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HomeMy WebLinkAboutMiscellaneous PLANNER 10/26/2006 JIM \:::> - CD~y' .. . PUBLIC WORKS DEPARTMENT ADMINISTRATION ENGINEERING DIVISION. ENVIRONMENTAL SERVICES DIVISION MAINTENANCE DIVISION TRANSPORTATION DIVISION TECHNICAL SERVICES DIVISION 225 FIFTH STREET SPRINGFIELD, OR 97477 www.ai.springfield.orusldepLPw.htm www.ai.springfield.orus PUBLIC IMPROVEMENT PROJECT CORRECTION LEITER: June 14, 2004 MOUNTAINGATE SUBDIVISION - PHASES 3 Land Development Eric Walter, Civil Engineer Plan Review Consulant: Ron Staehlin, Southwood Engineering Storm Drainage: Matt Stouder, EIT PIP Construction: Don Branch, Sup. Civil Engineer Transportation: Dean Bishop, Traffic Technician IV FIRST SUBMIITAL PROJ #: P30406 Plans and documentation as submitted was reviewed by Public Works staff for Public Improvement requirements. The following corrections below are based on this review. Two red marked sets of plans are included with this letter. Please return these two red marked sets along with seven (7) sets of revised plans and necessary documentation. In addition to addressing each red marked comment on attached City marked plan set, the applicant is required to resubmit plans addressing the following items: MASTER PLAN CONDITIONS AND ADDITIONAL PUBLIC WORKS REQUIREMENTS 1. Submit pavement designs showing conformance with City of Springfield Engineering Design Standard and Procedures Section 1.02.7. This project shall incorporate the standard drawings for development of hillside areas recommended in Hillside Pavement Distress Study, 1994, by Dames and Moore per EDSP Section 7.04.10. Please note that maximum fire truck loading is 80,000 Ibs. 2. Please provide a concrete street section alternate for Park Drive in addition to the AC pavement section. (This requirement is under review) Southwood Engineering to provide recommendation after research 3. Sewer design for each phase shall address specific problems and special design considerations for steep hillside development such as flow velocity, energy dissipation, turbulence in manholes and bends and restraints on pipe movement. Southwood Engineering to verify 4. Trench drainage measures, or other approved methods of handling flow of water in trench backfill, must be incorporated into all trench sections with slopes exceeding 10 percent and elsewhere when required by the City Engineer. I 5. Design of the storm drainage system must be done so that no net change in volume or flow rate is experienced in any of the wetlands on or ai:tjacent to the site. I I 6. The project shall incorporate the standard drawings for development of hillside areas recommended in Appendix A the Hillside Pavement Distress Study, 1994, by Dames & Moore, deviation from these requirements may be considered on a case-by-case basis, at the sole discretion of the City Engineer, during the development of each phase. 7. During the design of each phase of the project, the developer shall provide catch basin-sizing calculations to show that adequate inlet capacity is provided to capture all of the water flowing in the street. Southwood Engineering to verify Date Received: lo-l/)-rl/:J ADMINISTRATION I TECHNICAL SERVICES I ENGINEERING: (541) 726-3753 . ~RfiW36-1 021 I 0 f 5 (Ja5/ld MAINTENANCE: (541) 726-3761 . FAX (541) 726-3621 TRANSPORTATlON~ '(b41)'126-3753 . FAX (541) 72'5-3781 ENVIRONMENTAL SERVICES: (541) 726-3694 . FAX (541) 726-2309 . ~, . 8. The developer shall include longitudinal drainage systems along the uphill side of all streets constructed on cut slopes for each phase of the development. These drains shall discharge to a piped drainage facility, not the street gutter. STORM AND SANITARY 9. Please include hydraulic grade line calculations for the storm sewer lines, and include the associated elevations on the profile drawings of the plans. 10. Provide calculations used to arrive at the time of concentration (Tc) values for existing conditions in the hydrology study. Show how these numbers were obtained, along with parameters used for the calculations ("n" value, slopes, method used, etc.). Basins E3 and E4 appear to have low time of concentration values, which could lead to over-prediction of existing flow, reducing the amount of post-developed detention required. Also, basins E1-E3 use the same length for Tc calculations, . which contradicts the basin map. . 11. Developed basins in the hydrology study are assigned curve numbers (CN) of 80 (assumes Y, acre lots, 25 % impervious) regardless of lot size in the basins. Due to the nature of the proposed development (hillside development, 1/3 to Y. acre lots, greater than 25 % impervious for many basins), staff feels the post developed flow may be under-predicted. Please use a "weighted" CN for developed basins to reflect actual conditions of post-development. 12. Plan sheet C22 depicts a detail drawing for a combination curb inlet. The curb inlet opening length is not dimensioned. Please ensure the use of the City standard 4A curb inlet with the use of the combination inlet. 13. Curb inlet sizing and efficiency calculations have been submitted for Mountaingate Drive, but are missing for inlets located on Park Drive and Dogwood Street. Please inch,Jde calculations for the missing inlets with the next plan submittal. 14. Calculations in the hydrology study indicate several of pipe reaches will achieve maximum velocities around 13 ftIs, with some over 20 ftIs. As required in the Master Plan Conditions of Approval number 18, and the City's EDSPM Section 4.04.D.2, please show how the effects of high velocities will be dealt with. Specifically, effects of hydraulic jumps at manholes and downstream water levels for peak flow situations shall be shown. 