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HomeMy WebLinkAboutFile Documents.309 Oak Ln.0021-2022-BRES (29) October 26, 2022 City of Aspen Engineering Department City Hall 130 S. Galena Aspen, CO 81601 RE: 309 Oak Lane Drainage Report JVA Job No. 3529c Dear Engineering Staff: The following Drainage Report and attached drainage maps have been prepared for the residence at 309 Oak Lane in Aspen, Colorado. The drainage report and drainage map have been produced in accordance with the City of Aspen's "Urban Runoff Management Plan" and comply with provisions thereof. It is our understanding that the information provided herein meets all requirements of the City of Aspen's Grading and Drainage Requirements for Major Grading and Drainage Design. Please contact us if you have any questions regarding this submission. Sincerely, ��\\0\\\ IIIIvo RIIEG j F. •' 41789 _ THECn oFAsrm ° ' __— To obtain sign off from the Engineering Department on the •�'� Certificate of Occupancy(CO)the following requirements must be met. ..... .'■..� q \\ Minor Drainage Reviews //4/011111 6/2022 •All Areas must be landscaped or stabilized per the approved plan. J.R S Uri , P.E. All drainage features must be installed per the approved plans including swales. p g 'All temporary erosion control devices must be removed. Senior Project Manager Major Drainage Reviews: All Minor(see above)review criteria must be met. Submit an as-built survey of all drainage features on the property. Reviewed by Engineering 'Submit a Grading and Drainage Certificate signed by the Engineer of Record. 12/14/2022 Submit a video(in DVD format)of any connections made to the City's infrastructure that shows that the connection is clean and in good working condition. "It should be known that this review shall not 'Submit an Operations and Maintenance Plan Agreement signed by the Owner. relieve the applicant of their responsibility to Right of Way improvements including sidewalk,curb and gutter,and other comply with the requirements of the City of appurtenances must be complete. Aspen. The review and approval by the City is offered only to assist the applicant's After all required documents have been submitted,a final inspection from understanding of the applicable Engineering the Engineering Department can be requested at 920-5080. requirements." The issuance of a permit based NOTE:These are only the requirements of the Engineering Department. on construction documents and other data shall Other departments may have additional requirements for obtaining a CO. not prevent the City of Aspen from requiring the correction of errors in the construction documents and other data. RECEIVEID 309 Oak Lane—Drainage Report 11/01/2 0 2 2 ASPEN BUILDING DEPARTMENT TABLE OF CONTENTS SECTION 1 -INTRODUCTION 1 GENERAL LOCATION AND DESCRIPTION 1 PROPOSED PROJECT 1 SECTION 2- HISTORIC DRAINAGE 2 MAJOR DRAINAGE BASIN DESCRIPTION 2 SITE DRAINAGE AND EXISTING FACILITIES 2 SECTION 3- PROPOSED (DEVELOPED) DRAINAGE 3 DRAINAGE DESIGN CRITERIA 3 HYDROLOGIC METHOD AND DESIGN STORM FREQUENCIES 3 PROPOSED SITE BASINS 3 RUNOFF AND STORM WATER QUALITY ENHANCEMENT/DETENTION FACILITIES 4 MAINTENANCE 4 SECTION 4-CONCLUSIONS 6 SECTION 5- REFERENCES 7 APPENDIX A-SITE MAPS SITE VICINITY MAP WEB SOIL SURVEY- HYDRAULIC SOIL GROUP GEOTECH REPORT FEMA FIRMETTE FIGURE 1 - HISTORIC DRAINAGE MAP FIGURE 2- DEVELOPED DRAINAGE MAP APPENDIX B- HYDRAULIC CALCULATIONS RECEIVED 309 Oak Lane—Drainage Report 11/01/2 0 2 2 ii ASPEN BUILDING DEPARTMENT SECTION 1 - INTRODUCTION GENERAL LOCATION AND DESCRIPTION The property owner for 309 Oak Lane proposes to construct a new residence at the subject property in the City of Aspen. The 0.09-acre site is located in Section 7, Township 10 South, Range 84 West of the 6th Principal Meridian,City of Aspen,County of Pitkin,State of Colorado.The existing mobile home, carport, gravel parking area, utilities, and landscaping will be demolished. The demolished features will be replaced by a new single-family home with a patio, a parking area, utilities, and landscaping. The primary purpose of this drainage report is to address the proposed runoff