SAC Minutes - 127 Edgehill Way 07-07-15.pdf

Minutes for SAC review for 127 Edgehill Way, San Francisco on July 7, 2015

Lou Gilpin, Geologist SAC member, was not present at the meeting.

A summary of the meeting follows:

• The minutes for the June 16^th meeting were accepted by the SAC members.

• John Hom indicated that since the last meeting, the shoring design has changed from soil nail to cantilever solider beam system. In addition, the design uses the cantilever beams to support the building making them part of the permanent structural system. Corbels in the piers will support the grade beams above.

• John Hom asked The City to check if merging the two permits is allowed.

• Harvey Hacker had no comments on the architectural drawings.

• Frank Rollo recommended putting a note on the plans specifying the required pier depth into bedrock for the 9’-0” piers.

• John Hom said there is a 4 inch pop-out from the grade beam due to the moment frame. He suggested the architect camouflage it.

• Sheet SH2.5 was revised on July 6, 2015, the SAC members do not have revised sheet before this meeting.

• John Hom red-marked the shoring plan and went over his comments with the shoring engineer.

• John Hom said the dimension from line A to line B is 25’-4”; he asked the engineer of record to make sure the steel moment frame dimension is correct.

• The design team agreed to merge the construction and shoring permit into one. DBI does not have an issue with it.

• John Hom suggested eliminating the 3 kickers and piers and installing a horizontal waler on top of the shoring. He said the kickers interferes with the construction.
• John Hom pointed out that detail 3/S3.1 is incorrect. It currently shows a slab tied to the retaining wall on top; however, the architect said it is a planting area not a slab. Also, the detail shows a concrete slab tied to the pier on the neighbor’s side which should not be on the detail.

• John Hom recommended that the drill pier locations and dimensions be shown on the plan for clarity.

• Allen Gruen said the two 9’-0” deep piers should have a note on the plan saying “5’-0” into competent bedrock or to practical drill refusal.”

• FTF Engineering needs to show the load path of how the slab, retaining wall and the piers work together to resist load from the soil.

• Allen Gruen should address the effect of passive on piers that are close to the other piers or retaining wall.

• John Hom said that there are two wall back fills, wall bracing maybe required.

• Frank Rollo asked the design team to check the plan again for the passive value. The current value is based on rock, but some piers are in soil. Allen Guren agreed to take a look at it again.

• Frank Rollo recommended that the plans state that all earthwork aspects of the project will be observed and checked by the appropriate design professional of record.

• Frank Rollo recommended that a weekly status report including photos be submitted to The City.

• Frank Rollo said in Lou Gilpin’s email he recommended the earthwork, stabilization of the slide be performed first, and a letter be written before work can be commenced on the uphill portion. However, the design geologist and the design geotechnical engineer felt that it is in the best interest of the project if the temporary shoring is in place before removal of the toe support from the hill by doing the earthwork. Frank Rollo concurred with the design team. The design team presented its reasoning for doing work on the uphill portion first.

• Frank Rollo recommended trenching the keyway sub-drain; the sub-drain should penetrate below the silty sand.

• Patrick came up with the keyway and bench locations, dimensions and drainage through emails and phone calls with Nik Fauretto.

• Patrick said there is sufficient space to cut a 1:1 slope without encroaching into neighbor’s property.

• Frank Rollo recommended that a note be placed on the plan stating that the slopes be no steeper than 1:1.

• Patrick said the keyway trench will need to be approved by him before any fill is placed.

• Frank Rollo recommended that clean-outs be shown on the plan. He also said the plan needs to show how the sub-drain water will be drained.

• Patrick said the land slide repair should stabilize the lower part of the site and the drilled piers and walls should stabilize the upper part of the site.

• Patrick said he prefers to construct the piers and lagging walls at the upper portion of the site before work on the landslide repair. Frank Rollo was fine with that.

• Frank Rollo said that the fill sub-drain can be drained to daylight and onto an energy dissipator on the slope.

• Harvey Hacker made a motion that was seconded by John Hom stating after review of several iterations of the drawings and reports, and the results of two SAC meetings, it is the SAC’s opinion that the design should result in a stable hill side suitable for residential construction provided: 1) the calculations for the retaining wall design are checked to determine if the upper wall influences the stability of the lower wall, if so the wall should be re-designed accordingly; 2) the drilled piers in all cases penetrate sufficient depth into rock recommended by the geotechnical engineer; 3) the geologist will observes the conditions exposed in the keyway and accepts the stability of the keyway excavation before placement of the back fill; 4) the architect and structural engineer check the dimensions shown on the drawing to reduce potential conflict at the moment frame; 5) The design team evaluates the possibility of eliminating the incline kickers and replace them  with a waler at the top of the soldier piles; 6) the geologist and geotechnical engineer review the geotechnical and geologic aspect of the structural plan and calculations, provide review letters concluding that the design parameters have been applied appropriately in the design of the wall and the recommendation for the keyway and buttress has been properly incorporated into the plans; 7) The shoring and structural plans be combined into one design submittal package; 8) All earthwork and foundation installation is observed by the geotechnical engineer and  geologist of record for this project; and 9) It is understood that all liabilities on this project lie with the developer and its design team.

Meeting adjourned at 3:00 p.m.