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HomeMy WebLinkAboutWESTBROOKE PUD SECOND FILING FINAL - 3 90H - SUBMITTAL DOCUMENTS - ROUND 3 - DRAINAGE REPORTFINAL DRAINAGE AND EROSION CONTROL REPORT FOR WESTBROOKE P.U.D. SECOND FILING AT SENECA STREET AND TROUTMAN PARKWAY December 29,1999 Prepared for: P & B Partnership Mr. Chuck Betters & Mr. Dick Pitner 2803 East Harmony Road Fort Collins, Colorado 80528 (970) 377-4913 Prepared by: Jeffrey W. Couch, P.E. Team Engineering, Inc. Town Center Plaza 350 East 7* Street, Suite 9 Loveland, CO 80537 (970) 613.2040 Project Number 701-9401 swale along the property line to the Pleasant Valley and Lake Canal. BASIN Dz Basin Dz represents the backyard grassed area adjacent to the Pleasant Valley and Lake Canal along lots 28 - 34. No impervious area is proposed in this basin and no flows will be concentrated. Al runoff will sheet flow into the ditch from lots 28 - 34. BASIN WI.&_Wz Basin W, includes lots 1 — 3 and a small amount of off -site backyard runoff from lots 26 — 29 in Westbrooke P.U.D. First Filing. Basin Wz includes lots 40 and 41 of Westhrooke Second Filing. These flows are directed easterly through the First Filing and are included in the design of the First Filing. They have no impact on the Westbrooke P.U.D. Second Filing. BASIN T, & Basin T, and Tz represent the flows in Troutman Parkway. Basin T, includes backyard flows from lots 25 = 27 and the south'/ of the paved area in the Troutman Parkway. Basin Tz flows represent the paved area in the north % of the Troutman Parkway. These flows are collected by inlets D and E at the east edge of the. proposed Troutman Parkway improvements and diverted into the proposed outfall storm sewer. OUTFALL STORM SEWER The backbone of the proposed storm drainage design is an outfall pipe which conveys developed 100 year flows from the site to the detention pond built as part of the Mountain Ridge Farm P.U.D. First Filing. There are several advantages to this design as follows: Flows from this project will not negatively impact the Pleasant Valley and Lake Canal. 5 7 2. 3. !� The routing of these flows match the regional Detention is not needed on the Westbrooke (Detention Pond 247). i I I drainage concept completed by RBD in 1994. I site. this need is provide I by the regional facility Potential impacts to the undeveloped property east of the Pleasant Valley and Lake Canal are eliminated. Figure 4 —.Storm Sewer Schematic shows the general layout of the storm water collection system. A UD-Sewer analysis is included as Appendix "A" EROSION CONTROL Wind erosion will be minimized by the seeding and mulching of disturbed areas. Water erosion will be minimized by the construction of temporary sediment�ponds adjacent to lots 19 1 & 20, 31 & 32 and 34 & 35. These ponds will be constructed along with silt fences prior to the start of site grading. Inlet filters will protect inlets B, C, D & E and silt fence will be constructed along the north, east and south perimeters of the site. CONCLUSION Flows from Westbrooke Second Filing, including off -site flows from the Johnson Elementary School, Will be conveyed by an outfall storm sewer to regional Detention Ponds 247 along Shield Street The following can be summarized from this report: This site does not exist in a defined floodway or flood hazard area. 21. Historic detained releases (Q,00'= 17.0 cfs)from the Johnson Elementary site will be conveyed through this site via the proposed storm sewer. me 3. These improvements are consistent with the outcome of the McClellands and Mail Creek Master Plan revisions completed by RBD Engineering in 1994. 