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HomeMy WebLinkAboutcoa.lu.cu.615 W Francis.A019-00CASE NUMBER PARCEL ID # CASE NAME PROJECT ADDRESS PLANNER CASE TYPE OWNER/APPLICANT REPRESENTATIVE DATE OF FINAL ACTION CITY COUNCIL ACTION PZ ACTION ADMIN ACTION BOA ACTION DATE CLOSED BY A019 -00 2735- 124 -26003 Kaplan ADU 615 W. Francis Nick Lelack ADU Aspen GK LLC./ Charlie Kaplan Peter Gluck & Partners 4/28/2000 Approved 5/9/00 J. Lindt DEVELOPMENT ORDER of the City of Aspen Community Development Department This Development Order, hereinafter "Order ", is hereby issued pursuant to Section 26.304.070, "Development Orders ", and Section 26.308.010, "Vested Property Rights ", of the City of Aspen Municipal Code. This Order allows development of a site specific development plan pursuant to the provisions of the land use approvals, described herein. The effective date of this Order shall also be the initiation date of a three -year vested property right. The vested property right shall expire on the day after the third anniversary of the effective date of this Order, unless a building permit is approved pursuant to Section 26.304.075, or unless an exemption, extension, reinstatement, or a revocation is issued by City Council pursuant to Section 26.308.010. After Expiration of vested property rights, this Order shalt remain in full force and effect, excluding any growth management allotments granted pursuant to Section 26.470, but shall be subject to any amendments to the Land Use Code adopted since the effective date of this Order. This Development Order is associated with the property noted below for the site specific development plan as described below. West, New York City, New York Address and telephone number Lots E & F, Block 22, City and Townsite of Leeal Description and Street Address of Sul: Property Administrative ADU Approval Written Description of the Site Specific Plan and /or Attachment Describing Plan Administrative Land Use Appt Dates (Attach Final Ordinances or Resolutions) May 6 2000 Effective Date of Development Order (Same as date of publication of notice of approval.) 7.2003 Expiration Date of Development Order (The extension, reinstatement, exemption from expiration and revocation may be pursued in accordance with Section 26.308.010 of the City of Aspen Municipal Code.) Issued this 7 th day of May, 2000, by the City of Aspen Community PUBLIC NOTICE Of DEVELOPMENT APPROVAL Notice is hereby given to the general public of the approval of a site specific development plan, and the creation of a vested property right pursuant to the Land Use Code of the City of Aspen and Title 24, Article 68, Colorado Revised Statutes, pertaining to the following described property: Lots E & F, Block 22, City and Townsite of Aspen, by administrative decision of the Community Development Director on April 28, 2000. For further information contact Julie Ann Woods, at the Aspen/Pitkin Community Development Dept. 130 S. Galena St, Aspen, Colorado (970) 920 -5090. s /City of Aspen Account Publish in The Aspen Times on May 6, 2000 Notice of Decision Accessory Dwelling Unit Aspen GK LLC, owner of a property located at 615 W. Francis Street, Parcel Identification Number 2735- 124 -26 -003, has applied for administrative approval of an Accessory Dwelling Unit (ADU). The Community Development Director shall approve, approve with conditions, or deny a land use application for an Accessory Dwelling Unit pursuant to Sections 26.520 and 26.304 of the Aspen Municipal Code if an application is found to be consistent with the following review criteria: 1. The proposed Accessory Dwelling Unit meets the requirements of Section 26.520.050, Design Standards. 2. The applicable deed restriction for the Accessory Dwelling Unit has been accepted by the Aspen/Pitkin County Housing Authority and the deed restriction is recorded prior to an application for a building permit. COMMUNITY DEVELOPMENT DIRECTOR DECISION The Community Development Director finds that the Accessory Dwelling Unit to be consistent with the review criteria, and hereby approves the ADU on this 10`h day of February, 2000 with the condition that the applicable deed restriction for the ADU be accepted by the Aspen/Pitkin County Housing Authority and is recorded prior to an application for a building permit. Qa - h J 'e Ann Woods, Community Development Director EXHIBITS Exhibit A: Accessory Dwelling Unit Design Standards Checklist. Exhibit 13: Floor plans and designated parking space. Case No. A019 -00 Parcel 1D No. 2735- 124 -26 -003 Reviewed By Nick Lelack Zone District: R -6 Date: March 14, 2000 EXHIBIT A Accessory Dwelling Unit Design Standards Checklist 26.520.050 Design Standards All ADUs shall conform to the following design standards unless