information and to address water quality enhancement facilities at the proposed development. Reference is made to the attached"Figure 2—Proposed Drainage Map." PROPOSED PROJECT The proposed project will consist of constructing a new single-family residence with a patio, parking area, storm drainage, drywell, sanitary utilities, and surrounding landscaping. Access to the site will be provided by the parking area on the south side of the property along Oak Lane. RECEIVED 309 Oak Lane—Drainage Report 11/01/2 0 2 2 1 ASPEN BUILDING DEPARTMENT SECTION 2 - HISTORIC DRAINAGE MAJOR DRAINAGE BASIN DESCRIPTION The site is located in the greater Roaring Fork River Basin and is within the boundaries of the Smuggler/Hunter Drainage Basin as delineated in the City of Aspen Master Drainage Plan. According to the FEMA Flood Insurance Rate Map Panel Number 08097 C0358 E, dated August 15, 2019, the site is located in Zone X which is designated as being outside of the 100-year floodplain area. A copy of the referenced flood map is included in Appendix A. SITE DRAINAGE AND EXISTING FACILITIES The existing site is a 0.09-acre lot with a mobile home, carport, and gravel driveway. The site is bound by Oak Lane to the south, Ajax Avenue to the west and existing developed residential lots to the north and east. The site is accessed by the gravel driveway from Oak Lane. The existing site slopes from north to south-southwest, discharging runoff to the Oak Lane right- of-way. Storm drainage systems are not present on the existing site,but existing storm water inlets are nearby on Ajax Avenue,Oak Lane, and Cottonwood Lane.According to the National Resource Conservation Service (NRCS) Web Soil Survey (see Appendix A), the site consists primarily of type C soils. The map unit name is listed as Uracca which is a moist-Mergel complex with 6 to 12 percent slopes. Natural hazard areas with risk of snow slide, avalanche, mudslide, or rockslide do not exist in the vicinity of the proposed site. The proposed site is north of the downtown core of the City of Aspen and outside the Aspen Mountain and Smuggler mud flow zones. As shown on the attached"Figure 1 —Historic Drainage Map",the site was analyzed to determine the historical runoff routing. Hydraulic calculations for the single historic basin are reference in Appendix B. Drainage Basin H includes the entire 309 Oak Lane parcel as well parts of the property to the east and the land between the parcel and Ajax Avenue. The overall 0.09-acre basin is characterized as 44.8 percent impervious with a maximum calculated time of concentration of 8.1 minutes. The peak runoff rate from the historic site for the 10-year storm event (Q10) is estimated to be 0.12 cfs. The peak runoff rate from the 100-year storm event (Q100) is estimated to be 0.29 cfs. The historic basin ultimately discharges to the Oak Lane right of way. RECEIVED 309 Oak Lane—Drainage Report 11/01/2 0 2 2 2 ASPEN BUILDING DEPARTMENT SECTION 3 - PROPOSED (DEVELOPED) DRAINAGE DRAINAGE DESIGN CRITERIA The proposed private storm drainage facilities for the project are designed to comply with the City of Aspen"Urban Runoff Management Plan—A Guide to Storm water Management in the City of Aspen"Revised November 2014 Edition (URMP). HYDROLOGIC METHOD AND DESIGN STORM FREQUENCIES The site is located north of the Aspen commercial core/downtown sub-urban area and does not drain directly to the storm water system delineated in Figure 1.1 in the URMP. A concrete pan along Oak Lane appears to convey runoff from 309 Oak Lane and adjacent residences to Cottonwood Lane. An inlet along the west curb line of Cottonwood Lane approximately 40 feet from the Oak Lane intersection ultimately captures this runoff. The storm system conveys runoff from this basin to the Roaring Fork River which is approximately 1,400 feet south of the inlet. Runoff from the existing site does not have any known impacts to neighboring properties. Additionally,the proposed improvements associated with this project only increase the impervious cover of the site by approximately 6.7% (44.8% to 51.5%). Due to the site being within the Smuggler/Hunters