4. Detention for this site will be provided by a regional detention facility completed as part of the Mountain Ridge Farm P.U.D. First Filing. 5. Impact on the Pleasant Valley and Lake Canal will be greatly reduced. Only runoff from nineteen grassed. back yards will flow directly into the canal. The historic Q,00 = cfs will be reduced to less than cfs. 6. A 36" RCP outfall pipe has been completed through the Mountain Ridge :'site as an outfall for this project. 7 7 WESTBROOKE P.U.D. SECOND FILING SUMMARY OF INLET ANALYSIS DESIGN THEORETICAL - FLOW PONDING THEORETICAL ALLOWABLE INLET INLET SIZE & CONDITION Qiuo DEPTH CAPACITY REDUCTION CAPACITY SIZE TYPE Ms feet cfs foot FACTOR cfs foot feet A 6 R Box Sump 6.8 0.6 1.40 0.80 1.12 6.0 B 15' R Box Sum 20.7 0.6 1.40 0.90 1.26 16.4 C 5' R Box Sum 5.1 0.6 1.40 0.80 1.12 4.6 D 5' R_Box On Grade 4.6 NA q 1 E 5' R Box On -Grade 3.6 NA 3 2 Note: Overflow for Inlet A will be in a backyard swale between lots 17 —19 & 20 — 22. Overflow for Inlets 8 & C will be in a concrete channel which discharges into the Pleasa4 Valley & Lake Canal. Overflow for lots D & E will initially spill into the Pleasant Valley and Lake Canal and eventually spill along Troutman Parkway when The canal crossing is complete. S4D doll? _ . �JSfhW�Q �a1�7f gZ a B, a BL AL C) Q Cz Li Cy Q CS d DI L DZ Ned 7 %W k4tf fe Dtic; Ali of I:r Ffia� W? T, d TZ Q i gOSM ,Tip fvt-074f/a1 j LiyA 6�4 ! 'C &to, (h(m, ivol Sfi�rf /.2 9S o. SD 330, Al-W 6yo ` StI.Of Iz� 1S o.S� 3yoI Sfiuf Oy5-70 9S o-76 Zeo Yak 1 0 /o 310,.ciou/ 1.0.1_ YS 0:73 I t y 3Se' Sfiuf I �,� o, v ° yf 1.50 70' yoiJ 71 to/d _ 1. o io o. r y Ys 0; yd 701 S7V' Cali e,y 9,0' y°,a yak al'ut 0 v %o . 20 ? 03 �a�` Yogi �. o o • Zo 0.6� _ sfpef m.y °ia . �yc' i•o fro' Sf/1t 0.5 0 %Y 0. 7? yro, Sfxf d<S% 7S 0 f0_ T#�4f TLz - 1. �Z �l •.l -.. 9or X LO) - -- - ----- ---- ---- ---- - - .- Tc--#a, - $7 �!•l - �9S ley-) 6Yo I.F7' 0175��� .c2 __ _ I P i ��d - y, >' _1_[� z = ' . g (• lS� I = 6.9 Cliq -- - -- --- ---- -- -r- q �(� - — ------ - ( 73( J live e ;rlht - rot/- Cf _.1 �_ -1 o (,93� ��-9� (eZ<) 4 0,7 cfs. (7.0) (4• ZO ?. 3 c{S < I11 0. r, C ,l. 1, ' ] :,. - --- - � �'�''- - _� ct _ - _—l•�7 �l•I - ��s a aa) tGc ` _ �I.87 � i a.,J �� (zS•67� - y. � . 7.16E ,r',, i lie - l �)."1- l Y'' k•Lts)� _7co � —= (ir s �75 l'75-X- -4 -- - -- - - - z �• S� 1r�ll� ---- -- --��� - - �Q �� �� _ _ � -►�- - 1�s ; (. y� (Ste; (y1�� = ;'. 7-- r{s-- -- -- -" - - - - lasl�i CZ - ��QU 0, 73 - - 72-=— o,_Cfs ' too (yr�_(S»� Z. 3 c{S �as1rJ- - C3 -.�._lo �1L171. ._17 �GISJ il�•G381 = IS Y Mir Q113 I' -- - ✓ �(�`r _.. - -- -' �-�. _ -- — --- ---- - --- l� �� �/,/ — l . 9,;�)' /•b j �� 0 1/`- --- - - I �I �. �S �r �lf_•� � ]• l /� i --- - 44/1.. f7 il1- �'lS }'11�� i110��/_- -_ I (GIDZY) ('/j-09)67 — - - 1� --- —•S��J -- �-G-l�c — -- l �7 ill - ('9S Y?S� %�50 ��/ - " �I �%� ��Gb7�i �Id k'�% ---- -y Z lli� 7,TGE' - 'rod - �l ?