otherwise approved, pursuant to Section 26.520.080, Special Review: An ADU must contain between 300 and 800 net livable square feet, 10% of which must be a closet or storage area. An ADU must be able to function as a separate dwelling unit. This includes the following: a) An ADU must be separately accessible from the exterior. An interior entrance to the primary residence may be approved by the Commission, pursuant to Special Review; b) An ADU must have separately accessible utilities. This does not preclude shared services; C) An ADU shall contain a kitchen containing, at a minimum, an oven, a stove with two burners, a sink, and a refrigerator with a minimum of 6 cubic feet of capacity and a freezer; and, d) An ADU shall contain a bathroom containing, at a minimum, a sink, a toilet, and a shower. One parking space for the ADU shall be provided on -site and shall remain available for the benefit of the ADU resident. The parking space shall not be stacked with a space for the primary residence. 0 An ADU shall be located within the dimensional requirements of the zone district in which the property is located. The roof design shall prevent snow and ice from shedding upon an entrance to an ADU. If the entrance is accessed via stairs, sufficient means of preventing snow and ice from accumulating on the stairs shall be provided. ADUs shall be developed in accordance with the requirements of this title which apply to residential development in general. These include, but are not limited to, the Uniform Building Code requirements related to adequate natural light, ventilation, fire egress, fire suppression, and sound attenuation between living units. This standard may not be varied. lu All ADUs shall be registered with the Housing Authority and the property shall be deed restricted in accordance with Section 26.520.070 Deed Restrictions. This standard may not be varied. Net livable square feet: 351 Deed restricted to mandatory occupancy: No 0 w 3 J O l 7 1 l 1 Y O M U �D N N {Hy O N H � Qppi 3 ° �q o y = Z N 0 t' 3 O ^_ n rn cV \ o Vn E Ci Z 7 O W rn L o Q d o O L C U C N C- U U LO v r7 c vi z o m Q � o w Ctf = N o O + Q Z (n N m Z fj fj 0 Q z m 3 w c� c� 0 3 O 0 z 3 m z w 0 0 w a 0 z m m 5 W U O U i � I I U_ I S II I I �I i1 I� I I� I� I 11 f- J Q m O Z w K w Z O U O n n 1 U �O N N O w W I \ J oo° w 0 w v t- m N v z ou �I I �I I II o I O �I z_ II II II II II II II II II II I i I I J co 00 zrq CD mQ Q� W N Q c' m Yo N n n 1 U �O N N ^ v� / G]y O cd 30o II o rn a �, Cj N z v . o . ^ E W v v N Pr z Q a o o Q co 00 zrq CD mQ Q� W N Q c' b U N a a� o M n U � N N � � O ~ Lv QI Q " M ?430 `o Q Z a C y O � C N N Y Z W Q O _I II rn o rn � oa E u N p p o W W CIO IVA" V ryz a W cn W CE U N /Y V ) Q. w F N Peter L. Gluck and Partners, Architects 19 Union Square West New York, NY 10003 Re: ADU for 615 W. Francis Job Number: 9911 Transmittal 212.255.1876 Telephone 212.633.0144 Fax pgluck @inch.com E -mail To: Aspen Community Development Date: February 18 2000 Attn: Chris Bendon Fax Number: C/20 - s73 `i Number of sheets including transmittal: 4 We transmit herewith: Via: For your: ® Drawings ❑ Samples ❑ Fax ❑ Approval ❑ Specifications ❑ Shop Drawings ❑ Mail ❑ Review & Comment ❑ Product Literature ❑ Change Order ❑ Messenger ❑ Distribution ❑ Other, specify: ❑ Federal Express ❑ Record ❑ Express Mail ® Information & use Chris, Attached are a site plan, floor plan and exposed exterior elevation for administrative ADU review( as per recent discussion with Charlie Kaplan) ADU has 351 s.f. of net liveable space located underneath garage. Space is accessed via an open tread metal grate stair to mitigate for snow and ice. Open plan incorporates kitchen and sleeping areas into one space with separate full bathroom. Full size 11 x 17 originals should come fed -ex tomorrow. Thanks and lets us know if there are any questions, etc. Jennifer Bloom Peter Gluck and Partners tvVI�40a- t��::�.v'CJ FFB 2 3 2000 COMMUNITY DEVELOPMENT Jennifer Bloom February 23, 2000 Charlie Kaplan Peter Gluck and Partners, Architects 19 Union Square New York, NY 10003 Re: 615 West Francis Street Dear Charlie: ASPEN • PITKIN COMMUNITY DEVELOPMENT DEPARTMENT I have completed the review of your residential proposal with the remainder of the City Planning Department and have found it to be in compliance with the Residential Design Standards as adopted by Ordinance No. 20, Series of 1999. This approval is based upon the plans and the model presented during our meeting on February 14, 2000. Amendments to your proposal may require re- review. Please contact me if you have any questions about the review, etc. 970.920.5072. Sincerely, oj Chris Bendon, AICP City of Aspen 130 S )LTn GALENA S MEET AsrEN, COLORAal 81611 -1975 PHONE 970.920.5090 Bx 970.920.5439 x,111W P.r�, FEB -23 -2000 WED 04:46 PM FAX N0. P. 04 ASPEN/PITKINj COMMUNITY DEVELOPMENT DEPARTMENT Agreement for Payment of City of Aspen Development Application Fees CITY OF ASPEN (hereinafter CITY) and (hereinafter APPLICANT) AGREE AS R ICANT has submitted to CITY an application for 4 S ? APPLICANT understands and agrees that City of Aspen Ordinance No. 45 (Series of 1999) establishes a fee structure for Land Use applications and the payment of all processing fees is a condition precedent to a determination of application completeness. 