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HomeMy WebLinkAboutStudies Applicant 2/23/2024Stormwater Management Plan and Drainage Study Teresa Schoonover Springfield, Oregon For Teresa Schoonover 1010 Kintzley Avenue Springfield, OR 97478 PROFF�S' G I N #69162PE DIGITALLY SIGNED OREGON �qN, lo, 20�� `� �FNEE C0 EXPIRES: 12/30/25 February 20, 2024 GIN EERING.= Since 1977 civil transportation structural geotechnical SURVEYING www. Branch Eng ineering. corn U Contents Page No. 1.0 Introduction...............................................................................................................1 2.0 Existing Conditions.................................................................................................1 2.1 Topography 1 2.2 Soils 1 2.3 Existing Storm System 1 3.0 Proposed Development.........................................................................................1 4.0 Stormwater Constraints........................................................................................2 5.0 Proposed Development Stormwater Description.......................................2 6.0 Maintenance...............................................................................................................3 7.0 Conclusion..................................................................................................................3 Appendices Description Appendix A Stormwater Management Drainage Basin Map Appendix B Site Soils and Map © Branch Engineering, Inc. 1.0 INTRODUCTION This Stormwater Management Plan (SWMP) report has been prepared for a Tentative Partition application to divide an existing lot at the property currently known as 1010 Kintzley Avenue. The subject site is at the southwesterly corner of the Jasper Road and Kintzley Avenue intersection, and is identified as Tax Map 18-02-06-24, Tax Lot 3800. The stormwater runoff from future roof drains and drive surfaces will be directed to treatment facilities prior to being discharged to the existing stormwater system in Kintzley Avenue or Jasper Road. The purpose of this report is to document feasibility for future development. 2.0 EXISTING CONDITIONS The subject site is located in Springfield, Oregon at the southwesterly corner of the Jasper Road and Kintzley Avenue intersection, and consists of 0.84 acres of private property. The development site is underdeveloped with a majority of the improvements on the southerly half of the property. 2.1 TOPOGRAPHY The existing improvements consist of a single-family home, carport, shop, and gravel vehicular circulation area. An existing garage on site will be removed. Jasper Road is fully improved; Kintzley Avenue is partially improved with 21.5 feet of pavement and roadside ditches. The whole site is between 478-479 feet in elevation above sea level. 2.2 SOILS The Natural Resources Conservation Service (NRCS) Web Soil Survey maps the development site as containing mostly Chapman Loam (24); the southeasterly corner of the site contains Cloquato Silt Loam (29). Both Chapman Loam and Cloquato Silt Loam are described as a well -drained alluvium and are in Hydrologic Soil Group B. A soils map and individual soil information is provided in Appendix B. 2.3 EXISTING STORM SYSTEM The northerly portion of the lot is open and vegetated with grass. The existing home does not connect to the public stormwater