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HomeMy WebLinkAboutDrainage Reports - 03/12/1997jr Final AwrOVed Reps% M [ Z4�6vate � � -�I a� it Final Drainage Design and Erosion Control Study for Total Petroleum Site On North College Avenue Fort Collins, Colorado February1996 THE SEAR -BROWN _ GROUP Slanclurds in Excellcwce ' THE SEAR -BROWN GROUP FULL -SERVICE DESIGN PROFESSIONALS t FORMERLY RBD, INC. 209 SOUTH MELDRUM FORT COLLINS, COLORADO 80521-2603 ' 970-482-5922 FAX:970-482-6368 tFebruary 2, 1996 ' Mr. Basil Hamdan City of Fort Collins Utility Services Stormwater ' 235 Mathews Street Fort Collins, Colorado 80522 t RE: Final Drainage and Erosion Control Study. Total Petroleum Site on North College Avenue ' Dear Basil: We are pleased to resubmit to you, for your review and approval, this Final Drainage and Erosion ' Control Study for the Total Petroleum Site on North College Avenue. All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage ' Design Criteria. All issues brought forth by the Stormwater Utility have been addressed at this time. ' We appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. ' Respectfully, RBD Inc. Engineering Consultants ' Prepared by: Richard Thornton, E.I.T. Design Engineer ' cc: Mr. Dan Clayton ' NEW YORK • PENNSYLVANIA COLORADO•UTAH 1 STANDARDS IN EXCELLENCE Reviewed by: xzur;, Kevin W. Ginge , P.E. Water Resources Project Manager EQUAL OPPORTUNITY EMPLOYER 11 1 1 1 1 1 1 1 1 1 1 I. GENERAL LOCATION AND DESCRIPTION 1 A. Location 1 B. Description of Property 1 II. DRAINAGE BASINS 1 A. Major Basin Description 1 B. Sub -Basin Description 1 III. DRAINAGE DESIGN CRITERIA 2 A. Regulations 2 B. Development Criteria Reference and Constraints 2 C. Hydrological Criteria 2 D. Hydraulic Criteria 2 E. Variances from Criteria 2 IV. DRAINAGE FACILITY DESIGN 2 A. General Concept 2 B. Specific Details 3 V. STORM WATER QUALITY 3 A. General Concept 3 VI. EROSION CONTROL 3 A. General Concept 3 B. Specific Details 4 VH. CONCLUSIONS 4 A. Compliance with Standards 4 B. Drainage Concept 5 C. Storm Water Quality Concept 5 D. Erosion Control Concept 5 REFERENCES 6 APPENDIX VICINITY MAP 2 HYDROLOGY 3 EROSION CONTROL 9 CHARTS, TABLES, AND FIGURES 15 EXCERPTS FROM MASTER PLAN DRAINAGE STUDY 19 Total pages 30 1 1 1 I. 1 1 1 ' II. 1 FINAL DRAINAGE AND EROSION CONTROL STUDY FOR THE TOTAL PETROLEUM SITE ON NORTH COLLEGE AVENUE FORT COLLINS, COLORADO GENERAL LOCATION AND DESCRIPTION A. Location The proposed Total Petroleum site will.be located at the southeast corner of Willox Lane and North College Avenue. The project is bounded by College Avenue on the west, Willox Lane on the north, the new Albertson's on the east, and the Country Club Comers Second Filing on the south. The site location can also be described as situated in the Northwest 1/4 of Section 1, Township 7 North, Range 69 West of the 6th P.M., City of Fort Collins, Larimer County, Colorado. The site location can be seen on Exhibit 1 in the Appendix. B. Description of Property The proposed Total Petroleum site will be located on approximately 1.21 acres of land located at the corner of North College Avenue and Willox Lane. Presently, the property is undeveloped. Native vegetation covers most of the property. The topography of the site generally slopes from west to east at approximately 1.0 percent. DRAINAGE BASINS A. B. Major Basin Description The proposed development lies within the Greenbriar/Evergreen Basin. Sub -Basin Description The project site has been broken into 5 sub -basins. Runoff from Basins 1, 2, and 3 is routed via curb and gutter, and a swale to the detention area located in the parking lot of the new Albertson's grocery store. Runoff from Basin 4 is conveyed in a historic easterly direction. Runoff from Basin 5 follows its historic path via curb and gutter along College Avenue and Bristlecone Drive to an existing storm sewer system. The sub -basins are illustrated on the Drainage and Erosion Control Plan in the construction drawing set. I 1 M. DRAINAGE DESIGN CRITERIA A. Regulations The City of Fort Collins Storm Drainage Design Criteria is being used for the ' subject