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HomeMy WebLinkAboutDrainage Reports - 05/17/1998ort Zvi W OF D FOR VINEYARD CHRISTIAN FELLOWSHIPf located on Lot 1 and a portion of fact A of the Riverside Commercial - P.U.D. 1st Filing CITY OF FORT COLLINS, LAREVIER COUNTY, COLORADO Prepared for Vineyard Christian Fellowship 1201 Riverside Avenue Fort Collins, Colorado 8052 December 1997 Project No. GRD - 272 - 97 Prepared By Engineering Associates 150 E. 29th Street, #238 Loveland, Colorado 80538 1blephone: (970) 663 - 2221 Engineering Associates ' Mr. Basil Y. Hamdan Stormwater Utility 235 Mathews P.O. Box 580 Fort Collins, Colorado 80522-0580 ' Dear Mr. Hamdan, 11 December 19, 1996 Project No. GRD - 272 - 97 The enclosed report represents the results of the drainage investigation for the proposed expansion of the "Vineyard Christian Fellowship" located on Lot 1 and a portion of Tract A of "Riverside Commercial P.U.D. 1st Filing" in the City of Fort Collins, Larimer County, Colorado. This investigation was based upon the proposed site development plan; 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. If you should have any questions, please feel free to contact this office. Respectfully Submitted, MESSNER Engineering Associates Dennis R. Messner, P.E. ' DRM/mkm Enclosures 1 cc: Vineyard Christian Fellowship Civil and Environmental Engineering Consultants 150 E. 29th Street, Suite 238 Loveland, Colorado 80538 Telephone: (970) 663-2221 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 TABLE OF CONTENTS Letter of Transmittal Table of Contents Scope Site Description "Historic" Conditions Proposed Development Erosion Control Measures Conclusions and Recommendations References Drainage Summary Erosion Control Cost Estimate Letter EXHIBITS Vicinity Map "Historic" Conditions Exhibit Proposed Conditions Exhibit Calculations ii i ii 1 1 1 2 2 3 3 F SCOPE The following report represents the results of a drainage investigation for the ' expansion of the existing facility for the Vineyard Christian Fellowship located at 1201 Riverside Avenue, Fort Collins, Colorado. The investigation was performed for the owner, the Vineyard Christian Fellowship.. The purpose of this investigation is to ' determine the effects ' of the proposed building expansion on the area's existing drainage conditions and to determine the improvements, if any, and the appropriate sizing for the 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; proposed building 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 DESCRIPTION The site is considered to be irregularly shaped and contains approximately 0.853 acres. The site's maximum East-West dimension is approximately 360 feet, its maximum North -South dimension is approximately 320 feet. The site abuts the southerly right-of- way of Riverside Avenue. The site is located in the SPRING CREEK DRAINAGE BASIN. "HISTORIC" CONDITIONS ' The site is developed and is surrounded by streets or existing development. The ground surface is covered mostly by existing structure and paved access driveways and parking lot. Approximately ten per cent of the site is landscaped. The sites surface ' slopes are considered to be moderate and range from 1 % to 5 %. The "historic" direction that the site sloped prior to development was from South to North toward the Poudre River. The major portion of the site has been graded to drain through the ' parking lot to a `sump area' located at the Northeast corner of the site. A portion of the roof of the existing structure drains to the West onto an open landscaped area between the Vineyard Christian Fellowship