15. In response to Master Plan Condition of Approval number 18, the applicant notes that pipes on slopes in excess of 10 percent shall be "restrained from movement via concrete pipe anchors." The locations of the proposed pipe anchors shall be shown on the plan and profile sheets at PIP submittal. 16. According to the Master Plan and submitted hydrology study, there is no storm sewer connection as shown on the SW comer of sheet C4. Stormwater from this portion of Mountaingate Subdivision will drain to the east in a future phase. Please remove the connection point as it is shown on the plan set. 17. The 20 foot Public storm drainage easement shown on plan sheet C5 is not shown on Lot 22, or on sheet C2 above lot 22. Please amend the plan set to show alllocaticins of this easement on the , ' proposed site. i I 18. Drainage easements shall be dedicated by the applicant for all jurisdictional drainage ways associated with this development. 2 '.. 19. The amount of flow routed through the proposed detention pipes for the 10 and 25-year design storm events does not match the outflow predicted for the developed basins by HydroCad in the hydrology study. Developed flow rates are 16.87 and 20.17 cfs for the 10 and 25-year storm events, respectfully. The routed flow through the detention pipes is 15.97 and 18.48 cfs. These numbers shall be rectified with the next submittal. 20. Additional calculations shall be submitted to the City showing drawdown times required for the detention pipes to completely empty. Inclusion of the orifice elevations (as shown in the hydrology study) will be required on the detail drawings of the construction plans. 21. As required in Chapter 4 of the EDSPM, calculations shall be submitted for the proposed detention facility showing how the system will safely bypass the 100-year, 24-hour design storm. . 22. Pipe bedding details shall be submitted to the City for review for the proposed 96 inch detention pipes. An engineered footing/foundation structure shall be provided for the detention pipes. Additional information shall be submitted to the City showing how the pipe will be constrained from moving or "floating." 23. There appears to be only a few feet of cover over the proposed detention pipes. Submit calculations showing how the proposed facility will handle an 80,000 pound fire truck apparatus. 24. A geotechnical evaluation of the entire proposed detention system shall be submitted to the City and shall be prepared by the Geotechnical engineer of the project. TRANSPORTA TlON 25. Submit street lighting, signing and striping plans. Transportation Comment - Kristi Krueger RESUBMITTAL REQUIREMENTS 26. Address all Public Works and Plan Review Consultant red marked comments per attached marked plans (One set red marked by Public Works and one set red marked by Southwood Engineering). Please note: The two red marked plans sets must be returned to the City with the next resubmit/al. 27. Address corrections / comments items 1 through 12 per attached letter from Southwood Engineering dated June 3, 2004. 28. Please provide a written response that describes how the plans and submittals have addressed and/or complied with the comments included in this plan review letter. After you had the opportunity to review this letter and the attachments, please contact me at your earliest convenience at (541) 736-1034 to arrange a meeting where we can go over comments in detail together. Please feel free to contact me at anytime if you have any questions or need further clarification. Sincerely, Z~~~ Eric Walter, Civil Engineer Public Works Land Development Section 3 '.. .' I SOUTHWOOD ENGINEERING CORPORATION 3301 SOUTHWOOD DRIVE PHILOMA TH, OR 97370 (541) 929-2533 FAX: (541) 929-2077 June 3, 2004 'i"'5 l:f',"" ',~" "'-:~1 4 '\., j ".' ._~ t !/,:-{; 1- JUII f' 4- ?nn4 ' W(. - '- - , ,~,===:::::d Eric Walter, P.E. Civil Engineer Public WorkslEngineering City of Springfield 225 Fifth Street Springfield, OR 97477 Dear Eric: Subject: Mountaingate Phase III Subdivision - Review of Construction Drawings I have reviewed the construction drawings dated December 11, 2003, for the Mountaingate Phase III Subdivision and have the following comments: 1. Show street lights on the plans. 2. Show pavement markings (stop bars, etc.) on the plans, 3. Show trees, if any, to be removed. 4. Provide alternative concrete street design if requested by City Engineer, 5. Provide anchor blocks at 100 foot maximum spacing on sewer pipes with slopes greater than I 0 percent. 6. Include applicable standard drawings for development of hillside areas, from Appendix A of the Hillside Pavement Distress Study, 1994, by Dames and Moore. 7. Provide water line design from SUB. Their drawings should be checked for conflicts with other utilities. I 8. Provide sanitary and storm sewer!service to Lots 12, 17, 19,45, 108, and 109. 9. Provide details and locations for lailboxes. I I ',. 10. Provide trench drains for sanitary and storm sewers with slopes greater than 10 percent. 11. Design standards require sanitary sewer manholes to be at the centerline of the street or within 5 feet of the centerline, but not in the wheel lane. Many of the manholes do not meet this requirement. 12. The Geotechnical Site Investigation and Recommendations recommends against construction of major cuts and fills and roads during wet weather. This should be stated on the drawings and the wet weather structure cross sections on Sheet C21 should be deleted. Also, add a note that temporary cuts should not be left uncovered for more than one month. Other pertinent recommendations in the report should be included on the drawings. Additional comments are marked on the enclosed drawings. Please contact me if you have any questions. Sincerely, ~~ Ron Staehlin, P .E. Enclosure