site. B. Development Criteria Reference and Constraints Runoff from Basins 1-3 during the 100-year storm event is routed via curb and ' gutter, and a swale to the detention area located in the new Albertson's grocery store parking lot. As reported by Landmark Engineering in the Amended Final Drainage Study for Country Club Corner, A Planned Unit Development, the ' detention area was sized using a 100 year Rational Method "C" value of 1.0 for the proposed Total Petroleum development,. and as a result, there is adequate storage in the detention area for the runoff from the Total Petroleum site. Runoff from Basin 4 is conveyed in a historic easterly direction. Runoff from Basin 5 during the 100-year storm event is routed via its historic path in a curb and gutter along College Avenue and Bristlecone Drive to an existing storm sewer system. ' C. Hydrological Criteria The Rational Method was used to determine surface runoff for the project site. The 10-year and 100-year storm event. criteria, obtained by the City of Fort Collins, were used in calculating runoff values. These calculations and criteria are included in the Appendix of this report. D. Hydraulic Criteria All hydraulic calculations within this report have been prepared in accordance with ' the City of Fort Collins Drainage Criteria and are also included in the Appendix. E. Variances from Criteria No variances are being sought for the proposed project site. IV. DRAINAGE FACILITY DESIGN A. General Concept Runoff from the proposed Total Petroleum site, Basins 1-3, drain to the detention area located in the new Albertson's grocery store parking lot. Runoff from Basin ' 4 is conveyed in the south gutter of Willox Lane in a historic easterly direction. Runoff from Basin 5 drains to College Avenue and eventually enters an existing 2 1 I storm sewer system on Bristlecone Drive. The detention area was designed with adequate storage to detain the runoff from the Total Petroleum site. Based on the previously mentioned Landmark Engineering Report, the detention facility was designed based on the use of a Rational Method "C" of 0.9 and 1.0 for the 10 year and 100 year events, respectively. The 10 year and 100 year Rational Method "C" for the proposed Total Petroleum site is 0.79 and 0.99, respectively, which will result in less runoff than predicted by Landmark Engineering. B. Specific Details Runoff from Basins 1 and 2 flows via curb and gutter and overland flow to the detention area located in the Albertson's parking lot. Runoff from Basin 3 drains to the parking lot detention area via a swale located on the southern boundary of the development. Runoff from Basin 4 will continue to be conveyed in the south gutter of Willox Lane in a historic easterly direction . The runoff from Basin 5 drains to the curb and gutter along College Avenue and enters an existing storm sewer system on Bristlecone Drive. The stormwater runoff flowrates from Basins 1-5 for the 10-year storm event are 0.60, 3.29, 0.16, 1.66 and 0.79 cfs, respectively. The stormwater runoff flowrates from Basins 1-5 for the 100-year storm event are 1.22, 8.32, 0.32, 3.33 and 1.58 cfs, respectively. V. STORM WATER QUALITY A. General Concept Beginning in October 1992, the water quality of storm water runoff was required to be addressed on all final design utility plans. The Total Petroleum site is ' anticipating construction beginning in Spring 1996. For this project, stormwater will be collected in an existing detention pond where pollutants will have an opportunity to filter. out into the grass as the pond drains. ' VI. EROSION CONTROL A. General Concept This development lies within the Moderate Rainfall Erodibility Zone and the Moderate Wind Erodibility Zone per the City of Fort Collins zone maps. The potential exists for moderate erosion problems after completion of the Total Petroleum site. It is also anticipated that the project site improvements will be ' subject to both wind and rainfall erosion before new vegetation can take hold or before the proposed improvements are constructed. 