05-0456 Peer Review No 1 110806
November 8, 2006
Mr. Jim Gibson, P.E.
Development Review Engineer
City of Yelm Community Development Department
P.O. Box 479
Yelm, WA 98597
Re: Peer Review – Site Construction Documents
Trump Plat
Dear Jim:
Per you request, Shea & Carr, Inc. has performed a peer review of the Trump Plat construction plans and stormwater drainage report. Our comments are as follows:
Storm Drainage Report:
Storm Drainage Report Section 1 – Project Description – The description indicates that the method of conveyance is swales. The plans show a catch basin and pipe system. Please revise.
Storm Drainage Report Section 8 – Aesthetic Considerations – The narrative indicates swales will be used for treatment. A wet pond is proposed. Please revise.
Storm Drainage Report Section 10 – Covenants, Dedications, Easements – Please revise the referenced maintenance agreement to read residential and not commercial.
Erosion Control Report Section 1 – Sequence – Add installation of construction entrance and catch basin protection to sequence.
Erosion Control Report Section 2 – Trapping Sediment – Please indicate the use of catch basin protection.
Erosion Control Report Section 3 – Permanent Erosion Control – The narrative indicates that there is an existing wetland on-site. Please revise.
Storm Drainage Report Appendix A – Soils Report – Please provide a map demonstrating the locations of the test pits used for stormwater infiltration testing.
Storm Drainage Report Appendix B – Calculations and Hydraulic Analysis – Please provide clarification on the non-tributary areas to the pond. Provide a description of the areas and
where they will drain if not draining to the pond. All site drainage should be directed to a stormwater management system.
Storm Drainage Report Appendix B – Calculations and Hydraulic Analysis – Please provide clarification on the off-site area. The total acreage, with off-site areas, appears to be 4.22
acres. This total acreage is not addressed in subsequent drainage information. Has this acreage been included in pond sizing?
Storm Drainage Report Appendix B – Calculations and Hydraulic Analysis – Please clarify where the pond is within the area summary. Ponds should be included in the impervious area calculation.
Storm Drainage Report Appendix B – Calculations and Hydraulic Analysis – Please match the units and the type of measurement. In several locations, an area is described with the units
of cubic feet, which is a volume measurement.
Storm Drainage Report Appendix B – Calculations and Hydraulic Analysis – Please indicate on the Hydra output information where the calculated required pond volumes can be found for both
the infiltration facility and wet pond.
Storm Drainage Report Appendix B – Calculations and Hydraulic Analysis – Please indicate allowable and actual flow for each pipe segment. This information may be provided in the Hydra
output but it is not readily apparent.
Storm Drainage Report Appendix B – Calculations and Hydraulic Analysis – On the table entitled Ritter Subdivision Zone Information, the invert and rim elevation information does not
match the information provided on the plans. Please revise the report to match what has been provided in the construction documents. Also please revise the Hydra calculations to match
this revised information.
Storm Drainage Report Appendix B – Calculations and Hydraulic Analysis – Please demonstrate adequate drawdown is provided in the infiltration gallery. Section III-3.6.5 of the 1992
DOE Manual requires that an infiltration gallery be shown to completely drain the stored runoff from the 10-year, 24-hour design storm within one day and the 100-year, 24-hour design
storm within two days.
Storm Drainage Report Appendix C – Please correct the appendix title to indicate residential and not commercial maintenance agreement.
Storm Drainage Report Appendix C – Please add a maintenance checklist for infiltration systems and ponds.
Construction Plans:
All Sheets:
The following comments apply to all sheets:
Some minor redline comments have not been called out in the letter but need to be addressed in the revised plans.
Sheet 1 of 17:
Please provide the Hearing’s Examiner Conditions of Approval on the cover sheet.
Sheet 2 of 17:
Show locations of catch basin protection on existing catch basins.
Please indicate catch basin protection be installed for all new catch basins.
Provide sizing calculations in storm drainage report for temporary swales and sediment pond.
Sheet 3 of 17:
The roof drain drywell references the Thurston County Drainage Design and Erosion Control Manual (DDECM). Sizing of drywells shall be per the requirements of the 1992 Department of
Ecology (DOE) Stormwater Management Manual.
Provide a detail for catch basin inlet protection for erosion control.
Sheet 4 of 17:
Please remove duplicate information.
Sheet 5 of 17:
Please call out the right-of-way width for Trump Street and Stella Court.
At the intersection of Longmire Street and Trump Street, install a handicapped ramp for connection to any future sidewalk.
According to Detail 4-7 of the City of Yelm Development Guidelines, local access roads require bulb outs at intersections. Please revise the layout to include the required bulb outs
at all intersections.
The plans as currently provided are not stakable. The road stationing needs to be tied down to some type of marker such as a monument or a benchmark.