Drainage Basin, the water quality capture volume and detention for the major and minor storm is required. Calculations for the detention volume were completed utilizing the formula outlined in section 8.5.4.2 — Drywells in the URMP. Calculations for the Water Quality Capture Volume were completed utilizing the Rational Method in accordance with Section 8 of the URMP. The runoff coefficients for various land uses were derived using Figure 3.4 in the URMP. Reference calculations are included in Appendix B of this report. PROPOSED SITE BASINS As shown on the attached "Figure 2 — Proposed Drainage Map", the entire site was analyzed to determine the proposed runoff routing from the redeveloped site area. The proposed site was divided into two subbasin with no significant offsite drainage entering the site as in historic conditions. Drainage Basin A consists of the roofed, paved, and landscaped areas that convey water to the proposed drywell. The 0.047-acre subbasin is characterized as 51.8 percent impervious with a maximum calculated time of concentration of 8 minutes. The peak runoff rate from the proposed site for the 10-year storm event (Q10) is estimated to be 0.07cfs. The peak runoff rate from the 100-year storm event (Q100) is estimated to be 0.16cfs. The runoff from Drainage Basin A will discharge into a proposed drywell at Design Point 1. Drainage Basin B consists of a portion of the roof, gravel parking area, concrete apron, and landscaping around the proposed residence. The 0.043-acre subbasin is characterized as 51.2 percent impervious with a maximum calculated time of concentration of 6.6 minutes. The peak runoff rate from the proposed site for the 10-year storm event (Q 10) is estimated to be RECEIVED 309 Oak Lane—Drainage Report 11/01/2 0 2 2 3 ASPEN BUILDING DEPARTMENT The peak runoff rate from the 100-year storm event(Q100) is estimated to be 0.15 cfs. The runoff from Drainage Basin B will discharge into the Oak Lane right of way from the south side of the site at Design Point 2. The concrete pan on the south side of Oak Lane will carry the runoff to Cottonwood Lane where it will be intercepted by existing storm water infrastructure. RUNOFF AND STORM WATER QUALITY ENHANCEMENT The site is located in the greater Roaring Fork River Basin. The site is bounded by Hunters Creek to the north, the Roaring Fork River to the west and the top of Smuggler Mountain to the east therefore within the boundaries of Smuggler/Hunter Drainage Basin as outlined in the URMP.Due to the site being within the Smuggler/Hunters Drainage Basin, the water quality capture volume and the detention for the major and minor storm is required. Detention and water quality enhancements are sized for the entire site while the design intent, due to the site size and grade constraints,is to only capture runoff from Drainage Basin A. Runoff from Design Point B will sheet flow into the Oak Lane right-of-way matching historic conditions while reducing runoff from 0.29cfs to 0.15cfs for the 100-yr event. A reduction of 0.14cfs being released undetained. A connection to City infrastructure is not proposed at this time due to proximity and the lack of information related to the existing City storm system. Calculations for the required detention volume were completed utilizing the formula listed below per the URMP section 8.5.4.2—Drywells Design Storm Runoff Volume = P11oo * Total Impervious Area Tributary to Drywell VDyt, = 1.23" * 4,023 f t2 VDW = 412.4ft3 Calculations for the Water Quality Capture Volume were completed utilizing the Rational Method in accordance with Section 8 of the URMP. The calculated water quality capture volume for the site is 33.5-cuft while the target design water quality capture volume is 50.30-cuft. The target design capture volume accounts for the required clogging factor of 1.5. The drywell has been sized to capture and detain both the WQCV and the detention volume as required. The calculated detention volume and target WQCV is 462.69-cuft and the drywell has been sized with an available volume of 476.80-cuft. A drain down time of 2-hrs is expected based on the percolation