3 ' The Erosion Control Performance Standard (PS) during construction for this project was computed to be 75.0 percent per the criteria in the City of Fort Collins ' Erosion Control Reference Manual for Construction sites. The Effectiveness (EFF) of the proposed erosion control plan during construction was calculated to be 64.1 percent. This during construction effectiveness was obtained using standard erosion control techniques such as a perimeter silt fence and soil roughening. Even though the effectiveness is less than the performance standard, for this relatively ' small commercial site it is our opinion that plan presented will adequately control erosion during construction. I spoke with Bob Zachley of the City Stormwater Utility Department regarding this matter on October 31st, 1996. During our phone 1 conversation, he also agreed that for the size of the site and the projected short construction time that the erosion control plan presented would be adequate. The Erosion Control Performance Standard (PS) after construction for this project was computed to be 88.3 percent. The Effectiveness (EFF) of the proposed erosion control plan after construction was calculated to be 99.0 percent. Therefore, the after construction erosion control plan below meets the City of Fort Collins' requirements. A copy of the calculations has been included in the Appendix. An ' erosion control escrow cost estimate of $4230 is also included in the Erosion Control section of the Appendix. The total site area is approximately 1.21 acres, most of which will be disturbed during construction B. Specific Details Before overlot grading is started, silt fence will be placed around the perimeter of the site to capture any soil eroded by storm events. After overlot grading, the ' disturbed soil will be roughened to help reduce the erosion potential. All disturbed areas not in a roadway, parking lot, or greenbelt area shall have temporary vegetation seed applied. After seeding, a hay or straw mulch shall be applied over the seed at a rate of 2 tons/acre minimum, and the mulch shall be ' adequately anchored, tacked, or crimped into the soil. If the disturbed areas will not be built on within one growing season, a permanent seed shall be applied. After seeding, a hay or straw mulch shall be applied over ' the seed at a minimum rate of 2 tons/acre, and the mulch shall be adequately anchored, tacked or crimped into the soil. In the event a portion of the roadway pavement surface and utilities will not be constructed for an extended period of time after overlot grading, a temporary vegetation seed and mulch shall also be applied to the roadway areas as discussed above. All the erosion control measures and structures installed prior to the construction of the Total Petroleum site will remain in place and in effect until the erosion control plan specified within the Total Petroleum plans has been established. 1 4 I VII. CONCLUSIONS ' A. Compliance with Standards All computations that have been completed within this report are in compliance ' with the City of Fort Collins Erosion Control Reference Manual for Construction Sites and the Storm Drainage Design Criteria Manual. ' B. Drainage Concept I I 1 I 11 F U This plan adequately provides for the transmission of the 100-year storm event runoff from the Total Petroleum site to the detention facility located in the parking lot of the new Albertson's grocery store and to College Avenue. Runoff from Basins 1, 2, and 3 flows into the detention facility in the Albertson's parking lot. Runoff from Basin 4 will continue to flow in a historic easterly direction. Runoff from Basin 5 flows into the curb and gutter along College Avenue and is collected by an existing storm sewer system located on Bristlecone Drive. C. Storm Water Quality Concept Because storm water quality has become a requirement, the site has addressed this storm water aspect. A grass -lined channel, and a detention facility will provide an opportunity for stormwater pollutants to filter out of the storm water runoff before the runoff eventually enters the Cache La Poudre River. D. Erosion Control Concept The proposed during construction erosion control plan employs standard erosion control techniques such as a perimeter silt fence and soil roughening. Because of the relatively small site area and lack of on -site drainage facilities, the during construction performance standards were not met. It is out opinion that the erosion control plan presented will adequately provide for the control of wind and rainfall erosion from the Total Petroleum site. The proposed after construction erosion control concepts presented in this report are in compliance with the City of Fort Collins erosion control criteria. 