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HomeMy WebLinkAboutApplication APPLICANT 2/3/2014 (4) ., _.P rn ,°k s -C .-. ' _ - ' IDPUBLIC WORKS DEPARTMENT/Engineering Division Phone:(541) 726-3753 Fax:(541) 736-1021 STORMWATER MANAGEMENT SYSTEM SCOPE OF WORK (Area below this line filled out by Applicant) ---------- (Please return to Matt Stouder @ City of Springfield Public Works Engineering;Fax# 736-1021, Phone#736-1035), email:mstouder aci.springfield or.us Project Name: Applicant: Assessors Parcel Date: Land Use(s): Phone#: 503-419-2500 Project Size(Acres): 4.59 acres Fax#: Approx. Impervious Area: Email: Project Description (Include a copy of Assessor's map): Drainage Proposal(Public connection(s), discharge location(s),etc. Attach additional sheet(s)if necessary: • Proposed Stormwater Best Management Practices: There are no proposed stormwater facilities. Site generated stormwater runoff will be managed within existing regional stormwater facilities. --(Area below this line filled out by the City and Returned to the Applicant) (At a minimum, all boxes checked by the City on the front and back of this sheet shall be submitted for an application to be complete for submittal, although other requirements may be necessary.) Drainage Study Type(EDSPM Section 4.03.2): (Note,UH may be substituted for Rational Method) ❑ Small Site Study—(use Rational Method for calculations) ❑ Mid-Level Development Study—(use Unit Hydrograph Method for calculations) ❑ Full Drainage Development Study—(use Unit Hydrograph Method for calculations) Environmental Considerations: ❑ Wellhead Zone: W A K1 Hillside Development: Y GS 1f Wetland/Riparian: Floodway/Floodplain: 1,ri/A ❑ Soil Type: 41G% - p}mo p d;lie .5;)17 G(4y marl ❑ Other Jurisdictions DownstreamAnalvsis5AD Havc(ar 5;)tt Ck. toga, 11 N/A • ❑ Flow line for starting water surface elevation: ❑ Design HGL to use for starting water surface elevation: n Manhole/Junction to take analysis to: �� Return to Matt Stouder @ City of Springfield, email:mstouder(Wcisprinofield.or.us, FAX;ji5 1 J 36v102 1L RECD f FEB 3 2014 COMPLETE STUDY ITEMS I For otrcwus<omr • *Based upon the information provided on the front of this sheet, the following represents a minimum of what is needed for an application to be complete for submittal with respect to drainage;however, this list should not be used in lieu of the Springfield Development Code(SDC)or the City's Engineering Design Manual. Compliance with these requirements does not constitute site approval;Additional site specific information may be required Note: Upon scoping sheet submittal, ensure completed form has been signed in the space provided below: Interim Design Standards/Water Quality(EDSPM Chapter 3) Re 'dN/A ❑All non-building rooftop(NBR)impervious surfaces shall be pre-treated(e.g.multi-chambered catchbasin w/oil filtration media)for stormwater quality. Additionally,a minimum of 50%of the NBR impervious surface shall be treated by vegetated methods. ❑ ® Where required,vegetative stormwater design shall be consistent with interim design standards(EDSPM Section 3.02),set forth by the Bureau of Environmental Services(BES)or Clean Water Services(CWS). ❑ ®For new NBR impervious area less than 15,000 square fret,a simplified design approach may be followed as specified by the BES for vegetative treatment ❑ ®If a stormwater treatment swale is proposed,submit calculations/specifications for sizing,velocity,flow,side slopes,bottom slope,and seed mix consistent with either BES or CWS requirements. ❑ ®Water Quality calculations as required in Section 3.03.1 of the EDSPM ❑ ©All building rooftop mounted equipment,or other fluid containing equipment located outside of the building,shall be provided with secondary containment or weather resistant enclosure. General Study Requirements(EDSPM Section 4.03) ® ❑Drainage study prepared by a Professional Civil Engineer licensed in the state of Oregon. ❑A complete drainage study,as required in EDSPM Section 4.03.1,including a hydrological study map. ❑Calculations showing system capacity for a 2-year storm event and overflow effects of a 25-year storm event ® ❑The time of concentration(To)shall be determined using a 10 minute start time for developed basins. • Review of Downstream System(EDSPM Section 4.03.4.C) ❑ ®A downstream drainage analysis as described in EDSPM Section 4.03.4.C. On-site drainage shall be governed by the Oregon Plumbing Specialty Code(OPSC). ❑ ®Elevations of the 14GL and flow lines for both city and private systems where applicable. Design of Storm Systems(EDSPM Section 4.04) Lr�l ❑Flow lines,slopes,rim elevations,pipe type and sizes clearly indicated on the plan set. ® ❑Minimum pipe cover shall be 18 inches for reinforced pipe and 36 inches for plain concrete and plastic pipe materials,or proper engineering calculations shall be provided when less. The cover shall be sufficient to support an 80,000 lb load �l without failure of the pipe structure. [At ❑Manning's"n"values for pipes shall be consistent with Table 4-1 of the EDSP. All storm pipes shall be designed to achieve a minimum velocity of three(3)feet per second at 0.5 pipe full based on Table 4-1 as well. Other/Misc ® ❑Existing and proposed contours,located at one