3. APPLICANT and CITY agree that because of the size, nature or scope of the proposed project, it is not possible at this time to ascertain the full extent of the costs involved in processing the application. APPLICANT and CITY further agree that it is in the interest of the parties that APPLICANT make payment of an initial deposit and to thereafter permit additional costs to be billed to APPLICANT on a monthly basis. APPLICANT agrees additional costs may accrue following their hearings and/or approvals. APPLICANT agrees he will be benefited by retaining greater cash liquidity and will make additional payments upon notification by the CITY when they are necessary as costs are incurred. CITY agrees it will be benefited through the greater certainty of recovering its full costs to process APPLICANTS application. 4. CITY and APPLICANT further agree that it is impracticable for CITY staff to complete processing or present sufficient information to the Planning Commission and /or City Council to enable the Planning Commission and/or City Council ro make legally required findings for project consideration, unless current billings are paid in full prior to decision. 5. Therefore, APPLICANT agrees that in consideration of the CITY's waiver of its right to collect full fees prior to a determination of application completeness, APPLICANT shall pay an initial deposit in the amount of S which is for hours of Community Development staff time, and if actual recorded costs exceed the initial deposit, APPLICANT shall pay additional monthly billings to CITY to reimburse the CITY for the processing of the application mentioned above, including post approval review, Such periodic payments shall be made within 30 days of the billing date. APPLICANT further agrees that failure to pay such accrued costs shall be grounds for suspension of processing, and in no case will building permits be issued until all costs associated with case processing have been paid. CITY OF ASPEN APPLICANT &W17- By:. 1�ta� tc� ll>�•, - %119it/ Julie Ann Woods Commo ty ni Development Director Date: 2'% Ot7 e:\su ppo rt \forms \agrpayas. d oe 12/27/99 Mailing Address: �/o C1��ic 1�9�G,ynl 14 oNlon! S4'vi1 / J /kf&w yon, AlY 10,0. r-T Peter L. Gluck and Partners, Architects Transmittal 19 Union Square West New York, NY 10003 002 9, el ©BA13038 Re: ADU for 615 W. Francis Job Number: 9911 212.255.1876 Telephone 212.633.0144 Fax pgluck @inch.com E -mail To: Aspen Community Development Date: February 24, 2000 Fax Number: flo - s'31 Attn: Chris Bendon Number of sheets including transmittal: 4 We transmit herewith: ® Drawings ❑ Specifications ❑ Product Literature ❑ Other, specify: Chris, ❑ Samples ❑ Shop Drawings ❑ Change Order Via: ❑ Fax ❑ Mail ❑ Messenger ❑ Federal Express ❑ Express Mail For your: ❑ Approval ❑ Review & Comment ❑ Distribution ❑ Record ® Information & use Attached are the warranty deed, bill of sale and fee agreement.. Original copies are behind in the mail. Let me know if there are any other documents that you need. Charlie Kaplan Peter Gluck and Partners to: Sent bv: Jennifer Bloom G WARRANTY DEED THIS DEED, made this 08 day of SEPTEMBER 1999, between JOHN E. THORPE AND NANCY M. THORPE 1AQ, --'S7v OF THE COUNTY OF PITKIN, STATE. OF COLORADO GRANTOR, AND ASPEN GK, LLC. A COLOLORADO LRIHTED LIABILITY COMPANY GRANTEE whose legal address is PO BOX 640 ASPEN, CO 81612 O COUNTY OF PITKIN. STATE OF COLORADO Z WITNESSETH, That for and in consideration of the sum of ten dollars LLI d 4. and other good and valuable consideration, the receipt and sufficiency of F which is hereby acknowledged, the grantor has granted, bargained, sold and W conveyed, and by these presents does grant, bargain, sell and convey and confirm unto the grantee, his heirs and assigns forever, all the real uLC property together with improvements, if any, situate and lying and being in the County of PITKIN, State of COLORADO, described as follows: Q�LOTS E AND F, BLOCK 22, CITY AND TOWNSITE OF ASPEN. II1111" III11 1111IIII111111111111V111111V1111111IIII 438292 09/08/1999 12:04P WD DAVIS SILVI \ 1 of 2 R 10.00 D 129.50 N 0.00 PITKIN COUNTY CO 435292 TRANSFER DECLARATION RECEIVED 09/08/1999 z Z TOGETHER with all and