structure and the Vineyard Press structure. The ' run-off that is captured between the structures flows to the North toward Riverside Avenue and to the South onto a grassed open area that is owned by the Fellowship. The run-off that flows through the parking lot to the `sump area' flows into a gravel sump ' at the corner of the parking lot. The stormwater then seeps into a concrete sump and is pumped from the sump into the gutter at Riverside Avenue. ' Neither a drainage plan or report for the Riverside Commercial P.U.D. was found in the City's records. ' PROPOSED DEVELOPMENT The proposed building expansion is to, consist of a 3,500 square foot addition at the ' Northeast corner of the existing structure. No change to the existing overlot grading, access drives and parking lot are proposed. 1 ' The current City policies require that the difference between the historic rate of run-off and the developed rate of run-off be detained onsite. The release rate is to be no greater than the 2 Year Storm historic rate. ' The City's policies normally require that the adjacent street flows be incorporated with the onsite detention requirements. This policy applies most efficiently when the street ' construction and onsite detention are performed concurrently. In this instance, it is not physically feasible to combine the two flows since the flow generated on the streets can not be intercepted and directed into an on -site detention facility and then routed ' back into the curb and gutter. The area within the southerly half of the Riverside Avenue right-of-way has not been considered as tributary to the existing detention facilities. The existing pumped facilities, although quite unusual and dependent upon a mechanical means to operate, appears to work successfully. The. facilities maintenance personnel have informed me that the pump has been replaced within the ' last three years and that to their knowledge there has not been an instance when the pump failed and that vehicles had been flooded. EROSION CONTROL MEASURES Erosion control considerations are based upon the short term activities that occur during construction and the long term measures that are to be placed for the life of the ' facility. The long term measures are the proposed methods and materials to be used to provide surface treatments for the driveways, parking areas, walkways and the landscape materials and plantings in the open areas that will provide a combination of ground covers to deter erosion. ' The anticipated construction schedule should have the site grading completed, within P g'r' g P one (1) week after commencing construction. The schedule for construction activities is ' anticipated to be: March 1 - March 7, perform site grading; March 7 - March 14, construct drainage related facilities; March 15 - March 21, install building foundation and water and sewer service lines; March 22 - May 30, construct structure; April 15 - ' April 21, construct curb, gutter and sidewalks; April 28 - May 1, place pavement; May 15 - May 25 install landscaping. ' The recommended short term erosion control methods to be incorporated with the construction activities consist of the following: prior to commencing construction a "Silt Fence" is to be placed along the eastern boundary of the site in order to control and ' contain mud and debris onsite; upon completion of grading operations ,and at the time that the drainage inlets are installed a "Straw Bale Filter" is to be placed at each inlet; and tracked mud to be cleaned up as required. ' Wind erosion measures are to consist of water application and roughening of exposed surfaces. 