2.40 ft. L = 220 ft. Slope, S = 2 / 100 = 1.09 % From Figure 3 - 2 @ Watercourse Slope, S = 1.1 % Flow Velocity = 1.65 ft. / sec. Ts = 220/ (1.65 x 60) = 2.22 minutes T2 = 21.14 + 3.57 + 1.67 + 2.22 = 28.60 minutes Two = 20.30 + 3.57 + 1.67 + 2.22 = 27.76 minutes Therefore, USE 27.5 minutes as Tc 12 = 1.55 in./hr. AREA'A' - D. P. #3 1100 = Q2=0.20x1.55x5.26x1.00= Qioo=0.20x4.90x5.26x1.25 = 4.90 in./hr. 1.63 c.f.s. 6.44 c.f.s. Page 6 of 11 DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project No: GRD-282-98 ' Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Date: Apr. 22, 1998 Location: Lott, BIk1, Heart of the Rockies 2nd Subd., Fort Collins, CO By: D.R.M. Rev. 2/19/99 ' PROPOSED CONDITIONS: (continued) AREA IX - D.P. #1 + D.P. #2 + D.P. #3 n CA@D.P.#1+D.P.#2+D.P.#3 = (0.72 x 1.87+(0.22 x 3.78)+(0.20 x 5.26) = 3.23 ac. Tc = 12.5 min. from D.P.#1 + D.P.#2 02 = 3.23 x 2.30 x 1.00 = 7.43 c.f.s. 12 = 2.3 in. / hr. and Qloo = 6.60 in. / hr. Qioo= 3.23 x 6.60 x 1.25 = 26.65 c.f.s. 1 11 [1 Adjacent Street Area Draining to Northeast Comer of Site - Area 'B' - D.P. #4 Building/Roof Area = 0 Sq.Ft. Street, Driveway and Walks Area = 100,795 Sq.Ft. Gravel Surfaced Landscape Area = 0 Sq.Ft. Undeveloped Open Areas Area = 21,150 Sq.Ft. Landscaped Areas Area = 6,535 Sq.Ft. TOTAL SITE AREA Area = 128,480 Sq.Ft. = 2.95 Acres Avg. C = [(0.95 x 0)+(0.95 x 100,795)+(0.50 x 0)+(0.20 x 21,150)+(0.15 x 6,535)) / 128,480 Avg. "C" = 0.79 Time of Concentration does not change from Existing Conditions. Therefore, consider @ Tc = 7.5 minutes: 12 = 2.80 in./hr. lion = 7.85 in./hr. AREA 'B' - D.P. ft4 Q2= 0.79 x 2.80 x 2.95 x 1.00 = 6.52 c.f.s. Qioo = 0.79 x 7.85 x 2.95 x 1.25 = 22.86 c.f.s. Basin Design Point Area, A acre C Sum of CA Q2 c.f.s. Qroo c.f.s. "A" #1 1.87 0.72 1.35 3.37 12.03 "A" #2 3.78 0.22 0.83 1.91 6.86 "A" 1 #1 + #2 2.18 5.01 17.99 "A" #3 5.26 0.20 1.05 1.63 6.44 "A" #1 + #2 + #3 1 1 1 3.23 7.43 26.65 "B" #4 1 2.95 1 0.79 1 2.33 6.53 22.87 rays r Vi I i 1 [I 11 [I 1 DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project No: GRD-282-98 Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Date: Apr. 22, 1998 Location: Lott, BIM, Heart of the Rockies 2nd Subd., Fort Collins, CO By: D.R.M. Rev. 3/28/99 PROPOSED CONDITIONS: (continued) Determine if Rip Rap is needed at Swale: From previous calculation Swale Slope = 4.2 % and flow velocity = 3.1 ft./sec. Criteria Table 7-3 indicates that a "grass mixture" is permissible. Therefore, no rip rap required. Check size for curb outlet at Northeast comer of proposed parking lot. (D.P. #1) Q2 = 3.37 c.f.s. & Qtoo = 12.03 c.f.s. Consider as a curb opening inlet in sump condition. From Figure 5 - 2 Consider open "grassed" Swale as outfall: at 6" flow depth in curb yo / h = 6" / 6" = 1.00 Q / L = 1.1 c.f.s./cu.ft. with 4' curb opening, Q = 4 x 1.1 = 4.4 c.f.s. Reduction Factor for sump condition = 80% Q = 0.8 x 4.4 = 3.52 > 3.37 Therefore 4' curb opening required for flow at Q2. Flow at Qioo to overtop curb and flow overland to swa/e. 0 For Section A - A: "V "shaped channel with Side Slopes at 4 : 1 & Depth = 1.65 ft. Determine capacity at minimum Slope, S = 1.5 % Area = 10.89 sq. ft.. n = 0.06 R = 0.8 ft. Slope, S = 0.015 ft./ft. 186AR2/3S12 / n = 1.486 x 10.89 x 0.802r3 x 0.01512 / 0.060 = 28.51 c.f.s. Q1oo from Basin "A" at Design Point #1 + #2 = 17.99 c.f.s. Swale requires minimum of 1 foot freeboard or 133 % of design flow. 133 % Q1oo = 17.99 x 1.33 = 23.93 c.f.s. 28.51 > 23.93 Therefore, use swa/e with minimum 1.65 foot depth. Page 8 of 11 DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project No: GRD-282-98 Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Date: Apr. 22, 1998 Location: Lott, Blk1, Heart of the Rockies 2nd Subd., Fort Collins, CO By: D.R.M. Rev. 2/19/99 PROPOSED CONDITIONS: (continued) Check capacity of existing open "grassed" Swale along Lemay Avenue: For Section B - B: "Trapezoidal "shaped char Area = 26 sq. ft.. with 5 ft. Bottom, Side Slopes at 4 : 1 & Depth = 2 ft. n = 0.06 Determine capacity at minimum Slope, S = 1.1 % R = 1.21 ft. Slope, S = 0.011 ft./ft. 186ARz3V2 / n = 1.486 x 26.00 x 1.21M x 0.011112 / 0.060 = 76.59 c.f.s. Qioo from Basin "A" at Design Point #1 + #2 + #3 = 26.65 c.f.s. Swale requires minimum of 1 foot freeboard or 133 % of design flow. 133 % Qioo = 26.65 x 1.33 = 35.44 c.f.s. 76.59 >> 26.65 Therefore, existing swafe, OK n Basin"A" D.P.