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Home My WebLink AboutTACO BELL RESTAURANT PRELIMINARY AND FINAL PUD - 51-90A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT (2)"PRELIMINARY' DRAINAGE INVESTIGATION FOR PROPOSED TACO BELL RESTUARANr FORT COLLINS, COLORADO Prepared for b%RCHUUECUUHE OKE 150 East 29th Street Suite 200 Loveland, Colorado 805338 October 28,1991 Project No. GRD-040-90 (Revised November 27,1991) PREPARED BY: LOOOM $ Engineering Associates 150 East 29th Street, Suite 225 Loveland, Colorado 80538 Telephone: (303) 663-2221 Civil and Environmental Engineering Consultants Client: ARCHITECTURE ONE Project No. GRD-040-90 By: DRM Date: Oct. 28, 1991 REVISED: Nov. 25, 1991 EXISTING CONDITIONS TIME -OF -CONCENTRATION Tc = 1.8 [ 1.1 - (0.755 x 1.0) ] 480 + 342.9 = 3.75 min.(Overland Offsite to North) Ts = 350 + [ 2.5 x 60 ] = 2.33 min.(Street Offsite to North) Ts = [230 + (3.5 x 60) + 150 + (2.5 x 60)] = 2.10 min.(Street Adjacent to Site) TTotal = Ts +Tc + Tr Therefore, T = 2.33 + 2.1 + 5.00 + 3.75 = 13.28 min. USE 10 minutes as Time of Concentration for Point of Concentration located at the Southeast Corner of the Site I2 @ 10 min. = 2.50 in./hr. Iioo ® 10 min. = 7.25 in./hr. RUNOFF Runoff, Q = C x I x A x Cf Cf at 2 year Storm = 1.0 Cf at 100 Year Storm = 1.25 RUNOFF FROM SITE AT EXISTING CONDITIONS: Q2 = 0.755 x 2.50 x 0.703 x 1.00 = 1.33 c.fs. Qioo = 0.755 x 7.25 x 0.703 x 1.25 = 4.81 c.ts. RUNOFF FROM SITE AT PROPOSED CONDITIONS Q2 = 0.767 x 2.50 x 0.703 x 1.00 = 1.35 c.fs. Qioo = 0.767 x 7.25 x 0.703 x 1.25 = 4.89 c.fs. The estimated difference in total runoff volume based upon the 2 and 100 Year Storms Determine Volume if Detention were to be provided. Time Q2Proposed Vol. ® Q2 QDis. @ 2 Yr. 10 (min.) 1.35 (c.f.s.) 822 (cu.ft.) 1.33 (c.f.s.) 15 1.13 1,019 1.33 20 1.00 1,200 1.33 Time QiooProposed Vol. ® Qioo Qnis. ® 100 Yr. 10 (min.) 4.89 (c.f.s.) 2,934(cu.ft.) 4.81 (c.f.s.) 15 4.04 3,636 4.81 20 3.50 4,200 4.81 Vol, nis. Vol. Diff. 798 (cu.ft.) 24.(cu.ft.) 1,197 078) 1,596 096) Vol. as. Vol. Diff. 2,886(cu.ft.) 48 (cu.ft.) 4,329 (-693) 5,772 (-1,572) Page 2 of 6 Client: ARCHITECTURE ONE By: DRM Project No. GRD-040-90 REVISED: Nov. 25, 1991 EXISTING CONDITIONS WITH OFFFSITE AREAS CONSIDERED• 1. Area to North of Site concentrating at College Ave. gutter on North Property Line Area = 0.61 ± acres Tc = 5 minutes C = 0.60 I2 = 3.30 in./hr. Iioo = 7.25 in./hr. Q2= 0.60 x 3.30 x 0.61 x 1.00 = 1.21 c.f.s. Qioo = 0.60 x 7.25 x 0.61 x 1.25 = 3.31 c.f.s. 2. Area to North of Site concentrating at Alley to East on North Property Line Area = 0.37 ± acres Tc = 5 minutes C = 0.60 I2 = 3.30 in./hr. Iioo = 7.25 in./hr. Q2=0.60x3.30x0.37x1.00=0.73c.f.s. Qioo = 0.60 x 7.25 x 0.37 x 1.25 = 2,41 c.f.s. 3. Area on the West side of the Site concentrating at inlet on the N.W corner of Prospect Rd. Area = 0.61 + 0.27 + 0.16 = 1.04± acres Tc = 10 minutes C = 0.70 I2 = 2.50 in./hr. Iioo = 7.25 in./hr. Q2= 0.70 x 2.50 x 1.04 x 1.00 = 1.82 c.f.s. Qioo = 0.70 x 7.25 x 1.04 x 1.25 = 6.60 c.f.s. 4. Area Onsite concentrating at Prospect Rd. gutter on East Property Line Area = 0.542± acres Tc = 10 minutes C = 0.755 I2 = 2.50 in./hr. Iioo = 7.25 in./hr. Q2 = 0.755 x 2.50 x 0.542 x 1.00 = 1.02 c.f.s. Qioo = 0.755 x 7.25 x 0.542 x 1.25 = 3.71 c.f.s. 5. Area from alley to East of Site concentrating at Prospect Rd. gutter on East Property Line Area = 0.37 + 0.36 = 0.73± acres Tc = 10 minutes C = 0:60- -- - - - I2 = 2.50 in./hr.