HomeMy WebLinkAboutSIP20-0003 LD 1460-Trans-Plans Ck 1 _Concept Review_2020-09-13 Department of Public Works Dennis Schmidt, Director Radley Ott, Assistant Director 7 County Center Drive T: 530.538.7681 Oroville, California 95965 F: 530.538.7171
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September 13, 2020 Mike Nelson, AICP President & CEO, Principal LACO Associates Re: River Ranch Subdivision – TSM18-0003, APN 078-090-043, 044 County TrakIt No SIP20-0003
To Whom It May Concern: With reference to the above subject, enclosed is:
Road and Drainage Plans -CK #1 Drainage Calculations
Engineers Estimate
ACTION REQUIRED:
Resubmit plans and /or other data in accordance with changes in red.
Review and comment on the following:
Remarks:
General:
1. A conceptual review has been requested. A conceptual review consists of review for
compliance with conditions of approval and review of concepts only; it does not consist of review for compliance with county standards or review of engineering design. A detailed review is not a part of this review and the Department reserves the ability to add additional comments or revise any of the below comments when more refined and complete submittals are made. The Department needs to be explicitly clear that comments not provided for incomplete or conceptual plan review does not constitute approval for the project or any element within. For the next submittal, please submit a complete plan set signed by a licensed civil engineer in the State of California. 2. Improvement plans must agree to the approved tentative subdivision map. The tentative map is not final and therefore may be revised. Revisions of the tentative map are submitted to the Planning Division for review and approval. 3. Show extents of water and sewer installation. 4. Show phasing of improvements. Each phase must comply with standards and conditions for access, circulation and drainage. 5. Add signature blocks for Water, Sewer and Public Works approval to the title sheet. Signature blocks for Fire and Environmental Health are optional. All signatures and
approvals shall be obtained before final plans are submitted to the Director of Public Works for signature.
Department of Public Works Dennis Schmidt, Director Radley Ott, Assistant Director 7 County Center Drive T: 530.538.7681 Oroville, California 95965 F: 530.538.7171
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Plan Notes:
6. Show notes when required by a mitigation measure. 7. A list of typical county notes has been included. Not all will apply. 8. Add note to refer to plans E-1959, E-1687, E-1333, E-1487, E-1675, E-1675, E-1696, and
E-2582 on file with the County of Butte for existing improvements. A link to download the files will be provided. 9. Plan notes and county standards should not conflict.
Drainage Concepts:
10. Not enough elevation data has been provided to verify conceptual viability of a storm water design. Elevations and grades should allow for minimum cover and velocity requirements from point of discharge to upstream grate inlets. 11. Please show grade/ spot elevations at each corner of the lot rather than cross reference between the elevation callouts at the back of the lot on the grading plans and the centerline of the road on the profiles. I checked one lot at random and found the gutter pan was
close to the same elevation as the back of lot. Lots should grade to drain to the road gutter pan. 12. Pipe crossings on Street A appear to be omitted. Show crossing utilities in profile to verify
no conflicts and vertical offsets in compliance with state and local requirements. 13. Submit plans and calculations that show there is no increase in peak flow runoff leaving the property. Engineering plans should detail existing drainage conditions and specify how
storm water runoff will be either detained or retained onsite and/ or conveyed to the nearest natural drainage channel or publicly maintained facility. 14. There are two tributary areas. It is not clear how compliance with county standards is to
be met with water draining to the east. 15. Provide engineering design details for drainage at the southeast corner of intersection of Lincoln Blvd. and Ophir Rd. 16. A pipe discharge is shown on Sheet 19 and Sheet 13. 17. Please note that the proposed ponds are sited with a size that has not been substantiated with any design calculations. Caution is made to the applicant that no exceptions to design standard and attenuation requirements will be allowed. Please utilize caution in progressing project forward without confirming adequate attenuation volume is provided.
