HomeMy WebLinkAboutC_Response_Letter_210128_V1LITCHFIELD ENGINEERING
Civil Engineering & Development Services
12840 81st Avenue NE, Kirkland, WA 98034
tel 425-821-5038 fax 425-821-5739 ka.litchfield@frontier.com
November 5, 2020
City of Renton
Community & Economic Development
1055 South Grady Way
Renton, WA 98057
Attention: Michael Sippo, P.E.
Subject: Green’s Landing Construction Permit – 1st Review
5008 NE 2nd Street
Permit # C19000460
Dear Rohini:
In response to tour comments dated April, 29, 2019, I have completed revisions to the Green’s Landing
short Plat. For your use and review we have prepared this letter along with the revised plans , revised TIR,
and revised covenant. The following is a description of the revisions in response to your comments. The
engineer’s response is provided in bold.
Corrections:
Civil Plans (Sheets 1-13):
Sheet 1:
1. Provide legend of all shadings & symbols used in the plan set.
The legend has been provided on sheet 1.
2. Adjacent property data-parcel numbers, plat names.
The adjacent property data has been added to the plans.
3. Fire access roadway shall be a minimum of 20-feet wide or the new homes on Lots 2 and 3 shall
be fully fire sprinklered and a note that clearly shows this shall be placed on this cover sheet
Note has been added to the cover sheet.
4. Per King County records, the current parcel area is 50,112 SQ Ft (1.15 Acres). Provide the site
area correctly. Also, NPDES permit is required for projects with disturbance exceeding 1 acre.
The surveyed parcel area is 50,534 SF (1.16 acres). Understood a NPDES permit will be applied
for.
5. Maximum Impervious Area Allowed on Lots = .
The maximum impervious area allowed on each lot has been added.
6. Disturbed Area Including Frontage = (Square Feet and ___Acres).
Disturbed areas have been added to the plan.
Michael Sippo – City of Renton
Page 2
November 5, 2020
7. Provide SEPA mitigation conditionals of approval (on cover page if room allows, otherwise
provide a separate page.
No SEPA conditions were imposed on the development of the Green’s Landing Short Plat.
Sheet 3:
8. Maximum slope for minimum 3 feet back of sidewalks is 4H:1V. Label accordingly (typical on all
frontages).
Note has been added to the plans.
9. Label the % longitudinal slope of the private access tract.
The longitudinal slope has been added.
Sheet 4:
10. Provide arrows that show the existing ROW limits.
Dimension arrows have been added.
11. Provide blowup of the project transition and connection to the adjacent existing features.
Include the grading information also.
Blow up figures of the transitions have been added to the plans.
12. Suggest adding site improvement note 19 – “Construct HMA pavement. See SD COR 103 Sheet
8”.
Site Improvement Note 21 “Construct HMA paving per SD COR 103 sheet 8” has been added
to the plans.
13. Label the type of CB (typical). Label both IE in and IE out along with the pipe direction (typical).
CB labels have been updated.
14. Add stop sign. Install stop bar. Location depends on location of new ADA ramp facing east.
Stop sign and stop bar have been added to the plans.
15. Remove ex. rpms beginning at the ex. Stop bar and extending to the west.
Site Improvement Note 20 regarding the ex. rpms has been added to the plans.
16. Show matching ADA ramp on opposite side of the street.
ADA ramps are now shown.
17. Add stop sign.
Stop sign and note added.
18. Install stop bar. Location is dependent on location of new ADA ramp facing south.
Stop bar and note added.
19. Salvage existing stop sign, post, and object marker (OM3-R) to City. An option would be to
remove, protect, and relocate ex. Stop sign and post and salvage object marker to City. With
either option, location of the stop sign is dependent on location of new ADA ramp facing east.
Note has been added to the plans.
Michael Sippo – City of Renton
Page 3
November 5, 2020
20. Curb & Gutter?
Curb and gutter have been called out.
21. Install centerline rpms 14 feet from north curb line. Extend from stop bar 30 feet to west.
Centerline rpms and note have been added to the plans.
22. Suggest adding Site Improvement Note 1.
Site Improvement Note 1 has been added as suggested.
23. Provide thicker line.
The storm lines have been thickened.
24. Site improvement note 1?
The note has been revised to be site improvement note 1.
25. Minimum width is 12 feet.
The driveway has been revised to be 12’ wide.
26. Private stormwater facility.
Private stormwater facility has been called out.
27. Building permit for the stormwater vault shall be obtained by applicant and approved structural
plans for the stormwater vault shall be provided prior to the construction permit issuance.
Understood. A note has been added to the plans.
28. Provide blowup of the project transition and connection to the adjacent existing features.
Include the grading information also.
Blow up figures of the transitions have been added to the plans.