singular the hereditaments and appurtenances thereto belonging, or in anywise appertaining, and the reversion and reversions, remainders, rents, issues and profits thereof, and all the Ot estate, right, title, interest, claim and demand whatsoever of the grantor Q either in law or equity, of, in and to the above bargained premises,. with _ the hereditaments and appurtenances. , L> C� � v TO HAVE AND TO HOLD the said premises above bargained and described, with the appurtenances, unto the grantee, his heirs and assigns forever. And the Grantor, for himself, his heirs and assigns, does covenant, grant, bargain, and agree to and with the Grantee, his heirs and assigns, that at the time of the ensealing and delivery of the presents, he is well seized of the premises above conveyed, has good, sure, perfect, absolute and indefeasible estate of inheritance, in law, in fee simple, and has good right, full power and lawful authority to grant, bargain, sell and convey the same in manner and form as aforesaid, and that the same are free C—' and clear from all former and other grants, bargains, sales, liens, taxes, V assessments, encumbrances and restrictions of whatever kind or nature soever, except those matters as set forth on Exhibit "A" attached hereto and incorporated herein by reference. The grantor shall and will WARRANT AND FOREVER DEFEND the above bargained premises in the quiet and peaceable possession of the grantee, his heirs and assigns, against all and every person or persons lawfully claiming the whole or any part thereof. The singular number shall include the Aural, the plural the singular, and the use of gender shall be applicable to all genders. C 4' A— } rl &p �L 1 1 Q" JO E. THORPE —V - -- NANCY M. THORPE STATE OF (���77k ` "6 ) COUNTY OF et. kt� ) ss. The foregoing instrument was acknowledged before me this 19016 , by JOHN E. THORPE AND NANCv M TWn( VC WITNESS my hand and official seal my commission expires: Charlotte D. lay/Notary Public My Commission evpi -s 6/23/2002 601 F.:p .c._ Avi,— . . day of i EXHIBIT "A" 1. Reservations and exceptions as set forth in the Deed from the City of Aspen recorded in Book 59 at Page 379 providing as follows: "That no title shall be hereby acquired to any mine of gold, silver, cinnabar or copper or to any valid mining claim or possession held under existing laws ". IIIIIII" III" III' INIIII 'IIIIIIIIIIIIIII"IIIIIIIIIII 435292 09/08/1999 12:04P WD DAVIS SILVI 2 of 2 R 10.00 D 129.50 N 0.00 PITKIN COUNTY CO B I L L O F S A L E KNOW ALL MEN BY THESE PRESENTS, That JOHN E. THORPE AND NANCY M. THORPE of the County of PITKIN, State of (Seller), for and in consideration of TEN DOLLARS AND OTHER GOOD AND VALUABLE CONSIDERATION to him in hand paid, at or before the ensealing or deliver of these presents by ASPEN GK, LLC. A CCLORADO LTMTM LIABILITY CCWANY of the County of PITKIN, State of the receipt of which is hereby acknowledged, has bargained and sold, and by these presents does grant and convey unto the said Buyer, his personal representatives successors and assigns, the following property, goods and chattels, to wit: AS -SET- FORTH- eN-- EXHI -B -IT-- AA A- TTAeHif - HER=(P l— located at 615 W. FRANCIS STREET, ASPEN, CO 81611 TO HAVE AND TO HOLD the same unto the said Buyer, his personal representatives, successors and assigns, forever. The said Seller covenants and agrees to and with the Buyer, his personal representatives and assigns to WARRANT AND DEFEND the sale of said property, goods and chattels, against all and every person or persons whomever. When used herein, the singular shall include the plural, the plural the singular, and the use of any gender shall be applicable to all genders. IN WITNESS HEREOF, the Seller has executed this BILL OF SALE this 08 day of SEPTEMBER, 1999. - 6L—, 2 - xl.P -b'1 /_ JOHN[ E. THORPE ��,� -, ��1�,(� -ems NANCY M. THOR E STATE OF l..(/ I bllra- " ss: COUNTY OF The foregoing instrument ,w,as acknowledg d before me this ,� /V day of, 19 K by Jb I Y �Of.Q.C,. ,�n c y M, -7-11, witness my hand and official seal. My Commission expires: SEAL Charlotte D. Lay /Notary puWic My Commission expires 6/2312002 601 East Hopkins Aspen, Colorado 81611 N Nlwe r, JEROME GAMBA & ASSOCIATES, INC. CONSUTING ENGINEERS k LAND SURVEYORS G� c, 118 Hint Hnffr, ears 214, PA BOX1488 O1BIWnOD BPPoNOB, COIAH/DO BIi02 -H8B PFIOH+1070)Y48 -2880 FAXN70)945 -1410 TRANSMITTAL Date: February 28, 2000 Time: 10:15 AM Project Name: 615 W. Francis Street Project Number. 