5 REFERENCES 1. 2. 3. 4 Storm Drainage Design Criteria and Construction Standards by the City of Fort Collins, Colorado, May 1984, Rev. 1991. Erosion Control Reference Manual for Construction Sites by the City of Fort Collins, Colorado, January 1991. Final Drainage Study for Country Club Corner, A Planned Unit Development. Landmark Engineering LTD. Loveland, Colorado. July, 10, 1995. Amended Final Drainage Study for Country Club Corner, A Planned Unit Development. Landmark Engineering Ltd. Loveland, Colorado. August 8, 1995. APPENDIX 1 1 1 i 1 1 1 i 1 1 1 1 1 i CCN I C J l r 7� .. . z o •.jQ aonjdS anl8 �O c i / -J U Iry :3 oCL 0 a co/110 •any a apo0 •N c Jr� 01 � • )` SU c I 0 0 �® o r II L's}iwl�;i� 3 1 L HYDROLOGY h J I CO O �0 v O L N m c O f�0 0: m L w (A m 7 (0 U a) N cA O a E •v cg m d w Uaa) C Q c_cu U mul (o (� a� o m a) m t U a N A) -a u) a �- F- NIA Lo OO •— c� co M c- O O a- EV 00000 O O: U .. v1 Cl) (O c� N to M c O ,O cf) V— CO N N � as ._ c�V:CMMcn c, N((00 r� COO OD 000 L OL m E a E ci o0000 Q m cn (O I-- 'T O cp e- O O 'cT ti o� o0000 Q y uO u) cn cn u) L ) N N N N N N o o 0 0 0 0 0 a y cn cn cn N to LO O O O) O O) O O_ 00000 O ZU m= a E NCMVLO m Q N m 5 Z 0 F Z O U ao z a 0 O w 0 1W- F- (D O C m CD CD ZW r 0 c ui 6U DQ 4: Y < N w O M O OO QC i(j p L6 to to Z LL Go0LOcMN .� O �:4NM� « v O d'Ooco I— M to co U v cV rn W W LU JW OOOGoU) �LOLOr`rn 0000 QO-eOD CV f- _ 0)N0MC) N M N M Z w J N c M O) M O C -P CO M <O ZW 000rnrn OOLOcoco of0�� ��NODGO W U (ON�NN F-Z� Zw J LO co �OocMncco U I) o0000 to01�- vO •- OR O ,T 'r- N 00000 Q� N • I Q _Z m� mU U) OF �NM'qLO vi c O N V 0 m w (1) CL C _T 5 c c U c0 U r L v .. F to O U CD cu in f` � C E 7 O U o S I w#; §!R � §|«e �#f � _ ■��` §2#, §,o, � !| 6- Po § !q § k© Ono ! !S § §|f/ s; 0 n d 2 d|| ! |S § § §£e d §_ ! ' .| S\! § �.�! � | � / q Eke k } I f o vi© � ! k`` ) ] �„ -- ci � Lu } k §� a ■ @@ a § § , � E ■ �/ ! N Z 0 Q F W O U NN O N U 0 O w w w 0 3 0 d a m H� } m Z w OW U o >� 0 0 U rn Z Q cD U Y N W O N O O O C LO LO LO LO LO Z 'E U- ' CRgigclN O �ttNV) w ro-I A(D00 U n N.- O wI w p > J W o0OOuO � u) LO r- O> O O. 0 QCL CDN 0 J Q' (n _ N O (l i ( � N M N (O Z W J IV ce) r.LO lq� 00 2w C EO �" "' v 0 Zw Oo0rnrn 00Lcoco g IL 0 0 cyi co co w 0 O O LO M (M toN�NN pzZ Z J NI--LO000 r� OD co r` 00 U c) o0000 �Q.-. LO (o r` 'It O �ODO�� Q� N 0 0 0 0 0C,4 ZQv m� In U w vi c 0 N U cci 0 O O) Q •c _ C U OJ Uv � N U w � U) �Q C U O c rn � O c E o W U O E 0 0 Z in I � �|I; � §!R , � \� §I= ! ,,, §� kk k§«` g55S viul k§ . §|#= d5! S !! � § z d|| § |! § ■-� d. ■!- |!! ! !! s { § �k° odd ! § _ � � dd o ... . 0- : § § � & u ||� �< � � rt- 0 �Kf� 2 � 90 .� 7 -No M V. , - lu | - k §§ e � ea k 8a 1 R8D INC. ENGINEERING CONSULTANTS ' CHANNEL RATING INFORMATION SOUTH SWALE - TOTAL PETROLEUM SITE ' STA ELEV ' 0.00 20.00 20.00 15.00 40.00 20.00 ' N VALUE --- ----- SLOPE ----- (ft/ft) ------- 0.060 0.0100 ' ELEVATION AREA VELOCITY DISCHARGE FROUDE (feet) (sq ft) (fps) (cfs) NO. --------- ------ -------- --------- ------ 15.50 1:0 1.0 0.97 0.34 16.00 4.0 1.5 6.14 0.311 16.50 9.0 2.0 18.08 0.41 17.00 16.0 2.4 38.94 0.43 17.50 25.0 2.8 70.59 0.45 18.00 36.0 3.2 114.77 0." 