29. Post Office approval of mailbox location.
An approval block for the US Postal Service has been added to the plans. Contact with the
local postmaster has recently been made and approval of the NDCBU is expected in the near
future.
30. Label the longitudinal slope of the private access.
Longitudinal slope has been added.
Sheet 5:
31. Provide legend of shadings, symbols, and hatchings use in the plan sheets (typical on all sheets).
The legend has been added to all pertinent sheets.
32. Full street grind & overlay.
Note has been added to the plans.
33. In all property frontages.
Understood. Note has been updated.
34. Provide a table of elevations of all utility pipe at utility crossings. Add column of the elevation
difference between the nearest edges of the pipes at the crossings.
A utility crossing table has been added to the plans.
Michael Sippo – City of Renton
Page 4
November 5, 2020
35. Label the vertical separation at the crossing.
The separation is included in the table.
36. Full street width grind & overlay required on NE 2nd Street. Label accordingly.
Note has been added to the plans.
37. Show how this connects to existing system.
A catch basin has been added to the plans.
38. Provide blowup and detail of the connection with the existing stormwater system. Stormwater
catch basin?
A blowup has been added to the plans. The connection will be made via a new catch basin at
the location of the existing culvert.
39. Private.
Private has been added.
Sheet 6:
40. Not enough cover for a PVC pipe. Use DI underneath driveway.
Plans have been revised to indicate DI pipe under the driveway.
41. Water quality water surface elevation? Define abbreviations.
The abbreviations are defined on the legend. The legend has been added to the sheet.
42. Cover is what’s above the pipe and does not include the pipe diameter. Cover in this case is
actually 2.5’ which is less than the minimum required for a PVC pipe. Use CPEP or PPP instead.
The callout has been revised to clarify that there is 3.5’ of cover over the water main. The
storm pipe has been revised to PPP.
43. Show the SS pipe crossing on the profile. Simply pointing to the location where the SS crosses
isn’t clear enough.
The SS pipe has been added to the profile.
44. 32’ to be dedicated to the City. Currently 30 feet is in an easement as per King County Assessor
Map. Show & label the property lines correctly.
The section has been updated accordingly.
45. Label pavement layer thickness in this sheet.
Layer thickness has been called out.
46. Curb and gutter?
Curb and gutter have been called out.
47. Label the pavement layer thickness.
Layer thickness has been called out.
Sheet 7:
48. Label elevation.
Michael Sippo – City of Renton
Page 5
November 5, 2020
Elevations have been added to the detail.
49. Label the depth.
Plans have been revised to call out depth.
50. Private.
Updated.
51. Separate building permit required for the structural review of the stormwater vault.
Understood. Note has been added to the plans.
52. Show the flow direction arrow.
Flow direction arrow has been added.
53. Standard detail comments.
Per our phone conversation, comments on the standard details are not applicable.
54. Why is this detail provided? A-A and B-B already show sections and dimensions of the vault.
Detail has been removed.
55. Label elevation of orifice.
The elevation of the orifice has been labeled.
56. Welded not bolted.
Understood. Detail has been updated.
57. Omit removeable screen.
Understood. Detail has been updated.
Sheet 10:
58. Private sewer easement to be provide in Lot 1 for the sewer service to Lot 2.
A private sewer easement has been called out.
59. Provide finished floor elevation (FFE) for each lot. Provide a Table that shows FFE of and IE of the
IE of the sewer stub for each lot. Preferred (FFE-IE) is minimum of 5 feet.
A table has been added.
60. Private sewer easement to be provided in Lot 4 for the sewer service to Lot 3.
A private sewer easement has been called out.
61. Move SS cleanout to location near the edge of the sidewalk (typical).
SS cleanouts have been relocated.
62. Concrete pad required to be provided around the cleanout. Show it in the plan sheet.
Concrete pad has been added.
63. Side sewer riser connection to sewer main.
Note has been updated.
64. Minimum side sewer slope is 2% add note in the plan.
Note has been added to the plan.
Michael Sippo – City of Renton
Page 6
November 5, 2020
65. Sewer manhole #2 is greater than 20 feet in depth. So the manhole is required to be a 60”
manhole. Sewer laterals into lots should have a cleanout at edge of concrete sidewalk, then
extend the 6” size to about 6 feet into each lot, and then transition to 4” size. (typic al on all
sewer laterals to each lot). Do not need the 4 feet stub at the end of the 8-inch sewer main, can
end at the sewer manhole.
Manhole has been revised to 60”. The 4’ stub at the end of the sewer main has been
removed.
Sheet 11:
66. Manholes > 20 feet deep required to be minimum 60” size sewer manhole.
Manhole has been revised to 60”.
Technical Information Report (TIR):
1. Directed drainage review.
Understood the TIR worksheet has been revised to indicate Directed Drainage Review.