�-; /Y��% (� `� (l•�1 _= '�� 7_ r�s_ -- --- - 0)) 7P Z7f t �IF 5,7 Tkf 2 2 YO �'14711')(,Orn-) /,/r 73W ir cf c -es(019)z Z16 17'1 7r, 77 7Ai Ira J7 113 0, q 13, 7 December 29,1999 Mr. Basil Hamden Stormwater Utility City of Fort Collins 700 Wood Street Fort Collins, CO 80524 RE: Westbrooke P.U.D. Second Filing — Erosion Control Estimate Project Number: 701-9401 Dear Basil: I am submitting this analysis of costs for establishing an erosion control escrow account as required by the City of Fort Collins. These costs are based on the final erosion control improvements shown on sheet 3 of 12 of the Westbrooke P.U.D.. Second Filing Final Construction Plans. Three alternatives were compared as follows: Alternative 91— Cost of Construction ITEM QUANTI 1. Silt Fence 1760 2. Straw Bale Filter 10 3. Curb Inlet Gravel Filter 4 4. Sedimentation Pond 1500 TOTAL UNIT COST AMOUNT L.F. 3.00 $5,250.00 EA 50.00 500.00 EA 2.00.00 800.00 C.Y. 2.00 3,000.00 Alternative 91 Total $9,550.00 Alternative 92 - Cost to Reseed in Lieu of Construction TOTAL ITEM QUANTITY UNIT COST AMOUNT 1. Seeding 500,940 Sq.Ft. .0149 $7,464.01 Reseeding cost of $0.0149/square foot as provided by the City of Fort Collins. 114 East 5th Street Loveland, CC 80537 Office:970-613-2040 • Fax:970-613-2038 • Toll-free:1-888-404-3612 Basra A Tcz = 1,17 0./ - (.2 x l,o)) SI/10 �J Tr 61 I.0113 4f Tito= 3.7kAr QZ Cf C I l� plop - 0,0 ) (.10) 0. yv ) (t,03) = p, 6 cfs UIS-) 00) (3.7 ) (?.03) = !, 9 cfs i L Boil" j j 4reer = 0. 7Z /11 rl,!s LUwn TcZ - 1-b'1 _(l./- t 4sxIre ))6al/Z = (l•81i(,Gs)(�7y`) /. o 3 1 S� (Il '_( 11•�% 9SX�4��yP0 /z 1.8%J (O•fS) (21.907) - 7.7 r i To fq -own Tr rrc I Y7 04 (y, f bl ril)(o. S (72q) _ F.3 If1,, $ �/u T ( (ca / !2 (75- X 1. if)) w �Z - oy) (Opr7 -) (. 77 j7 ) ToTa 1.14f �z = Cf C /,0) (, 9s)(2.0) ( )z) = NJ- 6 V) (7?) 7.7 rro (su Novi) fim Fi w4 2—) foo p ?Z HI, 010 NOW) qz - �{ C J� _ (i.e) l 9s)it•�)(. yo) = l; l rfs C/I040?1 CofACI iy (my 61oSS -1,1fel cl 44Ael �L J� 4 0` 2`-0` 9'a� 9 f Z/i S'li A n Asome f-loW 4A = . s' Dio k 3Y - Y/) Qz 04 CIS _ Qrao ' l9 cfs l yy (. 914 y) � 1 � �7.0) = Z. Ll NO c111(i ff u board Assum.c d glfk = 1. o " 0 cfs X 1.33 = ? S cls (� � f•N9 �.E99b'�(.L�i6.�� Oho A - 41 _ 2 0 IR = . R94? Z. N cfs 7 /•7 cfs Dk q z to- r cfs /4% n ow 4iP ` lo•ts .Tlkt OPsl,�rr Tn fe I %� affi IC4 sj/te f fas'1 si�h- i QPSIj% QJsb 1 T'S CAS 3 CfJ (t) sup Ca,ro�`iaa rr / 3�Iff `8 cFs/80 - 8S CIs' wIN alw(lla4 1-4p(f01- Tale f ( Veil ifoik dfiw - %tJf S/Ye ) �Pdl h u• = /3.7 c{s (c) f 2.J Cfs l c6 �C3) = ea.7 r VJe !s� .T,,�ef 2d•1 cF�90 23.0 cft wr� l��vr�i�i Fr/�� 11.(e1 ( W &tV4 Gi/w - Fait Sih ) 3.q C{S ((s) t /•7 CfS-Tj lCy� ' S�1 CT3 � S. I cis No Text it two Jk FD _ _ 'Ex 61 Pa 4A La f at )CY 7 Z-0. % al .01 v I It/1\\ tJps\�/-,� CD iS � �:1' it �`�.� `.'� Oi� ' ``�C/ O v `. M •'�' �' w '- . .......... ....... ... . . % Ij 93 117 " O(A. co (A rr— AIS\ tT P"r-1 r4 117/43 MAIL CREEK BASIN, DEVELOPED CONDITIONS 1987 100-YEAR STORM (FILE: MTRD100.DAT) REVISION OF PREVIOUS HYDROLOGY TO INCLUDE MOUNTAINRIDGE PRELIMINARY 4/15/94 '•• PEAK FLOWS, STAGES AND STORAGES OF GUTTERS AND DETENSION DAMS •'• CONVEYANCE PEAK STAGE STORAGE TIME ELEMENT (CFS) (FT) (AC -FT) (HR/MIN) 206 60. 1.8 0 36. 203 56. 1.8 0 36. 205 17. .1 1.6 1 10. 207 15. .1 1_4 1 10. 204 82. 2.2 0 38. 201 107. 3.1 0 40. 202 15. 1.2 1 22. 200 192. (DIRECT FLOW) 0 40. 49 327. 3.7 0 46. 260 59. 2.1 0 38. 25 157. 2.9 0 40. 24. 51. 3.2 0 44. 23 318. 3.9 0 46. 48 341. 3.3 0 48. 44 q 2.1 48. 222 222 r14� 1 5 1 e 0 40. TJOW f(OIM 3400A 5'�i. (DIRECT FLOW) 185 59. 1.7 0 36. 50 402. 5.1 6 48. 46 ((671 2.0 0 36. 22 Z2. .1 29.5 2 28.. 364 107. 1.0 0 38. 278 _ 129. .1 17.8 1 42_ POND 279 1001 Fl ,10* lw/ F1' fan veil i/oeb lAj 45 156. 2.9 0 40. 221 166. 2.5 0 38. 