2 ' CONCLUSIONS AND RECOMMENDATIONS 1. The proposed building expansion will retain the existing drainage patterns. The change in site conditions that may increase the site run-off is the addition if building roof area. No additional site paving is to be installed in conjunction with the building addition. 2. The site is located in the SPRING CREEK DRAINAGE BASIN. The site is not located within a defined floodway or flood plain. 3. All new construction is to be performed in accordance with City of Fort Collins criteria. A variance to the City's policy that requires on -site detention of adjacent street flows is requested. The established street and site improvements make the routing of stormwater from the street into the On -site detention facilities physically impractical. 4. Onsite detention of storm water is required by the City of Fort Collins. The volume of run-off to be detained based upon the City's current criteria is estimated to be 10,836 cu. ft. This detention volume has been determined based upon the calculated volume of run-off generated under the proposed conditions by a 100 Year Storm. The entire site, one-half of the adjacent Riverside Avenue, and one-half of the adjacent private drive at the East side of the site have been considered as the tributary area to determine the volume of the detention required. The release rate determined for the `historic' rate of run-off from the site has been estimated based upon a 2 Year Storm. The estimated release rate is 0.95 c.f.s. 5. The City of Fort Collins Standards for temporary erosion control measures are to be incorporated with the construction activities. Specifically, the following are to be incorporated in the site construction activities: A "Silt Fence" is to be placed along the northeasterly side of the site adjacent to the proposed construction area. 6. Since a pump is .used to discharge stormmwater from the detention area, a program to establish a maintenance schedule and routine operation checks is strongly recommended. Posting signs and possibly varying the color of the parking striping to identify the area in which flooding of vehicles may occur is also recommended. REFERENCES 1. City of Fort Collins, STORM DRAINAGE DESIGN CRITERIA AND CONSTRUCTION STANDARDS, May 1984 with subsequent revisions and additions. 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 STORM WATER DETENTION SUMMARY SITE DRAINS TO "SPRING CREEK" DRAINAGE BASIN GROSS SITE AREA (includes 1/2 of Riverside Ave.) = 81,805 Sq. Ft. = 1.88 Ac. ± NET SITE AREA = 62,444 Sq.Ft. = 1.43 Ac. ± HISTORIC "C" = 0.20 DEVELOPED "C" = 0.89 HISTORIC "Q2" = 0.55 c.f.s. CRITERIA BASED DETENTION VOLUME = 16,850 Cu-.Ft. ± PLAN DETENTION VOLUME = 6,009 CuYt. MAXIMUM DEPTH OF DETAINED WATER = 1.5 Ft. Q High Water Elevation 5054.5 m PEAK DISCHARGE FROM DETENTION, Q = 0.55 c.f.s. I mi-fmmmgn Engineering Associates December 22, 1997 ' Project No. GRD - 272 - 97 Mr. Basil Hamdan Stormwater Utility City of Fort Collins 235 Mathews P. O. Box 580 ' Fort Collins, Colorado 80522 - 0580 Re: Vineyard Christian Fellowship, 1201 Riverside Avenue, Fort Collins, Colorado Dear Mr. Hamdan, The estimated cost for erosion control devices for the subject site has been estimated to be: ' 1. Silt Fence 100 l.f. Q $2.50/ft. _ $250.00 Cost Q 150% = 1.5 x $250.00 = 075.00 ' The cost to re -seed the 3,700 square foot site at $0.0298/sq.ft. _ $110.26 150% of the re -seeding cost = 1.5 x $110.26 = $165.39 Therefore, the subject project's estimated erosion control security amount is determined to be $375.00. This amount is to be included as surety for the erosion