2. Permit bond before construction & maintenance bond after construction.
Understood. TIR worksheet has been revised to indicate “Yes” for Financial Guarantees and
Liability.
3. Existing parcel area is 50,112 square feet (1.15 acres)-per King County Records. Provide the
parcel area information. Also provide the net project disturbance area information (project
disturbance includes site plus frontage + street work area).
The surveyed parcel area of 50, 534 SF (1.16 AC) was used for the project. The net project
disturbance area has also been added to the TIR.
4. Mention if the site has or does not have any critical areas. If there are critical areas, mention the
type.
The TIR has been revised to state that there are no critical areas onsite.
5. Provide the north arrow in the vicinity map.
North arrow has been added.
6. Is there any are drainage to the site from the north?
There is no significant drainage from the north. There is an existing CB located to the north of
the site within Hoquiam Ave NE that collects drainage from the north. A note stating that
there is no significant drainage from the north has been added.
7. Mention the value of the 100-year peak discharge and the corresponding discharge device (I.E.
rock pad, etc.). Provide size and description of the ditch.
The existing grass lined ditch is approximately 2’ wide by 1’ deep. The ditch is proposed to be
replaced with 12” CPEP and backfilled with gravel. The discharge will be via a new catch basin
at the location of the existing culvert. Therefore, the outfall is to an existing conveyance
system.
8. Private.
TIR has been revised to indicate a private detention/water quality system.
Michael Sippo – City of Renton
Page 7
November 5, 2020
9. Mention about the upstream analysis.
The TIR has been revised to discuss the upstream analysis.
10. Discuss about the stormwater vault design. The maximum depth from finished grade to the vault
invert. Dimensions. The control structure. Restrictor device provided. Etc.
The TIR has been revised to include a detention system section that describes the proposed
vault design.
11. Confirm the On-site area. King County shows parcel area as 1.15 ac.
TIR has been revised to indicate the surveyed area of 1.16 ac of on-site area prior to ROW
dedication.
12. Add note: For flow control durations standard matching forested site conditions, match the flow
duration of the predeveloped rates for forested site conditions over the range of flows exceeding
from 50% of 2-year up to the full 50-year flow and matches peaks for the 2 year and 10 year
return periods.
TIR has been revised to include the note.
13. Total area after project = .
The total onsite area after project completion is 39,808 SF (0.91 acres). This area is reflected
as the Total Onsite area under the Developed Conditions section on page 14.
14. Confirm the onsite area.
TIR has been revised to indicate the surveyed area of 1.16 ac of on -site area prior to ROW
dedication.
15. Add note that the highest point of a vault bottom shall be at least 6” below the outlet elevation
to provide for sediment storage over the entire bottom.
Note has been added to the TIR.
16. Private.
TIR has been revised to indicate a private detention/water quality system.
17. Mention how the cell is separated into two cells (removable baffle?).
The TIR has been revised to state that the vault is separated into two cells by a baffle wall.
18. 2017.
TIR has been revised.
19. Mention the design depth of the combined vault and the actual provided depth.
The water quality section of the report has been updated to discuss the required depth and
depth provided.
20. Include the internal dimensions of the vault (LxWxH).
The internal dimensions of the vault have been added.
21. Onsite.
TIR has been revised to clarify that the flow control BMPs are onsite.
Michael Sippo – City of Renton
Page 8
November 5, 2020
22. Mention the required amount of onsite BMP and the amount of onsite BMP provided.
BMPs are required to be implemented to the maximum extent feasible. All proposed onsite
target surfaces are mitigated through the use of limited infiltration, permeable pavement,
and soil amendment. The TIR has been revised to include the square footage of hard surfaces
mitigated.
23. Discuss if rain garden and/or bioretention BMPs were studied. If they were studied, mention why
they were considered infeasible.
The TIR has been revised to include a discussion regarding the feasibility of bioretention and
rain gardens.
24. Did not see it in the following page.
TIR has been revised to include the trench sizing calculations.
25. Mention about the perforated pipe connection onsite BMP.
The perforated pipe connection onsite BMP has been added to the BMP discussion.
26. Verify the site area with the area in the King County Records.
TIR has been revised to indicate the surveyed area of 1.16 ac of on -site area prior to ROW
dedication.
I am hopeful that the above comments and enclosures are sufficient for you to complete your final review
and project approval will be forthcoming in the near future. I thank you in advance for the time that you
have committed to this project.
Sincerely,
Litchfield Engineering
Keith A. Litchfield, P.E.
Principal Engineer
Enclosed: Revised LE Green’s Landing Short Plat Civil Plans dated 10-28-20
Revised LE Green’s Landing Short Plat TIR dated date 10-22-20
Copy: Sid Constantinescu, Pacific Crest Realty Advisor LLC