---I1oo = 7.25 in./hr. _- Q2= 0.60 x 2.50 x 0.73 x 1.00 = 1.10 c.f.s. Qioo= 0.60 x 7.25 x 0.73 x 1.25 = 3.97 c.f. s. 6. Area from Prospect Rd. concentrating in gutter on East Property Line Area = 0.07± acres Tc = 10 minutes C = 0.85 I2 = 2.50 in./hr. Iioo = 7.25 in./hr. Q2= 0.85 x 2.50 x 0.07 x 1.00 = 0.15 c.f.s. Qioo= 0.85 x 7.25 x 0.07 x 1.25 = 0.54 c.f.s. 7. Total area concentrating at Prospect Rd. gutter on East Property Line Area = 0.542 + 0.074 + 0.37 + 0.36 = 1.35± acres Tc = 10 minutes C = 0.70 I2 = 2.50 in./hr. Iioo = 7.25 in./hr. Q2 = 0.70 x 2.50 x 1.35 x 1.00 = 2.36 c.f.s. Qioo = 0.70 x 7.25 x 1.35 x 1.25 = 8.56 c.f.s. Page 3 of3 Client: ARCHITECTURE ONE By: DRM Project No. GRD-040-90 REVISED: Nov. 25,1991 PROPOSED CONDITIONS WITH OFFFSITE AREAS CONSIDERED: 1. Area to North of Site concentrating at College Ave. gutter on North Property Line Area = 0.61 ± acres Tc = 5 minutes C = 0.60 I2 = 3.30 in./hr. Iioo = 7.25 in./hr. Q2= 0.60 x 3.30 x 0.61 x 1.00 = 1.21 c.f.s. Qioo= 0.60 x 7.25 x 0.61 x 1.25 = 3.31 c.f.s. 2. Area to North of Site concentrating at Alley to East on North Property Line Area = 0.37 ± acres Tc = 5 minutes C = 0.60 I2 = 3.30 in./hr. Iioo = 7.25 in./hr. Q2= 0.60 x 3.30 x 0.37 x 1.00 = 0.73 c.f.s. Qioo = 0.60 x 7.25 x 0.37 x 1.25 = 2,41 c.f.s. 3. Area on the West side of the Site concentrating at inlet on the N.W corner of Prospect Rd. Area = 0.61 + 0.272 + 0.146 = 1.03± acres Tc = 10 minutes C = 0.70 I2 = 2.50 in./hr. Iioo = 7.25 in./hr. Q2 = 0.70 x 2.50 x 1.03 x 1.00 = 1.80 c.f.s. Qioo = 0.70 x 7.25 x 1.03 x 1.25 = 6.53 c.f.s. 4. Area Onsite concentrating at Prospect Rd. gutter on East Property Line Area = 0.332± acres Tc = 10 minutes C = 0.767 I2 = 2.50 in./hr. Iioo = 7.25 in./hr. Q2 = 0.767 x 2.50 x 0.332 x 1.00 = 0.64 c.f.s. Qioo = 0.767 x 7.25 x 0.332'x 1.25 = 2.31 c.f.s. 5. Area Onsite concentrating at inlet in parking lot onsite Area = 0.225± acres Tc = 10 minutes C = 0.767 I2 = 2.50 in./hr. Iioo = 7.25 in./hr. Q2 = 0.767 x 2.50 x 0.225 x 1.00 = 0.43 c.f.s. Qioo = 0.767 x 7.25 x 0.225 x 1.25 = 1.56 c.f.s. 6. Area from alley to East of Site concentrating at Prospect Rd. gutter on East Property Line Area = 0.37 + 0.36 = 0.73± acres Tc = 10 minutes C = 0.60 I2 = 2.50 in./hr. Iioo = 7.25 in./hr. Q2 = 0.60 x 2.50 x 0.73 x 1.00 = 1.10 c.f.s. Qioo = 0.60 x 7.25 x 0.73 x 1.25 = 3.97 c.f.s. 7. Area from Prospect Rd. concentrating in gutter on East Property Line Area = 0.12± acres Tc = 10 minutes C = 0.85 I2 = 2.50 in./hr. Iioo = 7.25 in./hr. Q2 = 0.85 x 2.50 x 0.12 x 1.00 = 0.26 c.f.s. Qioo=0.85x7.25x0.12x1.25=0.93c.f.s. Page 4 off Client: ARCHITECTURE ONE By: DRM Project No. GRD-040-90 REVISED: Nov. 25,1991. PROPOSED CONDITIONS WITH OFFFSITE AREAS CONSIDERED: (cont.) 7. Total area concentrating at Prospect Rd. gutter on East Property Line Area = 0.332 + 0.12 + 0.37 + 0.36 = 1.18± acres Tc = 10 minutes C = 0.70 I2 = 2.50 in./hr. Iioo = 7.25 in./hr. Q2 = 0.70 x 2.50 x 1.18 x 1.00 = 2.07 c.f.s. Qioo = 0.70 x 7.25 x 1.18 x 1.25 = 8.49 c.f.s. THEREFORE, THE QUANTITY OF RUNOFF FLOWING IN THE GUTTER TO THE EAST OF THE SITE WILL BE REDUCED FROM THAT AT PRESENT. SIZE INLET IN PARKING LOT From Fig. 5-2 with 6" deep opening and 6" depth of flow in gutter Q/ft. = 1.1± cfs/ft. with 4' long opening Q = 1.1 x 4 = 4.4 cfs Reduction Factor for sump condition = 80% Q allowable = 0.80 x 4.4 = 3.5 cfs >> 0.43 & 1.56 SIZE PIPE Q = 1.486/n A R*2/3 S*1/2 Consider 15" dia. Pipe @ 1.0 % Q = 1.486/0.013 