Loading...
HomeMy WebLinkAboutDrainage Reports - 10/25/1995PROPERTY OF FORT COLLINS UTUXrM DRAINAGE AND EROSION CONTROL REPORT FOR MISCELLANEOUS STREETS J.F.K. PARKWAY AND MITCHELL DRIVE FORT COLLINS, COLORADO ftl6/ma � "� '� �� —� J \WVVC1�w ■ =%a.. WELSH ENGINEERING SCIENCE & TECHNOLOGV. INC. "Nw VV CM-� ■ Cam.. WELSH ENGINEERING SCIENCE & TECHNOLOGY, INC. DRAINAGE AND EROSION CONTROL REPORT FOR MISCELLANEOUS STREETS J.F.K. PARKWAY AND MITCHELL DRIVE FORT COLLINS, COLORADO PREPARED FOR: THE CITY OF FORT COLLINS PREPARED BY: WESTEC 2629 REDWING ROAD, SUITE 200 FORT COLLINS, COLORADO 8052E AUGUST 4, 1995 2629 Redwing Road, Suite 200, Fort Collins, Colorado 80526-2879, Ph. 970 226 3535 Fax 970 226 6475 Reno Tucson 'Elko Winnemucca Pleasanton Englewood Nevada Arizona Nevada Nevada California Colorado \W YV C W=111I ■ C %. WELSH ENGINEERING SCIENCE & FECHNOLOGY. INC. August 4, 1995 Mr. Glen D. Schlueter City of Fort Collins Utility Services Stormwater 235 Mathews Fort Collins, Colorado 80522 WESTEC PRJ# 94417 RE: MISCELLANEOUS STREETS - MITCHELL DRIVE AND JOHN F. KENNEDY PARKWAY Dear Mr. Schlueter: Transmitted herewith is a copy of the subject report for your review and approval. All calculations for this report have been made in accordance with criteria established by the City of Fort Collins. If you have any questions or require any modifications please call me. Thank you. Sincerely, WESTEC J. Thomas Knostman, P.E. Project Engineer JTK/sea 2629 Redwing Road, Suite 200. Fort Collins. Colorado 80526-2879, Ph. 970 226 3535 Fox 970 226 6475 Reno Tucson Elko Winnemucca Pleasanton Englewood Nevada Arizona Nevada Nevada California Colorado DRAINAGE AND EROSION CONTROL REPORT FOR MISCELLANEOUS STREETS MITCHELL DRIVE and J.F.K. PARKWAY FORT COLLINS, COLORADO DEVELOPMENT LOCATION AND DESCRIPTION Location Mitchell Drive and John F. Kennedy Parkway will be completed along two segments between Horsetooth Road and Bockman Drive. The completed roadways will allow for through traffic between these two east -west drives. The street improvements areas are shown on the vicinity map Figure 1. The land on which the two street segments will be completed is owned by a number of entities. The Site is located within the northwest quarter of the northwest quarter of Section 36, T7N R69W, City of Fort Collins, Larimer County, Colorado. Prooerty Descriotion Mitchell Drive will be completed from Larimer Canal Number 2 (the Canal) south to the existing segment of Mitchell Drive through Toys "R" Us and Western Auto P.U.D. and includes approximately 550 feet of new pavement. This segment will be on Right -Of - Way (ROW) previously dedicated or new ROW dedicated by Spiro Palmer owner of Lot 5 of the Observatory Heights Subdivision (Showtime Video). The contiguous properties to the west of the new pavement have all been developed and will have new access drives installed with this work. The contiguous properties to the east are undeveloped except for the very easterly end of the Showtime Video lot which will be separated from the west portion by the new street. The land drains generally to the north and east to the Canal. JFK Parkway will be completed from the existing segment traveling south from Horsetooth Road west of First National Bank to the existing segment east of the Toys "R" Us and Western Auto Stores P.U.D. which extends from Bockman Drive to a point north the Canal. This segment will include 560 feet of new pavement and will be located on various parcels of land. The only development on either side of this street segment is the south parking area associated with the Strachan - Continental Subdivision located along the west side of the north 100 feet of the new road section. The land drains generally to the north away from the Canal. 41/1UUhl US/22/95 HB T EAST HORSETOOTH ROAD � m� log HB PROPOSED JFK PARKWAY o PROP SED MITCHELL RP l DRIVE l w �.. HB w 1 ❑ �- ¢1 RLP I 1 w w WARREN LAKE a — Q rp I RESERVOIR o lJ U C� hb rmp rp �. w o rp BP RLP w 2 bp ¢ rh bp JHARMONY —1 F` -1 F "'Rypr MISCELLANEOUS S-REETS MITCHELL DRIVE iD JFK PARKWAY FIGURE No. 1 SITE LOCATION MAP DRAINAGE BASIN IDENTIFICATION Description The two street sections will be located within Foothills Drainage Basin. Mitchell drive is also located in the Heart Special Improvement District (SID) [11 and Attachment A. For purposes of analysis, Mitchell drive was divided into Basins A-E as shown on Figure 2 and The Drainage and Erosion Control Plan (Drawing 5) attached to this report. JFK Parkway was evaluated as four basins. DRAINAGE DESIGN CRITERIA Regulations The City of Fort Collins Storm Drainage Design Criteria [21 is being used as the basis for this report. Develooment Criteria Constraints The Mitchell Drive improvements falls within the area controlled by the Heart Special Improvement District (Attachment A). The Heart SID allows all properties east of College Avenue and west of Larimer Canal Number 2 to drain to the Canal at a rate equal to or less than 0.87 cubic feet per second (cfs) per acre. Improvements were made to the Canal under the Heart SID to allow for these storm flows. JFK Parkway, north of the Canal, has no drainage constraints other than the City of ' Fort Collins street encroachment criteria. The street improvements will be installed to allow drainage to flow to Horsetooth Drive at this time. Improvements to the land West and east of this roadway section will be responsible for the contiguous half street ' drainage in accordance with the drainage criteria set forth for the Foothills Drainage Basin. ' Hydrologic Criteria The Rational Method was used to predict the peak and cumulative runoff from the ' proposed development. The 100-year storm event was used as the basis of design of the drainage systems for . Calculations are included in Appendix I. ' Calculations All calculations for this report have been made in accordance with criteria established ., by the City of Fort Collins. Variances ' It is requested that the Stormwater Utility grant a variance to allow the depth of ponding in Detention Pond B, located on the east side of Mitchell Drive, to be 18 inches maximum during the 100-year storm event. No Text ' DRAINAGE DESIGN Concept Mitchell Drive, Pond A: Drainage to the Canal from the eastern portion of Showtime Video will be collected in Detention Pond A (Pond A). Basin E, as shown on Figure 2 ' and Drawing 5, will be ponded and release in compliance with the Heart SID. Pond A will be formed by a high curb adjacent to the Canal and the Mitchell Drive Embankment. The outlet to the pond will be through a small orifice in the curb at the low point. Mitchell Drive, Pond B: Drainage from centerline of Bockman Drive to the Canal will be conveyed and collected in two 4-foot curb inlets at the low point of the sag curve located just south of the Showtime Video lot. A 15 inch Reinforced Concrete Pipe (RCP) will convey drainage from the street to the Canal. Drainage from the combined ' Wendy's/Palmer Gardens detention pond, located in the east parking area of Palmer Gardens will be connected to the east curb inlet and storm sewer system to the Canal. ' The discharge to the Canal from the storm sewer shall be regulated by a orifice plate located in the area inlet in Pond B. The orifice plate will back water up in the storm sewer and up through an area inlet in a parking/detention pond (Pond B) located east ' of the road until the head in the pond roughly equals that of the curb inlets with a maximum elevation of 5030.5 feet. At this elevation, the ponding in Pond B will be equal to or greater than the volume required during the 100-year storm event in accordance with the Heart SID. Pond B will be formed by earthen berms on the north ' and south, the Mitchell Drive embankment to the west and an 15 inch wall to the east with ponding not exceed 18 inches. As the hydrograph to the curb inlets recedes and water in the storm sewer system drains to the Canal, both the Palmer Gardens Pond and Pond B will drain to the