#1 + D.P. #2= Q2 = CIACf = 3.23 x I x 1.00 = 3.23 x I (in./hr.) Time min. Q2 c.f.s. Volume cu. ft. RELEASED c.f.s. VDI.Released cu. ft. Volume Det. cu. ft. 10 8.08 4,845 3.12 1,872 2,973 15 6.78 6,105 3.12 2,808 3,297 20 1 5.98 7,171 3.12 3,744 3,427 25 5.33 7,994 3.12 4,680 3,314 30 4.68 8,430 3.12 5,616 2,814 40 3.88 9,302 3.12 7,488 1,814 50 3.39 10,175 3.12 9,360 815 60 2.91 10,465 3.12 11,232 6 70 2.75 11,531 3.12 13,104 1,573 80 1 2.42 1 11,628 1 3.12 1 14,976 3,348 90 1 2.10 1 11,337 1 3.12 1 16,848 5,511 Therefore, a minimum storage volume of 3,427 cu. ft. is required for the settling basin. Page 9 of 11 LJ 1 DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project No: Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Date: Location: Lott, BIk1, Heart of the Rockies 2nd Subd., Fort Collins, CO By: PROPOSED CONDITIONS: (continued) DETERMINE OUTLET CONTROL SIZING FOR SETTLING BASIN: Refer to attached Figure 13 and Figure 5 - 3 for Outlet Sizing Detention Volume to be provided at 2 ft. depth = 3,600 cu. ft. = 0.083 ac. - ft. Depth = 2.0 feet From Figure 5 - 3 required "Area per Row" = 0.17 sq. in. Minimum of eight (8) holes per row is to be provided. Therefore, the size of each hole is: 0.17 / 8 = 0.02125 sq. in. per hole Try 1/8 in. diameter holes at 0.013 sq. in. per hole 0.17 / 0.013 = 13 hole per row with 1/8 in. dia. hole For pipe with 13 columns (holes per row) use 6 in. dia. pipe from Figure 13. DETERMINE PIPE SIZE FOR DISCHARGE FROM SITE: GRD-282-98 Apr. 22, 1998 D.R.M. Rev. 3/28/99 Refer to the "Supplement to the Final Drainage Report foot Brittany Knolls P.U.D. - Filing 2" (See Attached; From Table 3 the maximum capacity for the downstream receiving 30" dia. pipe is 29.0 c.f.s. From table 3 the maximum capacity of the 21" dia. pipe is 19.4 c.f.s. with a design discharge of 13.2 c.f.s. The estimate Qioo for the proposed site at Basin "A" D.P. #1 + D.P. #2 + D.P. #3 = 26.65 c.f.s. Therefore, ponding will occur in the Swale section adjacent to Lemay Avenue during the 100 Year Storm. n Basin"A" D.P.#1 + D.P. #2= Q2 = CIACf = 3.23 x I x 1.25 = 4.04 x I (in./hr.) Time min. Qioo c.f.s. Volume cu. ft. RELEASED c.f.s. Vol.Reieawd cu. ft. Volume Det. cu. ft. 10 28.87 17,321 13.20 7,920 9,401 15 24.23 21,802 13.20 11,880 9,922 20 21.00 25,194 13.20 15,840 9,354 25 18.57 27,859 13.20 19,800 8,059 30 16.96 30,523 13.20 23,760 6,763 Therefore, 9,922 cu. ft. of detention ponding volume is required in the Swale section adjacent to Lemay Av( Page 10 of 11 I ' DRAINAGE INVESTIGATION CALCULATIONS Client: ARCHITECTURE ONE Project No: GRD-282-98 Project: HEART OF THE ROCKIES CHRISTIAN CHURCH Date: Apr. 22, 1998 Location: Lott, Blk1, Heart of the Rockies 2nd Subd., Fort Collins, CO By: D.R.M. Rev. 3/28/99 ' PROPOSED CONDITIONS: (continued) DETERMINE DEPTH OF WATER IN SWALE FOR DETAINED VOLUME: ' Swale requires minimum of 1 foot freeboard or 133 % of design flow. ' Swale section is "trapezoidal" shaped with 5 foot bottom and 4 : 1 side slopes Swale bottom has 1.1 % slope ' Consider depth at 21" outlet pipe to be 3.5 feet Area, A = 66.5 sq. ft. Length of Swale at 1.1% and 3.5' depth = 3.5 / 0.011 = 318.2 ft. ' Volume = (Ai + A2) / 2 x L = (0 + 86.5) / 2 x 318.2 = 10,580 cu. ft. 10,580 > 9,922 Therefore Swale depth at 3.5 ft., OK 1 Check for Freeboard capacity: ' At 133% of required volume = 9,922 x 1.33 = 13,196 cu. ft. Consider depth with Freeboard to be 4.0 feet Area, A = 84 sq. ft. ' Length of Swale at 1.1 % and 4.0' depth = 4.0 / 0.011 = 363.6 ft. Volume= (Ai +A2)/2xL= (0 + 84)/2x363.6= 15,271 cu. ft. ' 15,271 > 13,196 Therefore freeboard at 4.0 ft, OK Page 11 of 11 No Text 1 1 1 1 1 1 1 1 1� 1 1 1 1 1 , DRAINAGE CRITERIA MANUAL 50 f- 20 z W U Ir w a 10 z W n O 5 W oNc 3 O U 2 cc W E- Q C? 1 5 .1 RUNOFF �■■■■1 11 WAWASI11111// ��■111 FA II FA ON •I r MINES 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 "UNDEVELOPED" LAND SURFACES IN THE DENVER REGION. REFERENCE: "Urban Hydrology For Small Watersheds' Technical Release No. 55, USDA, SCS Jan. 1975. 5 -1-84 URBAN DRAINAGE & FLOOD CONTROL DISTRICT 1.0 L 12 5 4 10 9 11 8 � 3 .8 C 6 10 F- U- F � � 2 9 O 4 t-= w i u. i 7 w 3 i' z 1.5 L N 2 O .6 7 'U E�%e'/ z 1.0 z 9 5 6 __ Example_Part a— J I'0 w —.8- ------ a- .8 5.5 0 N .6 U. .7 w w z u- .4 5 Z z, 4, I- _ w 0 .6 ? 4.5 z p .3 w u- .5 4 _ .2 z z o w '3 3.5 w W 4 r CL o_ w 1 w 0 0 u_ u_ 0 .08 o. 25 --- 3 a 06 ; 0 3 o z U. w w M .04 .25 2.5 = n. .03 a 3 U. .2 a .02 0 2 I— o_ o .15 .15 L .01 w 0 0 t Yo ►- _ a 1.5 .10 a=2" h Figure 5-2 NOMOGRPAH FOR CAPACITY OF CURB OPENING INLETS IN SUMPS. DEPRESSION DEPTH 2- Adapteo from Bureau of Public Roads Nomograph MAY 1984 5-10 DESIGN CRITERIA G. EXTENDED DETENTION (DRY) BASINS Threaded Cap Water Ouality Capture Volume''?"• Level (including 20% additional volume for sediment storage) tl Gravel (1.12'to 3" Rock) Around Perforated Riser 'd .Filler Fabric Water Ouall'ry (M Riser Pipe (See Dalai]) .., Nobs: 1. The outlet pipe "be sized to control •`::ai'::`.: L :q:7d overflow into the concrete riser. '•"�' . 2. Alternate designs include a Hydrobrake outlet (or orifice designs) as lo^9 as the hydreolic ppdomnarxs malCreeb tleb configuration. OUTLET WORKS NOT TO SCALE Notes: 1. Minimum number ol holes . 8 2. Minimum hole diameter . 1/8- dia i r 1.12' diameter Air _ Vent in Threaded Cap O O WaterOuality . • 4 Outlet Holes O O O ' 4 Ductile Iron or Q Steel Pipe c o WATER QUALITY ' RISER PIPE ' N OSCA Removable & Lockable ;�;•;y, Overflow Grate for :..•. Larger Storms Outlet Pipe—� :s Pit 3 tt) Size Base to Prevent Hydrostatic Uplift Maximum Number of Perforated Columns Riser Hole Diameter, in. _ Diameter 114- 12- 3/4- 1. (IN) 4 a 8 6 12 12 9 • •• 8 16 16 12 8 10 20 20 14 I 10 12 24 24 - 18 12 Hole Diameter Area of Hob In) Im.21 Its 0.013 114 0.049 - 3/8 0.110 112 0.196 516 0.307 314 0.442 718 0.601 1. 