18.50 49.0 3.5 173.11 0.47 19.00 64.0 3.9 247.13 0.48 19.50 81.0 4.2 338.30 0.49 20.00 100.0 4.5 448.02 0.50 .32 cfs 8 0.33 feet deep 0 I 1 1 1 EROSION CONTROL n 1 1 L 1 1 no tRBD, Inc. RAINFALL PERFORMANCE STANDARD EVALUATION jai -nny PROJECT: Total Petroleum STANDARD FORM CALCULATED BY: RBT DATE: 02/02/96 DEVELOPE ERODIBILIT Asb Lsb Ssb Lb Sb PS SUBBASIN ZONE (ac) (% ft 1 moderate 0.15 110 1.00 2 moderate 0.86 230 1.00 3 moderate 0.07 220 1.00 4 moderate 0.44 337 0.78 5 moderate 0.19 137 0.95 Total 1.71 236 0.94 75.0 EXAMPLE CALCULATIONS Lb = sum(AiLi)/sum(Ai) _ (0.15 x 110 + ... + 0.19 x 137)/ 1.71 236 ft Sb = sum(AiSi)/sum(Ai) _ (0.15 x 1.00 + ... + 0.19 x 0.95)/ 1.71 ' = 0.9 % PS (during construction) = 75.0 (from Table 8A) PS (after construction) = 75.0/0.85 = 88.3 L ' RBD, Inc. 1 1 1 C 0 1 1 EFFECTIVENESS CALCULATIONS PROJECT: Total Petroleum STANDARD FORM B CALCULATED BY: RBT DATE: 02/02/96 Erosion Control C-Facto P-Facto Comment Number Method Value Value 8 Sin Fence Barrier 1 0.5 1 placed around site 9 AsphaWConcrete Pavement 0.01 1 lexisting pavement SUB PS AREA BASIN % ac Site 75.0 1.71 SUB SUB AREA Practice C' A P • A Remarks BASIN AREA ac DURING CONSTRUCTION 1 Total 0.15 Impervious 0.00 9 0.00 0.00 Asphaft/Concrete Pavement Remain. 0.15 8 0.15 0.08 Sift Fence Barrier 2 Total 0.86 Impervious 0.05 9 0.00 0.05 Asphaft/Concrete Pavement Remain. 0.81 8 0.81 0.41 Sift Fence Barrier 3 Total 0.07 Impervious 0.00 9 0.00 0.00 Asphaft/Concrete Pavement Remain. 0.07 8 0.07 0.04 slit Fence Barrier 4 Total 0.44 Impervious 0.34 9 0.00 0.34 Asphaft/Concrete Pavement Remain. 0.10 8 0.10 0.05 Sift Fence Barrier 5 Total 0.19 Impervious 0.17 9 0.00 0.17 Asphaft/Concrete Pavement Remain. 0.02 8 0.02 0.01 Sift Fence Barrier Cnet = [0.00x0.01+...+0.02x0.00y1.71 = 0.68 Pnet = 0.840.00x1.00+., +0.02x0.50y1.71 0.53 EFF = (1-C•P)100=.(1-0.68.0.53)100 = 64.12 ««< 75.0 (PS) Assume paving not constructed within 6 weeks of initial site grading and foundations are constructed within 6 weeks Use silt fence at swales and downstream perimeters. 12 RBD; Inc. EFFECTIVENESS CALCULATIONS &Ao1-1ns PROJECT: Total Petroleum STANDARD FORM B CALCULATED BY: RBT DATE: 02/02/96 Erosion Control C-Facto P-Facto Comment Number Method Value Value 9 Asphalt/Concrete Pavement 0.01 1 paved and constructed 20 Sod Grass 0.01 1 installed SUB PS AREA BASIN % ac Site 88.3 1.71 SUB SUB AREA Practice C' A P' A Remarks BASIN AREA ac AFTER CONSTRUCTION 1 Total 0.15 Impervious 0.10 9 0.00 0.10 AsphaB/Concrete Pavement Remain. 0.05 20 0.00 0.05 Sod Grass 2 Total 0.86 Impervious 0.76 9 0.01 0.76 Asphak/Concrete Pavement Remain. 0.10 20 0.00 0.10 Sod Grass 3 Total 0.07 Impervious 0.01 9 0.00 0.01 AsphaR/Concrete Pavement Remain. 0.06 20 0.00 0.06 Sod Grass 4 Total 0.44 Impervious 0.34 9 0.00 0.34 Asphaft/Concrete Pavement Remain. 0.10 20 0.00 0.10 Sod Grass 5 Total 0.19 Impervious 0.17 9 0.00 0.17 Asphah/Conerete Pavement Remain. 0.02 20 0.00 0.02 Sod Grass Cnet = [0.10x0.01+...+0.17x0.01y1.71 = 0.01 Pnet = [0.10x1.00+...+0.17x1.00j/1.71 = 1.00 EFF = (1-C-P)100 = (1-0.01.1.00)100 = 99.00 > 88.3 (PS) l3 RBD, Inc. EROSION CONTROL CONSTRUCTION SEQUENCE 1 'STRUCTURES: INSTALLED BY MAINTAINED BY VEGETATION/MULCHING CONTRACTOR ' DATE SUBMITTED APPROVED BY CITY OF FORT COLLINS ON, n RBD, Inc. l 1 EROSION CONTROL COST ESTIMATE PROJECT: Total Petroleum #491-003 PREPARED BY: RBT DATE: 10/30/95 CITY RESEEDING COS Unit Total Method Quantity Unit Cost Cost Notes Reseed/mulch 1.72 ac $650 $1,118 See Note 1. Subtotal $1,118 Contingency 50% $559 Total $1,677 EROSION CONTROL MEASURES Unit Total Number Method Quantity Unit Cost Cost Notes 8 Silt Fence Barrier 940 LF $3 $2,820 Subtotal $2,820 Contingency 50% $1,410 Total $4,230 Total Security $4,230 ' Notes: 1. A<1 ac=$1300/ac; A=1-10 ac=$650/ac; A>10 ac=$500/ac. 1] /5 1 1 11 1 CHARTS,.TABLES AND FIGURES 1 t • U La Z (t U- 0 wm DOC 0 �- -j L03 1 :D UJ z C[: w 0 0 Xj 0 cc w :3 0'-i t 0 0> LLJ V) Na N I I Z 0 < -J � o Ll U- <<<� _j F- I 0�->.< z 4 _j H 0 ZU) < QQ. Li w LL, L) 6 L' < ccz MZLLD cl V) MO co Lo In rn pnoH jad sa4zul )AIISUINI -1-MMIYU Table 86 C-Factors and P-Factors for Evaluating EFF Values. ' C-Factor P-Factor Treatment SOIL . 'BARE xl / Packed and smooth............................................................... 1.00 1.00 f! 2 Freshly disked........................................................................ 1.00 0.90 �3 Rough irregular surface.:......................................................... 