Canal. The orifice plate at the end of the storm sewer was designed to discharge during the t100-year storm event: • The allowable discharge of 1.6 cfs from the Palmer Gardens Pond (Attachment B), plus • The 100-year peak flow from the Mitchell Drive ROW between the centerline of Bockman Drive and station 3+50, plus (this drainage flows undetained to ' the curb inlets but is accounted for by the Toys "R" Us and Western Auto development, See Attachment C) ' • Discharge equal to 0.87 cfs/Ac for the remaining undetained area which has previously been developed or will be paved with this project. ' Storm drainage from the undeveloped properties to the east of the Mitchell ROW, when developed, will be detained on -site and flows discharged directly to the Canal. ' JFK Parkway, Basin A: Storm drainage from JFK Parkway between Boardwalk and Horsetooth Road splits at the high point just north of Boardwalk and flows north toward Horsetooth Road. Storm Drainage along JFK Parkway, south of the two 15- ' foot curb inlets, for events up to the 100-year storm will be collected and detained by the properties adjacent to the street. The hydrologic and hydraulic discussion and evaluation of this area is detailed in the Final Drainage and Erosion Control Report for JFK Parkway September 19, 1991 (Revised May 19, 1992) (3). Pertinent pages of this report area included as Attachment D. Storm drainage north of the two 15-foot curb inlets will drain in the street gutters to Horsetooth Road and to Warren Lake. This ' drainage will be collected and detained on the contiguous properties when these properties develop. Details ' Support for the following discussion will be found in the calculations in Appendix I and on the drawings furnished with this report. As stated above, the Rational Method was ' used for drainage estimates. Mitchell Drive, Pond A: Pond A was size based on a mass balance of the inflow and discharge from the pond. The tributary area to Pond A is included in Basin E as shown ' on Figure 2 and encompasses 0.253 acres. The allowable discharge from Basin E, in accordance with the Heart SID, is equal to 0.22 cfs. The runoff coefficient for Basin ' E in 0.902. Using the above parameters in a mass balance the required ponding is 1,694 cubic feet. The available volume in Pond A is 2,070 cubic feet. ' Discharge from Pond A will be through a 2.5 inch section of PVC pipe located in the northeast corner of the curb forming the pond. The maximum head on the pipe will be 1.5 feet. Using a orifice coefficient of 0.6, the discharge will be 0.20 cfs which does not exceeds the allowable discharge of 0.22 cfs. Drainage release to the north ' side of the wall will be routed to an existing rip rap drop structure located to the northwest, on the south bank of the Canal. ' Mitchell Drive, Pond B: Detention for Basins C and D will be provided in Pond B. Pond B was size based on a theoretical mass balance of the inflow and discharge from the pond. For the mass balance, Basins C and D, with a combined area of 1.0 acres ' and a runoff coefficient of 0.863, was used with an allowable discharge of 0.87 cfs. Using the above parameters in a mass balance the required ponding is 6,696 cubic feet. The available volume in Pond B is 6,726 cubic feet. The tributary area to the storm sewer system discharging to the Canal includes Basins A,B,C and D as shown on Figure 2 and encompasses 1.43 acres. The allowable ' discharge to the Canal is 6.47 cfs and is made up of the following flows during the 100-year storm event. • 4.00 cfs from Basins A and B • 0.87 cfs from Basins C and D, and ' • 1.60 cfs from the Palmer Gardens detention pond Discharge from the storm sewer system will be through an 11 inch orifice plate mounted on the downstream wall of the area inlet to be constructed in Pond B. The maximum head on the pipe will be 4.0 feet. Using a orifice coefficient of 0.6, the discharge will be 6.35 cfs which slightly exceeds the allowable discharge of 6.33 cfs. ' Drainage release to the Canal will drop 2.5 feet to the bottom of the Canal down a rip rap drop structure. JFK Parkway: Gutter flow on JFK Parkway was evaluated to check that encroachment will not exceed that allowable. Encroachment was checked at the north end of the section to be constructed. This is where the flows will be the greatest and ' the street grades the least. The 100-year peak flow was evaluated assuming the peak flow will come from the paved section between the flowlines downstream of the 15- foot inlets. The minimum time of concentration equal to 5 minutes was used to ' estimate the rainfall intensity of 9.0 inches per hour. With these parameters, the 100- year peak flow at the end of the new roadway section is estimated to be 4.52 cfs per gutter. The computer model UDINLET was used to evaluate the depth of flow in the ' gutter and thus the spread in the street. Gutter flow encroachment is estimated to be less than 0.33 feet in the gutter and will leave 24.5 feet of street open for travel. I 1 1 1 1 WIND AND RAINFALL EROSION EVALUATION Site Soils ' The Larimer County, Soil Conservation Service Soils Report identifies the soils as belonging to the Heldt Clay Loam and Thedalund Loam described as having slight to moderate rainfall erodibility characteristic. The rainfall erosion season as detailed in ' the City of Fort Collins, Erosion Control Reference Manual [21 (the Manual) is between May 1 and October 31. ' The Manual details the area as having moderate wind erodibility characteristics and that the predominant wind direction is from the west-northwest in this area. The wind erosion season as detailed in the Manual is between November 1 st and May 31 st. Construction at the site is estimated to begin in August 1995 and continue through ' October of 1995, with the majority of the grading and paving work completed by September of 1995. This schedule places the project within the rainfall erosion season. ' Performance Standard The estimated "During Construction" and "After Construction" Performance Standards for JFK Parkway and Mitchell Drive are 80.9/95.2 and 78.8/92.8 percent, respectively. For the purpose of estimating the Performance Standards, the disturbed areas for the two street sections were considered separately based on the developed contours. The ' disturbed areas, as shown on the Drainage Study and Erosion Control Plan appended at the end of this report, consist of: ' • 1.29 acres including Basin A for JFK Parkway, and • 1.44 acres including Basins C and D for Mitchell Drive. The Performance Standard for the site was estimated using the methods detailed in the Manual and the estimated, average slope length and slope for each basin. Flow ' lengths and slopes developed for calculation of the "During Construction" Performance Standards are presented on Standard Form A in Appendix II. The Performance Standards were taken from Table 5.1 of the Manual. The "After Construction" Performance Standards were calculated by dividing the "During Construction" ' Performance Standards by 0.85. ' Practice Factor Measures Sediment control practice measures for the streets will consist of the construction of ' silt fencing, a straw bale dike, and a straw bale inlet filter. The location and details of these practice measures are shown on the Drawing 5. ' After construction, practice factor measures for the site will be dismantled and thus a weighted P - Factor of 1.0 was used to calculate the effectiveness. The calculations for the weighted P - Factor for each street section both during and after construction ' are presented on Standard Form B in Appendix II. Cover Factor Measures Cover factor measures for the streets during construction will consist of existing and ' new paved areas. The paved areas were assigned a C - Factor value of 0.01. Cover factor measures for the streets after construction is completed will consist of ' implementation of the landscaping plan which calls for establishment of grass cover of at least 60 percent over the disturbed, non -landscaped areas of the site. Grass will be established with the use of hay or straw mulch applied and secured at a rate of 2 ' tons per acre. The mulched and revegetated areas were assigned C - Factor values of 0.06 as selected from Table 5.2 and Figure 5.1. Cover factor values for the paved areas were not changed from during construction conditions. The calculations for the ' weighted C - Factor for areas for each street for both during and after construction are presented on Standard Form B in Appendix Il. ' "During Construction" Effectiveness Evaluation The Net Effectiveness for the erosion control measures for JFK Parkway and Mitchell Drive during construction was calculated to be 88.8 and 90.0 percent, respectively, and exceeds the "During Construction" Performance Standard values of 80.9 and 78.2. "After Construction" Effectiveness Evaluation ' The Net Effectiveness for the erosion control measures for JFK Parkway and Mitchell Drive after construction was calculated to be 96.0 and 97.5 percent, respectively, and exceeds the "During Construction" Performance Standard values of 95.2 and 92.8. I ' WIND EROSION ANALYSIS The surface soils in area of the street improvements are rated as moderately wind ' erodible. Construction at the site will occur prior to the windy season and the site does not fall under any of the exclusions available in the Manual. ' The limited size of the construction area and the necessary access in this area will restrict the available area for placement of a wind barrier. For this reason the wind erosion features to be constructed at the site will consist primarily of natural features ' at the sites, water erosion controls and the features to be constructed. The wind erosion control measures which will be implemented during construction will ' include the items listed below and are detailed on the Grading and Drainage and Erosion Control Plan. ' • The silt fencing. • The new street paving. ' • The Larimer Canal Number 2. • The existing buildings to the west of Mitchell Drive. ' Wind erosion control measures which will be implemented after construction will consist of mulching and seeding the disturbed areas. Hay or straw mulch will be applied and crimped into the soil surface at a rate of 2 tons per acre after seeding of the site. ' INSTALLATION SCHEDULE ' The approximate date of implementation of the erosion control measure during construction are shown on Standard Form C in Appendix IL As shown on Form C the silt fencing and the straw bale dike will be constructed prior to grading. Paving of the ' parking and walk areas is scheduled to begin in September and be complete by October. Permanent vegetation will be seeded and mulched during the fall cool season planting beginning in August. ' EROSION CONTROL SECURITY ' The erosion control security requirement for the Miscellaneous Streets site was estimated based on the specification of Section 2.0 of the Manual. The cost of the erosion control measures at the site as detailed above were estimated to cost $2,231 with a security requirement of $3,346. The estimated cost to revegetate the disturbed areas with a dryland grass mix according to the city's 1993 mulch and revegetation bid was $1,775 with a security requirement of $2,660. The larger amount is required ' prior to construction. Both cost estimates are detailed in Appendix II. 1 REFERENCES 1. Engineering Professionals, Inc. Final Drainage Report for Heart Special Improvement District, Fort Collins, Colorado, Project 311.2, December, 1984, (Revised January, 1985). 2. City of Fort Collins, Colorado, Storm Drainage Design Criteria and Construction Standards, May 1984, Revised January 1991. 3. Parsons & Associates Consulting Engineer. Final Drainage and Erosion Control Report for JFK Parkway, Fort Collins, Colorado, Project 91.13, September 19, 1991 (Revised May 19, 1992). I 1 APPENDIX I ' HYDROLOGY AND HYDRAULIC CALCULATIONS [1 1 1 1 1 1 1 `&Ao —� �� �� ��® RENO, NEVADA ELKO, NEVADA WELSH ENGINEERING SCIENCE & TECHNOLOGY, INC. WINNEMUCCA, NEVADA 1 ENGLEWOOD, COLORADO O BY TT� DATE SUBJECT SHEET NO. OF ' CHKD. BY DATE - PROJECT ^ALL PROD. NO. �� lr-�E l�>✓c� , arc-�(qG_ n_�_��lc, �,�,r "�o�� A 1 T A� , -30 Z- r ib r Nk _ Ti4e-E 1 1 1 CorJ���r Masi 1 )Lo' L53 lye.! 9 F, 7 f ( co- n')4-z�_ !J, 111n,4(--) �1 1 1 [l L G7 Q � Q a 0 G � O U \0 W) M O ri r4 , d0 N w \0 N 00 d O �O N 00 00� V J H CN N en M Vm'1 � ti N .�-� d N N N N N N N N N N N 3 0 w N N N N N N N N N N N C 0 0 0 0 0 0 0 0 0 0 0 0 a � � CT \0 en 00 00 kn M m C = ,,_, M 00 00 �o [— e .-t 4 00 \0 N N \O m N M v') \0 00 C; 1 ti r- r-i N N N N N a 0 0 0 0 0 0 0 0 0 R J 0 O 0 O 0 O 0 0 N V1 0 0 0 0 0 00 [— \0 IT N 0 7 y M \p CT 14 N M tr lz O CD o N kn O \ M 00 M 000 N EL f V --i r-i .--+ r-i .--i O 6 0 C 0 M M M M M M M M cn cn cn '.� kn (q W) tr)rq N t4 In Q Q N N N N N N N N N N N rq C'4 rq N O O O O O G C C C C C -oknOOoOvnO00vkn O N \O N M \O 00 "T O r-: �-6 vy 7 4 cn (V .-4 4 lcT O N N N N N N N N N N N CUm 0 0 0 0 0 0 0 0 0 0 0 CNa,mamo\rnrnrnrn a C O C C C C C O C C C E.t � oknOknoknOOOO -+ 00 E C I 1 1 11 I WESTEC PROJECT: PRJ. NO.: POND: DATE: Mitchell Drive 94417 Pond A, East Pond 08/03/95 INPUT VALUES TRAPEZOIDAL AVERAGE END AREA INCREMENT CUMULATIVE INCREMENT CUMULATIVE ELEV AREA VOLUME VOLUME VOLUME VOLUME SF CF CF CF CF 28.50 0 29.00 210 35 35 35 35 29.50 11370 353 388 395 430 30.00 5,900 1,686 1 2,073 1,818 1 27248 \&I im � .OM. \I/ VV C s ■ C C. WELSH ENGINEERING SCIENCE & TECHNOLOGY. INC. I 1 1 I 1 I L i I I RENO, NEVADA ELKO, NEVADA WINNEMUCCA, NEVADA ENGLEWOOD, COLORADO O BY:7T K DATE 1 SUBJECT SHEET NO. OF CHKD. BY DATE PROJECT � .4Z PROD. NO. cis%/r/ Z g. 50, zg,o(). 2°, 1150 06,0C` ' C 2 ►:� It Q 0I Z_ c�5 C) ' �•'_ _ -- -- -- —■ TM KENO; NEVADA VV C t� C� WINONEMUCCA, NEVADA WELSH ENGINEERING SCIENCE & TECHNOLOGY, INC. ENGLEWOOD, COLORADO O FORT COLLINS, COLORADO BY -DATE �uT SUBJECT SHEET NO. OF 1 CHKD_ BY - DATE PROJECT - -T ry _- z.s'rT r — _--PR0J. N0.% zzm ---tLt���_-Cam_.-__ ��'�E�---►�C`�.�--=L �`J_ - g -- - - - _ - 11 _- -_ — — ' 1 I i , -=_ �'-I 1 I r I I " 1 I_ i I-i t It I ' t - �%�( _ _ I_ _--'--•._-1._- - �_ ' 05- 25 1 , ' Y ,'rIt _— 1 ----- i-. " -_.- -_.-_ r I i - V � Imo• __-1 , _ i _ I - , r , , , --�-_ , I 1 — -- -- -- FT--- — -- -- — — -- — — -- ---- —j --- — — to _ 1 i , t � ! I - -- --�--- -- . ' ' - --- -- - - -- - - t KENO, NEVADA _ -- — -- -TM `W VV C� CL. ELK,`•'_ WINONEMUCCDA,NEVADA ' WELSH ENGINEERING SCIENCE & TECHNOLOGY. INC. ENGLEWOOD, COLORADO FORT COLLINS, COLORADO O I _-T 7/ BY DATE SUBJECT SHEET NO. OF CHKD.BY DATE PROJECT 1 f PROJJN0. -• ^�` � _-_--- `~- -- __- i It I i 1_ � � �': _'_• �� i� `./ 5�--��-�.� 11 i ', � '.-J I , r I i 1 1 1 11 1•��'--LL�../// 11 1 I :_ l; I I t i I i- 1 -___ -_i j TT 1 I_L� 1 L- I -. _I �_I ,/_o/,� I -'i i I RENO,NEVADA TM ELKO,NEVADA zmp 0 CAI. ...WINNEMUCCA, NEVADA WELSH ENGINEERING SCIENCE 8, TECHNOLOGY, INC, ENGLEWOOD, COLORADO FORT COLLINS, COLORADO 0 BY -TTJL —DATE✓ c*4_SUBJECT t""�S7E—'1fLL5 SHEET NO. — OF— CHKD.BY__DATE PROJECT PROJ. NO.'Fqql'-7 f 1�7 010-7. 7 41- r7c-11r, It -77 I -7 QI 1I If 1!III i f :I;,; I it; it if I If If ;q 14 i) It 1-1 1 1 It If I I I I I I ;fill It I if I lill;j Ii 1; 1 1 If I I fill I I : I I I t I I I I 'l -I i 1 1 j I it I fill i 1 1 1 1 1 1 1 1 !1! 1 1! —1 T it —11 1 11 Ito it 'i I I it LL j I I I I i I I I L j L L L4�'if — — --------- --------- ---------- I I r V) ,> U Sy A VUoC4 ' U CG `� v)tizA A O Qom"' n. e C)00r`�ovnI:t,�0000vv M �o �--� C� C) C� C) N O O d• C U 7 I ^ �O kn CA �lO N "q - O, o N M d V•) kn V) �O Wn et 11i \Y ca H N M et to AO C) N 00 'r �O O N 00 It O �o � cM C) �O m 11O U^ U N in r O M V) enrl N enj .- y- N M 'Rd' �O CN U U t`t`r00rrt`t`rrr 3 oo ao ao 00 00 00 00 00 00 00 00 0 0 0 0 O O O O O O O O O O a U 0 0 0 0 0 0 kn 0 00 00 0 of CDC,ovo�c't�oo"o,t t` N O N CN to O M O M en > o (,T ir vi e �e r CT CT a) ti 0 O O O 0 0 0 0 0 0 0 0 0 w U H OM � CD O N O O o 0 � 00 t` �o 0 0 � N 00 3 o O y .. O .