05-0770 Revised Review No. 1 102307
City of Yelm
Community Development Department
105 Yelm Avenue West
P.O. Box 479
Yelm, WA 98597
October 23, 2007
Jeff McInnis
Petra Engineering
535 Dock Street, Suite 213
Tacoma, WA 98402
RE: Samantha Ridge- City of Yelm Project No. PRD-05-00770-YL
REVISED Initial Review of Civil Construction Documents
Mr. McInnis:
The City of Yelm has completed the initial review of the proposed Planned Residential Development. Your application included:
Drainage and Erosion Control Report
Operation and Maintenance Plan
Full Size Plans
We have reviewed the plans for compliance with the City of Yelm Development Guidelines, the DOE Stormwater Manual and general standards of civil engineering practice. The following
comments need to be addressed before the plans may be approved for construction. Our comments are summarized below:
Storm Drainage Report:
Storm Drainage Report Section 9 – According to this section, on-site soils were categorized as Group C soils. The geotechnical report does not support this classification. According
to the report, the underlying soils are Spanaway recessional outwash sand and gravel. Spanaway soils are typically a Group A or B soil with good infiltration. Please revise this section
as well as any computations based on this grouping.
Storm Drainage Report Appendix B – Please provide at minimum: elevation/area/volume computations for the proposed stormwater facility compared to volume required; sizing computation
showing treatment flow required versus flow provided by Vortechs; discussion regarding maximum allowable flow through Vortechs versus maximum expected flow and whether a bypass will
be required. The modeling output is back up to support calculations provided demonstrating that the requirements of the 1992 DOE Manual have been met. Please provide labels or comments
on the model information identifying the purpose of each printout and what it is showing. It is difficult to determine what it being presented within the model without having any information
on your printouts. Please make sure on the resubmittal that you provide a level pool routing showing the predeveloped rates and post developed rates to verify that the project in not
releasing excess stormwater.
Storm Drainage Report – The geotechnical report should be provided as an appendix to the stormwater report as the determination of infiltration rates are based upon this report. On
future submittals, please include.
Storm Drainage Report – Please provide a drainage basin map showing areas included within drainage calculations. Please note, only undisturbed areas maybe excluded from the drainage
area. The drainage area should include all areas that are disturbed.
Storm Drainage Report – Roof runoff shall be directed to on-site roof drain drywells (Hearing’s Examiner Condition #9). Please revised design and provide sizing guidelines for the roof
drain drywells or explain why you have chosen to route the roof runoff through the treatment device and not directly to the stormwater pond.
Storm Drainage Report – Please include a copy of the FEMA map that shows the elevation of the 100 year floodplain and a copy of the LOMA in the stormwater report.
The Storm Maintenance Report appears to missing maintenance cost estimate and construction inspection report.
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.
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 1 of 17:
The conditions of approval shall be shown on the cover sheet.
Sheet 3 of 17:
The construction sequence should be modified to indicate when construction entrance, filter fabric fence, interceptor dike, check dams, and sediment pond will be installed.
Sheet 5 of 17:
The proposed grades are very difficult to read as they are they have a broken line type which is the same as the existing. Please revise the proposed grade lines to have a different
line type that is easier to differentiate.
There is a proposed contour on the south side of the site that is labeled as both a 338 and a 336 contour. Please clarify. If this is 338 feet in that area, it appears that there would
be some missing grades between the 2 buildings.
At the entry drive on Crystal Springs Road, there is a missing 340 contour between 341 and 339.
Indicate the elevation out the outflow pipe in to the stormwater facility. The outflow pipe needs to have an erosion control pad added.
The maximum height of a Type 1 Catch Basin is 5 feet. Catch Basins 1 and 2 shall be revised to Type 2 structures.
Please provide information on the grading of the 2 parking stalls on the southwest corner of the private road. Unless these stalls are at grade, there appears to be some missing grading
information.