system. As the site is very flat, most rainfall infiltrates on-site with minimal off-site runoff. The public stormwater system in Kintzley Avenue was recently constructed as part of the Mountainvale Subdivision. A 72 -inch stormwater main is located within Jasper Road and there are no noted downstream deficiencies. Curb inlets within the adjacent intersection feed into the 72 -inch main. 3.0 PROPOSED DEVELOPMENT As shown on the attached Basic Map in Appendix A, the partition consists of three parcels. Parcels 1 and 2 lie within the undeveloped portion of the property. Each parcel is larger than 4,500 square feet and can have a maximum building footprint of 45% of the total lot area. Parcel 2 includes a 20.00 foot -wide access easement for the benefit of Parcel 1. Both parcels will take access through this easement with a single access connection on Kintzley Avenue. Parcel 3 consists of the existing improvements on site. The home, shop, and carport encompass 30% of the total parcel area. Removal of the existing garage on the line between Parcels 1 and 3 is the only construction to be made on-site as part of this development. Parcel 3 will continue to take access along Kintzley Avenue via a separate a driveway from Parcels 1 and 2. Public improvements along Kintzley Avenue are proposed in accordance with the Annexation Agreement associated with the land. The public improvements consist of sidewalk, curb and gutter, a street light, planter strip, and widening the existing asphalt. The public improvements will be designed and approved for construction prior to platting. No public stormwater improvements are required as a part of this development. 4.0 STORMWATER CONSTRAINTS Two significant constraints affect the site: Wellhead Time of Tavel Zone - The site lies along the 2- and 5 -Year Time of Travel Zones to the nearest wellhead. Per SDC 3.3.233(B)(5) treatment of stormwater runoff must occur prior to conveyance to an infiltration facility. 2. Site Elevations - The site is extremely flat with little to no grade change across the site. There are high points throughout the site which may be the product of in -fill. There is a shallow ditch along Kintzley Avenue which is the assumed discharge point for the existing site runoff. This appears to drain southward toward the improvements constructed for the Mountainvale Subdivision. 5.0 PROPOSED DEVELOPMENT STORMWATER DESCRIPTION The stormwater facilities will be designed to meet Chapter 3 of the City of Springfield's Engineering Design Standards and Procedures Manual for water quality. As stated previously, the proposed development consists of 3 parcels (one with existing improvements, and two without). The two undeveloped parcels (Parcels 1 and 2) are both large enough for the City of Springfield's Land Use Code to allow a variety of development types including: single family home, duplex, triplex, fourplex, or cottage cluster. As it is unknown at this time which type of development will be constructed, the following is a conceptual analysis to determine feasibility. Nothing in this analysis is intended to be definitive or binding on future development. For the purpose of this analysis, a duplex on each parcel will be considered. It should be noted that Parcel 3 (Basin 3 in the Basin Map in Appendix A) is not being analyzed here as it is fully improved. Per SDC 3.2.250, duplexes