00118 To: Building and Planning Department Company: City of Aspen Address: 130 S. Galena Aspen, CO 81611 Phone: 970 - 920 -5090 Fax: From: Robert W. Pennington, P.E. Re: Above Project, Drainage Mitigation Plan CC: We herewith transmit the following: 2 copies • Drawings ❑ Contract Documents ❑ Bid Documents ❑ Specifications • Product Literature ❑ Change Order x Other Foryour: x Approval ❑ Review & Comment ❑ Distribution to Parties ❑ Record x Information x Use e Comments: FEB 2 9 ?i i10 f oundAI- ;rJ/P ,,T,.,, 0 v y - :'mtn , JEROME GAMBA & ASSOCIATES, INC. CONSULTING ENGINEERS & LAND SURVEYORS 113 9TH STREET, SUITE 214 PO. BOX 1458 GLENWOOD SPRINGS, COLORADO 81602 -1458 PHONE: (970) 945 -2550 FAX: (970) 945 -1410 DRAINAGE MITIGATION PLAN For 615 W. Francis Street Aspen, Colorado 81611 Prepared for Peter L. Gluck and Partners, Architects 19 Union Square West New York, NY 10003 (212) 255 -1876 Prepared by Robert W. Pennington, P.E. Jerome Gamba & Associates, Inc. i i X11 • � � i 1 s 11,4 � ...� February 24, 2000 G: \00118 \DMP. doc Drainage Mitigation Plan -• 615 W. Francis Street February 24, 2000 _. INTRODUCTION -� This evaluation is concerned with the impacts that the offsite drainage basins and 100 -year storm for the proposed construction within the existing City of Aspen. A site visit was performed as part of this evaluation to verify the flow regimes and provide the necessary information to model the potential stormwater runoff. PROPERTY DESCRIPTION The project is located within the 600 block of W. Francis Street, three blocks north of Highway 82 between 5`h and 6`h Streets on the south side. The approximate Latitude and Longitude being 390 11' and 1060 50', respectively. The property has an existing house that is _ landscaped with tur grass, ornamental shrubs and trees and has an overland slope of approximately 2% from the alley to W. Francis Street. The project is surrounded by adjacent urbanization including paved streets and mature landscaping. r New construction in the immediate area includes a 24 -inch stormdrain above the property that will intercept offsite flows as they cross individual inlets. The remaining upstream flows collect along the West Side of 5`h Street within a valley pan and are captured by a storm drain inlet near the northwest corner of the intersection with W. Francis Street. Local storm flows w are conveyed in a shallow swale just off the edge of the pavement in front of the property. w Topography and Time - Intensity- Frequency Curves for the property were obtained from the Architect and the City of Aspen, Engineering Department, respectively, for use in this mitigation plan. The proposed improvements shall collect, detain and dispose the 100 -year storm event flows that exceed the historic rate generated from the increased impermeable surfaces resulting from development'. This evaluation is performed with the following general assumptions: 1. To use the Rational method, it is assumed that the maximum rate of flow from a certain rainfall intensity over the drainage area, is produced by that rainfall which is maintained for a time equal to the period of concentration of flow at the point under consideration. For small drainage basins with simple drainage patterns, the time of .. concentration approximates the lag time of the peak flow. City of Aspen, Interim Standards for Drainage Design and Erosion — Sediment Control Practices, 12/27/99. w w Page 2 of 9 JEROME GAMBA & ASSOCIATES. INC. CONSULTING ENGINEERS & LAND SURVEYORS Drainage Mitigation Plan 615 W. Francis Street February 24, 2000 METHODOLOGY The Rational method is an empirical solution that incorporates the use of several .. assumptions and coefficients to estimate the peak flow rates for given return periods. Since the drainage basins are small with simple drainage patterns, the use of the Rational Method is appropriate. The following sections outline the data and calculations used for estimating the peak rate of runoff utilizing the Rational method: Q; = CIA Where: Q; = Peak Discharge, cfs for the return period, i C = Runoff Coefficient I = Rainfall Intensity, inches /hour A = Drainage Area, acres EXISTING CONDITIONS Runoff Coefficient, "C The runoff coefficient is selected according to the drainage basin characteristics including the effects of infiltration, evaporation, retention, flow routing and interception, w. all which effect the time distribution and peak rate of runoff. Several references list commonly used coefficients for use in the Rational method and the calculation of a composite coefficient will produce results that are more accurate where applicable. For existing conditions, the coefficient ranges from 0.20 to 0.50 for lawns 2. Values for the runoff coefficient for existing residential areas range from 0.30 to 0.50 3. The existing condition composite runoff coefficient for use in this evaluation will be calculated as follows: p [Lawns (0.35) +Residential (0.40)] / Total Area z Urban Storm Drainage Criteria Manual, Volume 1, Table 3 -1 3 Chow, Handbook of Applied