rate of 60-ft per day referenced from the Subsoil Study report prepared by Kumar and Associates, Inc. dated November 30, 2021. An overflow path has been provided in the event of clogging and runoff will match historic conditions flowing into the Oak Lane right-of- way. Calculation supporting the basin imperviousness, WQCV and detention volumes are provided in Appendix B of this report. RECEIVED 309 Oak Lane—Drainage Report 11/01/2 0 2 2 4 ASPEN BUILDING DEPARTMENT MAINTENANCE The homeowner will maintain the WQCV drywell per the following requirements: Required Maintenance Objective Frequency of Action Action Inspection Monitor water level and accumulation Annually and following all rainfall of sediments in wells. events>0.25 inches. Dispose of sediment, debris/trash, and Sediment/ any other waste material removed Once per year or when needed to debris from a drywell at suitable disposal promote drainage. removal sites and in compliance with local, state, and federal waste regulations. Routinely evaluate the drain-down time of the drywell to ensure the maximum time of 24 hours is not being exceeded. If drain-down times are exceeding the maximum, drain the drywell via pumping and clean out the Evaluation percolation area (the percolation barrel Routinely following rain events. may be jetted to remove sediment accumulated in perforations). Consider drilling additional perforations in the barrel. If slow drainage persists, the system may need to be replaced. The homeowner will keep records of all maintenance performed including action(s) taken and dates. RECEIVED 309 Oak Lane—Drainage Report 11/01/2 0 2 2 5 ASPEN BUILDING DEPARTMENT SECTION 4 - CONCLUSIONS With the proposed development,the impervious area of the site will increase from 44.8%to 51.5%. To provide treatment for the water quality capture volume (WQCV) and detention for the minor and major storm events,a drywell is proposed.Detention and water quality enhancements are sized for the entire site while the design intent, due to the site size and grade constraints, is to only capture and treat runoff from Drainage Basin A. Runoff from Design Point B will sheet flow into the Oak Lane right-of-way matching historic conditions while reducing runoff from 0.29cfs to 0.15cfs for the 100-yr event. A reduction of 0.14cfs in flows being released undetained. The recommendations of this report are in conformance with all applicable storm drainage regulations. Calculations, a vicinity map, and other reference materials used are attached in the Appendices. RECEIVED 309 Oak Lane—Drainage Report 11/01/2 0 2 2 6 ASPEN BUILDING DEPARTMENT SECTION 5 - REFERENCES 1. "Urban Runoff Management Plan — A Guide to Storm water Management in the City of Aspen", City of Aspen, Revised December 2014 Edition 2. "Urban Storm Drainage Criteria Manual," Urban Drainage and Flood Control District, Revised Edition 2008. RECEIVED 309 Oak Lane—Drainage Report 11/01/2 0 2 2 7 ASPEN BUILDING DEPARTMENT APPENDIX A - SITE MAPS RECEIVED 11/01/2022 ASPEN BUILDING DEPARTMENT Appendix A k'i, .'s':'-1'1''7a, jt-.-,7-, z\ \`, .\• ru PROJEC77T SITE -w ' rRGP!rk -' #1111.% ' EF`ocis Sr ,\• ••• i �� r VJ II 1 1 1ae 411144;i1 sr r '✓ r 4 -j 7 r� R X 4F ` e ` ��� r,, Fork Rrter SILL, .. � r N t J Newbury Par,J —7 « ai E 'rrersr a �� v pn9�e5�0 ~R-AYesjglif j,K,� '-..ndcz.. to.tom . 'A �1 + i` . Matcrw b,.,:s.,.1: /:. }' NZ rr y4, v �,�, �� rr j 1 j ! _ ' /Nerrondark f i - i- • I�' �F �y1 Irk ebto,pie 1x X Jr :I.A 70i in Ce Arapaho National Forest 1 Georgetown /, Gyps m Fagle k on /f it Silvertjhorne a G nno s Frisco Sp �Pri nk;s ��II(� White River National horeet Breckenridge Carbondale Basalt PROJECT SITE 'eadrille Fairplay As en Hunter Fryingpan Wilderness Crested Butte Buena Vista VICINITY MAP � 'VA I ,III\-; I r:\ Gle l t E D 309 OAK LANE `J`" III 970.404.3100 www.jvajva.com DECEMBER 2021 CONSULTING ENGINEERS BouldeGlenwood Springs•Denver G:\3529c — 309 Oak Lane\Drawings\3529c-05—HDP-00(FIG 1).dwg, 12/07/2021 — 12:07 PM, MG AS P E A 1 4 BUILDING DEPARTMENT Appendix A City of Aspen Urban Runoff Management Plan - Roads \kSit HSG `' OB C \ - D Harmony PI11111 d SITE LOCATION ill Stage Rd SZ A . - ,.:, __......44416„ _ ,.. " \Ur' ` ��r Spruce St a_=i�1 -:AT a`4rsS` G Maroon Creek Rd �� --a OSo 1 ``as aaa a_ asa a 0,- ` / lift ,=�~ = j ' r �aTa,�a a� a ter~ 2 �� - > ` Ave ir 0 awir6r.'n1,1ive < /4: Qii ` . 