x 1.23 x 0.46 x 0.1= 6.47 cfs>>0.43 & 1.56 Therefore, 4 ft inlet OK Therefore, 15" dia. OK Page-5 of,fi DETENTION VOLUME DETERMINATION FOR "RATIONAL METHOD" Time Q100 Prop. Vol. @ 0100 Q dis. @ 2 Yr. Vol. dis. Vol. Diff. (min.) (c.f.s.) (cu.ft.) (c.f.s.) (cU.ft.) (cU.ft.) 10 4.89 2932 1.33 798 2134 15 4.04 3640 1.33 1197 2443 20 3.50 4206 1.33 1596 2610 25 3.10 4651 1.33 1995 2656 30 2.80 5035 1.33 2394 2641 40 2.36 5662 1.33 3192 2470 50 2.02 6066 1.33 3990 2076 60 1.75 6309 1.33 4788 1521 At Q2 Existing Q = CIACf = 0.755 x 2.50 x 0.703 x 1.0 = 1.33 At Q100 Proposed Q = CIACf = 0.767 x I x 0.703 x 1.25 CACf = 0.767 x 0.703 x 1.25 0.67 Therefore, the Detention Volume desired is 2,656 cu. ft. at a release rate of 1.33 c.f.s. This is based upon detaining the difference between the present site conditions with runoff generated by a 2 Year Storm event and the proposed site conditions with runoff generated by a 100 Year Storm event. NOTE that it is not possible to detain the desired volume of runoff on the site due to existing conditions and grading parameters. ARCHITECTURE ONE TACO BELL Proj. No. HYD-040-90 Page 6 of 6 11/25/91 DRM Engineering November 27, 1991 Project No. GRD-040-90 Mr. Al Hauser, Architect ARCHITECTURE ONE 150 East 29th Street Suite 200 Loveland, Colorado 80538 Dear Mr. Hauser, The enclosed report represents the results of a 'revised' preliminary drainage investigation for the proposed TACO BELL to be located on Lots 7 thru 10, Block 6 of the R. C. Moore's Second Addition to the City of Fort Collins, Larimer County, Colorado. This investigation was based upon the proposed site development plan and plat; proposed site grading plan; on -site observations; and available topographic information. The investigation was performed in accordance with the criteria established in the City of Fort Collins "Storm Drainage Design Criteria and Construction Specification Standards" manual and incorporates the comments and concerns expressed through the review by the City's staff. Thank you for the opportunity to be of service to you. If you should have any questions, please feel free to contact this office. Respectfully Submitted, Dennis R. Messner, P.E. MESSNER Engineering Associates DRM/mkm Enclosures Civil and Environmental Engineering Consultants 150 E. 29th Street, Suite 225 Loveland, Colorado 80538 Telephone: (303) 663-2221 TABLE OF CONTENTS Letter of Transmittal Table of Contents Scope Site Description Existing Conditions Proposed Development Erosion Control Measures Conclusions and Recommendations i ii 1 1 1 2 2 3 Vicinity Map Existing Conditions Exhibit Grading & Drainage Exhibit Calculations ii SCOPE The following report represents the results of a drainage investigation for a proposed TACO BELL restaurant to be located on a parcel of land situated in the Southwest Quarter of Section 13, Township 7 North, Range 69 West of the 6th P.M., Larimer County, Colorado. The site legal description is: Lots 7 thru 10, Block 6 of the R. C. Moore's Second Addition to the City of Fort Collins.The investigation was performed for ARCHITECTURE ONE. The purpose of this investigation is to determine the effects of the proposed development on the area's existing drainage conditions and to determine the improvements, if any, and the appropriate sizing for proposed improvements so that it may be incorporated with the construction of the project. The conclusions and recommendations presented in this report are based upon the