1.00 0.90 ' %'I SEDIMENT BASIN/TRAP................................................................. 1.00 0.50"1 715/04(,,07 STRAW BALE BARRIER, GRAVEL FILTER, SAND BAG ........................ 1.00 0.80 ' #B SILT FENCE BARRIER..................................................................... 1.00 0.50 r-9 ASPHALT/CONCRETE PAVEMENT ................................................... 0.01 1.00 t-/9 ESTABLISHED DRY LAND (NATIVE) GRASS .......................... See Fig. 8-A 1.00 0Z4SOD GRASS................................................................................. 0.01 1.00 tI�*,2A TEMPORARY VEGETATION/COVER CROPS .................................... 0.451.1 1.00 023 HYDRAULIC MULCH @ 2 TONS/ACRE........................................... 0.10131 1.00 U-39 SOIL SEALANT....................................................................0.01-0.601'1 1.00 '437 EROSION CONTROL MATS/BLANKETS............................................ 0.10 1.00 it3g GRAVEL MULCH Mulch shall consist of gravel having a diameter of approximately ' 1/4" to 1 1/2" and applied at a rate of at least 135 tons/acre.............. HAY OR STRAW DRY MULCH 0.05 1.00 After planting orass seed, apply mulch at a rate of 2 tons/acre (minimum) and adequately anchor, ' tack or crimp material into the soil. Slope (%) 039 1 to 05.............................................................................0.06 1.00 ' ' "a 6 to 10.............................................................................0.06 #y/ 11 to 15.............................................................................0.07 16 to 20................ ........ -.................................................0.11 ay3 21 to 25.............................................................................0.14 xyy25 to 33.............................................................................0.17 -wys > 33.......................................................................... 0.20 1.00 1.00 1.00 1.00 1.00 1.00 ' NOTE: Use of other C-Factor or P-Favor values reponed in this table must be substarriated by docvmenta-ion. (1) Must be constructed as the first step in overlot grading. (2) Assumes planting by dates identified in Table 11-4, thus dry or hydraulic mulches are not required. 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O ONNNNNNNNNNNNNNNNNNNric-i44(r 0 (� I` I` I` I` I` I` I` I` I` I` I` I` I` I` r- I- I- I- I` I` I` I` I` I` �{�� o0000000000000000000000000 00000000000000000000000000 azt-. 1iNnclnOr�gOl0HNnCU)1. r- co m o U) o to 0 Lo 0 PL4 W— HT-4Hrgrir-qriririHNNnnvCtn 1.4 N,ARCH 1991 2.4 DESIGN CRITERIA r 19 I I I I EXCERPTS FROM THE MASTER PLAN ' DRAINAGE STUDY 1 u I 1 FINAL DRAINAGE STUDY FOR COUNTRY CLUB CORNER, A PLANNED UNIT DEVELOPMENT Prepared For. Denver Holdings, Inc. 70065 E. Harvard Avenue, Suite 803 Denver, CO 80231 Updated. July 10, 1995 Project No. DENHO-94099C-04-110AD CONSULTING ENGINEER Landmark Engineering Ltd. 3521 West Eisenhower Boulevard Loveland, Colorado 80537 f,. ,r % 1' �rlr:r t•.r 1, ,.iV1Yt1 /' / l NORTH COLLEGE AVE. 4 I Irn ._.. I 0 0.._.`I I I I o �Z EXISTING A C 1 �l1fT�l A NTION O rq FUTURE INLET r� I,^`^•r •�'•, UKSTOM MSE I ti AND DETENTION p W I i IN { I \� I I I /d It / y? Bo �4 qt 1 q7q El b Y TRIPLET True a 4� 0 =o.aa . _ o �.... IN1Er �7/ _._. ... ,y _-- I r0.24 w .. ..VVya VkT,--URB 18 \ 9 �z7.oz jA2 90 1516 Al 2 4.33 I � pal /'T' w 5[[ miu( 6 ICUf0.i) 7 / r jW Ora-072 1u�..•.... , ,r ,7 _ [ 1 k Ir 6976 x r i2 o re �. . I .0 I J \ V i 85 0.44 3 ❑., NDo j ) ' 92 I In (41 I t� '.INLET 11 I I I j I I II rlrr vnr..... o_ ces xuteI �,I is a a.