--1 O C) N N �O -ov,or�Cn N M �O 00 7 0 O O O O O O O O O O O yU O O O O O O O O O O O a 0 0 0 0 0 0 0 0 0 0 0 4 r4 e-4 `� N` O In O O O O vl O� d• �%) 04 W M M M M M M M M M M M � U o0 00 00 0o ao 0o ao 00 00 00 00 p;ol 0 0 0 0 O 0 0 0 O O C �S,nOv1OtnOv)OOcq� E - N N en 7"C m4 r~ i U Q Q a Q W 3 w \0,��c U A O N N r W W cl CI 0 >z> �\.C�� U j O �U F- It) 00 M h O � "tt O W e- N N U QVO a? O N O O O 00 O O O tr tr N Vn W a Cl) W) kf) Q W O O O O O 00 O Vi O N N N N M M w z �. \I BY CH RENO.NEVADA va � " � � � � rm ELKO,NEVADA Mir = � I 1= WINNEMUCCA, NEVADA WELSH ENGINEERING SCIENCE & TECHNOLOGY, INC. ENGLEWOOD, COLORADO FORT COLLINS, COLORADO 0 r� DATE SUBJECT Tf*�*3-D-M SHEET NO. Of- "-/ BY -DATE -PROJECT PROJ. NO. ptz-4-:7- T1--Qp--jE) tit I fill 1 i lit -T- J! I -L-L- -�- h7l-' -T— III I I I lit i• I i I I i TT —777 7EW it dr • Q6/ • - - - - - - - - - - - - II RENO,NEVADA IM � AW � d I � � �� `" ELKO, NEVADA VV C -i C` WINNEMUCCA, NEVADA WELSH ENGINEERING SCIENCE & rECHNOLOGY, INC. ENGLEWOOD, COLORADO O FORT COLLINS, COLORADO Ems- DATE =�� SUBJECT C SHEET NO. OF - BY -DATE -PROJECT Tn Zv PROD. NO.4 � /"'/' /04 _ -x3� �=�� -ram. ��►�.. p1 I1. '� - I t' I I t i' I •�-�r 2 i I!1 I' I. I I II II I -T-I I I• _! i I_I r� 11 , i :j i- -I I T T j � � -✓�/ • I _- i I_ i 1 i 1 I �I ---------------------------j- --------------------------- 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:Water Waste and Land -Ft Collins CO.. N DATE 07-26-1995 AT TIME 16:54:48 I ISER:Wi �N DATn C P, CT TITLE: MITCHELL DRIVE CURB OPENING INLET HYDRAULICS AND SIZING: INLET ID NUMBER: 10 INLET HYDRAULICS: IN A SUMP. GIVEN INLET DESIGN INFORMATION: GIVEN CURB OPENING LENGTH (ft)= 4.00 HEIGHT OF CURB OPENING (in)= 6.00 INCLINED THROAT ANGLE (degree)= 63.40 LATERAL WIDTH OF DEPRESSION (ft)= 2.00 SUMP DEPTH (ft)= 0.17 Note: The sump depth is additional depth to flow depth. STREET GEOMETRIES: STREET LONGITUDINAL SLOPE W = 0.83 STREET CROSS SLOPE 2.00 STREET MANNING N = 0.016 GUTTER DEPRESSION (inch)= 1.50 GUTTER WIDTH (ft) = 2.00 STREET FLOW HYDRAULICS: WATER SPREAD ON STREET GUTTER FLOW DEPTH (ft) = (ft) = 15.63� 0.44 �InuT cf FLOW VELOCITY ON STREET (fps)= 3.12 FLOW CROSS SECTION AREA (sq ft)= 2.57 GRATE CLOGGING FACTOR (°s)= 50.00 CURB OPENNING CLOGGING FACTOR(%)= 20.00 INLET INTERCEPTION CAPACITY: IDEAL INTERCEPTION CAPACITY (cfs)= 8.28 BY FAA HEC-12 METHOD: DESIGN FLOW (cfs)= 7.94 FLOW INTERCEPTED (cfs)= 7.41 CARRY-OVER FLOW (cfs)= 0.53 BY DENVER UDFCD METHOD: DESIGN FLOW (cfs)= 7.94 FLOW INTERCEPTED (cfs)= 6.62 CARRY-OVER FLOW (cfs)= 1.32 ----------------------------------------------------------------------- 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 ----------------------------------------------------------------------- Ater Waste and Land -Ft Collins CO ...................................... 07-26-1995 AT TIME 16:55:14 1 I 1 Pressure Pipe Analysis & Design Circular Pipe l 1 �IWorksheet Name: Misc Streets I! : 15" Storm Sewer Under Pressure Flow 1 ,! Solve For Discharge 1 Given Input Data: Elevation @ 1..... 30.70 ft I Pressure @ 1...... 14.40 psi Elevation @ 2..... 29.00 ft Pressure @ 2.... 14.40 psi 1 Diameter.. .. 15.00 in L th 150 00 ft 1 1 1 1 1 1 1 1 1 1 1 1 eng ............ Hazen -Williams C.. 135.00 'Computed Results: Discharge......... 4191.31 gpm Velocity.......... 7.61 fps Headloss.......... 1.70 ft Energy Grade @ 1.. 64.82 ft Energy Grade @ 2.. 63.12 ft N Friction Slope.... 11.333 ft/1000 ft �,� . Cam? �c,a�� �F » xc;:� v�'t--jam, �2.��v `ice �,��'� • Open Channel Flow Module, Version 3.41 (c) 1991 Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708 1 RENO,NEVADA 1 •V& - AW -� -- -TM ELKO, NEVADA `W WNW C� I C%Wm WINNEMUCCA,NEVADA WELSH ENGINEERING SCIENCE & tECHNOLOGY. INC. ENGLEWOOD, COLORADO 1 O FORT COLLINS, COLORADO BY:-: DATE u' SUBJEC��`— ► /��0(--ov'l � SHEET NO. OF CHKD. BY DATE PROJECT%'f= -n PROJ. NO. — 1 Eg i 1 I! i ! I 1 I •. I I I t l i I I t l f 1 i t ��"•� �Kr--"'�;�•�-f��s�Y �+. • V I I 1 YJIM _ b V I+ - - 11 1 i- I I I I •�- I l i - _ I I I 1 f I I! l i l= I- 1 I i I! I .—G•�l __�.___� 1 OI IVr V!l_/ I 1 i 4 1 1 I I I _-_ .ej - L 1- 1 I f 1 f V• __ I_ f I- /` I I- i I � 1 1 _� 1 G �- .-,,,ter+� I i i I i 1 I i I I � I •- 1 f l 1 1! �J- 1 1 I 1 1 �_•-_ � 11 I I I- I f i I I I I 1 1 I v - t I I I I I I I 11 1 i I I I I I 1 i i I II--r I I _—y I - lp -1 i-I 1 t i To I I ! I� I 1 ' r- LE .__... _..._......_.. *** CURB OPENING INLET HYDRAULICS AND SIZING: INLET ID NUMBER: 10 ✓� �' INLET HYDRAULICS: ON A GRADE. INLET DESIGN INFORMATION: ' GIVEN CUR§`-­OPE ENGTH (ft)= 5.00 REQUIRED CU�B—OBENI TH (ft)= 22.68 IDEAL _,, -CURB OPENNING EFFIC = 0.36 CURB OPENNING EFFICIENCY = 0.33 STREET GEOMETRIES: ' STREET LONGITUDINAL SLOPE W = 1.69 STREET CROSS SLOPE (%) = 2.00 ' STREET MANNING N = 0.016 GUTTER DEPRESSION (inch)= 1.50 GUTTER WIDTH (ft) = 2.00 ' STREET FLOW HYDRAULICS: WATER SPREAD ON STREET (ft) = 10.47 GUTTER FLOW DEPTH (ft) = 0.33 FLOW VELOCITY ON STREET (fps)= 3.66 FLOW CROSS SECTION AREA (sq ft)= 1.22 ' GRATE CLOGGING FACTOR (U = 50.00 CURB OPENNING CLOGGING FACTOR(%)= 10.00 INLET INTERCEPTION CAPACITY: ' IDEAL INTERCEPTION CAPACITY (cfs)= 1.63 BY FAA HEC-12 METHOD: DESIGN FLOW (cfs)= 4.50 FLOW INTERCEPTED (cfs)= 1.48 ' CARRY-OVER FLOW (cfs)= 3.02 BY DENVER UDFCD METHOD: DESIGN FLOW (cfs)= 4.50 FLOW INTERCEPTED (cfs)= 1.46 -----------CARRY_OVER-FLOW--(cfs)=------3.04 '----------------------------- 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:Water Waste and Land -Ft Collins CO. N DATE 07-26-1995 AT TIME 17:24:29 *** PROJECT TITLE: JFK PARKWAY ***. CURB OPENING INLET HYDRAULICS AND SIZING: ' INLET ID NUMBER: 10 INLET HYDRAULICS: ON A GRADE. GIVEN INLET DESIGN INFORMATION: I 1 APPENDIX II ' RAINFALL AND WIND EROSION CALCULATIONS I I I I I I I I I 1 1 1 1 1 I I 1 1 1 I 1 i 1 1 Ll 1 -- -- 5 T �� fob C„ _ � �" — -- `,�i' :� li i Project i lu.. c�:ea �y: l C�j iC : � �! � r "�-s� ►J �.- � f-I'�_-� i�L�'���C 4� l iD�l�`���'� I`t=rZ- J F}C �a2� Y Nrc H F �i--r--7 �)C.S �L- 5LVtvEy Gf �2�� 6LZk-rTo W� �e2QLZ7,`r' rot. SOT � t( G-- Cyr i az� G��-cam, SuJ \ ,Lz--5 Aip . J' Y 2-" Ar��C�►� �-P,(-�-D A 1 > ,' ✓, JA Y o �(55�c—--- � (a7 1 2629 REDWING RD:.0 SUCE 200 PORT ..CLDNS. CCLOR:D -6 (� '_j 226-d=�5 rA:4 RAINFALL PERFORMANCE STANDARD EVALUATION ----------,-q---------------------------------------------------------- IPROJECT: /"l�SC„ sr�•�5 J AFC' if�L�G�-�Rr STANDARD FORM A (COMPLETED BY: DATE: -----------------------------.------------------------------ ----- S -I IDEVELOPEDIERODIBILITYI Asb I Lsb I Ssb I Lb I Sb I, PS SUBBASIN I ZONE I (ac) I (ft) I W .I(feet) I(*) I (o) I ----------- ----- ------ ------ ------ t pl--O-z- ELM ----------------------------- HDI/Sr--A:1939 EFFECTIVENESS CALCULATIONS ---------------------------------------------------------------------- PROJECT: �/ ��� �"7�J� STANDARD FORM B , COMPLETED BY: Nan-�/, r�!. DATE: Erosion Control C-Factor P-Factor Method Value Value ---------------------------------------- L--7— �L r l o - 6,1T ------------- MAJORI PS BASINI (;) SUB BASIN it AREA (Ac) ----Comment --------- I 10'/IOA,9 ,4 /C ' UALK} El��r �l^emu l�azC I I CALCULATIONS ---------- ---r�. ,---- ---------- yLl, / C - l�Arr�2 sr� ______--- D �2 �( �rF�Tr✓��� ,� ---------------------------------------------------------------------- HDI/SF-B:I989 [1 ' -EFFECTIVENESS-CALCULATIONS----------------- - ---------- 1 PROJECT 4r� / ��� j, J�J STANDARD FORM B ' 1COMPLETED BY: [n� hT�� �r1� DATE: Erosion Control C-Factor P-Factor 1 I Method Value Value Comment ------------ --------------------------------------------- I I SE7¢ a v�-O ' I ---------------------------------------------------------------------- IMAJORI PS I SUB I AREA I E BASINI (;) BASINI (Ac) I CALCULATIONS I I----- I------ i----- I------ I ---- r----------------------------------- I I I D c� cw,( D1) 75D"/7-� �/u I�:O KD;vci iSC 'rL I I 1�r(.c,b11/17L) 75.z�Lq Dry ---------------------------------------------------------------------- HDI/SF-a:IoBQ 1 1 1 1 1 1 1 1 i 1 1 1 1 i 1 i 1 1 RAINFALL PERFORMANCE STANDARD EVALUATION ------------------------------------- PROJECT: ✓ l� l ✓�CK�r�� STANDARD FORM A COMPLETED BY: b.)E—Ti�C_.