control guarantee along with any other surety requirements that may be a part of the City's "Developer's Agreement" requirements. If you should have any questions or desire additional information, please feel free to contact this office. Respectfully Submitted, MESSNER Engineering Associates OnR z `\\\\\``` Q • s • • E f' ea�j���i 0 Dennis R. Messner, P.E.AV F ���►►! l l 11,1111110 cc: Vineyard Christian Fellowship 1 Civil and Environmental Engineering Consultants 150 E. 29th Street, Suite 238 Loveland, Colorado 80538 Telephone: (970) 663-2221 I 1 1 1 1 1 1 1 1 1 1 1 1 T,es�i Jr • • ♦ e'NQe Disposal (Not -to -Scale) %ii ` III � � ■ i _ � IN i. \ i . I lip i t • (\ \ L f tv �I L• "d' II y.. i I 1 I ■ \� ?d(/ r� ■ j II ' � e VICINTY MAP for VINEYARD CHRISTIAN FELLOWSHIP 1201 RIVERSIDE AVENUE, FORT COLLINS, COLORADO Property Description: Lot 1 and a portion of Tract A of 'Riverside Commercial - P.U.D.1st Filing;' Fort Collins, Colorado 1 1 1 1 1 1 1 1 1 1 1 1 1 1 (Okl(cTulk,TTDH�� hil 0 DRAINAGE INVESTIGATION CALCULATIONS 1 Client: VINEYARD CHRISTIAN FELLOWSHIP Project No: GRD-272-97 Project: VINEYARD BUILDING EXPANSION Date: 19-Dec-97 Location: 1201 Riverside Avenue, Fort Collins, Colorado By: D.R.M. This investigation is being performed to determine the required detention volume, discharge rates, and structure sizing for the subject project site. The site is located in the "Spring Creek" Drainage Basin. RATIONAL METHOD Runoff Coefficients, "C" RATIONAL METHOD City of Fort Collins S.D.D.C.&C.S. (Table 3-3) Frequency Adjustment Factors Land Use Description Building/Roofs 0.95 Drives and Walks 0.95 Gravel Surfaced 0.50 Undeveloped n Areas 0.20 Grassed Landscaped Areas 0.15 EXISTING CONDITIONS: Storm Return Period ears Freq. Factor "CP' 2 1.00 5 1.00 10 1.00 100 1.25 THE SITE HAS BEEN DEVELOPED FOR SEVERAL YEARS. THE LATEST REVISION TO THE P. U. D. PLAN FOR THE SITE HAS BEEN FOUND TO BE DATED MAY 18, 1978. THIS PROPOSAL IS TO ADD APPROXIMATELY 3,500 SQUARE FEET TO THE EXISTING STRUCTURE. THE STRUCTURE ADDITION IS TO TAKE PLACE IN EXISTING LANDSCAPED AREA AND CONRETE WALKWAY AREA. Building/Roof Area= 15,714 Sq.Ft. Drives and Walks Area = 57,601 Sq.Ft. (Includes Riverside Avenue & Center Dr; Gravel Surfaced Landscape Area= 0 Sq.Ft. Undeveloped Open Areas Area= 0 Sq.Ft. Landscaped Areas Area = 8,490 Sq.Ft. (Includes Riverside Ave. R-o-W) TOTAL SITE AREA Area= 81,805 Sq.Ft. = 1.88 Acres Avg. C = [(0.95 x 15,714)+(0.95 x 57,601)+(0.50 x 0)+(0.20 x 0)+(0.15 x 8,490)] + 46,401 Avg. "C" = 0.87 Page 1 of 4 0 DRAINAGE INVESTIGATION CALCULATIONS ' Client: VINEYARD CHRISTIAN FELLOWSHIP Project No: GRD-272-97 Project: VINEYARD BUILDING EXPANSION Date: 19-Dec-97 Location: 1201 Riverside Avenue, Fort Collins, Colorado By: D.R.M. EXISTING ' Time of Concentration Consider sheet flow across site from Southwest to Northeast L = 275 ft. Elev. Diff.= 98 - 96 = 2.00 ft. Slope, S = 0.73 % T = 1.87(1.1-CCf)gL+(S^1%3)=1.87(1.1-(0.87x1.00))4275 +( 0.73^1/3) = 7.92 Minutes Since surrounding area is developed consider for 'urbanized' condition as a check Tc = L / 180 + 10 for 'urbanized' condition with longest flow path considered Length, L = 450 ft. Tc = 450 / 180 + 10 = 12.50 minutes Average of the two methods = (7.92 + 12.5) / 2. = 10.21 minutes ' USE Tc 10 area to have more intense development = minutes since -is ' Rainfall Intensities based upon 10 minute Time of Concentration: I2 = 2.50 in./hr. I5 = 3.65 in./hr. I10 = 4.40 in./hr. I100 = 7.15 in./hr. Determine Run-off from Site and adjacent Street under present conditions: ,Q = CIACf Q2 = 0.87 x 2.50 x 1.88 x 1.00 = 4.09 c.f.s. Q5 = 0.87 x 3.65 x 1.88 x 1.00 = 5.97 c.f.s. Q10 = 0.87 x 4.40 x 1.88 x 1.00 = 7.20 c.f.s. Q100 = 1.00 x 7.15 x 1.88 = 13.44 c.f.s. NOTE that the estimated run-off rates are for information only and have not been considered in the design. Offsite Run-off @ Existing Conditions: ' Offsite run-off is to be considered to the extent that existing site grading provides protection from offsite flows. No offsite area contributes to the site in its present condition. 