HomeMy WebLinkAboutSPU Forest Terrace Project-- Comments 7-31-2020Comment #
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Sheet
23, 51, 49
23, 25, +24, +49
48, 50
48, 50, 49
48, 50, 49
2 of 2 (DHC Pipe Support Plan)
2 of 2 (DHC Pipe Support Plan)
1 of 2 (DHC Pipe Support Plan)
RISA analysis (page 1-- Member Section Deflections Strength)
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General
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48, SPU Plan/Exhibit 1 od 2
Forest Terrace Project
Date: 7/31/2020
Reviewer: Ryan Manning (SPU)
Description (per Developer Engineer)
Currently there is an existing 24” storm line running down the west side of Union Ave that discharges onto our property. We are proposing to reroute this storm line starting at STA
32+04, sheet 23 of 87, underneath the proposed sidewalk so it will bypass the Forest Terrace site. This will require the replacement of EX CB#10475 with a new shallow manhole, CB#41B,
per the City of Renton standard detail 400.2 which can be found on sheet 51 of 87. The structure does not have a sump and will minimize the impact on the SPU line.
Proposed 12-inch storm line between CB#20 and CB#21, sheet 23 & 25 of 87, has a horizontal separation of +/- 2.8’ between SPU line. Structures along the section has been minimized
to reduce potential impacts to the SPU line and still collect storm runoff from Lot 25.
Proposed Water connection a STA 36+17, sheet 48 & 50 of 87, we have moved the water connection to the north to avoid crossing underneath the SPU main as previously designed.
Water service crossing for Lot 25 @ STA 32+34, sheet 48 & 50 of 87, which is placed over the SPU line maintaining 18-inches of vertical separation. A crossing detail has been provided
on sheet 50 of 87.
Sewer service crossing for lot 25 @ STA 32+58, sheet 48 & 50 of 87, which is a 6” ductile iron pipe going over SPU line maintaining 24-inches of vertical separation. A crossing detail
has been provided on sheet 50 of 87.
Sewer main crossing @ 36+39 is the only proposed crossing going under the SPU line, potholed elevations indicates there is +/- 3’ vertical separation between the two lines. We have
coordinated with D.H. Charles Engineering, Inc for structure support design while trenching under the SPU line. Please see attached documents for structural calculations and plans.
In addition, sheet 2 of 2 of the structural plans has been added to the Civil set on sheet 49 of 87.
Sewer main crossing @ 36+39 is the only proposed crossing going under the SPU line, potholed elevations indicates there is +/- 3’ vertical separation between the two lines. We have
coordinated with D.H. Charles Engineering, Inc for structure support design while trenching under the SPU line. Please see attached documents for structural calculations and plans.
In addition, sheet 2 of 2 of the structural plans has been added to the Civil set on sheet 49 of 87.
Sewer main crossing @ 36+39 is the only proposed crossing going under the SPU line, potholed elevations indicates there is +/- 3’ vertical separation between the two lines. We have
coordinated with D.H. Charles Engineering, Inc for structure support design while trenching under the SPU line. Please see attached documents for structural calculations and plans.
In addition, sheet 2 of 2 of the structural plans has been added to the Civil set on sheet 49 of 87.
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Comment
Shallow CB being proposed on top of 36" WATER. Can this be a bend (delete CB-- CBs shouldn't be on top of SPU 36" main in the first place-- could cause damage/leak on pipeline), or less
desirable-- some kind of CDF load distribution to prevent settlement?
Per 5/1/2020 phone call with Trenton Skoka:
they will look into replacing with bends, but need City of Renton approval. Otherwise, distributing loading over pipeline via CDF or foundation-- need to decrease likelihood of settlement
onto pipeline. Bends replacing CB highly preferred to prevent damage on high-pressure, large-diameter, regional supply main.
SPU crews need min. 5-ft clearance for shoring to perform maintenance on 36" pipeline; anything less than that is an encumberance. Note that 10-ft is the guideline/standard, so 5-ft
is the lowest SPU is willing to go for clearance from a parallel main.Why not connect CBs to 24" storm in sidewalk and start the 12" line at NE 27th Pl?
.
Per 5/1/2020 phone call with Trenton Skoka: will look into removing this 12" line and using the 6" line in planting strip-- this collects water from Lot #25. Has to check with City of
Renton.
OK
SPU wants 0.25" steel casing extending 10-ft either side of SPU pipeline.
Per DOH, sewer crossing must be ductile iron pipe (see that it is 6" DIP-- OK, just noting that we need to keep this material type). Pipe section must be centered, or cut to be centered,
over 36" SPU water.
Assume this is being trenched? (see attached pdf). If so, need to make sure that soil is mechanically stabilized (not just for safety, but to prevent movement) since this is in close
proximity to SPU 36" water and could settle pipeline. The less open trench adjacent to SPU pipeline, the better-- have contractor inform SPU of how they plan to perform this work so
SPU.