� HIM co fr IIscol 1�1�&1■ RONNIE m i I loll MENOMONEE 22 0 z U) LU z cc a L r �E �W LLz Q KLK L.L C U a u "C U co I�ill�l Ilk 23 T Lh ti 7 29 AMENDED -_, FINAL DRAINAGE STUDY FOR COUNTRY CLUB CORNER, A PLANNED UNIT DEVELOPMENT Prepared For: Denver Holdings, Inc. 10065 E. Harvard Avenue, Suite 803 Denver, CO 80231 August 8, 1995 Project No. DENHO-94099C-04-110AH ' CONSULTING ENGINEER Landmark Engineering Ltd. 3521 West Eisenhower Boulevard Loveland, Colorado 80537 i 25 1 AMENDED FINAL DRAINAGE STUDY for COUNTRY CLUB CORNER, A PLANNED UNIT DEVELOPMENT PURPOSE The Final Drainage Study is herein amended for changes to the drainage improvements at the request of Denver Holding, Inc. GENERAL DESCRIPTION OF CHANGES The changes are applicable to improvements that will be constructed under Phase I. The improvements identified in the final drainage study which were to be constructed under Phase I and herein amended include: 1. Detention pond 2. Detention pond concrete inlet structure 3. Six foot concrete pan through detention pond 4. Detention pond concrete outlet structure with an orifice plate 5. Onsite dual 30" storm drain from the outlet structure to Junction Boxes (JB) 4 and 3 6. Offsite dual 30" storm drain in Bristlecone. Drive from JB 3 to JB 1 and 2 ..._. 7. Offsite 34"x53" HERCP storm drain in Bristlecone.Drive from JB 1 to the new -headwall at the existing open channel to the regional Evergreen West Pond 8. Offsite existing 30" RCP storm drain in Bristlecone Drive from JB 1 to the new headwall 9. Relocation of an existing 24" storm drain and manhole in the intersection of Bristlecone Drive and Blue Spruce Drive The changes with this amendment are: 1. Detention pond accommodating a larger volume 2. Detention pond concrete inlet structure that has been modified and incorporates rip -rap 3. Six foot concrete pan through the detention pond 1 4. A 24" FES with an orifice plate and rip -rap at the detention pond outlet 5. Onsite 24" storm drain and open channel from the. pond outlet to JB2. The open channel ' will have a concrete pan. FESs and rip -rap will be used on the 24" storm drain. 6. Offsite dual 30" storm drain in Bristlecone Drive from JB 1 to 2. 7. Utilization of the offsite existing 30" storm drain in Bristlecone Drive from JB 1 to the existing headwall at the existing open channel to the regional Evergreen West Pond. It is intended that the onsite storm drainage improvements identified in the Final Drainage Study for Phase I will constructed under Phase I. The changes are shown on Exhibit B, Drainage Plan Phase I Interim. The changes utilize the Bristlecone Drive existing street section and existing 30" storm drain to convey the Phase I release rate from the site. The limiting parameter to the release rate is the capacity of the existing 30" storm drain which results in additional .volume in the Phase I interim detention pond. RUNOFF SUMMARY A summary of the developed Phase I runoff for the changes is as follows: Q in street Q in pipe Q 100 Subbasins cfs cfs cfs As 0.00 5.99* 62.35 Bs 7.90 18.40 26.30 Cs 10.15 0.00 10.15 Totals 18.05 24.39 08.80 *Restricted release from detention pond based on: Release rate = 25.00 (Ex 30" SD capacity) - 0.61 (Burger King) - 18.40 = 5.99 cfs The total Phase I release rate from the site is 45.25 cfs. Bristlecone direct runoff 18.05 cfs Willox direct runoff 2.81 cfs �■ Bristlecone existing 30" SD 24.39 cfs ■ Total 45.25 26 .1 27 There is sufficient capacity in the Bristlecone Drive street section to accommodate the Phase I release rate as shown below: Bristlecone Drive street section capacity = 43.22 cfs Less direct release to Bristlecone Drive = 18.05 cfs Less offsite contributory area = 7.55 cfs Unused capacity 17.62 cfs The volume of the Phase I interim detention pond has increased from 1.68 of to 2.05 af, however, the configuration has remained essentially the same. The runoff computations shown in the Final Drainage Study have been used for this amendment. Computations applicable to the changes are shown in the Appendix. i I APPENDIX 1 Nx� .-i M N 000 000 Cl as 9 A A C4 N C4 E/- 15 v k26A (Sir) 045P7P(f-,) Val- Ve (16 F W- 720, 5 z 10 70' 7/ ILI 7511 70 zf 7?t- 58850 74 .15ZE 7f - 5758(a- /(v3536 -76 AD 0 7S41 -.74, eS.4 716. - #,VF)�OV- MKII WL 2105; jq7p 7 PWL 7? 