0.785 Figure 13. An example of a perforated riser outlet Rd: UDFCD (1992) t Aesthetics Aesthetics is what the public judges how "succesd-ul" or "useful" a detention basin is within the community. Although there are examples of unattractive basins, most new facilities are tastefully incorporated into the neighborhood Aesthetics is important! Using a landscape architect to assist with the design should always be considered ' Safety. For larger on -site basins and for regional facilities safety has to also include the structural integrity of the water impounding embankment. As discussed earlier, the embankment should be protected from catastrophic failure. In the United States dam failure is almost always judged as an absolute liability of its owner. Always consider this principle of common law when designing detention facilities. When the facility is in operation, safety concerns need to focus on flow ' velocities, water depths and how to keep the public from being exposed to high hazard areas. During dry weather periods safety is enhanced by minimizing the use of high vertical walls and steep side slopes. Outlets and inflow structures and adjacent area require special attention, and ASCE (1985) suggests the use of thorny shrub and the use of trash/safety racks at all outlet orifices, pipes and weirs. ' Page G-5 I 1 1 1 1 1 1 1 1 1 1 DRAINAGE CRITERIA MANUAL (V. 3) 10.( 6.( 4.( 2.1 11 m 0.6 m U CS 0 0.4 E m Cm0." T m 7 Q 2 0.' 3 0.( 0.1 rol STRUCTURAL BMPs FAR PA WQCV. 2-1 acre-feet' Row 1.75 in. PAP WHO. 0. 0.-02 0.04 0.06 0.10 0.20 . Required Area per Row (in.2 ) Source: Douglas County Sturm Drainage and Tedrnkal Criteria, 1986. FIGURE 5-3. WATER QUALITY OUTLET SIZING: DRY EXTENDED DETENTION BASIN WITH A 40-HOU9 DRAIN TIME OF THE CAPTURE VOLUME 9-1-1992 UDFCD G-s:/ RAINFALL PERFORMANCE STANDARD EVALUATION PROJECT: STANDARD. FORM A A/E-.4,e r VF y'N�' �oc. rcfe s �>�va ,t", L J�v:, COMPLETED BY: .MF'56A1E,< Ceyuxt• Js/e. C/-?�2rv}� DATE: DEVELOPED ERODIBILITY Asb Lsb Ssb Lb Sb M PS M SUBBA$IN ZONE (ac) (ft) M (feet) 'Ico.�' V 83,E MARCH 1991 8_14 DESIGN CRITERIA 1 1 1 1 1 1 I, EFFECTIVENESS CALCULATIONS PROJECT: r— 6A- 71le PAX Vw c, e V C .�, "W G STANDARD FORM B COMPLETED BY: DATE: /t' Erosion Control C-Factor P-Factor Method Value Value Comment /� %4w- r =vc L A00 /1 DO )PAvGsrn& e.p/ /400 J 144U FiGTS11lJ O•Sf� 1.1/1+k. n/nii.c %rw6C /),2.2 !JO MAJOR PS SUB AREA BASIN ($) BASIN (Ac) CALCULATIONS Cn3.;e 7$ //J,73' 3are Soi! - / 52 -A 3,79 = �ln� -/,27 =,38ac 04ve,ne n7� f, Z 7 c Alle e G. s s r, / 3 .0 C, CG:D 1 Y >,27 (�4 L. 13 .0 c. Z z:) r 7� 35 = o, OD �pl) j x ok MARCH 1991 8-15 DESIGN CRITERIA I CONSTRUCTION SEQUENCE PROJECT:. //5*IQ7— cF >Ra-ReE'eie�s — 2-'/" STANDARD FORM C SEQUENCE. FOR 19 f 9 ONLY COMPLETED BY: A&SW&+�< Gy�4 , JrYG DATE: /p - Z$ -5S by use of a bar line or symbols when erosion control measures will be installed. 'Indicate Major modifications to an approved schedule may require submitting a new schedule for approval by the City Engineer. ' YEAR /9ri 5 ! � ---------------MONTH -I ------- -------------------------------------------- OVERLOT GRADING i rr WIND EROSION CONTROL Soil Roughing ' Perimeter Barrier I Additional Barriers Vegetative Methods ' Soil Sealant Other 'RAINFALL EROSION CONTROL STRUCTURAL: I Sediment Trap/Basin ' Inlet Filters Straw Barriers i Silt Fence Barriers i Sand Bags ' Bare Soil Preparation Contour Furrows Terracing ' Asphalt/Concrete Paving Other VEGETATIVE: Permanent Seed Planting Mulching/Sealant ' Temporary Seed Planting Sod Installation Nettings/Mats/Blankets ' Other ----------------------------------------------------------------------------------------I STRUCTURES: INSTALLED BY MAINTAINED BY 'VEGETATION%MULCHING CONTRACTOR DATE SUBMITTED APPROVED BY CITY OF FORT COLLINS ON ' HOI/SF-C:1989 SUPPLEMENT TO THE FINAL DRAINAGE REPORT FOR BRITTANY KNOLLS P.U.D. FILING 2 PREPARED FOR: CITY OF FORT COLLINS STORMWATER UTILITY 235 MATTHEWS FORT COLLINS, CO 80521 PREPARED BY: LIDSTONE & ANDERSON, INC. 736 WHALERS WAY, SUITE F-200 FORT COLLINS, CO 80525 IN SUPPORT OF: TST, INC. 748 WHALERS WAY FORT COLLINS, CO 80525 MAY 81 1992 INTRODUCTION This supplement presents the results of a drainage evaluation of Brittany Knolls P.U.D. Filing 2. The evaluation consisted of the following: (a) a detailed review of the final drainage report for Brittany Knolls P.U.D. Filing 2 dated July, 1990 and prepared by Engineering Professional, Inc. (EPI) of Fort Collins, Colorado, and (b) preparation of revisions to the analysis documented by EPI in the July 1990 Final Drainage Report. This supplement consists of this text, 2 revised sheets illustrating the drainage plan for Filing 2, revised tables associated with the hydrologic analysis and design, and technical documentation for the analysis. Also enclosed with this supplement are copies of the initial ' and final submittals by EPI entitled "Final Drainage Report for Brittany Knolls P.U.D. Filing 2". ' GENERAL The overall master plan for