1 Page 2 of 4 INVESTIGATION CALCULATIONS DRAINAGE Client: VINEYARD CHRISTIAN FELLOWSHIP Project No: GRD-272-97 Project: VINEYARD BUILDING EXPANSION Date: 19-Dec-97 Location: 1201 Riverside Avenue, Fort Collins, Colorado By. D.R.M. EXISTING CONDITIONS (continued) IConsider predeveloped condition L = 275 ft. Elev. Diff.= 98 - 96 = 2.00 ft. Slope, S = 0.73 % T = 1.87(1.1-CCf)gL=(SAI/3)=1.87(1.1-(0.2xl.00))4275,( 0.73^lj3) = 30.99 Minutes Rainfall Intensities based upon 10 minute Time of Concentration: I2 = 1.45 in./hr. I100 = 4.15 in./hr. Determine Run-off from Site and adjacent S treet under pre -developed condition: I Q =CIACf Q2 = 0.20 x 1.45 x 1.88 x 1.00 = 0.55 c.f.s. Q100 = 0.20 x 4.15 x 1.88 x 1.25 = 1.95 c.f.s. PROPOSED CONDITIONS: Building/Roof Area 19,214 Sq.Ft. Drives and Walks Area 56,901 Sq.Ft. (Includes Riverside Avenue & Center Dr.; Area 0 Sq.Ft. Gravel Surfaced Landscape = Undeveloped Open Areas Area = 0 Sq.Ft. Landscaped Areas Area = 5,690 SgFt. (Includes Riverside Ave. R-o-W) ' TOTAL SITE AREA Area 81,805 Sq.Ft. = 1.88 Acres Avg. C = [(0.95 x 19,214)+(0.95 x 56,901)+(0.50 x 0)+(0.20 x 0)+(0.15 x 5,690)] + 81,805 Avg. "C" = 0.89 USE Tc = 10 minutes since there is no change from present condition I2 = 2.50 in./hr. I5 = 3.65 in./hr. Q = CIACf Q2 = 0.89 x 2.50 x 1.88 x 1.00 = 4.18 c.f.s. Q100=1.00x7.15x1.88 = 13.44 c.f.s. Page 3 of 4 Undeveloped Grassed Area •ySr �s Q i / / / Existing Structure / / / f 7.02 / 56,73 / 1 i Y b /94�y \ issi 57.93 491 a / b� b0 / ° d C Existing \ Concrete ExieUnq Structure \ ° /eyard Christian Fellowship \.54 \ \ / 1201 Riverside Avenue — — • , pholk, Surfaced DriRe @ Parking 4. � \ 1\\\\\ 55.30 5].O o .1\ /Al CPO / / / 55.,' �Asphalt Surfaced 0 eW \ / Drive k Parking ° Q J 55.91 / 1 p d � 55.83 / 56.35 56.04 6 / / J B� 55. r� Central 10 40 MENQ 0 20 60 I" = 20' Contour Inteveh 1' *Concentration Point Area draining to concentration point= 54,166d: sq.ft. Qz — 4.lcfs Q,.=13.4cfs Volume — 2784 co.ft. *BS 53.6] 53 / 54.35 m `—Existing Wet Well with Submersible Pump _ryr2 Typically Indicates Existing Ground Surface Contour Typically Indicates Drainage Basin Limit x 99.11 T pically Indicates Existing Surface Spot Elevation �v T pically Indicates Drainage Flow Direction Typically Indicates Existing `\ Curb dt Gutter U GRD-272-97 SHEET 1 of 2 9-161 \ / / / Existing Structure / / \/ 3 � /// y L l / 0 Praposed 'Slk Fence'00 °D \\ Existing Structure \ \ ° /YnChristian Fellowship .20, \ \ 1201 Riverside Avenue- \ 0 e \'� R 0 1 i s> \ r� Central % .14 C �� r 1a 40 a 20 60 1"20 Contour Intevtevnl: 1' *Concentration Point Area draining to concentration point= 54,166i sq.ft. Oy = 4.2cfe grrs=13.4cf5 Volume = 2764 cu.ft. Exciting Force Main +ydL �G Existing Wet Well with Submersible Pump _.. _,fig Typicolly Indicates Existing Ground Surface Contour Typicolly Indicates Drainage Basin Limit 99.11 Tyypically Indicates Existing x Surface Spot Elevation FlpicallDy Indicates Drainage ow irection a x z o p4 o qJz W o�� Ci y a Z OzW aFQ aw RUC Ui x Wr" U a5 :z) a �w w� z z> w w 0 o- o a SCALE AS NOTED DRAWN: M S.R. CWD: D.R.M. Project No. GRD-272-97 Typibcally Indicates Existing `\ Curh Gutter SHEET 2 of 2