GMS Review Letter 1IPM.Note
GMS Review Letter 1
Steve Harrington
EX
/O=CITYOFYELM/OU=FIRST ADMINISTRATIVE GROUP/CN=RECIPIENTS/CN=STEVEH
GMS Review Letter 1
Steve Harrington
EX
/O=CITYOFYELM/OU=FIRST ADMINISTRATIVE GROUP/CN=RECIPIENTS/CN=STEVEH
Jim Gibson
GMS Review Letter 1
00000002SERVER1/o=CITYOFYELM/ou=first administrative group/cn=Recipients/cn=stevehMicrosoft Exchange Server
00000002SERVER1/o=CITYOFYELM/ou=first administrative group/cn=Recipients/cn=stevehMicrosoft Exchange Server
This is in the project file
<DC90029353CCCD468AA2A2858FFCD8F50A8469@server1.ci.yelm.wa.us>
GMS Review Letter 1.EML
Steve Harrington
Steve Harrington
11.0
Microsoft Exchange Server
00000002SERVER1/o=CITYOFYELM/ou=first administrative group/cn=Recipients/cn=steveh
GMS Town Homes Review Letter # 1
GMS Town Homes Review Letter _ 1
Jim Gibson
EX
/O=CITYOFYELM/OU=FIRST ADMINISTRATIVE GROUP/CN=RECIPIENTS/CN=Gibson
jimg@ci.yelm.wa.us
jimg
Community Development
Jim Gibson
Jim Gibson
Gibson
GMS Town Homes Review Letter # 1.doc
April 27, 2007
GMS Construction
P.O. Box 422
Spanaway, WA 98387
Re: Site Construction Documents - Yelm Town Homes
City of Yelm Project Number - SUB-05-0657-YL
To Whom It May Concern:
The following need to be corrected on the GMS Town Homes construction plans, stormwater drainage report. Comments are as follows:
Storm Drainage Report:
Storm Drainage Report Part 1 – Drainage Plan – Conveyance of roof drainage is not addressed. According to the grading and drainage plan, it will be tightlined to the storm drainage
system. Please specify how roof runoff will be handled and revise calculations as necessary. Currently, the drainage calculations do not include the total amount of impervious area
if roof drains are included.
Storm Drainage Report Appendix 1 – Storm Drainage Calculations – The SCS curve number assigned to the lawn areas is high for the type of on-site soils. Given the high infiltration rate
recommended by the geotechnical engineer, it is more appropriate to use a Type A soil for Table III-1.3. This would yield a curve number of 68.
Storm Drainage Report Appendix 1 – Storm Drainage Calculations – The StormShed input data does not match the post developed basin area summary. The total amount of impervious area is
0.54 acres (including roof area) not 0.30 acres. If roof runoff is also to be directed to the infiltration trench, it needs to be sized for the entire 0.54 acres of impervious area.
Therefore, the StormShed computations need to reflect this total impervious area. Please note, roof area drainage need not be included in computations of required treatment volume
or flow as long as roof flow does not mix with dirty flow. Therefore, separate StormShed computations may be required to assess treatment requirements and storage requirements. Please
revise StormShed computations and related facility sizing computations.
Storm Drainage Report Appendix 1 – Storm Drainage Calculations – The calculations for the infiltration trench are hard to follow and don’t seem to follow a logical flow. For instance,
in one step, the hydraulic gradient is assumed to be 1. With a hydraulic gradient of 1, the distance L is not longer required. However, the value of L is subsequently given and used
for calculation of the flow. Please be consistent between assumptions and calculations provided.
Storm Drainage Report Appendix 1 – Storm Drainage Calculations – Please provide a calculation of the storage volume provided by the proposed infiltration trench.
Storm Drainage Report Appendix 1 – Storm Drainage Calculations – Please provide drawdown calculations for the 10 year, 24 hour storm. According to Section III-3.6.5 of the Department
of Ecology (DOE) Stormwater Manual, infiltration trenches shall be designed to completely drain stored runoff within one day following the occurrence of the 10 year, 24 hour storm.
Currently, drawdown calculations are only provided for the 100 year event.
Storm Drainage Report Appendix 5 – Soil Evaluation Report – Please provide a map of the site showing the location of the test pits used for establishing the proposed infiltration rate.
In addition, although groundwater was not encountered in any of the test pits, an assessment of the high groundwater elevation needs to be provided. Infiltration facilities need to
have a 3 foot separation from the high groundwater elevation.
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.
When using keynotes, you need to provide a number for each note. Since location information is given in the keynote, a typical notation number cannot be used. Please revise all keynotes
to have individual call out numbers.
Sheet 2 of 10:
Please provide filter fabric fence along the southern property boundary as shown on the plans.
Inlet protection should be indicated for proposed catch basins. Please provide a notation on this sheet and a detail on Sheet 3 of 10.
Will the existing curb be removed to install the construction entrance? If the curb is to remain, it will likely be damaged during construction and require repair. Please note what
will occur with this curb.