0 1Ciate l ,. 7°. • Figure 3.1 Natural Resource Conservation Service (NRCS) Soil Map for Aspen RECEIVED Chapter 3- Runoff 3-2 Rev 2/2010 11/01/2 0 2 2 ASPEN BUILDING DEPARTMENT Appendix A National Flood Hazard Layer FIRMette $ FEMA Legend 106°49'W 39°11'47"N SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT 11 �DWAY;� " ,, _ Without Base Flood Elevation(BFE) l tto e AE , 'tom Zone A.V.A99 r0 • 11111k With BFE or Depth zone AE.AO,AH,YE,AR r� 1� SPECIAL FLOOD N. • HAZARD AREAS Regulatory Floodway Zone A , \ --- — • IA • • w i ,, ` • ;� _ a 0.2%Annual Chance Flood Hazard,Areas •d • - •�• v _ r' of 1%annual chance flood with average ♦♦ = • '� depth less than one foot or with drainage i ` , � 11 • areas of less than one square mile zone x P. `S , ,. , Future Conditions 1%Annual ��kr - 7• + �-�;14 Chance Flood Hazard Zeeex • ,,. 40 + � Area with Reduced Flood Risk due to • ,, , •. Levee.See Notes.zone x • t OTHER AREAS OF V 1 air . . • ;°:V:*SfAjp..., ,. 1 ♦ V Y • • FLOOD HAZARD �� Area with Flood Risk due to Leveezone D 7 0111111 lb • �v r NO SCREEN Area of Minimal Flood Hazard zonex . 1 !eh.' . • l••.• ' - Pk • •'i 4 'w l � 0 Effective LOMR5 • ♦♦♦ OTHER AREAS Area of Undetermined Flood Hazard zone o iiiii .14` T"7♦r OF ASPEN t• ' ,I GENERAL ---- Channel,Culvert,or Storm Sewer • 13 • STRUCTURES I I I I I I I Levee,Dike,or Floodwall �c�' Si • t " ,. PIT&IN •o 0 1, ' O20.2 Cross Sections with 1%Annual Chance AECb - • U8U?8T'• �T•s Water Surface Elevation 1 REA OF MINIMALLOOD HAZARD 8_ _ _ Coastal Transect i.T10S R84W r r,, I Zone X ` tit ^-- Base Flood Elevation Line(BFE) ZOn� " ,� - -• II • Limit of Study ,O Q0�'r+� Boundary E ",, 4, 1� v 8FE 03 4'+4i1r ♦ .t # • FLe)ODWP 6 •, / .,,,i'._ 1$r0 ♦ --- Coastal Jurisdiction Baseline Zone AE { ir, ‘• OTHER 08097C0354E �• Profile Baseline 08097C0358E 7867 FEEFEATURES Hydrographic Feature r' 1 eff."8/15/2019 r -' • , I •e • '• eff.8/15/2019 ,•\ �(0. ---viu '� •0 •• : 110101g. _ Digital Data Available N 1 Zone 4 } • No Digital Data Available ��GU!1%ir 1 4^�J .� � / •. 'Ir � MAP PANELS Unmapped l' • - 441:NI' k:,..:Allih,.. ... ..,'- , - %it o !te• •. 4iiir •a " The pin displayed on the map is an approximate 14N‘• ^� �r(1 fjLlt♦j•Y ♦ Y •_ point selected by the user and does not represent 151, ( j84 cEE - an authoritative property location. 41, . di- 1 �!� / � � This map complies with FEMA's standards for the use of 19•q F� / digital flood maps if it is not void as described below. 00. • �� ,,AV:„ - The basemap shown complies with FEMA's basemap FLOODWL 78 ♦ - 1, accuracy standards Zr-- -FEt i7 47- : k ! The flood hazard information is derived directly from the _' 92 ��'t _ ; t ` w'• 'jJ S r authoritative NFHL web services provided by FEMA.This map - iarbili r -,• was exported on 12/7/2021 at 1:36 PM and does not 44$ i ZOrAl E ,`�•• v ••. reflect changes or amendments subsequent to this date and !(�vF�• jC r ►' - •1►. time.The NFHL and effective information may change or - (03. '1 ' /� i —.r• i • become superseded by new data over time. • 4' . rA" ° ry CUB Zonf E N ,k . r •�,• p . _ . 1 1 R4F 4-.)ODVIY e w •* • •low . This map image is void if the one or more of t �Ig Th I\1E D rq�••1 •^ lL W _ • elements do not appear:basemap imagery, one bRl Of'OP'QE�I •- �'~ • !, _'�•' legend,scale bar,map creation date,community identifiers, ►, _ SjTiLY'T:�!ST,1)L.'iLT:� ^ Z(Ine'._ �: nb'aE .!� FIRM panel number,and FIRM effective date.Map images for Feet 1:6,000 106°48'22"W 39°11'19"N unmapped and unmodernized areas cannot be ufedfor/ / 0 1/2 0 2 2 0 250 500 1,000 1,500 2,000 regulatory purposes. 