Brittany Knolls P.U.D. was approved in 1987 and consisted of three initial residential phases and one commercial phase. In conjunction with the submittal and approval of the master plan, a final drainage study for Filing 1 was submitted and approved (Kellogg Engineering, Inc., September 29, 1986)..The final drainage study for ' Filing 2 was submitted by EPI in July of 1990 but was not formally approved. Hence, with the recent re -submittal of the Brittany Knolls P.U.D. Filing 2, the final drainage report prepared by EPI is hereby resubmitted with the revisions noted in the following paragraphs...:. DESIGN CRITERIA ' The drainage plan prepared by Lidstone & Anderson, Inc. (I.A) follows the guidelines set forth in the City of Fort Collins Storm Drainage Design Criteria and Construction Standards Manual (SDDC) dated May, 1984. To be consistent with the EPI final drainage report, the ' Rational Method was utilized for the hydrologic analysis with the minor and major storm events selected to be the 2-year and 100-year storms, respectively. Furthermore, procedures utilized by EPI to design storm inlets and storm sewers as well as evaluate the capacity of the proposed streets were also duplicated. DRAINAGE PLAN ' The drainage plan for Filing 2 identified eleven (11) subbasins which are impacted by the proposed development and increase the historic flows from the property. These subbasins ' are delineated on Sheets 1 and 2. It should be noted that the EPI Final Drainage Report identified two additional subbasins (presented as Subbasins L and M). These subbasins do not contribute to an increase in runoff associated with proposed development of Filing 2 and were not included in this analysis. The grading proposed for each lot is presented on the FHA grading plan in Sheets 3 and ' 4. This information along with data obtained from the previous drainage reports was ' 1 utilized to delineate drainage subbas ins and determine the flow paths for storm runoff. A discussion of the storm runoff from each subbasin follows. Subbasin A (Design Point 1) ' Subbasin A consists of 2.92 acres with a 2-year and 100-year peak discharge of 23 cfs and 8.9 cfs, respectively. The street capacity near Design Point 1 is 6.8 cfs and 13.4 cfs for the minor and major storms. Although a storm inlet is not necessary at ' this point, a 15-foot continuous grade inlet is recommended to alleviate potential flooding problems near Subbasins F (Design Point 6) and G (Design Point 7). 11 1 11 1 1 Subbasin B (Design Point 2) The 2-year and 100-year peak discharges at Design Point 2 are 5.8 cfs and 22.1 cfs, respectively. These peak discharges include the runoff from Subbasins A and B. After the reduction of the peak flows by the inlet at Design Point 1, the design discharges at Design Point 2 become 3.9 cfs and 16.9 cfs for the minor and major storms. At this point, the capacity of the street during the 100-year event is exceeded; consequently a storm inlet is needed. To reduce the potential for downstream flooding, a 15-foot continuous grade inlet is recommended.. Subbasin C (Design Point 3) Subbasin C consists of 4-53 acres which are distinctly separate from Subbasins A and B.. Runoff from this subbasin results in 2-year and 100-year peak discharges of 4.4 cfs and 16.6 cfs, respectively at Design Point 3. The street capacity at this location exceeds the peak runoff for both the minor and major storm events; however, a 15- foot continuous grade inlet is recommended at Design Point 3 to prevent downstream flooding. Subbasin D (Design Point 4) Design Point 4 includes the storm runoff from Subbasins A, B, C and D. The developed condition peak discharges at this location are 9.8 cfs and 37.4 cfs for the minor and major storms. After reduction by upstream inlets at Design Points 1, 2 and 3, the peak discharges at Design Point 4 become 2.1 cfs (2-year) and 13.3 cfs (100-year). Although these values are less than the capacity of the street, it is recommended that an additional 15-foot continuous grade inlet be installed at this location. Subbasin E (Design Point 5) Subbasin E consists of the northern half of Buchanan Street. The FHA grading plan does not permit contribution of runoff from Lots 18 to 29 which are immediately 0 I ' adjacent to the street. The runoff from this subbasin is estimated to be 0.6 cfs and 2.2 cfs, respectively for the minor and major storm events. These values are much ' less than the street capacity of 6.8 cfs (2-year) and 13.4 cfs (100-year); consequently, a storm inlet is not required at this location. ' Subbasin F (Design Point 6) Subbasins A, B, C, D and F contribute runoff to Design Point 6; these subbasins ' generate a peak discharge of 11.6 cfs and 445 cfs for the minor and major storms. Upstream inlets at Design Points 1, 2, 3 and 4 reduce the storm runoff at Design Point 6 to 23 cfs (2-year) and 12.6 cfs (100-year). The corresponding street capacity ' at this location is 6.0 cfs and 11.9 cfs; hence, a 10-foot continuous grade storm inlet is proposed for Design Point 6. Subbasin G (Design Point 7 Design Point 7 