-1! DATE: ------------------------------------------------------------- DEVELOPEDIERODIBILITYI Asb I Lsb I Ssb I Lb I Sb I PS SUBBASIN-I ZONE I (ac) I (ft) I (.%) [(feet) I (%) I (%) ----------- I------- I------- I------- I------- I D �l MB A II /, yyi I z Z N 1T )T m ------------------------------------------- DI/SF-A:I98S Z, 2— c5l j qo1 s 10 �zde �i (O WATER 1 Project: r7 �N `'�' CalcUlated By: Tkf ' W A S T E � (x Project No.: to IChecked By: & LAND Task: ski Date: y INC. � TJZC �jj FO vv z ArEUK4� 5�f-- L6-&4g ll ' Z��0 uJ 4 �( 5rA c/-�-tC fo <Ff56 (kra = 515a6�7z = Lp I C4,rzoA - f4c)6 hL & LN�-7774 _ ((»' 1 1 m J\L�G�1•'�1 \� (Y`���.{-i = Z�' / LV Ali L - /r 2629 REDWING ROAD SUITE 200 FORT COLLINS. COLORADO 80526 (303) 226-3535 FA.0 (303) Z26--6475 I — VAX WAT'ER' Project: _,1L1 Calculated By: �T W A S T E Project No.: I"T , �(`� Checked By: & LAND Task: Lf'Al I Date: --INC. Ir 00 o= z3I9� Z �� ��-� rat ►JL�C� ' 104c nwuuw KUAU �, , zuu tUHI CULUNS, COLORADo 80526 (303) 226-3535 FAX (302) 226--64 I I 1 1 1 1 I 1 EFFECTIVENESS CALCULATIONS ---------------------------------------- - �� ✓ PROJECT /�' ��T� J /I%L(jCQcrr2� STANDARD FORM B �I COMPLETED BY: DATE: Erosion Control C-Factor P-Factor Method Value Value Comment I�-------------------- ✓�iJ[ — ;------------- ----------------- l) rim, c ����vs co bb ' 015 z k, 1, D„ p�Er�oa �y �A ,vr,�,�.T.�,-; I I------------------------- IMAJORI PS SUB I AREA IBASINI (;) +BASINI (Ac) F -----CALCULATIONS ---- ----- ------------------ C5 = 1, 0 0 AL 0. Hy AL 1, L14 C � 0.5K0.8x�,�. Er-F�c'rs✓� dl� fj ; I .3]Zx &3,2F �( I CC� °To �,� G'�,vl I I I I I I I---------------------------------------------------- HOI/SF-B:I989 t EFFECTIVENESS CALCULATIONS --------------------------------- ✓_---------------- -------- ----- �"�V► PROJECT: �� cr� F,,F, �,��_ STANDARD FORM 8 j COMPLETED BY: (���L , CT4 DATE: I Erosion Control Method -�-y---------------- ------------ MAJORI PS BASINS (;) SUB BASIN I AREA (Ac) 1' yq C-Factor P-Factor Value Value Comment --------------------------------------- 0.01 /6,b FL 6Ln� �i --------------------------------- CALCULATIONS --------------------------------------- �A✓�7 1. c�c:�c.. aL o =D,�2� SFr, ce-T ew 2ss g�rF = C/,o (0.az-5�c fir= q�5��>.� ✓�;� ---------------------------------------------------------------------- HOI/SF-B:Ia89 ' CONSTRUCTION SEQUENCE r-ra, STANDARD FORM C 'PROJECT: IQUENCE FOR 19 75 ONLY COMPLETED JJ -� BY: l�t/t ST L !I� DATE:�� '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 199 I 19Gib MONTH ' OVERIAT GRADING i ; WIND EROSION CONTROL ' Soil Roughening Perimeter Barrier I I Additional Barriers I I Vegetative Methods Soil Sealant I Other M4-r,.t'a--FCA-r 'LL5 I I •, RAINFALL EROSION CONTROL i j I STRUCTURAL: ' Sediment Trap/Basin ! Inlet Filters Straw Barriers Silt Fence Barriers i Sand Bags Bare Soil Preparation Contour Furrows t Terracing i Asphalt/Concrete Paving ' Other I , I I 1 VEGETATIVE: I I ' Permanent Seed Planting I-a--�—• Mulching/Sealant I Temporary Seed Planting Sod Installation ' Nettings/Mats/Blankets I Other 'STRUCTURES: INSTALLED BY MAINTAINED BY VEGETATION/MULCHING CONTRACTOR ' DATE SUBHI:':ED APPROVED BY CITY OF FORT COLLINS ON ' MARCH 1991 8-16 DESIGN CRITERIA 9 J I 1 1 1 1 1 1 1 1 1 1 1 1 k 0 WATER Project: rk�e- • Calculated By:IM W A S T E Project No.: yI `'J 1Ly Checked By: & LL'11\D Task: Date: arc L yi�T� -�r2p5��Cc � CO��2 zo Z y LTti1 ra u.FtT�o �l = 7-5 Sys C�'ST err (!:�;QTa-m� s z1 7, 3 3, 2629 REDWING ROAD SDITF 700 FORT COLLINS COIORADfI A057fi On-1) 796-111S =AY ATTACHMENT A FINAL DRAINAGE REPORT FOR HEART SPECIAL IMPR. DISTRICT CITY OF FORT COLLINS COUNTY OF LARIMER STATE OF COLORADO DECEMBER, 1984 REVISED: JANUARY 1985 PROJECT NO.: 311.2 Prepared by: Engineering Professionals, Inc. 2625 Redwing Rd., Suite 110 Fort Collins, CO 80526 (303) 226-3852 INTTRODUCTION This final drainage report is submitted in conjunction with construction drawings for Heart Special Improvement District prepared by Engineering Professionals, Inc. The City of Fort Collins "Storm Drainage Design Criteria and Construction Standards" were used as guidelines for runoff calculations and storm sewer system design. SITE DESCRIPTION Heart Special Improvement District is located in the West half of Section 36, Township 7 North, Range 69 West of the Sixth P.M. Proposed improvements consist of construction of portions of JFR Parkway and Troutman Parkway, realignment of the Larimer #2 Canal, construction of a 5-foot by 20-foot box culvert under the intersection of JFR and Troutman Parkways, and construction of water, sanitary sewer, and storm sewer utilities. Future land use in the District will primarily be commercial and business -related, although .approximately 10 acres in the southeast portion of the District is intended to be developed as high -density residential. The District contains approximately 45.3 acres, is predominantly covered with native vegetation, and slopes to the south and east at from .5 to 2%. The site is bordered on the north and east by Boardwalk Drive, on the west by business and residential properties, and on the south by agricultural land. The Larimer #2 Canal crosses the site in a general northeast -to -southwest direction. HISTORIC DRAINAGE Before construction of the Landings and Whaler's Cove residential areas, the portion of the site below the Larimer #2 Canal drained to the major basin thalweg to the south, while the area above the Larimer #2 Canal discharged into the canal. At present, the majority of the site drains into the Larimer #2 Canal, a portion drains south toward the basin thalweg, and the remainder drains into an open channel leading to Harmony Reservoir (see Figure 1). Estimated historic 2-year and 100-year peak discharges into the Larimer #2 Canal from the site are 5.9 cfs and 20.5 cfs, respectively. Estimated 2-year and 100-year historic peak discharges from the site area below the Larimer #2 Canal are 4.2 cfs and 15.5 cfs, respectively. MASTER DRAINAGE A report entitled "Master Storm Drainage Report for the Landings P.U.D.," by Cornell Consulting Company recommended that areas above the Larimer #2 Canal be allowed to release storm flows at the historic 2-year level directly to the Larimer #2 Canal. Those portions of the site below the Larimer #2 Canal, with the exception of Troutman Parkway, were to drain into an open channel running to Harmony Reservoir, as outlined in the above report. DRAINAGE UNDER DEVELOPED CONDITIONS City of Fort Collins Storm Drainage Utility staff has recommended that the Larimer #2 canal running through the site be sized for a total discharge of 240 cfs, 155 cfs of irrigation flows and 85 cfs of stormwater flows. Assuming only those areas above the canal and to the east of College Avenue, (with the exception of the Jetty P.U.D., which discharges to Harmony Reservoir) contribute to stormwater discharge into the canal, the allowable release rate per tributary acre is approximately 0.87 cfs per acre (see Figure 1). We request that the City of Fort Collins require all future developers in this basin east of College Avenue above the Larimer #2 canal to design and construct facilities sized to detain the developed 100-year runoff volume and release at a rate of 0.87 cfs per tributary acre. Curb inlet lengths were sized for the 10-year event according to City of Fort Collins Drainage Design Criteria. Storm sewers discharging from future building sites into curb inlets were sized based on a detained release rate of .87 cfs per acre summed with any offsite discharge. The remainder of the storm sewer system from- curb inlets to the Larimer #2 Canal were sized to handle the larger of the peak discharge from the 10-year street runoff intercepted by the curb inlets, or 10-year peak discharge .from the total tributary area assuming a time of concentration of 20 minutes. According to recommendations made in the Cornell Report, those portions of the District below the Larimer 12 Canal (basins H, I, and M; see map) were to drain undetained to Harmony Reservoir via a grass lined, trapezoidal channel. Due to circumstances unforeseen during preparation of the Cornell Report, we propose that detention facilities sufficient to detain the 100-year event and releasing onto "Somerset" at the 2-year historic rate be constructed by future developers of basins H. I, and M. An undeveloped area of 3.6 acres at the Northwest corner of Landings Drive and Boardwalk discharges under Boardwalk via curb inlet and culvert onto Basin E. The inlet and culvert were sized by others based on undeveloped conditions; future developers of that parcel will need to detain on -site to limit future discharges to .87 cfs per acre, as this area historically discharged into the Larimer #2 Canal. We assumed that these undeveloped flows passed through Heart S.I.D. undetained to the Larimer #2 Canal. ENGINEERING PROFESSIONALS, INC. Jonathan B. Howard /I Michael N. Schmid, P.E. JBH:psm N u 14 C •� a �a� 11 11 � � I \ I � / N' W W k�_ .