11 Basemap:USGS National Map:Orthoimagery:Data refreshed October,2020 ASPEN BUILDING DEPARTMENT / // 04) / / / III1rr1 tIil 0'�°� �� JrimCONSULTING ENGINEERS 's �.eweo sa, ,��l9 / / \ WµR70.606.3100e.,15uit; V� / / / awlaer.Foa,COlfinaN.Winter Paa< 29 / / Glenwood sa�mNe.Denver LQ / / 9� . m SS 55 SS SS SS 55 ss /� ss ss ss `\__ss ss ss / ss ss ss ss /� s / \ / Z �Q� \-,, _\ 79 O 79 9,, • n A� n n / 3cff, 3n�3n�3n�3n 3, // AJAX AVE , g ,� > >�S 2 I i / GCS G--- �/G-------G // \ o0 00 �\ / v ��/A O C� �� RR TIE WALL o 00 / F �� E \ / , r "V./ II 1-•—'i 1 \\ 2 I \ I Elb :V ` ce II/ : /\\ \7 —/- _��. S 3�°534" W/ 78.59_- �\ �� 'It I \ / t- —.9AS�-- E 1 cLP N 23�33 1� w o I , I � . 1 11 �56� 1 �� I _ C3-o � �; so I 1 I © \\ /� I < I I 1 I 'QUI ,I �` D 1 �M I i I / 1 I w D 1 d o m c� W ())/)rrn i A `0 1 0 m cn I�.I i I ? / ■0 I — Mz(n I S i " I \O T I z R. / - I 0— I �j-Y I .• I I : I v\ • I I I �( �� o-� DAD / z I Igl I L.,' DESIGNEDDRAWN BYBY: DAD I j A I I 1 I ` CHECKED BY: JLS JOB#: 3529c i i I �s5" DATE: 01/07/2022 / \ / I I `,.Xr' I ©JVA,INC. ,vim 1 1 I ——— - Ns WI I �,'o: I o-- � •��� NB"— 3°50t45" 7 �II ♦so0 1111 111161:moo DRAINAGE MAP LEGEND 4. 0 1 _ x `_ �_ EXISTING INDEX CONTOUR w a LLJ I I Q s�2� 0 _ EXISTING INTERMEDIATE CONTOUR QEt Q 33, "9,0 Q� ��?� PROPOSED INDEX CONTOUR J O Q 1 PI i / \?X,--__i PROPOSED INTERMEDIATE CONTOUR < O Q • 3.3 EXISTING SPOT ELEVATION 0 yQ �\ W p Z U Qy I-—' +03.54 PROPOSED SPOT ELEVATION p W I O ZFI 0 •m m m m• HISTORIC DRAINAGE BASIN BOUNDARY(MAJOR BASIN) Q 0 I 9 — — HISTORIC DRAINAGE BASIN BOUNDARY(SUB BASIN) (/) D •m m=m• DEVELOPED DRAINAGE BASIN BOUNDARY(MAJOR BASIN) I i-n 0 v -————- DEVELOPED DRAINAGE BASIN BOUNDARY(SUB BASIN) ,� _I> DIRECTION OF FLOW ��/i I �s. I DIRECTION OF FLOW(DEVELOPED) I .p'0 "9� .L BASIN DESIGN POINT F\Q,�-/ a DRAINAGE BASIN IDENTIFICATION BUBBLE — SHEET NO. �— -7 �� 50 DE OLOYPRE RUNOFF CCOEFFICIENT , F I CEf,' IVED 1.0=AREA ACRES SCALE IN FEET F —a._ ; 11/01/2C22 ASPEN BUILDING DEPARTMENT 4s\ J1JCl �'�Q\ I CONSULTING ENGINEERS �s / e»Lnln,atlea.a.,paRGG.,^. / / ,§C \ Glenwa°tlW,5 970.006.3100 �� / / .IVGIVG.COT BpulEer•FM Colfna.Winter PaM 2 Glenwootl Springs.Denver -V §o . m ss 55 ss s5 55 ss s ss ss s SS SS SS sin 6_ss ss ss ss / ss ss ss ss ss, I s// / 4, ti6 m // 1/ \ ��� ,.. 79 \\\\ .,,,‘ 7gs, 7g / n a-- 3n 3 4) o o ` � 3�� / AJAX AVE v 3 s � — . 3 / / a C/ WATER am � 9 F, 7 QUALITY / L / 0-�5 / DRY WELL / / / m c�G //,� I G c c c c c c G C �G _ _ 000 0 I v� / J-'• j z C \ I - RR TIE WALL / F ,70 a / 7� ,� , - I 45 ; , t9. o J �, A ' i 44 I _ ,/I I " O CP I 43 \ I i i/ # ; / ; , • 42 / , a ; ; ce '1 S 37—°5�'34 78.59 I -\ A 23.33' E rn 1 /�\ _ I .� _ ..._E...._f...._E. —E}..._E...— —E..._E..._E..._E..._E..._E.._E..._E...1 E... .�F... -_ s N o0 0 � ,... <I X�X 567.90 E 1 i , .''0 SD,.� Ss—�sp_ �1s _ �X� ff� F., ♦• o 1 , I Dn 1 I ` ♦ i �i �4 T._, m Ln m '�I I 0 I 0 1 p ♦� i i 4� I % o \ 2 cun) t-1 I t 1 , - ' t , m t , 1 _— ,,, -,-, 7 -,c 1 \--r, I 1 - r 0 d 1 i `I FF309 0OAK0' - ���� 1j DESIGNED BY: DAD DRAWN BY: DAD W, A r- W I I awi 1 GL CHECKED BY: JLS I I i JOB#: 3529c L__\---1 I ■ Ix DATE: 01/07/2022 ■ �y• ©JVA,INC. 1 I C T ■ Ix •:-- I I 0 _ 43 � 4� -421•>t���� �� �M-f���M'f� 0 0_ sl �'I DRAINAGE MAP LEGEND 0 IN 110-4---; I xS?2p EXISTING INDEX CONTOUR w ❑ 11 52� EXISTING INTERMEDIATE CONTOUR Z Et Z ��2p�I PROPOSED INDEX CONTOUR 1 ��,,,. PROPOSED INTERMEDIATE CONTOUR Q 0 Q 'G�. 0� 03 3 EXISTING SPOT ELEVATION 0 I ❑ 1 y0I. 0 0 CP r as +03.54 PROPOSED SPOT ELEVATION �O W W - 1 ? IZ 0 =m• HISTORIC DRAINAGE BASIN BOUNDARY(MAJOR BASIN) Q 0 1 I -9 - HISTORIC DRAINAGE BASIN BOUNDARY(SUB BASIN) O Oa 1- O m m m m m• DEVELOPED DRAINAGE BASIN BOUNDARY(MAJOR BASIN) d 1 m 0 v -����- DEVELOPED DRAINAGE BASIN BOUNDARY(SUB BASIN) V 1 /� 1 DIRECTION OF FLOW(HISTORIC) \�1 .0 * I DIRECTION OF FLOW(DEVELOPED) I �%�� 1 Q BASIN DESIGN POINT 1 <0 0+ -p I DRAINAGE BASIN IDENTIFICATION BUBBLE rSH,E.ETT NO. `� F�j�-9 l a 50 DEVELOPED RUNOFF CCOEIFFICIENT 0ON 5 r I!1SEgI VG® al O ,\ ®® 0=AREA ACRES SCALE IN FEET 1 V° T _ 11/01/2Q2 ASPEN BUILDING DEPARTMENT APPENDIX B - HYDRAULIC CALCULATIONS RECEIVED 11/01/2022 ASPEN BUILDING DEPARTMENT JVA Incorporated JVA Office: E_ 81ZO717 Colorado Ave,Ste 301 Glenwood Springs Glenwood Springs,CO 81601 Ph:(970)404 3100 CONSULTING ENGINEERS Version 2016 XT: 5/25/2016 Project Information: Job Name: 309 Oak Lan Job Number: 3529c Date: 10/26/2022 Designed by: I DAD Municipality: I Aspen Soil Type: Runoff