Hydrology, Table 14 -1 Page 3 of 9 JEROME GAMBA & ASSOCIATES. INC. CONSULTING ENGINEERS & LAND SURVEYORS r r •w Drainage Mitigation Plan 615 W. Francis Street February 24, 2000 or: C = [0.35(2,996) + 0.40(2,992)] / 5,988 C = 0.37 Rainfall Intensity, "I" The rainfall intensity is the average rainfall rate in inches per hour for the period of maximum rainfall of a given frequency having a duration equal to the time of concentration. The time of concentration, being the time required for surface runoff from the remotest part of the drainage basin to reach the calculation point and can be empirically estimated using the following formula: t� = t; + tt where: tc = time of concentration, minutes t, = initial or overland flow time, minutes tt = travel time, minutes. The initial time in non - urbanized areas is estimated using equation 3 -3 (ref 2), or: t; = 1.8(1.1- CS)(1_) Os / (S) 033 where: t; = initial or overland flow time, minutes L = the length of overland flow, feet C5 = the 5 -year frequency runoff coefficient (Table 3 -1, ref 2) S = the average basin slope, percent or: Page 4 of 9 t, = 1.8(1.1- 0.45) (147)05/(2.04)033 JEROME GAMBA & ASSOCIATES. INC. CONSULTING ENGINEERS & LAND SURVEYORS Drainage Mitigation Plan 615 W. Francis Street February 24, 2000 therefore: t; = 11.2 minutes .. Travel time is calculated utilizing the hydraulic characteristics of the swale, channel or cross section of the conveyance. Figure 3 -2 (ref 2) is used for this purpose and results in a velocity of 1.0 foot per second (Short grass pasture & lawns). And : t, = U60(V) = 147/60(1.0) = 2.5 minutes. The time of concentration, t. is: 11.2 + 2.5 = 13.7 minutes The procedure used to develop precipitation depths for durations of less than 1 hour are outlined within the NOAA Atlas. The calculations involve the use of statistical parameters to develop equations from regional precipitation patterns and the reported 6 -hr and 24 -hr depths. The resulting 2 -yr and 100 -yr one -hour precipitation values are plotted on a precipitation depth verses return period graph to determine the remaining return period precipitation depth values. The one -hour depths are converted to the various durations using coefficients and later converted to inches per hour. These calculations are summarized on a Time - Intensity- Frequency Curve ° located in the Appendix. For this evaluation, the 13.7- minute duration (equaling the time of concentration) intensity values will be used. Drainage Area, "A" The total drainage area for the project is 0.137 acres (5988/43560) and is shown on the Drainage Mitigation Plan located within the Appendix. Calculations Using the information developed in the previous sections, the peak rate of runoff for -� the 100 -year storm event, for existing conditions, is calculated as follows: Q; = CIA 0 ., or: Q ,00 = (0.37)(4.9)(0.137) = 0.248 cfs —• < Time- Intensity- Frequency Curves, Aspen, Colorado, Wright - McLaughlin Engineers, Denver, Colorado Page 5 of 9 JEROME GAMBA & ASSOCIATES, INC. CONSULTING ENGINEERS & LAND SURVEYORS r Drainage Mitigation Plan 615 W. Francis Street February 24, 2000 DEVELOPED CONDITIONS For developed conditions, the runoff coefficient C is modified to reflect the amount of impervious areas, landscaping and other features resulting from the various improvements constructed within the project area. The difference is excess runoff that must be mitigated onsite such that downstream facilities are not impacted adversely. The composite runoff coefficient, C for use in the Rational Formula for developed conditions is calculated as follows: Given: Roof area = 2,384 SF CS = 0.85, C,00 = 0.90 Driveway = 162 SF C5 = 0.87, C,. = 0.89 Landscaping = 3,442 SF C5 = 0.02, C,. = 0.25 C5 = [0.85(2,384) + 0.87(162) + 0.02(3,442)] / 5,988 Or; C5= 0.373 And; C,. _ [0.90(2,384) + 0.89(162) + 0.25(3,442)] / 5,988 Or; C,00 = 0.526 Time of concentration calculations for developed conditions are: t; = 1.8(1.1- 0.373) (50)"/(2.0)"' where; t; = 7.4 minutes From Figure 3 -2 (ref 2, Paved area), V = 2.8 fps And : t, = L/60(V) = 131/60(2.8) = 0.8 minutes. The time of concentration, t, is: t =t; +t, 7.4 + 0.8 = 8.2 minutes Minimum value typically used for the time of concentration is 10 minutes. Page 6 of 9 JEROME GAMBA & ASSOCIATES. INC. CONSULTING ENGINEERS & LAND SURVEYORS Drainage Mitigation Plan 615 W Francis Street February 24, 2000 Calculations Using the information developed in the previous sections, the peak rate of runoff for the 100 -year storm event, for developed conditions, is calculated as follows: Q; =CIA or: Q _ (0.526)(5.9)(0.137) = 0.425 cfs uWY ?Mi The increase in peak runoff associated with development of the project is : QD,, - Qas, = 0.425 - 0.248 = 0.177 cfs The volume of excess runoff that requires mitigation can be estimated using the 90- minute standard storm duration adopted by the City of Aspen Engineering Department - less the amount infiltrated during that same period by the drywell, or: VD = [90(60) x Co., - Qa,s,] - wetwell infiltration 5 ,.