- 01"T ku qs. kD Nqo 1 v Y 1 1 I i I ^n/ • w l .ate , : Y•. ; , : f I •° i Y nIt a. 1 `� I / IMP I i' -1 � 1 V 11 i u\ I i r I er. •------i ----`III �• aW ..� `�'' _. 1•�14�: _._--- —(_- - -- ---r ir i • _ ., ��— ... �•� .. ' PAP )1�' �4�� } `� �• �. G' , r EpuniY .. - ��. • � Y m0. Y a- Q• .c NN3H1/105 ONV OOVLl0700 =« - --- = / _MERGER_-__ ._ - 1 _! „ ....Mt----'�..: •• i.—i1N•; ._\ I 1 ATTACHMENT B I "O'CIMPUTATIONS STEWART&ASS&JATES Consulting Engineers and Surveyors .502 z 214 N. Howes St. Ft Collins, CO 80521 *.(303) 482-933.1 - Y: Date f----f--Client: -57-7 1 r a Pa !ram r Sheet No. hkd By: Date� Project: 4v 77� Subject ->±O 04 The vric 1!nodl I I orr . ' I pr ep /I 7T/i . fd�4e'o4dI. ! ;0. e, elr c Al03 Id V 1.7 ;ee 7 e-,-7 pC! rot, ides vlle.� CA A'J I I - a p 5141r�' C e I - 6XI 1 i -)L-0 ;rV n - !04T -N,! e- e pop M, is des 1:5J, e2 CA V— Im -I). I I I I l i I f ;' i ' T� i5 J-rJ 'O'Y (7i i i i� I I I i i I I I: e 0' Z: ;of- e FIEVie 4 d, CYO Lo e 0 ,A F01PO e- r re 7LO 4:t e)Z I Y0 4e!. fv-�Lir- :� e C A;e p> JI Op - 1� 7L S/ (L kov'i 'N �-e)l \'lal d e! F e Teex is 1.rij- i I -rci 1 dil4 1 r-q '4 the re �-e "14-1 V'V7 1 1 1 pond V -e -rLe n 0 I On will be i s u c �Ie �,e e- 4- 0, op,�/ x r 'C qc{ V� V V L, eel- e j R 7f.0 �5- or-� !I at r Q.L Fee,,; 7; 9 7 c7' p I R Date Z 2 Client: - ly. Chkd By: Date Project: ConsuI103 Err3ineersand Surveyors 214 N. Howes St. Ft. Collins, CO 80521 (303) 482-9331 r o P` i/ P r r r Sheet No. Z of 3 ion 40 Pcdr-fei Norm- l..i- Z FeehPv 5L5�_ / tbject S T11 U r rti ! r• a I' h a q r Dei=e�i;rJ1�.� IJolv !.�i I I Lq ��l + I' ! �tq0 l Icy i i � �47 i t 3or Z ' j i IN L1'3`.7 I I ' 33 7/1 t ' I la8o I I i..l. 13Z11 I. I I I { I I�3.70 I i. ZqZ I _ I L 1 u. 2h_ =1 .. I0rr.. 1 Q4{j4 r j-1ii I i ,14- ; o.Z,;, I I I I ! IJ f7o4 i I I ii� .z3r�l� 1...1 ���n�; . - J5! RPI d I I ! I I I -.t. I I! I ., I , t L ATTACHMENT C Fina pproved Report Date FINAL DRAINAGE REPORT FOR TOYS "R" US AND WESTERN AUTO STORES SOUTH COLLEGE AVENUE AND BOCKMAN DRIVE FORT COLLINS, COLORADO JUNE 4, 1991 (REVISED JANUARY 14, 1992) PREPARED FOR: ROSENBAUM/DEAN 101 North Cascade Suite 400 Colorado Springs, Colorado 80903 719-630-0066 PREPARED BY: PARSONS & ASSOCIATES CONSULTING ENGINEERS 432 Link Lane Plaza Fort Collins, Colorado 80524 303-221-2400 PROJECT NO. 91.03 TOY ' FINAL DRAINAGE REPORT FOR TOYS "R" US AND WESTERN AUTO STORES ' SOUTH COLLEGE AVENUE AND BOCSMAN DRIVE INTRODUCTION This drainage investigation has been prepared along with final plans for the Toys "R" Us and Western Auto Store to be located ' northeast of the intersection of South College Avenue and Bockman Drive. This study was prepared in accordance with the City of Fort Collins "Storm Drainage Design Criteria and Construction Standards" ' and based on the site plan prepared by Masterplans Design Concepts, Inc., a topographic survey completed by Rick Lewis, P.L.S. and preliminary review comments completed by the City of Fort Collins staff. SITE DESCRIPTION ' The study area is situated in the Northwest Quarter of Section 36, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, Larimer County, Colorado. The site is ' bounded by: South College Avenue on the West, Western Wardrobe and Larimer County #2 Canal on the North, JFR Parkway on the East and Bockman Drive on the South. The site comprises approximately the northern one third of Superblock 5 plan prepared for South College Properties. The Western Auto Store site is located approximately in the area of the previous South Grove S.I.D. The site is presently undeveloped except for an abandoned house and an existing lumber yard which will be relocated. The site slopes generally to the North and Northeast at 0.5% to 6%. Vegetation consists of native grasses and brush along with a few scattered trees. HISTORIC DRAINAGE The project area falls within the limits of the Heart Special Improvement District (S.I.D.) Final Drainage Report completed in January, 1985. This area (shown in Figure 1) includes the 2.4 acre Western Auto site, the 5.4 acre Toys "R" Us site and approximately 5.1 acres of undeveloped area to the south. -1- I, -2- u I ' Three different.subbasins contribute to the historical runoff.` Existing Area #1 is a sliver of land which drains into South College Avenue. This area is approximately .4 acres and is the area between the East curb of south college Avenue and the front of buildings in this area. Existing Area #2 is approximately 2.0 acres in area and covers a level area just East of South College Avenue along Area #1. Flows here continue to the North where they ' are intercepted by the Western Wardrobe, Wendy's, and Palmer House drainage system and held in a retention pond behind the Palmer House. The remainder of the flows in Area #3 are surface flows which continue Northeasterly before they are intercepted by the Larimer #2 Canal. Once intercepted by the canal they are transported in the canal Southeasterly to either Warren Lake or the Larimer #2 extension ditch. A small 0.38 acre portion of this area ' north of the Larimer #2 Canal continues to drain to the north away from this project. ' These existing basin patterns are modified by the development of this project. Existing area #1 will be reduced by approximately one-half as the Western Auto Store grading and landscaping are ' completed. The runoff from Area #2 will be totally contained on the Western Auto Store site and will eliminate any runoff to the .existing commercial properties to the north. Area #3 will continue to discharge into the Larimer #2 Canal; however, through controlled ' outlets at reduced flow rates. ' MASTER DRAINAGE ' Following the guidelines developed under "Master Storm Drainage Report For the Landings P.U.D." by Cornell Consulting Company and reaffirmed by "Final Drainage Report for Heart Special ' Improvement District" by Engineering Professionals, Inc., only a two year historic discharge should be allowed into the Larimer #2 Canal. This discharge was further defined by the Heart S.I.D. final report at a limit of 0.87 cfs/acre of development. This release rate was used to compute the required detention volumes for each basin identified in this report. ' DRAINAGE UNDER DEVELOPED CONDITIONS The final site layout and grading are attached as Figure 2. In general, the grading plan will follow the contour of the existing slopes, tipping to the northeast. A summary of the proposed drainage basins follows: 1 -3- 'J ' BASIN AS (Western Auto South Parking Area) Basin AL includes the South parking lot of the Western ' Auto store site, the north one-half of Bockman Drive from South College Avenue to Mitchell Drive,and the west one- half of Mitchell Drive from Bockman Drive to the first driveway entrance. This basin is 1.20 acres large and ' will require 10,260 ft.3 of detention volume discharging at 1.17 cfs (See Table 1). ' BASIN A, (Western