includes the storm runoff from Subbasins A, B, C D, F and G. The ' developed condition peak discharges at this location are 12.4 cfs and 47.2 cfs for the minor and major storms. After reduction by upstream inlets at Design Points 1, 2, 3 and 4, the peak discharges at Design Point 7 become 1.6 cfs (2-year) and 9.4:cfs ' (100-year). These values correspond to a street capacity' of 6.0 cfs and 11.9 cfs. - It is necessary to install a 10-foot sump inlet at this location to convey the runoff from the upstream subbasins to the open channel located north of Filing 2.:: It is ' recommended that a 10-foot sump inlet be installed. Subbasin H (Design Point 8) ' Similar to Subbasin E, this subbasin consists of the northern half of Buchanan Street. The combined peak discharges of Subbasins E and H at Design Point 8 are 0.8 cfs ' and 2.7 cfs, respectively for the minor and major storm events. These values correspond to a street capacity of 6.8 cfs and 13.4 cfs at this location; consequently, no storm inlet is necessary. ' Subbasin I (Design Point 9) ' Design Point 9 combines the runoff from Subbasins E, H and I and results in a peak discharge of 1.1 cfs and 3.8 cfs, respectively for the 2-year and 100-year storm events. The corresponding street capacity at this location is 6.0 cfs for the minor storm and ' 11.9 cfs for the major storm. To remove the runoff at Design Point 9, it is necessary to install a 5-foot sump inlet. 1 3 I ' Subbasin J D—ens rr Ioint 101 ' The runoff from Subbasin J is conveyed to Design Point 10. The peak discharge from this subbasin is 0.5 cfs and 1.9 cfs, respectively during the minor and major storm events. At this location, this runoff is combined with runoff contributed from ' Filing 1 in the amount of 10.0 cfs (2-year storm) and 39.3 cfs (100-year storm). An existing 10-foot Type R inlet has been installed at Design Point 10 to convey approximately 8.9 cfs (minor storm) and 18.5 cfs (major storm). from Filing 1; consequently, no contribution to the existing storm sewer has been assumed for the drainage plan for Filing 2. Alternatively, the runoff from Subbasin J will, be conveyed in Brittany Street. Bypass flows from Filing 1 contribute to the street flow ' within. Brittany Street in the amounts of 1.1 cfs and 20.8 cfs for the minor and major storms. The combined street flow at Design Point 10 (contributed from both Filing 1 and 2) is conservatively estimated to be 1.6 cfs (1.1 cfs + OS cfs) for the 2-year event and 22.7 cfs (20.8 cfs + 1.9 cfs) for the 100-year event. This corresponds to a street capacity of 12.9 cfs and 172 cfs. ' Subbasin K (Designn Point 11) The runoff from both Subbasins J and K is conveyed to Design Point 11 via Brittany ' Street and South Lemay Avenue. The combined peak discharge from these subbasins is estimated to be 4.7 cfs for the 2-year storm event and 17.7. cfs for the 100-year storm event. Upstream bypass flows from Filing 1 will contribute runoff to ' Design Point 11 and result in a combined peak discharge of 5.8 cfs and 38.5 cfs, respectively for the minor and major storm events. An existing curb chase (10-foot sump inlet) at Design Point 11 conveys runoff collected along the west half of South ' Lemay Avenue to the open channel immediately north of Filing 2. In the vicinity of Design Point 11, the existing street capacity of South Lemay Avenue is estimated to be 8.5 cfs during the minor storm and 269 cfs during the major storm; consequently, ' the street capacity is not exceeded at this location. The existing curb chase has an estimated capacity of 9.8 cfs and 150 cfs, respectively for the minor and major storms. Comparison with the peak discharges at DesignPoint 11 (5.8 cfs and 38.5 cfs) tindicate adequate conveyance capability associated with the existing curb chase. The results of analysis are presented in Tables 1, 2 and 3. Table 4 (obtained from the EPI ' Final Drainage Report) presents design data utilized to determine the capacity of the proposed streets. The procedures utilized to design the riprap at the storm inlets are presented in the technical documentation. A riprap blanket with a median diameter of approximately 9 inches is proposed at all storm outlets. Additional information is provided in Sheets 1, 2, 3 and 4 which illustrate the detailed drainage plan for Filing 2. 1 • 4 Ln Basin TA13LE 1. HYDROLOGIC CALCULATION WORKSHEET. Design Area Cumulative Point) (acres) Area (acres)* Runoff Coeff C Cf Cf Coeff Coeff 2-yr 100-yr Cumulative C(Cf)A 2-yr Cumulative Overland Average C(Cf)A Flow O'Land Flow 100-yr Length Slope OWN (x)** cII =_==== =c_=_a==_== _====_==== a=z====c Gzazaazaa aacaaacasz zasGc::¢saaac ea=vcacnav anaaceca aa=azaa===a A 1 2.92 i 2.92 0.45 1.00 1.25 1.31 1.64 300 1.3 8 2 5.25 ✓ 8.17 0.45 1.00 1.25 3.68 4.60 300 1.3 1 D 4 1.83 ✓ 14.53 0.45 1.00 1.25 6.54 8.17 300 1.3 F 6 3.51 ✓ 18.03 0.45 1.00 1.25 8.11 10.14 300 1.3 G ----- 7 ------ 1.49 ✓ ----------- 19.52 ---------- 0.45 -------- 1.00 --------- 1.25 ---------- 8.78' 10.98/ 300 1.3 ---- C 3 ---- ✓ -- -------5-- -----4-- --------- ---------- -----•------- ---------- ----4--- -----------' E 5 0.57 ' 0.57 0.45 1.00 1.25 -..?