Calculations: 7937.7 Minor Design Storm: 1.10 year Major Design Storm: 100 year Detention Calculations: Detention Volume by: EURV(UDFCD) WQCV: cf Rainfall Data Information: Enter City,Town,or County: Aspen Frequency of Design One Hour Point Rainfall P1 Do you need to Calc P1? Event 2 yr 0.47 in 5 yr 0.64 in 10 yr 0.77 in 100 yr 1.23 in Runoff Coefficient Calculations: Use UDFCD Equations? Yes Intensity Duration Values: I-D-F AspenlDF Drainage Report Calculations Checklist: Reference Spreadsheet: X Historic Rational Rational Calculations Historic Flows Rational Calculations Developed Rational Rational Calculations Developed Flows(Minor and Major Events) Rational Calculations Drainage Developed&Historic Maps CAD Figures Water Quality Vol Calcs Rational Calculations Inlet Calcs Rational Calculations or Criteria Vol 1&2-UD-Inlet v3.01 Include Vicinity Map and IDF Curve Charts Report-Bina Maps Firm Map Report-FEMA Map Service Center Hydrologic Soil Map w/Soil Description&Type) Report-Web Soil Survey RECEIVED 11/01/2022 3529c-Rational Calculations-309 Oak Ln-Rd.2 Comments INTRO ASPEN BUILDING DEPARTMENT C� JVA Incorporated Job Name: 309 Oak Lane J _ •' Ph1 7(970)404r310000 Colorado Ave,Ste 801601 Job Nu er: 3529c Dat /22 By: DAD CONSULTING ENGINEERS 309 Oak Lane Historic Runoff Coefficient&Time of Concentration Calculations Location: Aspen CA=KA+(1.31'3-1.44i2+1.135i+0.12) Minor Design Storm: 10 Major Design Storm: 100 CCD=KCD+(0.858i3-0.786i2+0.774i+0.04) Soil Type: C/D CB=(CA+CCD)/2 Basin Design Data I(%)= 100% 90% 90% 90% 40% 40% 2% 2% I(%) Runoff Coeffs Initial Overland Time(t) t` Final keyed n AiscapeB Alscape Upper Basin Design "drives/cone Aroof Apatios Agravel Apavers ATotal ATotal Imp most Slope ti streets (sf) C2 C5 C10 C100 Min Name Point (sf) (sf) (sf) (sf) (sf) (sf) (sf) (sf) (st) (ac) (%) Length (%) (min) to H 1 0 14 1,408 0 1,234 0 1,367 0 4,023 0.09 44.8% 0.31 0.37 0.44 0.59 100 4.5% 8.1 8.1 0 14 1,408 0 1,234 0 1,367 0 4,023 0.09 Runoff Coeffs Rainfall Intensities(in/hr) Area Flow Rates(cfs) Time of Basin Design Conc C2 C5 C10 C100 2 5 10 100 Arotai (sf) AT°tal Q2 Q5 Q10 Q100 Name Point (tc) (ac) H 1 8.1 0.31 0.37 0.44 0.59 1.72 2.48 3.10 5.27 4,023 0.09 0.05 0.08 0.12 0.29 TOTAL SITE 4,023 0.09 0.05 0.08 0.12 0.29 RECEIVED 11/01/2022 3529c-Rational Calculations-309 Oak Ln-Rd.2 Comments Historic ASPEN BUILDING DEPARTMENT � '�� JVA Incorporated Job Name: 309 Oak Lane III1\/�/ t 817 Colorado Ave,Ste 301 Job Number: 3529c WgeVi`gValli Glenwood Springs,CO 81601 Date: 10/26/2022 �� �� \ Ph:(970)404 3100 By: DAD CONSULTING ENGINEERS 309 Oak Lane Composite Runoff Coefficient Calculations Location: Aspen Minor Design Storm: 10 Major Design Storm: 100 CA=KA+(1.31 i^3-1.44'2+1.135i+0.12) Soil Type: C/D CCD=KCD+(0.858i^3-0.786i^2+0.774i+0.04) CB=(CA+CCD)/2 Basin Design Data I(%)= 100% 90% 90% 40% 40% 2% 2% I(%) Runoff Coeffs Basin Design Apaved Adrives/c Aroof A p iscape(B Aiscape A A Imp avel paves Totsi Total Name Point streets one (sf) (sf) (sf) (sf) soil) (C/D soil) (so (ac) (%) C2 C5 C10 C100 (sf) (sf) (sf) A 1 0 145 1,061 0 0 0 927 2,133 0.049 51.8% 0.35 0.41 0.47 0.61 B 2 0 111 666 646 0 0 467 1,890 0.043 51.2% 0.35 0.40 0.46 0.61 TOTAL SITE 0 256 1,727 646 0 0 1,394 4,023 0.09 51.5% 0.35 0.41 0.46 0.61 RECEIVED 11/01/2022 3529c-Rational Calculations-309 Oak Ln-Rd.2 Comments Developed C ASPEN BUILDING DEPARTMENT JVA Incorporated Job Name: 309 Oak Lane jAali. 817 Colorado Ave,Ste 301 Job Number: 3529c Glenwood Springs,CO 81601 Date: 10/26/22 Ph:(970)404 3100 By: DAD CONSULTING ENGINES, 309 Oak Lane Time of Concentration Calculations Location: Aspen Minor Design Storm: 10 Major Design Storm: 100 Soil Type: C/D Sub-Basin Data Initial Overland Time(t;) t0 Comp tc Urbanized Check ON t° Final Upper Time of Total Basin Design ATocal most Slope t; t�(L/180)+10 ConName Point (ac) C5 Length (%) (min) +tt= Length (min) Min (ft) t, k (ft) t A 1 0.05 0.41 76 2.66% 8.0 8.0 76 10.4 8.0 B 2 0.04 0.40 60 3.3% 6.6 6.6 60 10.3 6.6 RECEIVED 11/01/2022 3529c-Rational Calculations-309 Oak Ln-Rd.2 Comments Developed Tc ASPEN BUILDING DEPARTMENT JVA Incorporated Job Name: 309 Oak Lane J�f 0 1 817 Colorado Ave,Ste 301 Job Number: 3529c 1 Glenwood Springs,CO 81601 Date: 10/26/22 Ph:(970)404 3100 By: DAD CONSULTING ENGINEERS 309 Oak Lane Developed Storm Runoff Calculations Design Storm: 100 Year Point Hour Rainfall(Pi): 1.23 Direct Runoff Total Runoff co a)U V C coz c 6 .T c m m Q K Si. CD — 0I° E w — 0 A 1 0.05 0.61 8.00 0.03 5.34 0.16 6.60 0.03 5.34 0.16 B 2 0.04 0.61 6.60 0.03 5.78 0.15 0.00 0.03 5.78 0.15 RECEIVED 11/01/2022 3529c-Rational Calculations-309 Oak Ln-Rd.2 Comments Q100 ASPEN BUILDING DEPARTMENT JVA Incorporated Job Name: 309 Oak Lane 81 Colorado Ave,Ste 301 : 3529c J`f ON Ph?