18. Please note that we strongly encourage the applicant to verify the outfall elevation and tailwater condition of stormwater outfall. If the in-field installation does not match the design condition, and conflicts are discovered during construction, the project may be
stalled until a resolution can be made. This may impact retention volume. 19. Please provide post-construction best management practices consistent with the Construction General Permit for this site. This project is not a part of the County’s MS4 permit area, and post construction BMPs will need to be incorporated. Please note that this requirement addresses volume in addition to peak discharge rates by the County standards. 20. Show drainage easements when not located in a public street, road or alley. 21. Storm drain profiles are difficult to read and understand with only in the road centerline profile and combined with all other utilities. Please provide a separate profile for storm drain sections or alignments that don’t parrellel the road centerline. 22. Provide dimensions that illustrate distance between various underground utilities.
Department of Public Works Dennis Schmidt, Director Radley Ott, Assistant Director 7 County Center Drive T: 530.538.7681 Oroville, California 95965 F: 530.538.7171
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23. Alignment for much of the storm drain is under curb and sidewalk. This can be costly excavation for repairs. Criteria does not specify this is not acceptable; but we request that
alignment for storm drains not be under curb and gutter if possible. Additionally, please provide adequate room in the side of inlets for larger pipe and skewed alignments so that sufficient reinforcement can be maintained. 24. Provide details or reference information for storm drain infrastructure.
Road Concepts:
25. Tie survey data to existing county monuments and road stationing. i.e. provide horizontal control for the project.
26. Provide engineering design details for installation of frontage improvements on Lincoln Blvd. and Ophir Rd. Show all existing and proposed infrastructure, utilities and easements. Show proposed ingress/egress from commercial lots. 27. It does not appear that a storm drain system has been designed for curb and gutter on Lincoln Blvd. and Ophir Road. 28. Please double check grade break, the grade break on Road A appears to be around 4%. That will be a high use roadway, and 4% grade break may not ride well or provide heightened pavement stress. 29. Comply with the recommendations of the traffic study (2018 version) for installation of frontage improvements and location of Street A relative to the intersection of Lincoln Blvd. and Ophir Rd. 30. Connect eastbound Ophir Road curb, gutter and sidewalk with existing curb, gutter and sidewalk at intersection. 31. Connect northbound Lincoln Blvd. curb, gutter and sidewalk with existing curb, gutter and
sidewalk at intersection. 32. Comply with conditions of approval for road section design. Exception requests are submitted in writing and approved prior to being shown on the improvement plans.
33. The plans should show the masonry wall, landscaping strip and other requirements of conditions of approval. Exception requests are submitted in writing and approved prior to being shown on the improvement plans. 34. Engineered road cross sections on 50’ stations are not required to be approved by the County. Show typical cross sections complying with the conditions of approval. 35. It is not clear why a section of AC is proposed south of the subdivision and east of Lincoln Blvd. There does not appear to be a 50’ transition before the new curb and gutter. Curb, gutter and sidewalk along the frontage should extend to the property boundary. 36. It is not clear why a driveway access is being retained on Ophir Road at Station 20+00. Abutter’s rights are to be relinquished along Ophir Road except at approved access points. 37. Backfill within the right-of-way shall comply with county standards in the notes and on the
plans. 38. Trench backfill details shall comply with improvement standard S-17. 39. Asphalt resurfacing and backfill in the right-of-way are measured to relative compaction
rather than relative density. 40. A pavement job mix design will need to be submitted that demonstrates compliance with the County Standard.
41. Road Cross Sections seem pretty small in scale, please consider increasing scale. 42. Place sewer and storm drain manholes outside of common wheel paths within the roadway. If certain locations cause significant challenges, please identify and note the reasons why challenging.
Department of Public Works Dennis Schmidt, Director Radley Ott, Assistant Director 7 County Center Drive T: 530.538.7681 Oroville, California 95965 F: 530.538.7171
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43. Bulb-outs and cul-de-sacs appear to not provide adequate vertical information. Please provide horizontal and vertical information at curb and slope/ grade information from
centerline to critical vertical locations (LP, HP, GB, etc).
NO ACTION REQUIRED: Per your request. If you should have any questions, please call (530) 538-7266, Monday through Friday, 8:00 a.m. to 4:00 p.m. Sincerely,
Radley Ott, PE Assistant Director
Eric Schroth, P.E., L.S. Associate Civil Engineer