do not adhere to the stormwater infrastructure standards for middle housing. Each parcel will need to treat all impervious surfaces prior to discharge to the public system for the first 1.4 -inches of rainfall. It is conservatively assumed that each parcel being developed (Basin 1 and 2 in the Basin Map in Appendix A) utilizes the maximum lot coverage of 45% and includes approximately 1,900 square feet of additional impervious area for the driveway and parking area. The simplified approach in the City of Eugene Stormwater Management Manual, utilizes a scaling factor of 0.03-0.06 for treatment facilities including stormwater planters, sand filters, rain gardens or swales resulting in 180 to 360 square feet of area needed per parcel. Between building, vehicular circulation and easement areas, there is between 2,400 and 2,700 square feet remaining on each parcel for stormwater treatment facilities. Additionally, the soils on site have the potential to allow infiltration of stormwater. Prior to the development of an infiltration facility, it is recommended that the site have an infiltration test performed. Also, as the site is located within the 2- and 5 -Year Wellhead Time of Travel Zones, any infiltration facility will need to be approved by the City of Springfield. The proposed public improvements associated with the partition will be graded to match the existing improvements within Kintzley Avenue. The existing road profile drains southerly, and an existing ditch lies along the westerly edge of the road. Beyond this ditch to the south are new improvements associated with the development of the Mountainvale Subdivision. These improvements include curb and gutter and curb inlets along Kintzley Avenue. Per the Annexation Agreement and conversation with the City of Springfield's Public Works Department, no additional capture systems will be needed along this site's frontage. 6.0 MAINTENANCE The stormwater facilities will be maintained privately since they receive water only from private improvements and will be constructed under a Building Permit. Maintenance will be per Chapter 3 of the City of Springfield's Engineering Design Standards and Procedures Manual. Repairs to storm facilities shall be made in accordance with an Operations and Maintenance Agreement associated with future development. 7.0 CONCLUSION Feasibility has been established for a stormwater system for the partition. Water quality can be accomplished through various treatment facilities. 3 APPENDIX A Stormwater Management Drainage Basin Map Vanch GNEERING= NEW EX6TING IMPROVEMENTS civil. t r a n s p o r t a t i o n IMPROVEMENTS IMPROVARIES L I svuctural. 9eotechnica SURVEYING 0.5' 13.5'� - 310 51h 5tree[ l LEGEND SpringBetl, OR 97977 EXISTING PROPOSED p: 541.746.0537 www:B, anc h Englneering.com - ELEVATION CONTOUR D ASPHALT iu! /ui Tui RECORDED PLAT BOUNDARY F BUILDING CONCRETE SECTION VIEW A -A CURB D CONCRETE - c CAS LINE STORM WATER CRAWL I� -YIWWASTEWATER UNE 0 20 - w - WATER LINE '' c0500 64p0 .,,o ® BRICK PATIO CR GAS METER 1llOt • L • 4L0� 4 -J A ' 1-2 FOOT RETAINING WALL ® CLEANOUT project title: M� I CURB ® WATER METER LED 8O. 25 -FEET TALL 7' W1000 FENCE - UNDERGROUND / - NIfANON LINE GAS LINE rao•o9•z7w zz0-4s �--�� STREET LIGHT 4 !