21 22. 1.3 2 36. 399 5. ..1 4.9 2 22. 365 97. 1.0 0 38. 247 43. .1 42.8 s._ . o. POA)D Z4 7 too YR WSEC=_S'085.71 368 56. .8 0 36. 370 121. 3.1 6 36. 369 95. 2.1 0 42. 367 57. 1.4 0 44. 366 83. 1.6 0 40. 320 61. .1 3.6 1 10. 372 66. .8 0 36. 244 256. (DIRECT FLOW) 6 46. 373 123. 3.4 0 40.. 371 149. 1.8 0 40. 254 72. 1.6 0 36. 19 61. 1.5 1 12. 28 45. 1.7 0 36. 287 In. 2.5 0 38. 40 63. .8 6 42. 362 98. 1.0 0 36. 104 17. .1 12.1 2 12. 243 272. (DIRECT FLOW) 0 40. 36 116. 1.1 0 36. 107 78. .1 1.5 1 6. 32 t65. 1.2 0 38. 29 160. 2.5 0 38. 27 163. 2.9 0 42. 375 43. 3.6 6 52. 374 84. 1.1 6 46. 38 201. 2.6 0 36. 43 31. 1 17.6 6 40. TKoyrM A A.1 Pn 9 K PoNO 321 78: .1 1.3 0 48. December 29,1999 Mr. Basil Hamden Stormwater Utility City of Fort Collins 700 Wood Street Fort Collins, CO 80521 RE: Westbrooke i=.U.D. Second Filing— Final Drainage & Erosion Control Report Project Number 701-9401 Dear Basil: We are pleased to submit this Final Drainage & Erosion Control Report for the Westbrooke P.U.D. Second Filing. This report is prepared in conjunction with the Westbrooke P.U.D. Second Filing Final Plat and Construction Drawings and in conformance with the City of Fort Collins Design Criteria. Except for minor backyard flows into the Pleasant Valley and Lake Canal, runoff from this project is intercepted by an outfall storm sewer which conveys 100 year flows into Detention Pond 247 recently completed as part of the Mountain Ridge Farm P.U.D. First Filing. Close coordination was maintained with the Sear Brown Group who addressed regional issues as part of the McClelland and Mail Creek Master Plan Improvement Design Analysis. Additional coordination was maintained with Development Engineering Services who designed downstream portions of the outfall storm sewer. We look forward to your review comments and feel free to contact me at (970) 613-2040 if you have additional question. Sincerely, Jeff Couch, P.E. Cc: Chuck Betters, P & B Partnership 114 East 5th Street Loveland, CO 80537 Office:970-613-2040 • Fax:970-613-2038 • Toll -free: 1-888-404-3612 Mr. Basil Hamden City of Fort Collins December 29,1999 Page Two Alternative #3 — Minimum Cost As per City of Fort Collins Policy, a minimum erosion control escrow balance shall be $1,000.00. Based on this analysis, Alternative #1 (Cost of Construction) should be used to establish the erosion escrow amount. City of Fort Collins Policy is to set the escrow amount at 150% of the highest alternative as follows: $9,550.00 (Alternative #1) X 1.5 = $14,325.00 Please feel free to contact me at (970) 613-2040 if you have additional questions. Sincerely, Jeff Couch, P.E. Cc: Chuck Betters, P & B Partnership CERTIFICATIONS OWNER P & B Partnership, a Colorado Partnership, hereby certifies that the drainage facilities for the proposed Westbrooke P.U.D. Second Filing shall be constructed according to the design presented in this report. I understand that the City of Fort Collins does not and will not assume liability for the drainage facilities designed and/or certified by my engineer. I understand that the City of Fort Collins reviews drainage plans pursuant to Colorado Revised Statutes Title 30, Article 28, but cannot, on behalf of P & B Partnership, a Colorado Partnership, guarantee that final drainage design review will absolve the Westbrooke P.U.D. Second Filing and/or their successors and/or assigns of future liability for improper design. I further understand