Auto Building and North Parking Area ' Basin AZ includes approximately the north parking area, the west one-half of the Mitchell Drive right-of-way from the southerly entrance to the northerly entrance, and the roof drainage from the proposed building. This basin is 1.05 acres large and will require 6,840 ft.3 of detention volume discharging at 0.78 cfs (See Table 2). BASIN A, (South College Avenue) The proposed site plan shows three graded and landscaped berms along the South College Avenue curb line along the west edge of the Western Auto site. The area which will flow from the side of these berms towards South College Avenue is reduced from .4 acres to .2 acres. In addition, the runoff from these grassed areas will be substantially less than the exposed dirt and packed gravel areas which now exist. We feel that this will allow us to improve the drainage conditions along South College Avenue. Existing flows in South College Avenue will continue to flow from South to North. A valley gutter at the intersection of Bockman Drive and South College Avenue will allow flows to continue Northerly without being diverted into this site. Bockman Drive grades increase from South College Avenue at a grade of 1.67% for a distance of over 150 feet. This is reflected in the street design for Bockman Drive as part of the site construction plans. A curb inlet has been provided in the curb line .along South College Avenue. This inlet has been sized to intercept and divert a portion of basin A3 flows into basin A1. The detention pond for subbasin A1. will be sized to detain these flows. Only a small portion of subbasin A3north of this curb inlet will flow offsite. -5- BASIN A4 (North End_ of Mitchell Drive) Due to the grades established by the design of Mitchell Drive through the Feeney Subdivision immediately North of this site it will be impossible to contain all of the Mitchell Drive runoff on site. Approximately .03 acres will be undetained at the North end of Mitchell Drive. In the short term, this runoff will be diverted to the East by a drainage swale and discharged into the Larimer #2 Canal. Ultimately, as Mitchell Drive is built, this_* area will drain into the Northerly Mitchell Drive ' improvements. ' BASIN B1 (Toys "R" Us Parking Area) Basin B1 includes all of the Toys "R" Us site to the west ' of the building, the east one-half of Mitchell Drive and the north one-half of Bockman Drive from Mitchell Drive to the approach at the west edge of the Toys "R" Us building. This basin is 2.42 acres large and will ' require 16,590 ft.2 of detention volume discharging at 2.00 cfs (See Table 3). ' BASIN B2 Basin B2 includes the remainder of the Toys "R" Us site which includes the roof drainage, the north one-half of Bockman Drive from the approach at the west end of the building to JFR Parkway, the areas directly north and ' east of the proposed building and the east one-half of the JFR right-of-way from Bockman Drive to the Larimer #2 canal. This basin is 2.24 acres large and will require 15,180 ft3 of detention volume discharging at 1.90 cfs (See Table 4). BASIN BZ Basin B, includes a 0.38 acre parcel at the northeast corner of the site which is north of the Larimer # 2 canal. This piece will be maintained in its natural state, (0.10 acres drain into the canal and 0.28 acres drain to the northeast). It is anticipated that ' detention needed for this area will be included in development to the north of this site. -6- ' BASIN #B4 (North End of Mitchell Drive) ' Due to the grades established by the design of Mitchell Drive through the Feeney Subdivision immediately North of i this site it will be impossible to contain all of the Mitchell Drive runoff on site. Approximately .03 acres will be undetained at the North end of Mitchell Drive. In the short term, this runoff will be diverted to the East by a drainage swale and discharged into the Larimer #2 Canal. Ultimately, as Mitchell Drive is built, this area will drain into the Northerly Mitchell Drive improvements. BASIN C ' Basin C includes all of the area south.of Bockman Drive between South College Avenue and the proposed JFK Parkway. The southerly limits of the basin extend approximately 450' south of the centerline of Bockman ' Drive to an existing ridge line. Approximately 5.1 acres contributes runoff to the southwest corner of Bockman Drive and the proposed JFK Parkway. A channel has been provided here to convey historical flows around the Toys ' "R" Us site and into the Larimer #2 Canal. The preliminary design of the JFK Parkway and Bockman Drive ' intersection includes inlets and storm drains which will carry JFK runoff and detention pond releases from this area to the Larimer #2 Canal. Drainage from the South. one-half of the Bockman Drive right-of-way is intercepted ' by this channel as well. The channel for this basin will convey the 100-year historic flow which is calculated as 7.2 cfs. Any detention or storm drainage improvements for this sub -basin will be constructed as the site develops or as the JFK Parkway is constructed. �I -7- 1 11 1 1 1 SUMMARY The total developed Toys "R" Us - Western Auto site includes ' approximately 7.72 acres. As per the allowed release rate of 0.87 acre/feet per acre, this site would be allowed 6.72 cfs of runoff in the 100 year event. To meet this requirement, several detention ' ponds with controlled outlets have been provided. The total runoff from the developed site (as summarized in the following table) is 6.97 cfs. ' Actual runoff from this site exceeds the allowable by .25 cfs. We feel that this is within the accuracy of the calculations. In addition, this is a temporary situation. Flows from Basins A41 B3, and B4 will be collected by detention ponds in future developments to the north. This means that approximately 1.12 cfs from these three basins will ultimately be detained. We feel that this is an ' effective and conservative solution to the Toys "R" Us drainage conditions. We request a variance to allow this .25 cfs to be discharged from the Toys "R" Us and Western Auto site in a 100 year ' storm. 1 1 1 1 1 i 1 1 -8- 1 SUBBASIN SUMMARY u 1 1 I ..1 Drainage Area Allowed Actual Req. Avail Ori- Remarks Subbasin (Ac) Runoff Runoff Deten Deten fice (On- (0.87 From (Ft3) (Ft3) Area Site) CFS/ Site (S. ACRE) (CFS) F.) Al 1.20 1.04 1.17 10260 11056 .111 Detention in parking lot u A2 1.05 0.91 0.78 6,840 6,9253 Detention in 0.07y parking lot A3 0.37 0.32 --- None --- --- Diverted into Basin Al A4* 0.03 0.03 0.22� None --- --- Undetained area of Mitchell Drive B1 2.42 2.11 2.00 16590 16305 .118 50 Year Storm Detention Underground B2 2.24 1.95 1.90 15180 16125 .118 50 Year Storm Detention Underground B3* 0.38 0.33 0.68 --- --- --- Natural area North of Canal lUndetained B4* 0.03 0.03 0.22 None --- --- area of Mitchell Drivel (On- 7.72 6.72 6.97 --- --- --- --- Site) Total Drainage Subbasin (off - site) C 5.10 4.44 --- --- --- --- Flow is Q-100 detention is part of future developement *'Note: Runoff from B4 and A4 will eventually continue down Mitchell Drive and be detained in detention ponds constructed as part of Palmer House Improvements. Runoff from the north end of Subbasin B3 will be detained by future development along the JFR Parkway. Table le✓ise) 3.72 f e re f �ecf " qs Ou;l f " Cmd l firt ' aJ rrjuejW d, slo(M wa l+r ui�l�l� / 11, f . �J r� I 1 ATTACHMENT D 1 L 1 1 1 1 1 1 i 1 1 1 1 1 i 1 1 1 1 r=inal Approved Report dateL; FINAL DRAINAGE & EROSION CONTROL REPORT FOR JFK PARKWAY (BOCKMAN DRIVE TO LARIMER #2 CANAL) FORT COLLINS, COLORADO SEPTEMBER 19, 1991 (REVISED MAY 19, 1992) PREPARED FOR: WAYNE K. SCHRADER PREPARED BY: PARSONS & ASSOCIATES CONSULTING ENGINEERS 432 LINK LANE PLAZA FORT COLLINS, COLORADO 80524 (303) 221-2400 PROJECT NUMBER: 91.13 JFK I I C 1 Larimer #2 Canal. This basin was included in the drainage analysis for the Toys "R" Us/Western Auto P.U.D.; however, due to the grade of the JFK Parkway it is not possible to direct these flows into the Toys "R" Us detention