Del's Farm Supply Review Letter No 1IPM.Note
Del's Farm Supply Review Letter No.1
Steve Harrington
EX
/O=CITYOFYELM/OU=FIRST ADMINISTRATIVE GROUP/CN=RECIPIENTS/CN=STEVEH
Del's Farm Supply Review Letter No.1
Steve Harrington
EX
/O=CITYOFYELM/OU=FIRST ADMINISTRATIVE GROUP/CN=RECIPIENTS/CN=STEVEH
Jim Gibson
Del's Farm Supply Review Letter No.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
Jim: Here is a copy of the Del’s Farm Supply Review Letter No.1 for you to mark up or add comments. I have also returned the packet to you with comments and markups.
Thanks,
Steve
<DC90029353CCCD468AA2A2858FFCD8F528F73E@server1.ci.yelm.wa.us>
Del's Farm Supply Review Letter No.1.EML
Steve Harrington
Steve Harrington
11.0
Microsoft Exchange Server
00000002SERVER1/o=CITYOFYELM/ou=first administrative group/cn=Recipients/cn=steveh
Engineering Review No. 1 Del's Farm Supply
Engineering Review No. 1 Del's Farm Supply
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
Engineering Review No. 1 Del's Farm Supply.doc
City of Yelm
Community Development Department
105 Yelm Avenue West
P.O. Box 479
Yelm, WA 98597
May 16, 2007
Hatton, Godat and Pantier
1840 Barnes Boulevard S.W.
Tumwater, WA 98512
Re: Del’s Farm Supply – Site Construction Documents Review No.1, Engineering, Planning, Water and Sewer Corrections and Comments
City of Yelm Project Number - SPR-05-0673-YL
Mr. Steven D. Hatton, P.E.
The following need to be corrected on the Del’s Farm Supply drainage report and construction plans. Engineering, Planning, Water and Sewer comments are as follows:
Storm Drainage Report:
Storm Drainage Report Section 1 – The project appears to include 2 parcels – 64303200700 and 64303200704. According to the Thurston GeoData mapping, these parcels total 7.47 acres.
Please revise the project description accordingly.
Storm Drainage Report Section 6 – The wrong FEMA Firm Map panel has been sited. This site is located on FEMA Firm Map 530188 0365 D. On this map, the flood plain for Yelm Creek is
between 344 and 345 feet. Please revise this section to indicate that there is a flood plain on the site and note the correct panel number. Further, the site is located in zone A7,
not zone X.
Storm Drainage Report Section 8 – Please specify how much pervious and impervious area is draining to each of the facilities (wet pond, bio swale, infiltration pond). This should correspond
to the sizing computations of Appendix B.
Storm Drainage Report Section 8 – The pond bottom area for the infiltration pond is identified as both 3,750 sf and 2,532 sf. Please revise to the one correct number.
Storm Drainage Report Section 8 – The required infiltration pond volume is specified as 1,467 cubic feet. Appendix B seems to indicate this required volume is 2,356 cubic feet. Please
revise or clarify.
Storm Drainage Report Section 8 – According to the DOE Manual Section III-6.3 General Criteria #1 – biofiltration swales that are located within soils that have good infiltration should
be lined. Please indicate that the bioswale be lined to prevent infiltration.
Storm Drainage Report Section 8 – According to the DOE Manual Section II-6.3 General Criteria #6 – if the slope of a biofiltration swale is less than 2%, an underdrain is required.
Please revise the swale design to include an underdrain.
Storm Drainage Report Section 8 – The slope for the swale, according to step P-2, should be 0.01 not the 0.02 shown. It appears that the correct value was used for the sizing of b.
Please revise the text.
Storm Drainage Report Appendix A – A geotechnical investigation performed by a registered geotechnical engineer is required to establish the design infiltration rate of the soils. The
report should also include an estimated elevation of the seasonal high groundwater table since the site is located in a high ground water hazard area. Per the requirements of the DOE
Storm Manual, a 3 foot separation is required from the bottom of the infiltration facility to the high groundwater elevation.
Storm Drainage Report Appendix B– According to the swale computation, the 6 month flow and the 100 year flow for the swale are 0.09 and 0.32 cfs respectively. Where are the computations
of those values? Please provide the modeling information for the sizing of the bioswale. If this has been included, please delineate where it can be found.
Storm Drainage Report Appendix B – The pond volume calculator for the infiltration pond seems to have incorrect information. The 100 year volume appears to be 2,356 cubic feet from
the model output. Further, several of the elevations have the exact same volume. With increasing height, the volume would increase. Further, there is a large jump between the volume
for 347.8 and 348. What happens here? Finally, the infiltration base area and base elevation do not seem to correspond to this pond. Between Section 8 and Appendix B, 3 different
pond bottom areas have been listed. Please review and revise as required.