-0-- 0.26 -------SS- 0.32 -------- 10 ---------S- 2.1 3 H 8 0.18 ✓ 0.75 0.45 1.00 1.25 0.34 0.42 10 2.1 1 9 0.44 ' 1.19 0.45 1.00 1.25 0.54 0.67 10 2.1 ----- ----- ------ ----------- ---------- -------- --------- ---------- ------------- ---------- -------- ----------- 4 K I 11 3.87 ✓ 4.34 0.54 1.00 1.25 2.34 2.93 170 4.1 Continued.... Basin Sub- Design Cumulative Average Gutter Overland Travel Time Tt `. Total Inlet Time Basin Point Gutter Flow Gutter Flow Tc Tc Gutter Travel TI Tf Length Slope Velocity 2-yr 100-yr Time 2-yr 100-yr G Gaaa aaGGG GGGGGG (ft) GGGGaGaaaaa M GaGGGGGGGG (fps) IIGGaaaaG (min) GGIIG.GGGG (min) (min) (min) (min) A 1 550 4.4 4.3 19.3 GLGIIGaGaGa 16.0 GGGII¢GGaGaaaG 2.1 nGGGGGIIGna 21.4 nnm.xamm 18.1 B 2 1190 2.1 2.8 19.3 16.0 7.1 26.4 23.1 1 D 4 1460 1.8 2.6 19.3 16.0 9.4 28.6 25.3 F 6 1735 1.7 2.5 19.3 16.0 11.6 30.9 27.5 ----- G ----- 7 ------ 1860 ----------- 1.7 ---------- 2.5 -------- 19.3 --------- 16.0 12.4 31.7 28.4 2*** ----- C ----- 3 ------ 712 ----------- 3.6 ---------- 3.7 -------- 11.0 ---------- 9.1 ------------- ., 3.2 ---------- . 14.2 -------- 12.3 E 5 875 0.95 • 1.9 --------- 3.0 ---------- 2.5 ------------- 7.7 --------- 10.7 -------- 10.2 3 H 8 1150 0.95 1.9 3.0 2.5 10.1 13.1 12.6 ----- 1 ----- 9 ------ 1560 ----------- 0.95 ---------- 1.9 -------- 3.0 2.5 13.7 16.7 16.2 J 10 •250 3.6 3.7 --------- 9.9 ---------- 8.2 ------------- 1.1 ---------- 11.0 -------- 9.3 --- I----- -- ---- ----------- ---------- -------- --------- ---------- ------------- 6.4 ---- -1..... ...14_4.... * cunulatfve areas for design points 4, 6, and 7 include area for Sub -basin C •• Located In the most upstream sub -basin +++ used only for design of Inlet #3 at design point 3 Rainfall Intensity Peak Discharges 1 I G Q 2-yr 100-yr 2-yr 100-yr (fn/hr) (1Nhr) (cfs) (cfs) asaasn=am=a ac¢M=aza aaazazz =&==Mazza 1.78 5.42 2.3 8.9 1.57 4.80 5.8 22.1 1.50 4.57 9.8 37.4 1.43 4.39 11.6 44.5 1.41 4.30 12.4 47.2 ------2.15------------------------- 16.6 --------------------- ---------------- 2.42 7.00 0.6 2.2 2.28 6.48 0.8 2.7 2.00 5.71 1.1 3.8 ----------------- ------- ---". 2.4119 2.00 6,05 4.7 17.7 o- IDesign sin Poin[ A I 1 8 2 D 4 f 6 G 7 C 1 3 TABLE 2. SUMMARY OF INLET ANALYSIS AND DESIGN. Average Nalf-Streat Peal Gutter 0 le pu[ter 0 Inlet Gu[ler Capacity Without Inlet, less then street length Slope 2•yr 100•yr 2-yr 100•yr cepeclty7 (%) (cfs) I <d c) (cis) I (cis) 2•yr 1100•yr I (it) 0.95 6.8 13.4 2.3 8.9 yes yes 15 0.95 6.8 13.4 5.8 22.1 yes no 15 0.95 6.8 13.4 9.8 37.4 no no 15 0.75 6.0 11.9 11.6 44.5 no 10 10 0.75 6.0 11.9 12.4 47.2 110 m 10 ....... 1.7 ....... ............. 10.7 ...... 21.0 .............. .............. 4.4 16.6 ....... ....... yes ..................... .............. yes 15 0.95 6.8 13.4 0.6 2.2 yes yes 0.95 6.8 13.4 0.8 2.7 yes yes 0.75 6.0 11.9 1.1 --• 3.8 yes yes •_-•• 5 ••- 4.0 12.9 172.0 1.6 22.7 yes yes 10 ... ....... ...... .....0 ...... ..1.... ....... ........ ...... • includes diversion of 2.9 cis at Design Point 3 •• Includes dlversi on of 9.0 cis at Design Point 3 ••• existing 10' Type R Inlet 20 0 U/S of dtalon pt. 100-yr 100•yr 01/0 Reduction 2•yr inlet 100•yr Inlet after reduction Depth at Topuidlh or factor perforatarca performance by U/S Inlets (Cis) floullne 0/L f Intercept bypass Intercept bypass 2•yr 100-yr (it) (it) (Cis) (eta) (cis) (cis) 2.3 8.9 0.42 19.3 0.65 0.90 1.9 0.4 5.2 3.7 3.9 16.9 0.51 19.4 0.65 0.90 2.9 1.0 9.9 7.0 2.1• 13.3•• 0.48 19.4 0.65 0.90 1.6 0.5 7.8 5.5 2.36 12.6•• 0.49 19.4 0.55 0.85 1.5 0.8 5.9 6.7 1.6• 9.4•• 0.47 X/A LIS 0.85 LIS 0.0 9.4 0.0 ........... ........... ........ ........ ..... ......... ................. ................. 4.4 16.6 0.47 19.4 0.60 0.90 2.9 1.5 9.0 7.6 ...................... ................................................................ 0.6 2.2 0.8 2.7 - - - - 1.1 3.8 0.39 X/A 1.15 0.80 1.1 0.0 3.8 0.0 .......................... ........ ..... ......... ................. ................. 0.5 1.9 ........... ........... I ........ I ........ ..... ......... ................. ' TABLE 3. SUMMARY OF STORM SEWER PIPE ANALYSIS AND DESIGN. saasasaaaasaaaaaaaasaaasaaaaassaaaaasasasaaaasaaasaaaaaaaaaaa=aaassaaassaaaysaasvaaasasasssaassaaaaasaaaa I I Design I Pipe I Pipe I Full Pipe (Flow depthlFtow vetocityl I ' I Discharge I Grade I Diameter I Flow Capacity Ifor designlfor design O I Remarks I Pipe Segment I (cfs)** I (x) I (in)*** I (cfs) I a (ft) I (fps) I I --- DP1* - outlet I 5.8 I 0.5 I 18 I 7.4 I 0.98 I 4.6 I I I I 8.1 I 18 I 29.9 I 0.45 I 13.2 I I I I 2.5 I 18 I 16.6 I 0.62 I 8.5 I pipe outlet I I---------------- I ----------- --------- DP2 - DP5 I 11.0 I I---------- 0.5 I I--------------- 21 I 11.2 I---------- I------------- I 1.36 i I 5.3 ---------------I I---------------- I-----------I---------i----------I---------------I----------I-------------I---------------I OPS - outlet I 11.0 I 7.7 I 21 i ".0 I 0.60 I 15.3 ' I I I I---------------- I ----------- I --------- 1.6 I I- 21 I -------- - I--------------- 20.0 I 0.93 I I ---------- I ------------- 8.5 I I pipe outlet I --------------- I OP3 - DP4 I 10.0 I 1.00 I 18 I --------- 10.5 I 1.13 I 6.7 I I I---------------- i----------- I--------- I DP4 - outlet I 18.7 I 1.00 I 24 I 22.6 I 1.37 I 8.0 I I ' I 8.57 I 24 I 66.2 I 0.74 I 18.2 I I I 1.20 I 24 I 24.8 I 1.28 I 8.6 I pipe outlet I I DP6 - outlet I 6.9 I ------ 0.6 I --------' 18 I --------- -- 8.1 I 1.04 I 5.1 I ' I 12.4 I 18 I 37.0 I 0." I 16.1 I I 2.5 I 18 i 16.6 I 0.68 I ., 9.0 I Pipe outlet I ----------------i----------- I---------I----------I---------------I----------I------------- DP7 - DP9 I 9.4**** 1 0.75 I 21 I ---------- 13.7 --------------- I 1.06 I ---------- I ------------- I 6.1 I I ---------------I I --------------- I -- --- ----------- I ----------- I --------- DP9 - outtet 113.2****' I I 9.10 j I 21 I 47.8 I I 0.63 I 17.0 I I 1.50 I 21 I 19.4 I 1.05 1 8.6 I pipe outlet I i---------------- I ----------- I ----- ---- I ---------- I --------------- 22-.9 I ---------- I ----------- 1.01 -- I 11.6 I --------------- I I I existing pipes I 18.5 I 4.77 I 18 I I I I 3.32 I 18 I 19.1 I 1.16 I 11.8 I I I 1.42 I 30 I 4a.9 I 1.C8 I 3.5 I I I I 28.0 I 0.50 I 30 I 29.0 I 1.93 I 6.4 I pipe outlet I I I(=1a.s•9.$)I I I I I I I * DP = Design Point ** Sum of theoretical inlet discharges *** Xinimun cosmercial size **** Based on 100-year peak discharge conveyed to sump inlet 1 I L F, TABLE 4. SUMMARY OF STREET CAPACITIES (FROM EPL 1990). LOCAL STREET CLASSIFICATION 361 FL-Fl. TWO YEAR (( 100 YEAR ROLLOVER CURS & GUTTER ... (( '....... •• ""'NO CURB TOPPING; IE: OEPTH =.39 1-**" 1 INO SW TOPPING; IE: OEPTH = .51 ..a........................ .r.....r.............. ............... s....... r.s.. •GRAOE ( THEOR. 2yr ( RED. ( ALLOW. 2yr THEOR. 100yr ( ALLOW. 100yr . ' X (CAPACITY; CFS ( FACTOR CAPACITY; CFS CAPACITY; CFS CAPACITY; CFS ............................................................................... 0.40 ( 5.49 ( 0.500 0.50 ( 6.14 ( 0.650 0.60 ( 6.73 ( 0.800 0.70 ( 7.26 ( 0.800 0.80 ( 7.77 ( 0.800 0.90 ( 8.24 ( 0.800 1.00 ( 8.68 ( 0.800 1.10 ( 9.11 ( 0.800 1.20 ( 9.51 ( 0.800 1.30 ( 9.90 ( 0.800 1.40 ( 10.27 ( 0.800 1.50 ( 10.63 ( 0.300 1.50 10.98 ( 0.800 1.70 ( 11.32 0.800 1.80 ( 11.65 ( 0.800 1.90 ( 11.97 ( 0.800 2.00 12.28 0.800 2.10 ( 12.58 ( 0.800 2.20 ( 12.88 ( 0.791 2.30 ( 13.17 ( 0.782 2.40 ( 13.45 ( 0.773 2.50 13.73 0.764 2.60 ( 14.00 ( 0.756 2.70 ( 14.27 ( 0.747 2.80 14.53 ( 0.738 2.90 ( 14.79 ( 0.729 3.00 ( 15.04 ( 0.720 3.10 ( 15.29 0.708 ( 3.20 15.53 ( 0.696 ( 3.30 ( 15.77 ( 0.684 ( 3.40 16.01 ( 0.672 ( 3.50 ( 16.24 0.660 ( 3.60 ( 16.47 ( 0.648 ( 3.70 16.70 0.636 ( 3.30 ( 16.93 ( 0.624 3.90 17.15 ( 0.612 ( 4.00 ( 17.37 ( 0.600 2.75 (( 3.99 5.38 (( 5.81 (( 6.21 (� 6.59 (( 6.95 (( .7.29 7.61 (( 7.92 (( 8.22 (� 8.51 (( 8.79 �( 9.06 (( 9.32 (( 9.57 �( 9.82 (( 10.07 (( 10.19 �( 10.30 (( 10.40 �( 10.49 �( 10.58 (� 10.65 �( 10.72 (( 10.78 (( 10.83 10.32 (( 10.81 (( 10.79 �( 10.76 (( 10.72 (( 10.68 (( 10.62 (� 10.56 �( 10.49 (� 10.42 (( li 10.83 12.10 13.26 14.32 15.31 16.24 17.12 17.95 18.75 19.52 20.25 20.96 21.65 22.32 22.96 23.59 24.21 24.30 25.39 25.96 26.52 27.06 27.60 28.13 28.64 29.15 29.65 30.14 30.62 31.09 31.56 5.41 7.37 10.61 11.46 12.25 12.99 13.69 14.36 15.00 15.61 16:20 16.77 17.32 17.85 18.37 18.87 19.37 19.84 20.08 20.31 20.51 20.69 20.85 21.00 21.13 21.25 21.35 21.34 21.31 21.27 21.21 32.02 ( 21.13 32.48 ( 21.04 32.92 ( 20.94 33.37 ( 20.82 33.80 ( 20.69 34.23 ( 20.54 Hm EROSION CONTROL NOTES: answer 9V£5 umm slRl FILTER FABRC FWALACE FORT or mr xx MARCH 2 vmm FOR BALE WOOD POST Si FOR Iaae ONLY MRmm m, Feiss Ivnxr aM' 3-21.-1L. The City of Fort Call" $Iarmwater Utility erwan conlnl na0«tar must De notived Win. Yual R IMi1rA 11 SYNOve VeR rxw W ary aL at least 24 M1oula prier to any construction on tM1a site nWl P]IM B 9 - I r e I DRAINAGE SUMMARY TABLE NFw Si , R, AT required perimeter au fencing soil be nxoll e; o, to any Iona a'amro nq ai stockpiling, stepping, grading, etc.) AT other required control measures Ox Oma JA RAN shall be installed t the appropriate time n the construction Saquerlee a indicated sApxnum TRENCH Design Basin (pprep) C CA (c,f.s.) (c.fs.) n the approved project schedule. construction plans and erosion control report LANE 11,1 i11 Rtm ORNEW Iwa S[cnon 'ALAI lit /1 'A' 1.87 0J2 1.35 J.37 12.03 n�HroS9oNcrrct Pre-dsturbance vegetation Shall be protected and retained whenever a possible. 1 11 II1� 1 Barre l or disturbance or existing vegetation atoll De limited to the arerequired a $ M H!IIl rer FILTER FABRIC /2 1 'A' 3JB 0.22 0.83 1.91 GASAli l semi � far mmedate conxrvtl'en opemton9 nd for the shortest protical Denad of time. V _ AIIK.N SECURELY uLrLnL i WOOD PpSr i0 PoSi cou al spla ea darn IorA daturDl atlM (Stepping, 9rctling, alit ty 'nalollat any l c[NEPAa sties: L /1+/2 'A' 3.18 5.01 17.99 OF", Ixere� rooLaoue) pored 9 kept a (xri i Ste m Mpu COMPACTED &kNnLL r stockpiling, filling, etc.) SM1all De kept in roughened condition by ripping or 1 FLTREO dlsCing along land contours until mulch, vegetation, or other permoneml erosion vi Of Imiuirro m oxsnK vc Iw RUrvoEF /r RUNOrr /3 'A' 5.26 0.20 1.05 1.63 6.44 r a se I LERN To fli control i9 installed. No soils In oIt09 outartle IO OCI el ex ri FITS of w y anal 3 FIT of FENCE R _ o/Nil project 9 1n x. rvsGEa A 9EPUP F FMCE Tiro `_ /t+/2+/3 'A' 3.23 7.43 26.65 reman exposed by land dot rbng actvity for o than thirty (JOJ dari before Z a� c flp srovu m. RE S`o NFx toil AR pW1ELy Two, ... arw m real temporary or permanent erosion control (ag seed/mulcM1 landscaping,O A e WHEN ME HALF E HEYcqr E MINL nerd �waan FNCE FIRST BEEN Ei Evan (.4 TRENCH /4 'B' 2.95 0.79 2.33 6.53 22.87 e Sov eRe, .