There is missing grading information between the two buildings immediately south of the entrance on to Crystal Springs Road. It appears that the west side of these buildings are at
elevations 344 to 341 or so (please note that this is hard to discern so please label these
contours where indicated). The buildings are at elevations 338 and 337 respectively. It is understood that the buildings are acting as retaining structures. However, what happens
between the buildings? It appears that proposed grading is missing between these structures.
Please add spot grades where indicated to add clarity to the proposed grading.
The driveway grades are all labeled at 2%. However, spot checks of grades show that the driveway grades vary and are typically much higher. Random checking did not yield one driveway
at 2% (please note all driveways were not checked). If this is a minimum allowed grade, this would be better handled with a notation. If graded as shown, there will be a disconnect
between roadway and driveway grades.
How do these units function? There are many units that have finished floors of, for example, 336 feet but show 335 foot contours tying in at the front of the structure. Are steps proposed?
Please clarify.
Please remove all references to Pierce County from the standard notes.
A fence is required to be installed around the stormwater facility. The fence shall be at a minimum 4 foot high chain link with black or green vinyl coating. The access gate shall
be placed at a location that the maintenance can be completed for the facility.
Sheet 6 of 17:
In order to evaluate crossings, the water and sewer should appear in the background on the plan view.
Please provide curve data for the horizontal curves.
Sheet 7 of 17:
Drainage from proposed frontage improvements needs to be collected and conveyed to the on-site drainage facility as much as is feasible. If this is not attainable than you need to provide
documentation in the stormwater report for the proposed design. Please provide sizing calculations, basins, release rates etc for the frontage stormwater system.
Please provide existing topography for the ditch in the vicinity of the discharge point.
The maximum depth of a Type 1 Catch Basin is 5 feet. Catch basins 9 through 11 all exceed 5 feet and shall be type 2.
Please provide information on the type of handicap ramps proposed at the entrance on to Crystal Springs Road. Please include a detail of the ramp type. These details need to be consistent
with WSDOT standard details.
Please clarify the project limits or construction limits for the “Frontage Improvements” on Edwards and Crystal Springs Roads.
Sheet 8 of 17:
The slopes across the handicapped ramps along Crystal Springs Road exceed 2%. Please revise.
The spot grades noted at the intersection of the internal roadways don’t seem to match the grading plan which calls out this road at 1 percent grade. Please review and revise if necessary.
Sheet 9 of 17:
You show 3 street lights on Crystal Springs frontage. Please include all required details for installation of these lights.
The pond detail does not show the proposed access road. The access cannot be constructed on a 2:1 slope. Please revise.
Sheet 10 of 17:
The driveway access to the site should be designed using a concrete drive way approach instead of a paved access to the development. The City uses the concrete driveway approach to
all private access roadways.
Sheet 11 of 17:
Please make sure the existing utilities show up on the plans clearly. Some of the line work is hard to make out.
Please label where all connections to the existing system is to occur as well as any kind of fittings or modifications that may need to be made to provide an extension. It appears 2
connections are proposed but only one reference is made.
Please provide 2 gate valves at each tee.
Please revise the pig ports to be an end of line cleanout per city detail 7-20.
Is the existing 10 inch force main between the 2 proposed connections to remain? If it is to be removed, please note on the plans. If it is to remain, there is not adequate separation
between the sewer and the proposed water.
The STEP and forcemain mainlines and services will need to be within an easement to be dedicated to the City. Please show this on the plans and label.
Please show the proposed water lines in the background of the plan and indicate the separation between water and sewer. A minimum of 10 feet is required.
The City of Yelm requires one tank per a building. Please revise the design to accommodate this.
The tank sizes, controller location, hose bib locations and pump types are not shown on this plan.
This existing step main is 8” instead of 10” as shown on the plan.
The proposed Sewer mains will need to be 2” diameter mainlines not 1”.
The existing reclaimed water line that crossed this property must be shown on the plans.
The City of Yelm is going to construct a 12” sewer main in the same easement as the existing utilities are currently shown. The plans need to make provisions to accommodate this main
and also the improvements that you are proposing.