foot interval. Include spot elevations and site grades showing how site drains ® ❑Private stormwater easements shall be clearly depicted on plans when private stormwater flows from one property to another [Z1 ❑Drywalls shall not receive runoff from any surface w/o being treated by one or more BMPs,with the exception of residential .building roofs(EDSP Section 3.03.4.A). Additional provisions apply to this as required by the DEQ. Refer to the website: www,deq.state.or,us/wq/groundwa/uichome.hcm for more information. ❑ Detention ponds shall be designed to limit runoff to pre-development rates for the 2 through 25-year storm events *This form shall be included as an attachment, inside the front cover,of the stormwater study • *IMPORTANT:ENGINEER PLEASE READ BELOW AND SIGN! • As the engineer of record,I hereby certify the above required items are ^. � complete and included with the submitted stormwater study and plan set Signature (GL ll-f A /Date ( 2''l(ft Form Version 2: March 2004 • PRE-SUBMITTAL REC'D - - - FEB 3 20,14 • • MEMORANDUM Cr Cardno® Shaping the Future To: Clayton McEachern, PE City of Springfield 5415 SW Westgate Drive From: Atalia Raskin, PE Suite 100 Water Resource Senior Project Engineer Portland,Oregon 97221 USA Date: January 24, 2014 Phone (503)419-2500 Project: Mountaingate Fax (503)419-2600 Cardno#: 21304830 Re: Preliminary Stormwater Analysis www.cardno.com This memorandum discusses the stormwater approach being proposed as part of the Mountaingate residential project. The stormwater management approach, as described below, is intended to meet the City of Springfield stormwater design requirements. These regualtions are identified in the City of Springfield Engineering Design Standards and Procudures Manual issued in January 2012. Project Overview The Mountaingate subdivision is proposed as a reconfiguration of the already approved and platted The Cottage Collection at The Heights located east of Mountaingate Drive on the south • side of Forest Ridge Drive and north of Jade Avenue. The site is within the City of Springfield City Limits, within the Low Density Residential (LDR)zoning district and is currently vacant. The current configuration has 25 developable lots and one track; while the proposed configuration has 15 developable lots and one track. With an assumed 2,640 sq.-ft per lot, the reconfiguration will reduce the amount of impervious area generated by the development by approximately 26,400 sq.-ft(0.61 acres). The property is 4.59 acres, with an anticipated 1.24 acres of impervious area. Water Quality and Water Quantity The site is part of the Mountaingate Master Plan area and will drain to regional stormwater facilities designed for the area. Double chambered catch basins will provide pre-treatment at the site. Double chambered catch basins trap oils and grease, provide spill control and sediment storage. They have an estimated phosphorous removal efficiency of 15%. Conveyance The City of Springfield design standards require storm drainage system be designed to convey the 25-year storm event with a minimum of 1.0 foot of freeboard in surcharged conditions. The onsite conveyance system will be designed with the final drainage report. This report evaulated the downstream system to ensure sigificant downstream conveyance capacity. The southern portion of the proposed project will discharge into Mountaingate Drive. The public storm sewer heads southwest to a detention pond at the bottom of the hill. The pipe has a • 12-inch diameter and a 5.7% slope. Its 94%full (maximum capacity)capacity is 9.15 cu-ft/sec. The northern portion of the proposed project will discharge north into Mountaingate Drive. The public storm sewer pipe has a 12-inch diameter. The slope is not known at this time. With a 0.5°/e p! r sloped, its 94%full (maximum capacity) capacity is 2.71 cu-ft/sec. PRE- UBMIUPI REC D Australia • Belgium • Indonesia • Kenya • New Zealand • Papua New Guinea 3 2��4 United Arab Emirates • Unted Kingdom • United States • Operations in 60 Countries FEB Page 2 January 24,2014 • Cardno® Shaping the Future The total anticipated site flow is 1.862 cu-ft/sec. Less than capacity of each of these pipes. Conclusion The proposed stormwater conveyance and water quality design follow the City of Springfield Engineering Design Standards and Procudures Manual issued in January 2012. The proposed conveyance system will be designed to convey the 25-year flow without any deficiencies in the final drainage report. Water Quality and quantity will be managed within regional ponds designed as part of the Moutaingate Master Plan. Double chamber catch basins will provide pretreatment at the site. The downstream analysis reviewed the pipe capacity of the downstream system. The proposed reconfiguration reduces the amount of impervious approved for this area, therefore, it is believed the downstream convey system has capacity to accommodate our site. The proposed Mountaingate development meets the requirements for the City of Springfield. Attachments: > Exhibit 1 — Preliminary Basin Delineation References: > MountainGate — A Proposed Residential Development Springfield, Oregon, Revised Spring 1997. 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