Sheet 6 of 17:
Stormwater ponds require a 10 foot setback from property lines. The wet pond grading does not provide this setback. Please revise.
A spot grade is called out along the flow line of Stella Court that is lower than the rim elevation of catch basin #1. This will create a ponding area. Please revise.
At catch basin #2, a 347 contour crosses the catch basin when the rim elevation is only 346.66. Please revise the rim elevation or the grading.
The proposed grading will direct flow out on to Cullens Street. Please revise grading or add catch basins to catch the flow prior to leaving the site.
The proposed grading plan shows grading off-site on to the adjacent parcel. Please revise.
I do not believe a type 1 catch basin can be used for catch basin #5. Please review pipe spacing and required knockouts to ensure that all three pipes can be accommodated within a type
1 structure. Please provide documentation.
Please call out all relevant invert information for catch basin #5. There should be three inverts total.
Sheet 7 of 17
The top elevation of the infiltration gallery appears to be in error. Please revise.
Provide sizing calculations and narrative discussion in the storm drainage report for overflow from wet pond to infiltration gallery. Overflow shall be designed to handle the 100 year
storm.
Sheet 8 of 17:
The water meters for lots 15 through 18 appear to be stationed incorrectly. In addition, a lot 19 is shown. Please revise.
Water and sewer services should connect to the respective main at a 90 degree angle. Please revise the services at the end of the cul-de-sac.
Call out the separation between water and sewer mains.
As the stationing on Stella Court and Trump Street share common numbers, please reference the road for the stationing of the fire hydrant and blow off.
Some stations for step services need correction. See plans.
As the stationing on Stella Court and Trump Street share common numbers, please reference the road for the stationing of the end of line valves and cleanouts.
The end of line cleanout in Stella Court shall be moved to the planter strip.
Please add a valve to the tee on the sewer main line where indicated.
Add horizontal bends in the sewer line to match the water line. Deflection is not allowed.
Sheet 9 of 17:
The grade transition where Trump Street connects to Cullens Street is too great. A vertical curve should be added.
The grade break at Station 5+17.79 should be revised to a vertical curve.
Indicate the pipe types for storm, water, and sewer. This can be provided this sheet or on plan view sheets.
The water service for the open space may need to cross under the sewer main. If this is required, the service will need to be encased.
The minimum allowable size of a water main is 6 inches. Please revise water main in Stella Court.
It appears that the water line in Stella Court at approximately station 2+12 will require deflection. The City of Yelm does not allow pipe deflections. Please revise or provide commentary
if deflection will not be required.
It appears that the sewer line in Trump Street at approximately station 5+12 will require deflection. The City of Yelm does not allow pipe deflections. Please revise or provide commentary
if deflection will not be required.
The sewer service lines for lots 15 and 11 appear to overlap. Please revise.
Sheet 10 of 17:
Please provide a cross section of the proposed frontage improvements. Cross section should be from right of way to right of way and should include the existing condition and proposed
improvements. The standard cross section for a neighborhood collector is not sufficient.
Please label row widths, sidewalk width, planter width, etc. It is difficult to discern what is occurring on this plan.
Based on the City Detail 4-5, the ultimate curb face to curb face width of Cullens Street should be 32 feet (2 lanes of 16 feet each). Therefore, as a part of this
project, there should be approximately 8 feet of lane widening in addition to the construction of curb, gutter, and sidewalk. Further, storm drainage from this widening should be collected
and directed to the on-site drainage system.
Remove the proposed barricades. Sidewalks shall be connected to the existing edge of pavement until future sidewalk connections can be made.
The planter areas on the south curb return at the intersection of Trump Street and Cullens Street are too narrow to be beneficial. Please fill in with concrete where indicated.
Sheet 11 of 17:
Please provide a cross section of the proposed frontage improvements. Cross section should be from right of way to right of way and should include the existing condition and proposed
improvements. The standard cross section for a commercial local access is not sufficient.
Please label row widths, sidewalk width, planter width, etc. It is difficult to discern what is occurring on this plan.
According to Sheet 1, there is 4 feet of right-of-way dedication proposed on Longmire Street. Please label on this plan.
Provide a 2 foot sawcut along existing pavement to provide clean edge for road widening.
Drainage along frontage improvements should be captured and directed to the on-site drainage system.
Remove the proposed barricades. Sidewalks shall be connected to the existing edge of pavement until future sidewalk connections can be made.
Provide a taper from the widened road to the existing edge of pavement.
Sheet 13 of 17:
Please provide a water system map.
Sheet 16 of 17:
Please revise the pavement section for local access. The current section indicates 2 inches of asphalt for Longmire Street. A commercial local access road requires 4 inches of asphalt.
Should you have any questions or comments, please contact me at (360) 352-1465 at your earliest convenience.
Sincerely,
SHEA & CARR INC.
Amy M. Head, P.E.
Project Manager