system. An inlet at the Larimer #2 Canal will be built to intercept these flows where they will be conveyed via storm sewer to a temporary detention facility along the east side of the JFK Parkway. These flows, along with the flows from Basin E, will need to be included in permanent storm drainage detention facilities to be constructed when property east of JFK Parkway develops. BASINS G & H A small portion of the JFK Parkway right-of-way lies north of the Larimer #2 Canal. Basin G is the west one-half of the JFK Parkway and Basin H is the east one-half of the JFK Parkway north of the canal. Basin G is approximately .10 acres and Basin H is approximately .07 acres. This area flows to the northeast away from the Larimer #2 Canal. The flows from these two JFK Parkway basins will not be detained and will continue to flow to the northeast. As this section of the JFK Parkway is extended to the north and development occurs on the adjacent property, these flows can be diverted to future detention ponds. Slope paving and riprap have been utilized to reduce erosion from this runoff. BASIN J The area between JFK Parkway and Landings Drive and between the ridge line just north of Boardwalk Drive and the Larimer No. 2 Canal contains 7.19 acres. Currently, runoff sheet flows from south to north where it is intercepted by the Larimer No. 2 Canal. Basins A, E & F also will discharge through Basin J as JFK Parkway is completed and as Basin J is developed. A temporary detention pond will be constructed to collect flows from these Basins and release them into the Larimer No. 2 Canal at a controlled rate of 0.87 cfs/acre. In addition, flows from the temporary detention pond on the west side of the JFK Parkway will be routed through this temporary detention pond. A 12 3/4" X 12 3/4" orifice plate mounted on an outlet structure will restrict flows. This will allow all drainage runoff from the construction of the JFK Parkway, and from the two proposed development areas along the JFK Parkway to be discharged into the Larimer No. 2 Canal in one location at the allowed rate as requested by the ditch company. SUMMARY PROPOSED STORM SEWER IMPROVEMENTS A proposed 15" storm sewer system will be installed in this phase of JFK Parkway (see figure 2) . This system will provide a drainage outlet for future development in Basin D as well as adjacent street improvements in Basin B. Basin B flows will be directed to the future 0 development via driveways and a future inlet at the southwest corner of Bockman Drive and the JFK Parkway. Temporary detention pond "A" and an orifice plate controlled outlet will insure that this system will function properly with an allowed release of 5.02 cfs. Flows from Basin "C" will be directed into an inlet at the southwest corner of Bockman Drive and the JFK Parkway. This runoff will be directed into the Toys "R" Us underground detention via a pipe under Bockman Drive. Inlets at the north end of Basins E & F will direct runoff onto property east of the JFK Parkway where it will flow into temporary detention facility "B". Detention Pond "B" will also collect runoff from Basins A and J. Eventually this runoff will be included in a permanent detention system as the site is developed. An outlet from this pond will be built to allow flows from both temporary detention ponds to be released into the Larimer No. 2 Canal. Riprap has been placed at the outlet to prevent erosion around the outlet pipe and inside the irrigation ditch (see attached calculations for sizing riprap). Also this site must detain for Basin F which is the west side of JFK. This is not a normal requirement since adjacent properties are normally only required to detain to the crown of adjacent streets. However, due to the site topography restrictions, this detention requirement will be imposed upon this site. In exchange for this, the usual site to be responsible, Toys "R" Us, will provide detention for Basin "C" (see Basin "C" discussion) -10- PROPOSED STORM cr II Ilan II II�� I I 1014, •I � II . 0.10 aceee rJeiMae wcn.Z ctuA.- -- >:Xl4TrNG eCTAW1uG Wd1L ''TOTAL u1J0ETAMJF-0 FLOW4x �Q,pO OGvGLOPED) ' sns1U o 1.6 cfe i sAorrJ N o•-7 Gf� #TO Bt DCTd1UED BY fuTu2E DeVBLOPYIL'uT ,,' DETA11.]£O FLdw3 (61,00 OevEe.c�PEO) ' 'BA�SILI B !e•7c�'S OFYd1uED lu Po"o *A 9A�JIU O 45.9 cf� - 9d'SIU G 4.0 -rOYb•C' u4 OETEuT1Ou 'BAh11.7 A 6.5 cFe OQ•rAIUEO UJ POUO'B' Baw q w sw E 3.6�5 :5A41U F 4.4 cps w IIII 5A,61 J J " • ' w III I uuos2Geoui.la }F oETELJ"r101j Ez»T. T `ALJ 34-eGP �� I IIII BA71u 16 ece T,E o 1 TOYS 2• uh DETElJTlolt I ' BOG Off. •N 'oe/FtGE P1_ATE T�F-[Poe:AeY OETFj.Si10rJ /� ijED11'ILL7TAYIGL.1 POLIO A IMPROVEMENTS P dceE4 UeW 5'a2o' GOLGY.ETE 9'f a uGTues �1. �Y m n 1 V o �. m�mo \ , Fo�,a �- 5'Oz 'ape, �[11 r ,Wu-ru2E Oe1vE L 6.5 c4's r�To rErtP: DeTeurlou i 1 C 64.7 ciy V li F ;URE 2 BASIN SUMMARY BASIN AREA nto a+oo PERMITTED COMMENTS (ACRES) (CFS) (CFS) RELEASE (0.87 CFSlACRE) A 0.65 �3.5 6.5 0.57 DETENTION PROVIDED FOR IN POND 8 B 0.67 3.6 6.7 0.58 DETENTION IS PROVIDED FOR IN POND A C 0.42 2.0 4.0 0.37 DETENTION IS PART OF TOYS "R" US SITE IN EXCHANGE FOR BASIN F D 5.10 - 45.9 4.44 PERMITTED RELEASE FOR BASIN B & D IS 5.02 CFS. DETENTION IS PROVIDED FOR IN POND A E 0.36 1.8 3.6 0.31 DETENTION IS PROVIDED FOR IN POND B F 0.44 2.3 4.4 0.38 DETENTION IS PROVIDED FOR IN POND B G 0.10 - 1.0 - DETENTION IS PART OF FUTURE DEVELOPMENT TO THE NORTH H 0.07 - 0.7 - DETENTION IS PART OF FUTURE DEVELOPMENT TO THE NORTH 7.19 - 64.7 6.26 PERMITTED RELEASE FOR BASINS A. E, F & J IS 7.52 CFS. DETENTION IS PROVIDED FOR IN POND 8 TOTAL 15.00 BASIN A Orr Q:__ = 2.00 CFS III Wor 7 I AWN B � •-.. -.....—...—ate ��•• BASIN B 0100 Or 2.00 CFS •'`-..,: SALT IN PEl1 BASIN C I MITCHELL DRIVE •;CAI' - 30' I �I fa l SHMME ADEQ _ uaExR o N! MG xIR, J I —.9.C— I UNK CIXIIWRS (I n ) W N12�3 PALMER FLOWERS ♦ ♦^ud .. )ml N . xEw warocWrz cgRWR f IN Lv.n- R,Y l0 NUMBER Or I x REFERENCE INEPT NUMBExi)-----. gdFWLP 9LSIN vv rzxcP (SEE DnuL D xe WEEI s) LMHs OF DISTURBED AREA 4 'NEEYES 1ASEE BnLIn LA H ♦ BASIN E a DPRAPPA,N -mce..• /., i.. ..1 INNUCCE: WAS& - 100 YEAR STURM B IN �__ - POND A s. •► INR 2.5A END YFIRE � FLAT DETAILS �i6 R �' V W28NO UP 4RI ) _... __ _ ♦w� i_ ___ ROL _ - _ .. _ _ ��..♦� Ooff .a � 1WOOMTFEATURES ARE B<D .xm WEASS mAR AND urDSArxc HAS BEEN EsTAUuONEDe. CONSTRUCTED EMOLM AND s - HI . Of 1I UUiIN STANDARDSND m a AmonD cE 1 TITS . NA I INR. N BN Ac n COMPLY ON END STATE OF Ctt(AAW PERMITTING PROCIEESS FOR-S,0.11M TEgSLxMCFS ASSCOARU WM CMSTiUCTM ACTUATES PON RETAWnp. PLEASE CONTACT CIXPiAW SENT OF HALM RARN WAIIM1 IX DAbW 'Att0 [ B2. ATM. FRONTS k ENFORCEMENT S. IF ADEATINHO IS USED TO Al UTILITIES, THEM A CONSTRUCTION MNATEAINII MnsRWA R DISCHARGE PERMIT — E ♦ A NE BE PEWIRED R OSENAR® INTO A STCPM rWO 7, PATCH NNESTATESlOR x R AI MV WARS Of END BASIN D; c % 2 ON, F P All ROMENE CMmas APPEBE FO AMLIAWE ON SCHEDULE BELCH ON RELL BASIS FROM START orz TRACKING IN AND SEDIMENT ONTO RSE O STREETS WALL R ie I CONSTRUCTED CONTROLLED By I) AND S DINE. FETE TUSE IC A GRASETS S PAD ORE D' CONSTRICTED AT ME SIM ENTRANCE. (IT •I gWIL. STTO%MING Ill PREPI BOUNDARIES WALL BE DONE RED 111E PFRYIs9M M1 MP OIIH[P. A. ,IX.IYITW iW'BO BMT IO Y®Rim TOM it _ \_ e1P MQLRE Y SAAN PogC All 1I ____ AN N...WONNII - - ---- R.r ti.. 1A. TM E1 AS 11 10 IN, I'lle'� RAOAT m. Al Al OAREMIE MATION AT EAST 'A Al Im .. I Al =17STO AllNNN minor L LAYa DE.TEPT IO\ R)N'D SIAWRY m/nNo biquand Aammunk Albs olAum. NwNd Son s,.c. R I SAMENT R HE kmd F I, BBd G.OiO nR. UDMURT IT Ix 5 090 SII 8A> All SCALE IN FEE, AD PApr FEAll lei{ ) JOHN F. KENNEDY PARKWAY SCALE: 1" = 30 MISCELLANEOUS STREETS MITCHELL DRIVE JOHN F. KENNEDY PARKWAY k 1k 1� .. - lT hL" 1a 41M NEAR UP T aPl> 01E0 OMa W Sd LY, SW5 G NPII mo OPT• So SO AE . Aac Oda oPM a" W s.o so aM Ii. )�OOt mr OS 0AS Od 50 50 5AS ne 5W A N BSI TS I,F IDNI ILEE INS. CUPLU . `-- UIIIIIY FLAI"i AFFTNElvAE OilIf IAl II I Eli wvJ �.�7ca.' DRIVE & JOHN F. KENNEDY PARKWAY 6 of 8 PLAN AND EROSION CONTROL PLAN J