(970)404rings, 00 CO 81601 Job Nu DD te:B 10/26 DAD/22 CONSULTING ENGINEERS 309 Oak Lane Developed Storm Runoff Calculations Design Storm: 10 Year Point Hour Rainfall(P1): 0.77 Direct Runoff Total Runoff N C N 0 \ L U U CZz C C f y L u (AC O) Q N Q N N C ' mC 0 SO) c6 47 2 fC wco o Q ce 4-2 0 C F E — 0 z A 1 0.05 0.47 8.00 0.02 3.14 0.07 8.00 0.02 3.14 0.07 B 2 0.04 0.46 6.60 0.02 3.40 0.07 6.60 0.02 3.40 0.07 RECEIVED 11/01/2022 3529c-Rational Calculations-309 Oak Ln-Rd.2 Comments Q Minor ASPEN BUILDING DEPARTMENT ,) JVA Incorporated Job Name: 309 Oak Lane 41 817 Colorado Ave,Ste 301 Glenwood wood Springs, 3100 CO 81601 Job Number:Date: 10/26/22 By:Ph: DAD CONSULTING ENGINEERS WATER QUALITY CAPTURE VOLUME (Reference:"Urban Runoff Management Plan—A Guide to Stormwater Management in the City of Aspen",City of Aspen, Revised December 2014 Edition) art Volume(f t3)= WQCV in Watershed inches x 12 tn�n x Area(sj) Water Quality Enhancement Provided For Basins A,B,and C Basin Name Area(ac.) Imperviousness % I*A A 0.05 51.76% 0.0253 B 0.04 51.17% 0.0222 Total 0.09 51.48% 0.0475 0.30 0.25 0.20 • yT 0.15 0.10 9 8 0.05 0.00 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 Effective Imperviousness of Tributary Area to BMP(percent) WQCV(watershed-inches)= 0.1 Total WQ Area(sf)= 4,023 WQCV(cu.Ft.)= 33.5 RECEIVED 11/01/2022 3529c-Rational Calculations-309 Oak Ln-Rd.2 Comments WQCV-A ASPEN BUILDING DEPARTMENT �■ JVA Incorporated Job Name: 309 Oak Lane J _f� �� Ph81 Colorado Ave,Ste 301 ?(970)d Springs, OOCO81601 Job NuD er: 3529c ate: By: DAD CONSULTING F.N,1N1_E RS DRY WELL SIZING (Reference:Figure 8.69 Typical WQCV Dry Well"Urban Runoff Management Plan—A Guide to Stormwater Management in the City of Aspen",City of Aspen,Revised December 2014 Edition) WQCV: 33.53 FACTOR OF SAFETY: 1.5 TARGET DESIGN CAPTURE VOL.: I 462.691 ft3 -WQCV+Detention Volume Dry Well 1 Inner Diameter: 6.00(ft) Outer Diameter I 7.33I(ft)(8"wall) Gravel Backfill Thickness 24(in) Diameter to edge of Gravel I 11.331 Rim Elevation 7942.14(ft) Invert In: 7937.70(ft) Overall Depth 16.61(ft) Pimary Chamber Depth: 6.44(ft) Primary Chamber Inv: 7935.70(ft) Primary Chamber Capture Depth: — 2.00(ft) Sump Inv 7925.53(ft) Active Perc.Area Depth 9.50(ft) Structure Capture Volume: 325.1 ft3 Vol.in Gravel Void Space 155.4 ft3(0.3 Void ratio) - Total Volume DWI: I 480.5 ft3 Total Captured Volume: I 480.47 1 K 0.00069 fUsec Required Percolation area: 7.711 fta Provided Percolation Area: 179.043 fta Drain Down Time(s)=Total Capture Vol./(K x Perc.Area x.5 clogging factor) Drain Down time DW1: 7729(s) 128.8(min) 2(hrs) 24"STANDARD MANHOLE CAST IRON RING AND GRATED COVER CEMENT GROUT, TYPE II FINISHED GRADE —\ \ \ PRECAST CONCRETE ADJUSTING RINGS \\\ T�I I I I I I I \// SEAL WITH RUB'R-NEK PREFORMED JOINT GASKET \\� • \\s„, '/N� PRECAST ECCENTRIC CONE SECTION. o `\\�\\�`. PLASTIC STEPS \ /��PENT MH PENETRATEIONS AWAY FROM OUTLETc. f� W _ ��*al FI O �•.+. ' PRECAST CONCRETE SECTION(TYP) \ 15' (TYP) 6"STEEL PERFORATED PIPE i o Ik COVERED BY MIRAFI FABRIC SOCK U w ' ,w Er THICK PRECAST CONCRETE a i\ UD SECTION WITH RUST J RESISTANT ACCESS HATCH a 1. n U \ Ida N 411111111e.1. •�.« WITH LIFTING HANDLES I. 's 011_S f.Oc 0 1-DIAMETER PERC HOLES I��JC 0I�I X '••I.� 72" ID ./••I ft .11.I e icy( — li.W 0 CLEAN 3/4"CRUSHED ROCK �. +. 0.4 95%COMPACTED i0110 •'OiOS a I10 SUMP ELEV 0I0 \ ^I 24"MIN A x THICKNESS AROUND STRUCTURE RECEIVED 11/01/2022 3529c-Rational Calculations-309 Oak Ln-Rd.2 Comments Dry Well Sizing-A ASPEN BUILDING DEPARTMENT