­ Where, VD= Runoff detention volume, cubic feet Therefore; Vu = [90(60) x .1771 - 90(1.7 cf /min) = 803 CF RESULTS Development of the site results in a 15% increase in impervious surface compared to the existing conditions and a 170% increase in runoff for the 100 -Year storm event. The minimum detention volume that must be withheld onsite is estimated to be 803 cubic feet or 6,006 gallons. Peak runoff leaving the site shall not exceed historical flows (0.248 cfs) once the minimum detention volume is captured. Said detention volume and peak flow shall be maintained by the use of a drywell, surface detention area and spillway structure set at elevation 7900.5 and .. shall utilize other improvements as shown on the Drainage Mitigation Plan. i USDA, Soil Survey of Aspen- Gypsum Area, Colorado, Table 15, Soil #107, Permeability = 6 -20 in /hr (used ,. (6 +20)/2 in /hr for study) or [13/12 ft /hr x 93.4 sf] /60 min /hr = 1.7 cf /min Page 7 of 9 is JEROME GAMBA & ASSOCIATES. INC. CONSULTING ENGINEERS & LAND SURVEYORS Drainage Mitigation Plan 615 W. Francis Street February 24, 2000 The drywell will capture and infiltrate lesser flows and volumes from the rooftop and foundation drains (including downspouts and floor drains). Offsite flows shall remain within the roadway section by constructing a shallow landscaping berm. Alley drainage patterns shall remain unaffected, particularly where the new driveway is to be constructed. .r RECOMMENDATIONS 1. A 2% positive drainage shall be constructed from the building foundation and away for a minimum of five feet, all around the proposed building; 2. A 4 -inch diameter perforated foundation drain shall be constructed as shown on the project drawings prepared by Peter L. Gluck and Partners Architects; 3. A 60 -inch diameter drywell shall be installed in which the foundation drains, roof downspouts and excess surface water runoff shall be collected and infiltrated. Infiltration rates and soils information used in this design are based upon previously constructed ` projects in the same general location. A site - specific report from a Geotechnical Engineer shall be obtained for the project. During construction, the actual soil conditions encountered may warrant changes in the size and configuration of the detention area and drywell; r 4. A drainage swale shall collect and convey the onsite runoff from the roof scuppers and landscaping to the detention area and drywell; 5. All new improvements shall maintain historic offsite flow patterns and channels; and 6. All disturbed areas created during construction, shall be protected by the installation of temporary erosion control improvements and immediately revegetated and landscaped as directed by the Architect /Engineer. 7. The drywell shall be checked and cleaned of silt and debris in the spring of each year. The drain fabric in the bottom of the drywell shall also be replaced each year. Page 8 of 9 JEROME GAMBA & ASSOCIATES, INC. CONSULTING ENGINEERS & LAND SURVEYORS Drainage Mitigation Plan 615 W. Francis Street February 24, 2000 Page 9 of 9 APPENDIX JEROME GAMBA & ASSOCIATES. INC. CONSULTING ENGINEERS & LAND SURVEYORS novel 09 0 Rmky M.bin ah� To Spring Gwe ftnlk Ski Carbondale 133 Park u 21 YM S—W—O I. ~AB=C Bonn I. 82 Maroon Rd A to M.. MiaT, A-7 A=�Aj:kM GLI� ......... H-5 7 Y4 3 Gen.* —H.2 ...... .... —4H-2 . ......... . . ... .. .. . d...__._......__._....._... &3 P! n . ........ ........ G-H-M ..... . ......... C» rd7 L2 14-1�7 E4 I .' Cmwemdta cll� upim M- M— White Hill A� 1ndYWb Q Tent alm % , lake - M,fk—Cl ........ —1-1-1-7 MuhsvR& .Ffi3 M'--iM ...... .... . .... 1�7 � 'id 5L . . ............... . .... -G-1-5 Momeh A ..................4x -5 �mj. Vj— �.--E2-3 M. �1 0. M. 0� Red Mououie R6.....__......6 54 RRdp %Rd .......... .. ..... ...... .... &5 CHRISTINE STATE WILDLIFE AREA Lake ;, n ElI ft VA Ad 82 MMESr DIRECT19 Aspe . d,.ed pnoott.pro P minder remnvnioi md., DRAINAGE CRITERIA MANUAL RUNOFF TABLE 3 -1 (42) RECOMMENDED-RUNOFF COEFFICIENTS AND PERCENT IMPERVIOUS LAND USE OR PERCENT FREQUENCY SURFACE CHARACTERISTICS IMPERVIOUS 2 5 10 100 Business: Commercial Areas 95 .87 .87 .88 .89 Neighborhood Areas 70 .60 .65 .70 .80 Residential: w. Single- Family * .40 45 .50 .60 .. Multi -Unit (detached) 50 .45 .50 .60 .70 Multi -Unit (attached) 70 .60 .65 .70 .80 -- 112 Acre Lot or Larger * .30 .35 .40 .60 Apartments 70 .65 .70 .70 .80 Industrial: Light Areas 80 .71 .72 .76 .82 Heavy Acres 90 .80 .80 .85 .90 Parks, Cemetaries: 7 .10 .18 .25 .45 Playgrounds: 13 .15 .20 .30 .50 W Schools: 50 .45 .50 .60 .70 Railroad Yard Areas 20 .20 .25 .35 .45 w Undeveloped Areas: - Historic Flow Analysis- 2 (See "Lawns ") Greenbelts, Agricultural Offsite Flow Analysis 45 .43 .47 .55 (when land use not defined) .65 Streets: W Paved 100 .87 .88 .90 .93 Gravel (Packed) 40 .40 .45 .50 .60 Drive and Walks: 96 .87 .87 88 89 Roofs: 90 .80 .85 .90 .90 Lawns, Sandy Soil 0 .00 .01 .05 .20 Lawns, Clayey Soil 0 .05 .15 .25 .50 a NOTE: These Rational Formula coefficients may not be valid for large basins. ✓ *See Figure 2 -1 for percent impervious. 