proposed site development plan and plat; proposed site development construction plans; on -site observations; and the available topographic information. The analysis was performed in accordance with the City of Fort Collins "Storm Drainage Design Criteria and Construction Standards" manual. SITE DESCRIPITION The site is rectangular in shape and contains approximately 0.703 acres. The site's East-West dimension is approximately 143 feet and its North -South dimension is approximately 213 feet. The site abuts the easterly right-of-way of College Avenue and the northerly right-of-way of Prospect Road. The site is located In the SPRING CREEK DRAINAGE BASIN. EXISTING CONDITIONS The site presently consists of two separate uses. A brick structure is located on the northern half of the site. This structure was originally constructed as a single-family residence but has been utilizied as an office building for the past several years. A TACO BELL restaurant is located on the southerly half of the site at the Northeast corner of the intersection of College Avenue and Prospect Road. The site slopes gently from North to South: toward- Prospect Road at a slope of approximately 3%. The site -does not receive run-off from the properties to the North. The runoff generated on the adjacent property is directed westerly into the gutter of College Avenue or easterly into the alley. Runoff that enters both the gutter in College Avenue and the alley flows southerly to Prospect Road. A storm inlet that is located at the easterly end of the curb radius at the northeast corner of the intersection of College and Prospect intercepts flow from the north. Excess flow continues easterly along Prospect to Remington and then southerly along Remington to Spring Creek. PROPOSED DEVELOPMENT The proposed re -development of the site is to consist of the demolition of the existing TACO BELL structure that is presently situated on the southerly portion of the site. The existing residential/office structure that is located on the north side of the site is to be renovated to be used as the "new" restaurant structure. The parking, landscaping and driveways associated with the "new" restaurant will be places following the existing structures demolition. The sequence of construction and demolition is anticipated to be 1 PROPOSED DEVELOPMENT(cont.) such that the existing restaurant will remain in operation while the existing structure is being renovated. Other improvements that will take place in the future and will ultimately effect the grading and drainage for the site is the proposed reconstruction of Prospect Road. This construction is being proposed in order to provide channelizing and turning lanes to improve traffic flow in the area. In order to do this the street will be widened. The curb and gutter is to be shifted to the North a distance of 15.5 ft. along Prospect Road in order to provide additional turning lanes. This roadway widening will also require that the existing storm drainage inlet located at the northeast corner of the intersection be reconstructed. The proposed grading and drainage plan for the site has taken this proposed future construction into account. The perimeter grades have been established by continuing the crown slope grades of the existing roadway to the proposed gutter locations. A portion of the site, approximately 0.2 acres, is to be routed to a new drainage inlet to be located in the parking lot on the site. This area