±. - _ T STORM LI _ -( STORM LINE Al NEIGHBORHOOD MAILBOX � 6T(� 1' � -(E)ww OVERHEAD WIRES ` �Ot - � I ' 00 WASTEWATER LINE Q/W OUTBUILDING DRIVEWAY ' I ,I ( ' ){ ,[ t�C, 53ASA WATER LINE - t0 REMMN '� AN 77HE OF TRAVEL BUILDING SETBACK UNE 38' EVERGREEN 4�w I 1p1 ■������r�®'�W DELINEATION _ ,_r •, ! I +. 30.00� EDGE NT ASPHALT ` a • SO4 HIPPING TO REMAIN - / $ 'r, DELINEATION PARCEL BASIN 1 l ( N y� FENCE DECIDUOUS TREE --78,50 SF•, ( .2O ACRES) _ 4 fX677N0 ' A [ EDGE OF ASPHALT • 1 0 D m Tapp SUB F CITY LIMITS 1 r 1 a R TAX LOT AA�'TqI� _ • BASIN 3 1 6' i FENCE I 1 j �1 � TRww1NLE EARENCE - - 4" FL 473.00 I r STREET LIGHT Z N00'09•27V 109.89 �+ .n PU£ ) TT 'r` PARCEL PARCEL3.+I STORM DRAN MANHOLE I • L$42339 WASTEWATER MANHOLE HOUSE (0.ACR)AJW 5700 EMN WIDTH POWER POLE - PRIVATE ACCESS k UTILITY EASEMENT SIGN AS NOTED II , �' X WATER VALVE O Z 5' WOW FENCE • , l -r 300 PARCEL 2 BASIN 2 0 - p ' N ; 9.593 SF ,n /� COMMU/NCATION O 1 (0.22 GA 1 y G METER y • I ; /' • h�P� NVAC UNC O !Az CURB NtE1 /.- RIM:47Q49 !# T I ���EJ1� • \ \ A _-i..4i - 4" FL 7.00 I 1 _ 1 e � WELL u O --r=\ S5 CO (,)So fy,Y� !� p J6' , + / PROPOSED ` y RIN:479.76 /I EAIERGR EN I n 7.00• PUE ) I' S ;4_ FL 472.00 I A• il� DECIDUOUS TREE 00 W 00 SD MH I- ( F �`N-,'' `\61 �•�, 4 1 E 1 J Z IT SO M75.J, i `110.60 1 Til ww 12 FL IN(S).-475.34.., '• / Qi 12' PL IN(WJ:472.07 L• j sTv9.2T$ 20.9.55 • t&0 ) �•�uJ 18' PL OUl(N).w77.99 /w D/W A ' � ti 'B-- EVERGREEN TREE } 0 SO MH' N .� NM.r7Ba0 (E)so-,-_(vs01"_'- WW MH C r''ly �,�� 1 , 1 J a.-(E)SD - E' �18• PL 1N(5):477.19 , I+ W N Q TO BE RELOCATED n 7B• PL OUT(I4E).w71.ig �27- F8.87`, L J ..rA[ 7�4 �iL DUT(E).M7r.03 v1w• �oT�{+or-�vn-->'{a.'rc'+r-'+e'A"-•1'7&80 'L: 27`fL NEM'}465.41 w - ` 27" FL. OUT(E):465.41 LEp 8D, 20.FEET TALL r Z / a a ,` ^� GD MH f'38• FL IN(MI:466.49 LL KINTZLEY AVENUE �1BK47&76 rI c - ! ,_ mI "+� • / s 12• Ft IN(SW):47t.r4 ! J 00 U . _ lt, u 12' FL OUT(N):47I.O9; � - 1 .-. { Z r, Q z '(E,-�¢�w��7yF- ' .. ,c--- Ew--cFw-..._._.(Lw -- - s. ` x �I'aRAf1►A$• W O "•�Ew_ __IE =E)(E) -j-c Ri ^icF"--"A`l� `- i' .f�!�- -. t''.�I �W _(�I�N^ - ka MM ")7s7 ` NTH ME TYPE OF s01Ls THAT HAVE BEEN NAPPED BY THE NRC$ R Is L � N L -WW NH { \ t g tu4'., H,flt ASSUMED 71fA1 ANE SOILS ONSITE HAW A HIGH Ih XTRATION RATE. DUE TO THIS RIM:975M .STOP SIGN t9. A 5 YA' _ 1. ly.:) 468.32' 8' FL IN(S):469.30 F N ,r 4#,r .7 ALL THE RUNOi'F FROM ANY DEVELOPMENT COULD INCLUDE INFILTRATION 6" FL IN(E).470.34 It (Wi.46+i.v.r FACILITIES OR FROM TO THE PUBIC S70RUMIER SYSTEM TO THE NORTHEAST 8' FL OUT(N):466.78(E)OHK-(E�w-(E)0[f-(E�rM'--(E)(N1Yl-(E)01M� (rjn'mr-tT)o.rr.-F)QrFw- (Exi,;rr (t7Vr+�' t ` r wn WWZA LOCATIONS ARE WG uV JASPER RDAs No FLOW OR FLOOD CONTROL date: FEBRUARY 14, 2024 1 1.THE MANHOLE. �NLOCATI: t� 500 gao0 A0 g50O of n6wLINE of PIPESdesigner: AWMS TL Y / nL7 t �'VOT 1 MAY SE INACCURATE. Y TRW 0 DENSITY NOTE _ NOTES: WE HYMN DENSITY FOR B1 5 6 DU/ACRE 1. DEVELOPER To CDORONATE mm SUB WATER k ELECTRIC FOR FINAL LOCATIONS OF project no: 23-108 SINCE THE SITE IS 084 ACRES AT LEAST 5 DWELUNG UNITS ARE WATER AND ELECTRICAL FACILITIES REQUIRED (ROUNDING PER SDC %2.235iA)). FIVE DWELLING UNITS 2. ALL NEW UTILfiES TO a PLACED UNDERGROUND. TENTATIVE CAN BE ACCOMPLISHED VIA INSUl1AYION OF DUPLEXES ON BOTH 1 EACH PARCEL WILL BE RESPONSIBLE FOR ITS OWN STORM MR DISCHARGE AN PARCELS 1AND 2. THIS IS ONE OPTION PRESENTED TO ESTABLISH �MNT' PARTITION FEASIBILITY. R IS NOT (MENDED TO BE A GUARANTEE OF HOW 4. THE