4-- -IFY09 - 73, a�5 76. ?3 17 0 SCALE P=20 LEGEND - .was - EXISRNG CONTOUR PROPOSED CONTOUR — FLONUME DIRECTION OF ROW QDESIGN POINT .he ,• DRAINAGE BASIN BOUNDARY IBASIN NUMBER 611foc BASIN AREA F.F. FINISHED FLOOR ELEVATION — . SILT FENCE — LOT LINE OITFALL CURB AN GUTTER INFLOW CURB k GUTTER EROSION CON—TROL NOTES I. A. ms fled'ant W msym,� <Fn .pw the mI.n ne eR note n u etdNe awn peMMw0 tbeehe protesttothe Memmm pnl a'tryi Mu2W N. vaeeep the she, hig91'^ as ] Ans the oMol o al one `IY y Metal Uwe Yna pN<M poi eo u reyhe „e n water on� x w.rpeee After xoooLa ro Eaton and — .boys. Ithe poshial o otaela: ea wmnm. (vass sa) x by alas lee .D ge, bow III a. it forse bon ED r«noyeCj/rmn the Installam aIIIefit the mu GENERAL NOTES- 1. ACCESS ROAD CURB. GUTTER AND ASPHALT AND SIOEWAt AS SHOWN BY OTHERS ON THIS PLAN ARE UNDER CONSTRUCIION AT THE TIME OF PREPARATION OF THESE PLANS THESE FEATURES ME CONSIDERED AS EXISTING CONDITIONS 2. DUE TO ONGOING CONSTRUCTION AT THE TIME OF PREPARATION OF THIS PUN, EXISTING CONTOURS SHOWN ARE ME PROPOSED CONTOURS FROM TIE GRACING PLAN FOR TIE COUNTRY CLUB CORNERS. 3RD FILING P.U.D. d. REFER TO SHEET 4 FOR REMOVAL OF EXISTING CURB. GUTTER AND SIDEYIALK. 4. ROOF DRAINS FOR CONVENIENCE STONE SHALL WTFALL DIRECTLY TO ME SOUTH. OIXO . 0.32 1 J1 DIM — OAT SLOPE . 1.01C SECTION A T EXISTING SITE HYDROLOGY TOTAL DISTURBED AREA — 1.20 ACRES RARONAL C — 0.25 DEVELOPED SITE HYDROLOGY 1 I I I I I I I I 1 1 I 1 1 1 I I 1 1 1 1 I I I 1 1 I 1 I I II I I r 1 'I 1 r I 1 , ' I Ulf 1 1 1 1 1 I 1 1 1 I I I I I I II 1 I I I I 1 1 I I �y I I `11 1 1 I ' I I t I I 1 I r 1 1 1 ' , 1 I 1 i I 1 1 I 1 I 1 I I I I I 1 I R EJDST. GURB 1 � R •1 TRAFFIC SOIAL ' «he Q14AC EXISTING Mo. 1 _ _ she - _ 4 _ low ti !U A 1 �EME. fur Ithe I I B she F rff. .f O.ISAC \ livallftbri EXISING IV In he ORION 1 - B• sroEwAlx I` } I I Ihey EXISTING LOT 1 PANW" sloEwgtN - 1 he l j 1 ; 1 I hall � 1 CANOPY _ Lu a 1 he j 15 UTI TY, ki J PEOES AN , 1 p EAseM r; I -on LOT 3 o ' ' her I ■ 1 PAN No 0.S, PAN . I I _Ap 1 0.19AC I � « d , I` I 4 3 52 No f({{I FUNCE T ) —-\ T METAL SIDEWALK CULVERT /1 Rol ? Go- � 1 OSON CWTRCL IS INSTALLED. NO SOILS IN.MEAS CU150E GTY OROMgN PROHIBITS ME T PROJECT STREET RIGHTS -AP -WAY SHALL REMAIN EXPOSED BY LAND DISTURBUiO. ANY OTHER UAL ONTO dNi ACTYTTY FOR MORE MAN THIRTY (.10) DAYS BEFORE REWIRED TEMPORARY dolt INADVER NNRT POSTED MATERIAI PERMANENT EROSION CONTROL T.G. SEEDMULCH, LANDSCAPING ETC.) IS INSTALLED:. CON RAC , I UNLESS OTHERWISE APPROVED BY ME STORMWATER UTILITY' I I'I III 1 II DINEUPEC KWG DESIGNED CHECKED . I Sal WMm sI 24M " AID ARNI. III Fort GWny fdvoi al 0.1IA. Gvob =I BAN WILLOX LANE __ T _—__ —lill Lot V CURB AND GU ER / (BY CAPERS) 1, It a \ I`_ '� FTAINEDI" I WIND�r�rQQ1USE NUE EC BY THE c I � xmx FOR less ONLY wo.. . theswasor City o on Teem "ewse� hem .wee wnu.,e . them eM.m,. r.thygdow Ill IFAR �J AI AI.I. I.I AI sln Ih to am w w KAAXNARKL .too" wal Nma FALL wDXMAAL s.aetwt Irm/HeWr offt slass, et out B n.e sheas again setting, Fbaoi �rwA.w.«r.+p garnet syst v«nrq , /G .hen Ad n I:re,w.. MoLwwv mnnCp' NWinp[e ev .X boss m wr Pr FPAT cw.«s w // II I I SEEDING CHART Ili L.F— ,.,. ,,:. .- w�� �L/: r... ones, goolho o o.« onsionst thasund light any an Debt wo, goo gg, As III Do log, Lot Ma is awn u.. .p shol LThen 11 4 engines along gor shot DID 11 any a. IIr I I,I oeT my II' hot Del it sm eft sto w r ft li Ishoot At ii .^. KKn ill II soon v r. r r y.thew. a.... I I dry« .Matta 1 1 1 .a 1 W ; .mir; « IIr both ., tea... II el TIN LI D In hat It JI IN hi aso.n....to. n. e,U I l I her w. ^ ° ^^" a.1. Insolent I LI III l ,I hunon mwr.. nn., tnot hhgL I y I I II I I CALL UTILITY t�� CAlTEp OF COLGRADOO" 1 I 1-800-922-1987 i C 'i' « 534-6700 JL ®"a hey — --- min01Aw ILIL otM Roe alaeAVA,e piaA�M" rao14 I'I II II III o MrM �� J51 [�%T MEASURES eIH BE INSPECTED A MY AFTER II� l City of Fort Collins, Colorado EACH R GRE EVENLI . -ORMANCE OF THEIR INTENDED FUNCTION. ALL — rH I T OT'Dj'frY APP OVAL ' THOSE ON PAVED ROADWAY SURFACES. SHALL I I APPROVED. A A MANNER AND LOCATION SO AS NOT TO CAUSE OBeMm of Erym WAY. 1 1 I CHECKED BY. Met 2J I¢'p-t SHALL NOT EXCEED EIGHT FEET l I I l Wslm f IOU 'ate FROMOCKPILES SE FROM SEDIMENT TRANSPORT BY SURFACE FA I I CHECKED BT: Ir 1�C s-As-lo ETE$SILT FENCING. _L{ 9farmmter 11 OAHA I I 1CKI DROPPING, OR DEPOSTING CE SOLS III CHECKED BY: N19- MEETS BY OR FROM ANY VEHICLE. ANY Pvb k ReawUoa yIA SHAILII BE CLEANED IMMEDIATELY BY ME III I I CHECKED BY. Mae I ill it CHECKED BY: —� TOTAL PETROLEUM JECo. Inc. DRAINAGE AND EROSION CONTROL PLAN I 6 I 4