that approval of the Final Plat and/or Final Development Plan does not imply approval of my Engineer's design. P & B Partnership Mr. Chuck Betters ENGINEER I hereby certify that this report for the Final Drainage and Erosion Control Report for the Westbrooke P.U.D. Second Filing was prepared by me or under my direct supervision in accordance with the provisions of the City of Fort Collins STORM DRAINAGE DESIGN CRITERIA and CONSTRUCTION STANDARDS for the owners thereof. I understand that the City of Fort Collins does not and will not assume liability for drainage facilities designed by others. Respectfully Submitted, Jeffrey W. Couch, P.E. Colorado Professional Engineer No.16584 For and on Behalf of Team Engineering, Inc. FINAL DRAINAGE AND EROSION CONTROL REPORT FOR WESTBROOKE P.U.D. SECOND FILING AT SENECA STREET AND TROUTMAN PARKWAY INTRODUCTION This report has been prepared in conjunction with the development of detailed site topography and final construction plans for Westbrooke P.U.D. Second Filing. It is the intent of this report to address drainage related issues and provide solutions to any problems identified in accordance with the criteria established by the "City of Fort Collins Storm Drainage Criteria Manual". SITE DESCRIPTION Westbrooke P.U.D. Second Filing is located in the Southeast Quarter of Section 34, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, Larimer County, Colorado or more generally described as being located at the southeast corner of Seneca Street and Troutman Parkway (See Figure 1- Site Location). This project is proposed for forty-one (41) single family home sites consistent with development completed in the. Westbrooke P.U.D. First Filing. The site platted area includes 11.47 acres and is currently vacant and covered with native grasses. The proposed average lot size is approximately 9,484 square feet. The drainage area which includes adjacent street right-of-ways is 15.24 acres. ADJACENT LAND USES A variety of land uses will exist adjacent to the Westbrooke site. The completed Westbrooke P:U.D. First filing sits adjacent to the southern border of this project and consists of 70 single family residences. Seneca Street borders the west side of the project and provides access to the exilsting Webber Junior High and Johnson Elementary School campuses. Undeveloped area to the northwest will become a city park and undeveloped property immediately to the north will be developed as single family units known as the Mountain i Ridge Farm P.U.D. The Pleasant Valley and Lake Canal runs adjacent to the east boundary of this project and provides a buffer between the proposed Pinewood P.U.D. The Pinewood P.U.D. will eventually be developed for commercial uses. DRAINAGE MASTER PLAN Westbrooke P.U.D. Second Filing is currently within an area recently master planned by the City of Fort Collins. The McClellands and Mail Creek Master Plan was updated by RBD Consulting Engineers in conjunction with the Mountain Ridge Farm P.U.D. project in late 1994. Westbrooke P.U.D. Second Filing is shown as Subbasin 46 in this report. (See Figure 2 — SWMM Basins.) A meeting was held on June 30,1994 between Kevin Gingery of ROD, Dennis Donovan of Development Engineering Services and Jeff Couch of Redpeak Engineering to review proposed master plan changes. Both the Mountain Ridge Farm P.U.D. and Westbrooke Second Filing P.U.D. will be in conformance with this master plan. It