MINIMUM NUMBER OF STREET TREES REWIRED ALONG JASPER ROAD 5 So. THE DENSITY W U BE ACCOMPLONED, 517E DEVELOPMENT MAY OCCUR MIMMUM NUMBER OF STREET TREES REWIRED ALONG KINTZLEY AVENUE IS SEVEN. DIFFERENTLY 50 LONG AS FEASIBILITY` OF LONG TERM COMPLIANCE DUE TO THE LOCATION OF DRIVEWAYS AND STREET LIGHTS A MAMMUM OF SIX TREES WIN 6 DU/ACRE 5 MAININNED. GANBE PLANTED ALONG KWZELY AVENUE. DEC TO THE LACK OF A PUNIER STRIP h THE UTILITY EASEMENTS ALONG JASPER ROAD, THE PLACEMENT OF STREET TREES IS ATEASIBI.E. 5. NO BUILDINGS STRUCTURES TREES OR OTHER OBSTRUCTIONS SHALL BE PLACED OR LOCATED ON OR IN A PUBLIC UIXI Y EASEMENT. B EXTENSION OF UTILITIES TO THE BACK OF THE PROPOSED PUBLIC UTILITY EASEMENT, sheer. SIDEWALK CURB k WlhR, ASPHALT WIDENING, STREET LIGHT AND ANY RELOCATION OF PUBLIC OR FRANCHISE UTILITIES OR STNICTURES TO BE COORONATED THROUGH THE My OF SPRINGFIELD PUBLIC IMPROVEMENT PROCESS. DRN£WAYS AND UTILRV EX7Ef'US WIMN THE PARCELS WILL BE CONSTRUCTED 7160UGH A SaINNG PERMIT APPENDIX B Site Soils and Map 44° 2' 9' N 40 2'6"N Sail Map --Lane County Area, Ort -,c a v I� 5MM 501680 501690 50170.1 507710 501720 501730 s 3 Map Sale: ER 1:439 if printed on A portrat (8.5' x 11") sheet Meters Oi N 0 5 10 20 30 ry — Feet 0 20 40 80 120 P PrcJcbon: Web Mercator Comer 000rdnates: WGS84 Edge tics: UTM Zane 1ON WGS&1 I �I a Natural Resources 'deb Soil Survey 1/10/2024 s Conservation Service National Cooperative Soil Survey Page 1 of 3 44° Z6"N c 0 m SD O ai m Q T 0 O U m c m JI tu a O U) Z O a O LL Z Ca G 0 Z LL! 0 W -j IL V M N — O O N O 0 m c O al m- d r m :3 m 0) m cc m p— a) a) m C m a) I 3 c o d io °> O 'o O• U O U `O c6 O N 00 c U (A m N 7 ;�_ U O c a U m 0 O N 'o N a U N _ O) E f —Y CL O) 7 N E _ ?� m '- 2 N — U N 5 cc E m c U N m ° o n ma m a) -3 ° E Na O E 16 CO w U Co c y c L M cO m 0 2�M w M w= j N O maim E 0 w 2� 2 o m U C6 - = 3 m m Q c0 m n 0 = a n= V% m m n c i W a U m= 0 t to c m D 2 n N � O O Q 0 = O 0 U m N N �� ° a) Q� �°a O7 n �•�- ITa > >= o o m m 2 ° m° m 3 T CL o my TN U O �j O O Taw a 0 me 00) 2 Za m m pa o c m, a N E m N 7 M •O _m ,� -o O a 0 f9 T a O m 0 U N — 2 O C N :G _ U m y ° N O J fn t/J o" c V1 (� y J> -0 U = c 0 m E n O a) fa a m Ir a d Q U c o in Co a) O N O Z caw Z m c m ...o . m o v c o c N n° T m � m m 5 u, o �� 0" E o o m n Z o c N 0 to o c CO� U X 3 0 � a Q m _.. ca � o v Q m -o mcmi- m °•oc oomma? > oQ no mrn o o '0 c •O N y N O a) w' U > 3 T m o r O) 0 0 L ro vOi m c m m m 7 a O n y U N w Z O O N m E m t N m c- c o U N 0 O o 0 m o n a° �� o 3 'o '?? m U m d E tn�U 0. -0 m .� o corn (n� � H v N T m U) 'o ZU) 7 41 � y O U a m m m U m m CL UU r c fA v m w o O m c 2 d d = K c '0 m m � E afVmU O Z e y o 0 d mo O W J!O = c VJ fnO m ,O Q In W � � LL O ` CL Im � C A N CL Q > m o m m a o a E 2 N «? m d m d m m a y c c c > > > _t Oa o. o m ov a O . -6m m aw mm a m co J.0 Z5 m m a o d > m m a mt; >. , c 12 2 '0 miumm U min mU 0 a m ii Fn m m +� a. m L 0 �sn ®a? X0•. 4( 10 3 t �N c a 0 0 a, 3 IA Ao z rl Soil Map—Lane County Area, Oregon Map Unit Legend u_SDA Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/10/2024 Page 3 of 3 Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 24 Chapman loam 0.8 96.5% 29 Cloquato silt loam 0.0 3.5% Totals for Area of Interest 0.9 100.0% u_SDA Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/10/2024 Page 3 of 3 Map Unit Description: Chapman loam ---Lane County Area, Oregon Lane County Area, Oregon 24—Chapman loam Map Unit Setting National map unit symbol. 