Storm Drainage Report Appendix B – The model input has the bio swale as 60 feet long and at a 2% slope. The rest of the report indicates that the swale is 100 feet long at a 1% slope.
Please revise.
Storm Drainage Report Appendix B – Overall, it is difficult to understand the model information given. The following information should be provided by the model:
Input data used (ie. area impervious, area pervious) for all drainage basins
6 month flow for all drainage basins
100 year flow for all drainage basins
Volume required for wet pond
Volume required for infiltration pond
This information may be provided but it is unclear. Please circle these items in each of the hydra models to help identify this information.
Storm Drainage Report – As there are 2 treatment facilities, there are at least 2 drainage basins. Please provide a drainage basin map identifying the drainage areas to each facility.
For each drainage area, please identify the total impervious and pervious area. In addition, please identify the drainage basin to the existing drywell.
Storm Drainage Report – Please provide pipe sizing computations for all drainage pipes.
Storm Drainage Report – Please provide further information regarding drainage to the existing drywell. This information should include the size of the drywell and sizing calculations
to ensure the existing drywell has adequate volume for the drainage area.
Storm Drainage Report - According to the report, 0.5 acres drain to the existing drywell. Given the building is only 8,205 square feet, the remaining drainage area is presumably asphalt
parking area. The parking lot drainage requires treatment prior infiltration.
Storm Drainage Report – Please demonstrate compliance with Section 14.08.120(G) of the Yelm Municipal Code.
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. Jim, I think this note confuses the designer or engineer when no marked
up plan sheet is included.
Sheet 1 of 13:
What is in the area that has a sump pump that will be direct to the catch basin #5? If this area is covered, the sump pump should be connected to sewer and not to the stormwater facilities.
According to the FEMA map for this area, the floodplain for this site is 344 feet at the north property line and 345 feet at Bald Hills Road. Please revise the floodplain shown to correspond
with the FEMA mapping.
Please identify the shoreline limits and indicate that this will be dedicated as open space per the mitigation measures of the SEPA MDNS.
Please add the SPR conditions of approval to the cover sheet.
Sheet 4 of 13:
According to Section 14.08.120(G) of the Yelm Municipal Code, a 6 foot separation is required between the bottom of the infiltration facility and the base flood elevation. Please ensure
that the pond bottom elevation meets this requirement.
Label all proposed contours. Several of the following comments are based on the assumed elevations of the contours provided.
The spot grades and the contours for the biofiltration swale don’t appear to match. Please adjust. It may be beneficial to provide a blow up of this area to help identify the proposed
grading.
The biofiltration swale should be hydraulically separated from the infiltration pond. As currently designed, it appears that flows less than the 100 year flood will back up in to the
swale. This is hard to determine as there appear to be errors in the storm report delineating where the 100 year flood elevation is in the infiltration pond. Please revise as necessary
to ensure that the biofiltration swale is above the 100 year flood elevation of the infiltration pond.
There is a notation to remove a temporary spillway but the note is pointing to the bottom of the wet pond. Where is this spillway?
The pipe connecting CB# 5 to the wet pond has an incorrect slope for the inverts given. Further, with the inverts provided for the CB and the downstream outfall, the pipe will have
a negative slope. Finally, it appears that the downstream outfall invert may be in error based on the contour information provided. Please revise.
The wet pond bottom is labeled as elevation 344 but the contour of the bottom is at elevation 345. Inlet pipes to the facility need to be at or above this elevation.
The slope for the pipe connecting the wet pond to the infiltration pond has a mislabeled slope. The slope, based on the inverts, is about 7%, not 0.5%. Further, the downstream outfall
invert is labeled as 347 but appears to be at 346.5 according to the contour information.
If the soils have an infiltration rate of 10 inches per hour, the wet pond will require a liner. If groundwater has the potential to be high, precautions against flotation of the liner
will need to be taken.
The wet pond should have a length to width ratio of 3:1. In addition, the inlet and outlet to the wet pond need to be at opposite ends of the pond. Currently, the inlet and outlet
are on the same face of the pond. Please revise.
Provide the elevation of the pond spillways.
Please provide existing rim and invert information for the catch basin north of the 8,205 square foot building. Does this catch basin convey the runoff to the existing drywell?
Is there a curb along the parking area adjacent to the wet pond? If not, much of the parking lot drainage will sheet flow around or directly in to the ponds. Provide a curb to confine
the drainage and a catch basin to collect the drainage and direct it to the wet pond.