Use finform boards on sides, around pipeline, or some means (CDF, etc.) to ensure pea gravel bedding does not unravel.
Regarding Note #10: SPU will verify general support design meets parameters utilized in developer's consultant design. Approval of plan does not serve as an implicit warranty.
Verify the max deflection of support beam as a surrogate for pipeline deflection-- is it 0.33-in max?
If not, that is the max y-deflection of the beam?
Thrust block . Ditch here could be problematic, long term. Could destabilize thrust block over time. Timeline, thinking 20-yrs, etc. Need to think what this is going to look like over
the longterm.
Per 5/1/2020 phone call with Trenton Skoka:
SPU asking for exhibit cross-section from here to ditch.
SPU pipeline isn't called Mercer Island pipeline anymore. May confuse SPU if you ever have to deal with anyone else who is new to this project, as the Mercer Island Pipeline is a now
a "diferent" pipeline and is located at I-90 -- names were changed/updated after original installation plan set. Can just call this 36" SPU Water. Recommend updating for correctness
and clarity.
Is there a thrust block going here, or just RJ w/ no blocking? If so, how close to SPU water is it? (see attached plans PDF for exact locations of comment)
2.) SPU is amenable to the parallel installation of the sewer, provided we get more info about the installation method.
a. If you are planning on installing via a trench, then we will want a stamped shoring plan for this, along with the geotech report for the soils in the adjacent construction zone (report
from the adjacent property being developed is fine, as long as the geotechs agree the report is applicable to this location at the parallel sewer installation—I assume it will be).
The stamped shoring plan will need to detail how the contractor will protect our pipeline from loss of support during installation and removal of the shoring.
b. If it is to be installed via trenchless methods, then we can discuss further. I am assuming you are planning on trenching, so I will not belabor this point here.
Reponse (with Initials)
The existing structure will remain and HDPE pipe will be used to bend the stormline away from the SPU line. (TJS)
The proposed 12" storm line has been removed. CB#20 has been relocated to be a minimum of 5 feet away from the SPU pipeline. (TJS)
Water connection has been adjust to maintain 10' of separation between the proposed sewer line. TJS
A 4-inch steel casing has been add to the water service crossing, spanning 10-ft to either side of the SPU pipeline (TJS)
Notation has been added to sheet 49. "6-INCH SEWER SERVICE PIPE SECTION SHALL BE CENTER OF THE 36" SPU LINE. NO JOINTS OR CLEANOUTS SHALL BE OVER THE SPU LINE. "
DHC Response: The Contractor is responsible for providing OSHA-compliant shoring as needed. (JCM)
BCE: Open trenching adjacent to SPU pipeline will be minimized as much as possible(TJS)
DHC Response: The Contractor is responsible for providing OSHA-compliant shoring as needed. (JCM)
BCE: Grout injection will be used to stabilize pea gravel bedding.(TJS)
DHC Response: Noted. (JCM)
DHC Response: The maximum deflection of the W14x109 pipe support beam is 0.033". (JCM)
Cross-section have been provide on sheet 49. (TJS)
UPDATED. (TJS)
Thrust blocking will not be used around the SPU pipeline. Restrain joint piping and deadman block will be used as necessary (TJS)
Sewer alignment has been updated to cross the SPU pipeline at an angle and has been approved by Ryan Manning on June 4, 2020. (TJS)
SPU Comment
Per phone call with Renton, CB and u/s pipe will be replaced with a sweep-- awaiting revised plans.
RESOLVED/OK
Per phone call with Renton, CB and u/s pipe will be removed.
RESOLVED/OK
OK
RESOLVED/OK
OK
Per 6/4 email chain and crossing exhibit, line is being bored, not trenched (previous notes in this chain are therefore not applicable).
SPU will approve given that bore pits are outside of SPU pipeline zone of influence, as measured from the pipe springline, at a 1:1 slope. Add note on plans. hone call Trent Skoda (7/31/2020):
entry for bore pit/launch at SSMH#1 sheet 48 (larger pit), smaller pit near SSMH#9031 (pit size of CB)-- OK.
Borehead will need to be exposed prior to crossing; do not proceed to within 5-ft of SPU line without exposing borehead first to ensure proper alignment. Add note on plans. hone call
Trent Skoda (7/31/2020): TS sent over revised page with note that addresses this. OK
Plage 51 has pipe being supported. Thought it was being bored. Phone call Trent Skoda (7/31/2020): this sheet just in here as a reference. OK
Not applicable if being bored.
Not applicable if being bored.
Not applicable if being bored.
SPU received plans and approved. Concerns have been addressed.
RESOLVED/OK
OK
Issue raised during phone call with Renton-- developer will propose alternatives such as RJ or dead man blocking on other side.
ON PLANS-- RESOLVED/APPROVED
OK