235z Elevation: 300 to 1,000 feet Mean annual precipitation: 40 to 60 inches Mean annual air temperature: 52 to 54 degrees F Frost -free period: 165 to 210 days Farmland classification: All areas are prime farmland Map Unit Composition Chapman and similar soils: 85 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Chapman Setting Landform: Stream terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across -slope shape: Linear Parent material: Alluvium from mixed sources Typical profile H7 - 0 to 8 inches: loam H2 - 8 to 42 inches: loam H3 - 42 to 50 inches: gravelly sandy loam H4 - 50 to 60 inches: very gravelly sandy loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.57 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: Rare Frequency of ponding: None Available water supply, 0 to 60 inches: Moderate (about 8.1 inches) Interpretive groups Land capability classification (irrigated): 1 Land capability classification (nonirrigated): 1 Hydrologic Soil Group: B Ecological site: F002XCO03OR - Low Flood Plain Group Forage suitability group: Well drained < 15% Slopes (G002XY0020R) Natural Resources Web Soil Survey 1/10/2024 ax Conservation Service National Cooperative Soil Survey Page 1 of 2 Map Unit Description: Chapman loam ---Lane County Area, Oregon Other vegetative classification: Well drained < 15% Slopes (G002XY0020R) Hydric soil rating: No Data Source Information Soil Survey Area: Lane County Area, Oregon Survey Area Data: Version 22, Sep 8, 2023 U5Da Natural Resources i Conservation Service Web Soil Survey National Cooperative Soil Survey 1/10/2024 Page 2 of 2 Map Unit Description: Cloquato silt loam ---Lane County Area, Oregon Lane County Area, Oregon 29—Cloquato silt loam Map Unit Setting National map unit symbol. 2365 Elevation: 290 to 800 feet Mean annual precipitation: 40 to 60 inches Mean annual air temperature: 52 to 54 degrees F Frost -free period: 165 to 210 days Farmland classification: All areas are prime farmland Map Unit Composition Cloquato and similar soils: 85 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Cloquato Setting Landform: Flood plains Landform position (three-dimensional): Tread Down-slope shape: Linear Across -slope shape: Linear Parent material: Alluvium from mixed sources Typical profile H1 - 0 to 14 inches: silt loam H2 - 14 to 50 inches: silt loam H3 - 50 to 60 inches: stratified sand to silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.57 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: Occasional Frequency of ponding: None Available water supply, 0 to 60 inches: High (about 11.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: B Ecological site: F002XCO03OR -Low Flood Plain Group Forage suitability group: Well drained < 15% Slopes (G002XY0020R) Other vegetative classification: Well drained < 15% Slopes (G002XY0020R) ,S _ Natural Resources Web Soil Survey Conservation Service National Cooperative Soil Survey 1/10/2024 Page 1 of 2 Map Unit Description: Cloquato silt loam ---Lane County Area, Oregon Hydric soil rating: No Data Source Information Soil Survey Area: Lane County Area, Oregon Survey Area Data: Version 22, Sep 8, 2023 Natural Resources Web Soil Survey 1/10/2024 wmim Conservation Service National Cooperative Soil Survey Page 2 of 2