The Step System Notes indicate 18” vertical separation of utilities. 10’ of horizontal separation is also required.
Sheet 12 of 17:
It appears deflection is proposed for the construction of the STEP mainline. The City of Yelm does not allow pipe deflection, please revise.
The labels on the length of the 10 inch force main are inconsistent between this sheet and Sheet 11.
Sheet 14 of 17:
Please make sure the existing utilities show up on the plans clearly. Some of the line work is hard to make out.
Please provide 2 gate valves at each tee.
Is the existing water line between the 2 proposed connections to remain? If it is to be removed, please note on the plans.
The water mainlines and services will need to be within an easement to be dedicated to the City. Please show this on the plans and label.
Please show the proposed sewer lines in the background of the plan and indicate the separation between water and sewer. A minimum of 10 feet is required.
Please note the location of the irrigation meter(s) and note the appropriate backflow prevention.
Please indicate the connection type for all fittings – FL, FLxMJ, etc.
The water main shall be C900 Class 150, not Ductile Iron.
The relocation of the existing ten inch water main is required to meet the ten foot separation from the sewer and reuse mains.
The plans need to show all gate valves at the tees.
The developer is responsible for the cost of the fire hydrant locks and the City of Yelm Water Department will order and install them. Please add this note to the plans.
Where water and sewer lines cross, if 18” of separation can not be maintained, the sewer should be sleeved.
Please submit irrigation plans and show the connection points to the water source. There is a reuse water main bisecting this property and may be utilized for reclaimed irrigation system.
A Reduce Pressure Back flow assembly is required to be installed each water meter if reclaimed water is to be utilized.
The well should be decommissioned per DOE/DOH regulations and a copy of the report sent to the City of Yelm.
Sheet 15 of 17:
It appears deflection is proposed for the construction of the water mainline. The City of Yelm does not allow pipe deflection, please revise.
It appears that there may not be 6 inches of minimum separation between storm and water at approximately station 3+40. Please revise.
Water lines require a minimum of 42 inches of cover. It appears that only about 24 inches has been provided. Please revise.
Landscaping Comments:
Please improve the Open Space tracts located to the North and to the South east per the Planned Residential Development Standards.
Please provide Type II landscaping in the form of an 8 foot planter strip and a 6 foot fence along the south property line without encroaching into the Shoreline Jurisdictional Area.
Please remove existing sidewalk AND continue proposed sidewalk, Planter Strip and Street Trees (ie Type III Landscaping) along the east side of Crystal Springs/ Edwards. (See Attached
Landscape Plans.)
Street trees along Crystal Springs shall be from the City of Yelm street tree list found on our website. Please provide 1 accent tree for every 3 street trees.
Please provide City of Yelm street tree planting detail on sheet L2.
Please remove landscaping at the southwest corner of the site which interferes with the access to the property located at 404 Edwards Street. (See Attached Landscape Plans.)
Please see attached landscape plans for clarification to the above.
Misc. Comments:
The Approved for Construction Title Block on all sheets, must read “Development Review Engineer”.
Please callout and show the location for the Mail Box Cluster. These must be CBU Units. Please coordinate with Yelm Postmaster for location.
Please include and show on plan views, the dry utility joint utility trench easement location and callout the width of the trench. This needs to be shown on the plan sheets to be sure
there is enough room for the installation of step tanks and the required building set backs on site.
Please review and revise the plans to address the above referenced comments. When the project is resubmitted you will need to submit 4 sets of plans, 2 stormwater reports. The project
engineer should include a written response with the resubmittal, indicating how all the review comments above have been addressed or responded to. This will significantly expedite our
review of the project. If you have any additional questions or comments please do not hesitate to call or contact me at jimg@ci.yelm.wa.us.
Community Development Department
Respectfully,
Jim Gibson P.E.
Development Review Engineer
cc. Applicant
enclosure: Landscape Plans