previously discharged directly into the curb and gutter located along the north side of Prospect Road. EROSION CONTROL MEASURES Erosion control considerations have been made based upon the short term,i.e., during construction activities and the long term, through the life of the facility. The long term measures incorporated to eliminate erosion are the proposed methods and materials to be used to provide a surface covering for the driveways, parking areas, walkways and the landscaped open areas. The structure and hard surfaced areas will provide a covering to deter erosion. The landscaping to be established will be a combination of plantings and ground covers to deter erosion.(Please refer to the proposed "Landscaping Plan" prepared by the project's Architect) The short term erosion control method to be incorporated into the construction requirements for the project is the placing of "Curb Inlet Filter Gravel" at the proposed storm drain inlet to be constructed onsite. It is not considered as necessary to provide any wind erosion measures due to the protected nature of the site. The anticipated schedule of construction activities is anticipated to be: remodel and addition to the existing structure; perform access and site related construction around remodelled structure; demolition -of existing Taco Bell structure and existing drives and -parking; construct new parking and drives; and instal landscaping and signage. With this schedule the site will be "open" and subject to water caused erosion for an extremely short period of time. This is due to the desire to have the existing restaurant remain in operation while the existing structure is being renovated. The demolition of existing facilities and subsequent grading and paving operations will be scheduled in a manner that will place the "new" restaurant in operation as quickly as possible. Therefore, depending upon the sequence of activities and the weather conditions it may be possible for no temporary measures to be required. 2 CONCLUSIONS AND RECOMMENDATIONS 1. The proposed development will retain the existing drainage patterns. 2. The site is located in the SPRING CREEK DRAINAGE BASIN. The site is not located within the floodway or flood plain. 3. All development is to be performed in accordance with City of Fort Collins Standards and Specifications. 4. Onsite detention of stormwater is desired by the City of Fort Collins. The difference between the existing and proposed conditions is estimated to be 2,656 cu. ft. when based upon the difference between the runoff from a 2 Year Storm at the existing condition and the runoff from a 100 Year Storm at the proposed conditions. It is not practical to detain this volume on the site due to existing topographic conditions and physical grading constraints that are placed on the site. The grading and drainage plan has been designed to assure that the proposed development will not adversely impact the existing drainage system. The design is such that the runoff from the site is to be routed to reduce the area that drains directly into the street curb and gutter. This will reduce the runoff that flows to the east along the north side of Prospect Road. A request for a variance to the City's policies is to be submitted in conjunction. with this report. 5. The City of Fort Collins Standards for temporary erosion control measures are to be incorporated with the construction activities. Specifically, 'filter gravel' is recommended to be placed at the proposed curb inlet to be constructed in the parking lot onsite. 