The pipe connecting CB#5 to the wet pond will daylight as it goes through the slope of the infiltration facility. Please revise to provide adequate pipe cover.
The curbing that has been added around parking stalls 25 through 34 will trap drainage and create pending as currently graded. This area needs to be regarded to allow the flow out or
a catch basin needs to be added to collect the drainage and direct it to the wet pond.
Sheet 5 of 13:
Drainage for frontage improvements shall be routed to the storm system for the proposed project installing the improvements. CB #1 shall be connected to CB #2 and conveyed to the on-site
drainage system. Modify pond and swale sizing as required.
Please show the utility crossings for the storm line.
It is unclear if there is an existing paved shoulder on Bald Hills Road. If there is, the asphalt sidewalk should extend to this shoulder.
The cross section shown does not accurately reflect the existing condition of Bald Hills Road. The actual centerline of the existing road does not match the centerline of the right
of way. Therefore, the existing crown appears to be about 5 feet south of the centerline shown. Please revise the cross section to accurately reflect the existing crown.
Sheet 6 of 13:
It appears that the details provided may conform to the City of Yelm details. However, the current standard City of Yelm details (with title block and notes) shall be used. Please
replace.
Provide design computations for the paving section. Per the Minimum Street Design Standards Table of the City of Yelm Development Guidelines, the pavement for an urban arterial requires
a special design.
Sheet 7 of 13:
Please provide a depth for the biofiltration swale detail.
Revise the pond sections per the comments on previous sheets.
Sheet 8 of 13:
Please label the length, size, and type of water line that is being installed.
Please provide a notation regarding the connection to the existing water main.
Replace the blow off called out at the end of the force main with an end of line cleanout.
The sewer service between the STEP tank and the service box should be much smaller (1-2 inch) than 6 inches and would be a pressurized pipe (slope information not required). Please
revise.
Sheet 9 of 13:
The sewer force main needs to be 10 feet from the existing water main. Only 8 feet of separation has been provided.
Show all utility crossings on profile.
Please call out the bend at the service connection.
The sewer force main should be rerouted as shown. This will require roughly the same amount of pipe but will require less open cutting of roadways. Further, the service should be moved
to provide a straighter service connection.
The proposed mainline extension is shown as 4” does it need to be this big of line.
Clearly show the method of connecting to the existing sewer main.
Please show the size of step tank.
Please include the bury depth of the step tank.
City of Yelm Sewer Department prefers Simplex pumps (How many pumps will the tank have installed).
Please show the location of the pump control panel on plans.
Where is the nearest hose bib located, in relation to the step tank.
The new step sewer mainline requires a clean out at the end of the line, not a blow-off.
What is the size of service line for the step tank.
Please place the Carson Box in the planter strip.
Please include the current COY Standards on the drawings.
Sheet 10 of 13:
Provide an end of line cleanout detail – COY Standard Detail # 7-20.
Sheet 11 of 13:
A 45 degree bend is referenced that does not seem to be present.
As the water meter is within an asphalt area, it will require a traffic bearing lid.
Please show the storm and sewer crossing on the profile.
Domestic water meter needs to be placed in the same location as the irrigation water meter.
Both domestic water meter and irrigation meter are required to back flow assembly devices behind the meters.
The water main on Bald Hills Road is a 10” water main, not 8”.
Why is there a 6” 45 degree bend on the fire hydrant note?
Bollards shown on the plans are not what are shown in the COY Standard Detail 6-12.
The existing well will need to be abandoned per DOE / DOH requirements and a copy of the report sent to the City of Yelm Water Department at 901 Rhoton Road Yelm Washington 98597.
Landscaping Plans:
76. Please provide 1 accent tree for every 3 street trees located on Bald Hills Road as a part of Type III landscaping requirements. Approved accent trees can be found on the City
of Yelm Street tree list located on our city website.
77. We suggest that the Worplesdon Sweetgum tree which is being planted as a part of the parking lot landscaping be replaced with something smaller due to the possibility of rapid damage
to the pavement caused by the shallow and widespread root system of the Worplesdon Sweetgum.
78. Please continue the Type V landscaping around the stormpond and also provide a 4 foot black or gray vinyl fence around the perimeter of the stormpond.
79. Please provide the City of Yelm street tree planting detail on the landscape plans, which can be found on the City of Yelm website.
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
May 16, 2007 Page 2 of 7
(360) 458-3835
(360) 458-3144 FAX
www.ci.yelm.wa.us
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ENGINE~2.DOC
Engineering Review No. 1 Del's Farm Supply.doc