� etc.) s installed. unless otherwise ODproved by tM1a Slormwater Ul l'ty - e E E Yvmw SHALL K DEPa41ED m MI �j o EIs I � mwPAw m A MDIMmr wsm 5EE110N y1Fw V LrwEEFl The property shalt be wetentd and maintaned et all Cmee aonnea =anamCnon y p OTHER r0.1EMNc MEPSURE. Ten/c vi Ten o: TO tJ al a am di continl wlntl-aQ fugitive echelon, impacts lone adjacene rope Lea atoll _ SILT FENCE DETAIL N : wei x,Nw e termined by, thee City of Forth cons aEn oust Department. ment. m properties. Qa m U u looloccoolr r0 six NAeRrnPATOREAryswem"lowns r n Engineering pa n °1 coW¢TEo BWRrLL p \\ \ \ L, I ca a le M LRIN al temporary (alrudurvlera90 control measures Shan be inspected one repaired d 0 \ rfinkno/Ban or re onslrucled m necessary after cn runoff even[ to assure continued performance ar their runCOon. al retained sediments. particularly those a pond ` e roadwork surfaces, shall be ved and d,'Sm d of in a manner and location L H \ \ �Y _- 9rISCRsd wII/Yta n Hwna9m n v= Qa aai m cause their release into any drainagaway. ^ 1 PRoraE VIEW �\\ \ ��- stro ONTO AuawU CWmM.,ar No soil from a anml t tram ten by De rest in ugheniht. All ail Stoing. and ethirim he er N ��r-nr` Z w Nis , ��- art 9.eranm Aaasvm n err ar rert awxs ox «mertetl fchm sedimeal traneama nin udace nuonenina, al shag d pmrimete ry 1. amem, maa.vo WA.ee as laDsanl FIE Mn NOTES! eol Nil ton. Proposed 6'� Pro o It resing. My soil xeckoile remaining 30 don anal) be eeedatl and ulchetl. Z eE W6 Ayer w IP1A® ME9 12 wM11161MC3 MRAM 6 aMlm BI / p m r amnEe9wa m.>soN Fee LONaEF LINE. \\ Cross n enc! C�ly Ordinance proM1ibile the tracking. droppiny or depositing of mile or sells n m D9 y other material onto City sheetsT Ira any vehicle. My inadvertently STRAW BALE DIKE CHANNEL APPLICATION / � r } dpp tted material shall be leaned esiately by the contractor. Existing RCP \� �� --Le_ Nor r000 scxE 9 2sl ''20. '� \ Existing RCP ° u �tarm Drain Lines /�i 4778 - - - -�lyw- Storm Grain Linea I - /j / 'm a �, e `o � rn S 3.4 i \ \ J e WL \ r /Pre' c eri 25 1/z IIIIr- 7.. 1. zM.. isisw'JI \ / 7, ` / Exiatin9 I I �T 25 Loa /�1� our a A pro o h Pei \\ 21' RCP 11 1 V w w 1 msne ae • vmER I\ C 9 A `$� v Storm Drain x I o yea t 5o r / ,/ \ Chase n w Ik rt \� Indicdtes� \ LP 1" 60 W = SECTION B-B > N`/ / g \ Propbsad -mom as k4l 2'95 Oc' Contour Intersi 1' c S 'Silt Fencq" 1 91 oa: 6.5 2. o ti Existing 6' i /'1 0 3 a. ST \ L/ 1 0 /�4W r�I Draina90 a3 CroaaPan c m C t. Swale aRmrw r • p �. . / DRm ..... \ ..' 1 03.76 F.F. OJ � . , rev. 21 e = � ' / __ _ T a / L GFO IrT,I Y'T PFbpp } e \ \ 5012- yPicaliy indicates Existing sit FEEE//¢[L D Indicates Bel os W vWnxD Lae • echo ,-. f / // Straw Bale Dike - Proposed Straw w n and Surface Contour SECTION C-C . / \ 3 oe 2 Bale Filter - 5012---- T piton Indicates Proposed Mei n y yy J .9 1, ) Fish SWood Contour xm ro sane All \ Bae1n m I Settling Basin O 7 1. I \ � � Outlet Structure � I)�� 9' SEE DETAIL `� Drainage Basin Limit Identifier �w �Settthg Basin I ) Typicolly Indicates Flowline W Other pelwp 21-W wn of Oitch or Swale Q y \ �^ /3 I I j Typically Indicates Silt Fence O i y O YWWI 'Eosin. HQ YG I � w� rw pwnax �� -1- 5.2 Ce a- y ed I Typically Indicates Straw Bale z O ids Irl I,1lll'LL1 `I FRED °' Y ,p 1.6 6. led in �Fiylter or Dike Application �J �s SECTION D-D 4os7 6' .0 c / S ± {y� O I I x99.11 pevtementn5urt°ce Elevatidicates on µ.l mro o B or Flow Line of Gutter z rd z b5 Y q p n w.7 / ti NMML' `� 1 Typically Indicates Proposed i d p o \ Pavement Surface Elevation K O i3 `-Proposed Dee. 1. 0 + c7 a U nc@' or Flow Line of Gutter 'Silt Fe spiel C*_ w T hat Direction Indicates Drainage T I J I iow �I y'g Proposed Si[Pance' I Concentration Pont Identifier I --I O I 1' Fees disturbed by grddingoperatM FrI ELF SECTION A -A / NOTE: . iods In Swale ,ypi�al) �I_ Ik /4 Das�n'B'��Design Point, 9asin Number LrJ.II a DRAINAGE SWALE DETAIL I IL I I I not to Escaped. paved or building areas shall it _ : I f Area of in Acres v 1 F H be reseeded and mulched. ` 3.41 aim c.f.s. L rl Type R Inlet D2 c.ts. asaOmOVErsmx,usJ�' _ _ -_ _ _ _ _ _ .' T of Fort Collins, Colorado U a Existing ` - -- -- UTILITY PLAN APPROVAL Of APPROVED I' ae _ ��L_ _. -_ C OATS APR CTED e --_ r -_ �'ExFe °fTng�rmenny ; I �� CHECKED BY: Wit ate. OtTrr sa u NorED r � 1l o T�tlby \ Roo r �' SECTION THROUGH MWN. kill- D SETTLING BASIN 'Alp Allo J CHECKED BY: l CHKD: D.R.M. roar"r - d yV Proro CHECKED BY: -28 GRD-282 - -98 CHECKED BY: SHEET ( C CHECKED BY: 3 of V see; re 39'.rl 90 Jw1 I+J 'penoi