3 VICINITY' MAP! i --- _....._ .... - - -- - - I ,no. Do OO - on m ...a N _ o II SCALE: 1"-20' INo D i II 1 :1�:.::: -n p W N U) W T -n n U) U) m D ' R/RTIE 1.0 I Ian y OFF LINE 9S 9s R TIE 00 LINE W r. O _ ��S _ �1 — ._ _ •.' :_ �y - 99>9s3 M�FENCE ON LIVE `41 GRAVEL D(ZIVE o '.• PHONE PEP.co M� ��' a • X 1 Odd P / \V A\Q . I I STORY BRICK m ,, 5 Zo.�' W/ BASEMEFJT 49 C7�2AVEL �` 3 cA BRICK ! I 9 GAPZAGE° 5.8 1530 S. COLLEGE - Ate° Su2FAc�- � FF. = N �110.42 B-1,41 in72 100.1, l, r r J 92' - �6 . • AI\L Q o`ti O '•—ice �� O 0 40 7 \0 . C71Z II' - PV .w O BRIGK aL3� 3 / 030' �1 24" DO PSTE O : jj R/R TIE PNOUE PEP. I u i RETAIN1106 WALL L 9!Av 01, AN j::'• ' PSI �.; ,. 7i v +( o I agclLP � GAS �� ...1 Q/ °`' i I . :... I 4"7.4' ASPNAL-T fl I S70�1 Q I "•. f.'I � I STCRY MA�GNRY _ i. � �.1 Wo BA5EMEO-( : 11 � TACO BELL �ESTAU(zA1JT :::� ^�\�-- LL y O.D I.: :: jSTONE \: • F.F. = 91.11 °�� a0� ~\ �e N I O °' oL m �... 41.4' .1 ° aA is o o II D90!2 9, Q Q 90 Fo o $IGN QQ� 3 0.0 qFq �::. c� RAFFIC- 5IGNAL Q2 0 1 \ cONTZOLE� ; ' t 'oo to C S4 qc a9 .•'t TRAFFIC 51GNAL, i CFS9vTr : x: O�1C. CURB GUTTER: SIDEWALK:.:. 77 aNMAO"OLF— S FLOW LINE %r Lio (6r. �l i T) 9� CURB CUT AREA = 1.04 AC. I /� a,� AREA = 0.07 AC. Q2 = 1.8 CFS �p Q2 = 0.15 CFS / a� L— - Q 100 = 6.6 CFS r— }� - Q 100 = 0.5 CFS -PROSPECT ROAD— AREA = 1.35 AC. EXISTING CONDITIONS EXHIBIT Q100 2• s 6 CFS Client: ARCHITECTURE ONE Project No. GRD-040-90 By: DRM Date: Oct. 28, 1991 REVISED: Nov. 25, 1991 Calculations for Drainage Investigation for Lots 7 thru 10 , Block 6 of R. C. Moore's 2nd Addition located in the SW1/4 of Section 13, Township 7 North, Range 69 West of the 6th P.M., City of Fort Collins, Larimer County, Colorado Total Site Area = 0.703 ± acres of existing platted property The proposed development of the site is to consist of demolition of the existing structures on the site and the construction of a new TACO BELL restuarant. The site will be required to dedicate property along College Ave. and Prospect Road due to proposed street widening projects proposed to occur in the near future. The net area of the site after right-of-way dedication is anticipated to be: Net Site Area = 0.634 ± acres EXISTING CONDITIONS - RUNOFF COEFFICIENT Rational "C" Factor = 0.20 for Lawns and Landscaped Areas = 0.95 for Roofs, Decks, Patios, etc. = 0.95 for Asphalt and Concrete Streets, Drives, and Parking = 0.50 for Gravel Streets, Drives, and Parking "C"avg (Existing) Lawns and Landscaped Areas = 3,728 sq.ft.± Roofs, Decks, Patios, etc. = 7,649 sq.ft.± Streets, Drives, and Parking = 12,196 sq.ft.± Gravel Drives, and Parking = 7.050 sq.ft.± Total Site = 30,623 sq.ft.± "C" avg = ((3,728 x 0.20) + (7,649 x 0.95) + (12,196 x 0.95) + (7,050 x 0.50)) + 30,623 = 0.755 "C" avg = 0. 755 PROPOSED DEVELOPMENT - RUNOFF COEFFICIENT "C"avg : Lawns and Landscaped Areas = 7,490 sq.ft.± Roofs, Decks, Patios, etc. = 2,825 sq.ft.± Streets, Drives, and Parking = 20.308 sq.ft.± -- ---Total-Site- - = 30,623-sq.ft.± "C" avg = {(7,490 x 0.20) + (2,825 x 0.95) + (20,308 x 0.95)} + 30,623 = 0.767 "C"avg = 0.767 TIME -OF -CONCENTRATION Time of Concentration (Roof to Ground) = 5 minutes Time of Concentration (Ground to Street): Tc(min.) = 1.8 [ 1.1 - (Cf x C) ] 4L(ft.) + 3qS(%) Time of Concentration (Street Flow): T(min.) = L(ft.) + [Vel. (ft./sec.) x 60 min./sec.] TTotal = TRoof + Tc + Ts Page 1 of 6