is intended that Westbrooke P.U.D. Second Filing (Subbasin 46) convey upstream detention releases from the Johnson Elementary School through the site. The initial SWMM Model routed these flows through the proposed Pinewood P.U.D. directly to the east These offsite flows and the flows from Subbasin 46 will now be routed directly to regional Detention Pond 247. (See attached letter dated 6-6-94.) (See Figure 3 — Revised SWMM Schematic.) Pond 247 will provide the necessary detention volume for the Westbrooke P.U.D. HISTORIC DRAINAGE On -Site Drainage runoff from the Westbrooke P.U.D. Second Filing historically ran from west to east and i discharged into the Pleasant Valley and Lake Canal. Approximately 30 cfs drained directly into the canal during a 100 year event. (See Appendix.) Off -Site Off -site flows have historically had little impact on this site since this project sits on the divide between the McClelland and Mail Creek Drainage Basins. The majority of the area to the south (Westbrooke First Filing) drains away from this site. Runoff crosses under Wakerobin Drive and is detained jn a regional stormwater ! facility. Backyard flows from Lots 24-29 and Lots 53-57 run onto this project and are included in the calculations. Flows from the north will flow northerly away from this site to the proposed regional detention facility and will have no impact. Flows from property to the east across the Pleasant Valley and Lake Canal also have no impact. Drainage from areas to the west (school sites) are collected in detention areas along Seneca Street. These flows are released via a controlled outlet into a N RCP under Seneca Street at a historic Cliw=17.0 cfs. This is the only off -site water which enters the Westbrooke site and this runoff will be conveyed via a storm sewer through the site to the northeast into Detention Pond 247. DESIGN CRITERIA The Rational Formula has been used to develop all stormwater flows for this project. The Rational Method of determining stormwater runoff is an excellent predictor of flows in basins less than 200 acres. 3 7 PROPOSED DRAINAGE A number of drainage basins have been identified as part of the design. A summary of each basin follows. BASINS A, A2 B, & Bz P.U.D. Second Filing Basins A,, A2, B, and 62 represent the paved areas within the Seneca Street right-of:way. These flows follow the existing curbs to a low spot adjacent to the school entryway. The street flows from the west'% of Seneca Street (Basins A, & Az) flow directly into an existing inlet. Flows from the east %z of Seneca Street (Basins B, & B2) will be conveyed by the curb and gutter and collected in proposed Inlet A. The existing curb depression and headwall will be removed and replaced by the new inlet at the location of the existing 24° storm drain. BASINS C; C & Cs BasinsCl, C2 and Cs are the proposed areas west of Westbrooke Drive including South Creek Court, Roaring Fork Court and West Creek Court. Inlet B collects these flows and directs them to the outfall storm sewer. BASINS C4 & Cs Basins C4 and C5 represent the front yards and roof drains from the area east of Westbrooke Drive. These flows are collected by Inlet C and directed into the outfall storm sewer. BASIN Di Basin D, flows include the grassed backyard areas of lots 35 — 41 in Westbrooke P.U.D. Second Filing and from grassed backyard areas from lots 52 — 57 in Westbrooke P.U.D. First Filing. These flows run to a 4 7