Sheet 3 of 10:
Please provide details for inlet protection and the proposed level spreader.
Please ensure notations and details match. The size of the quarry spalls called out for the construction entrance does not match between the details and notes. The depth of post bury
for the filter fabric fence also does not match between the details and notes.
Sheet 4 of 10:
As a separate drawing for frontage improvements has not been provided, comments related to frontage improvements on Longmire Street will be made on this sheet.
A cross section showing the existing conditions and proposed improvements for Longmire Street shall be provided. It appears that the curb is existing and planter and sidewalk are the
only items to be added, but it is not clear based on the drawings provided.
Please include City of Yelm Standard Detail 4-11 – Cement Concrete Sidewalk.
Sheet 5 of 10:
.Backflow prevention is required for the irrigation and fire lines. A backflow prevention detail has been provided on Sheet 6 but backflow prevention is not indicated on this sheet.
If the backflow prevention for the fire line is within the building, please note this on the plans.
Where is the fire line going in to each building? A separate fire service is needed for each building. Please show the required fire lines and indicate their size.
Please indicate the location of the post indicator valve for each building. If it will be located on the building, please make a note of it.
The FDC for the building on the north side of the drive aisle (units 1-6) needs to be located in the vicinity of a fire hydrant. The fire hydrant must be located on the same side of
the drive aisle as the FDC.
Please indicate size of existing water mains.
Please indicate type of pipe material for the water main.
Please provide a profile of the proposed water main. The profile should provide the information indicated in the plan checklist provided in Chapter 3 of the City of Yelm Development
Guidelines.
Please show an easement over the water main per the requirements of the City of Yelm Development Guidelines.
The water main to the fire hydrant will need to be an 8 inch main.
All water lines, sewer lines, connections and fittings need to have 10 feet of horizontal separation.
A back flow prevention assembly will be required for the irrigation system.
Sheet 6 of 10:
If the backflow prevention for the fire line will be on the exterior, please provide a detail.
Sprinkler systems will require a back flow prevention assembly at the connection point on the water main.
Note 5 should read “fire hydrant assembly”.
If the Town Homes are over two stories high, each domestic service will require a back flow prevention assembly.
The Developer will be responsible for the cost for fire hydrant locks, The City of Yelm Water Department, will order and install the fire hydrant locks.
Sheet 7 of 10:
Please indicate size of existing sewer mains.
Please indicate type of pipe material for the sewer mains.
Please provide a profile of the proposed sewer mains (both the gravity and STEP main). The profile should provide the information indicated in the plan checklist provided in Chapter
3 of the City of Yelm Development Guidelines.
Each gravity service shall have a cleanout. Please indicate these on the plans, including invert information.
Please provide an easement over the sewer force main and STEP tank per the requirements of the City of Yelm Development Guidelines. No easement is required for the gravity main as this
will remain private.
City of Yelm Sewer Department recommends using the existing 2 inch service connection located near the northwest property corner along Longmire Street this service is located closer
to the proposed step tank location.
A hose bib will be required within 50 feet of step tank.
There is a typo calling out a 2 inch SS, this is incorrect and will need to be changed to read 8 inch.
The Step Tank is located in the parking area, this will require the tank and lid to be traffic bearing.
Sheet 8 of 10:
Provide a detail for the gravity service connections to the gravity main.
Sheet 9 of 10:
A notation indicates that roof drainage will be tightlined to the storm drain system. Roof drainage was not included in storm drainage sizing calculations. Please revise the storm
drainage report to reflect the roof drainage tightline.
Please show the proposed roof drain tightlines. It is not clear how they would connect to the storm system. If they connect upstream of the AquaSwirl, the AquaSwirl will need to be
sized for the roof drainage as well. If they connect downstream, how will this occur?
Please show the sewer and water systems in the background to ensure no conflicts occur. This will be especially critical once the roof drain tightline system is shown.
According to the infiltration trench detail on Sheet 10, the trench shall have a minimum cover of 2 feet. With a pipe invert of 336 feet, the top of the trench will be at elevation
340 feet. Therefore, the first 40 feet of the trench will not have minimum cover. Please revise the grading or lower the trench to achieve minimum cover.
Sheet 10 of 10:
Please revise the infiltration trench detail as shown.
Sheet L 3 of 3:
Relocate or shift the trees that are within the water easement on the east property line to avoid damage to waterline from tree roots.
47. Relocate or shift the trees on the northwest property corner outside of the utility easement to avoid damage caused by tree roots.
Any trees that are relocated should be replanted through out the project site, possibly along the south property line.
Please provide more dense sight obscuring landscaping around the refuse container.
Trees need to be planted at least 5 feet from any water meters.
Should you have any questions or comments, please contact me at (360) 458-8423 or e-mail me at steveh@ci.yelm.wa.us at your earliest convenience.
Respectfully,
Community Development Department
Steve Harrington
Civil Inspector
Copy: Jim Gibson, Development Review Engineer
April 27, 2007
Page 5
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GMSTOW~1.DOC
GMS Town Homes Review Letter # 1.doc