11 -1 -90 "' URBAN DRAINAGE AND FLOOD CONTROL DISTRICT 14-8 RUNOFF I-w% Table 14 -1. Values of Runoff Coefficient C Type of drainage area Runoff coefficient, C Lawns: Sandy soil, flat, 2 % .............. 0.05 -0 Sandy soil, average, 2 -7 %........ 0.10 -0 Sandy soil, steep, 7 % ............ 0.15 -0 Heavy soil, flat, 2 % .............. 0.13 -0 Heavy soil, average, 2 -7 % ......... 0.18 -0 Heavy soil, steep, 7 %............ 0.25 -0 .10 15 20 17 22 35 Business: Downtown areas ................. 0.70 -0.95 Neighborhood areas .............. 0.50 -0.70 Residential: Single- family areas ............... 0.30 -0.50 Multi units, detached............ 0.40 -0.60 Multi units, attached............ 0.60 -0.75 Suburban ....................... 0.25 -0.40 Apartment dwelling areas......... 0.50 -0.70 Industrial: Light areas ..................... 0.50 -0.80 Heavy areas .................... 0.60 -0.90 Parks, cemeteries .................. 0.10 -0.25 Playgrounds ...................... 0.20 -0.35 Railroad yard areas ... ............ 0.20 -0.40 Unimproved areas ................. 0.10 -0.30 Streets: Asphaltic ....................... 0.70 -0.95 Concrete ....................... 0.80 -0.95 Brick .......................... 0.70 -0.85 Drives and walks .................. 0.75 -0.85 Roofs ............................ 0.75 -0.95 III. TIME DISTRIBUTION OF RUNOFF A. Hydrograph Analysis 1. Features of a Hydrograph. A graph showing stage, discharge, velocity, or other properties of water flow with respect to time is known as a hydrograph. When the stage is plotted against time, the graph is a stage -time graph or stage hydrograph, which is usually shown on the recorder chart from a recording -gage station (Subsec. 15- VIII -B). When the discharge is shown against time, the graph is a discharge hydrograph, or commonly called simply a "hydrograph." By use of the stage -dis- charge relation at a gaging station, the discharge hydrograph can be obtained by conversion from a given stage hydrograph (Subsec. 15 -XI). The hydrograph can be regarded as an integral expression of the physiographic and climatic characteristics that govern the relations between rainfall and runoff of a particular drainage basin. It shows the time distribution of runoff at the point of measurement, defining the complexities of the basin characteristics by a single empiri- cal curve. A typical hydrograph produced by a concentrated storm rainfall is a single - peaked skew distribution curve; multiple peaks may appear on a hydrograph indicating abrupt variation in rainfall intensity, a succession of storm rainfalls, abnormal groundwater recession, or other causes. In hydrograph analysis, multiple - peaked complex hydrographs may be separated into a number of single - peaked hydro - graphs by methods to be discussed later. A typical single - peaked simple hydrograph (Fig. 14 -1) consists of three parts: the approach segment (limb or curve) AB, the rising (or concentration) segment (limb or I H Z � } 1= R 3 2 im �n, r r s r 2 IV -3 o [7 r . I :: . i 9 elf 100 Y i 5 Year 2 Y*ar • C IL,7 20 30 40 50 60 TIME IN MINUTES TIME- INTENSITY - FREQUENCY CURVES ASPEN, COLORADO. TAOS., R.85W. WRIGHT- McLAUOMLIN SNOINEERS 0420 ALCOTT ST. OENVER, COLO. 60219 .w w .e DRAINAGE CRITERIA, MANUAL RUNOFF 3( �- 2( Z W U W CL 1C 2 W CL O 5 rn W ¢ 3 O U 2 W H 3 1 5 .1 2 .3 .5 1 2 3 5 10 20 VELOCITY IN FEET PER SECOND FIGURE 3 -2. ESTIMATE OF AVERAGE FLOW VELOCITY FOR USE WITH THE RATIONAL FORMULA. *MOST FREQUENTLY OCCURRING "UNDEVELOPED" LAND SURFACES IN THE DENVER REGION. REFERENCE: "Urban Hydrology For Small Watersheds" Technical Release No. 55, USDA, SCS Jan. 1975. 5-1-84 URBAN DRAINAGE & FLOOD CONTROL DISTRICT MEEEIINn A=010151Iffm """""`=1=1 WAWA RAM ,�■ I . I ' ��■ MEIN �nnn I � ■ ■ ■ ■ ■ ■� ■�_� inn �n�Inr1 ■I,�� / / /nnn� n� ■� ��inr�n�■ ►inr/��nnn�■■■■nn 2 .3 .5 1 2 3 5 10 20 VELOCITY IN FEET PER SECOND FIGURE 3 -2. ESTIMATE OF AVERAGE FLOW VELOCITY FOR USE WITH THE RATIONAL FORMULA. *MOST FREQUENTLY OCCURRING "UNDEVELOPED" LAND SURFACES IN THE DENVER REGION. REFERENCE: "Urban Hydrology For Small Watersheds" Technical Release No. 55, USDA, SCS Jan. 1975. 5-1-84 URBAN DRAINAGE & FLOOD CONTROL DISTRICT