Structural Comments
Reviewed by: Ron Wilde Permit #: C13-1529
Phone: 343-8371 Date: 08-22-2013
Fax: 343-8200
Email: wilderg@muni.org
Permit Tech: Tony Barganier
Phone: 343-8339
Email: barganierta@muni.org
Project: Dimond Center – West Mall Addition – Fill and Grade
1. PERMIT STATUS
7-01-2013 – Permit reviewed. Comments issued.
7-11-2013 – The July 8, 2013 submittal reviewed. Comments issued.
08-02-2013 – Submittal reviewed. Comments issued.
08-19-2013 – Submittal reviewed. Comments issued.
08-22-2013 – Submittal reviewed. Permit approved.
2. Advisory Comment (no response required): This review is based on the requirements of the Anchorage Administrative Code (AMC 23.10), 2009 International Building Code (IBC), Grading, Excavation and Fill code (AMC 23.105), and all adopted references thereto as amended by MOA. The following comments must be addressed before a permit can be issued. The approval of plans and specifications does not permit the violation of the codes, or any federal, state or local regulations.
Please submit a written explanation for how each comment has been resolved.
Changes to drawings should be clouded to indicate what has been changed.
3. 08-02-2013 Comment Resolved.
PROVIDE SOILS REPORT
This project is for a future building foundation. As such, a geotechnical report needs to be submitted in accordance with IBC 1803.1. It can be the same report that was used for the building immediately adjacent to the new work.
07-11-2013. Not provided.
08-02-2013 Report provided.
4. FILL MATERIAL
08-19-2013 Comment Resolved (See comment below for the basis)
08-19-2013 NOT RESOLVED
08-02-2013 NOT RESOLVED
07-11-2013 NOT RESOLVED
The drawing shows a 24 inch layer of Type II soil at the bottom of the hole, then an undetermined depth of reused existing silty sand fill, followed by a another compacted layer of Type II soil. The depth of the upper layer of Type II fill needs to be specified, as well as the appropriateness of the sandy silt material that will be reused beneath the footing. This should be addressed as part of the geotechnical report recommendations.
7-11-2013. The appropriateness of the sandy silt material for reuse beneath the footing should be addressed in the soils report.
08-02-2013. According to the geotechnical report the existing inorganic fill is a silty sand with gravel containing between 20% to 30% silt. The report specifically states on page 9 that the existing inorganic material cannot be considered to be “structural fill.” Use of such a fill to support footings can be problematic and very placement- and compaction-sensitive.
Before any existing fill is used as compacted fill on this project, a letter from the Geotechnical Engineer needs to be submitted to either a Building Safety inspector or plan reviewer. The purpose of this letter is to assure that the material and its compaction is adequate for its purpose. The engineer needs to see the material in the field and verify that it can actually be correctly compacted. The letter then is to inform Building Safety that the Geotechnical Engineer has approved both the material and its ability to be properly placed. Please add a bold note, showing this requirement on the drawings.
On page 13 the geotechnical engineer recommends using only structural fill below the water table. Further, on page 13, the report says that any use of the existing inorganic material needs to stop at least one foot below the footings or slabs. The wording is as follows:
“The existing fill material could be used as backfill above the water table to a depth of one foot below floor slabs and footings.”
Please note that the current note on Section A indicates that the upper structural fill extends only a minimum of 24 inches below finished grade. The footing is shown visually and incorrectly within this 24-inch dimension. Warm wall footings, however, are required to extend down at least 42 inches below the finished grade. Spread footings could be even deeper. Structural fill would then need to extend at least a foot below any footings
The drawings need to be modified to show structural fill below the water table and at least one foot below the footings. The note should use a definitive distance from finished grade because the contractor will not know where the bottom of the footing elevation is.
08-19-2013 In Maria’s, email as in her geotechnical report, she was not comfortable with using the existing fill material as structural fill. We concur with her in that we also see the existing fill as problematic. She however says that it is suitable if correctly compacted, but only above the water table. Therefore please revise the drawings to show that structural fill will be placed below the water table and that any existing fill material will be limited to above the water table as per her recommendations. Please note that IBC 1804.5 Compacted Fill, requires the compacted fill to be placed in accordance with the provisions of an approved geotechnical report.
Further, we agree that the special inspector will be able to determine whether the material is being placed at 95 percent compaction and therefore the geotechnical engineer would not necessarily need to be involved. However, please add a note that the Building Safety inspector on the project needs to be advised when the contractor switches from structural fill to existing fill.
08-22-2013. This permit has been approved because the geotechnical engineer, Maria Kampsen, revised her recommendation. In her letter dated August 20, 2013 she now says that it is okay to place the existing silty soil beneath the water table. The following explanation email was sent to Dee High, Houston Carr, Mike Pollock, Walt Bullock, Sharen Walsh, and Tony Bargainer.
Dee,
The project is now approved based on the August 20, 2013 letter from the geotechnical engineer, Maria Kampsen, which revised her recommendations to allow the existing silty soil to be placed below the water table.
STRUCTUAL FILL BELOW THE WATER TABLE
Dee, in your latest email you stated your belief that the both you and the geotechnical engineer think I misinterpreted what was written in the geotechnical report. This is not true. On page 13 of the geotechnical report it states:
“We recommend fill material placed below the water table consist of structural fill. The existing fill material could be used as backfill above the water table to a depth of one foot below floor slabs and footings.”
Further in an email response to Jose Hernandez, Keri Nutter, Houston Carr, and Mike Pollock, the geotechnical engineer said.
“So I have recommended, structural fill below the water table, and existing fill between that layer and the bottom of footings.”
These statements are clear and unambiguous, and leave no room for misinterpretation. The recommendation in the submitted geotechnical report was for structural fill to be placed below the water table, not reused existing fill.
Dewatering was required either way. All fill, whether structural fill or reused existing fill, has to be compacted to 95% of maximum density. This is not possible in standing water. No fill can be legally dumped into standing water. Such a practice would be stopped by the Special Inspector as well as the Building Safety Inspector. At no point in the geotechnical report did it say that the structural fill was required below the water table because the plan was to place fill in standing water.
BUILDING SAFETY APPROVAL
This project has not been approved until now because the building code requires the compacted fill to comply with the provisions of an approved geotechnical report. See IBC 1804.5.
“1804.5 Compacted fill material. Where shallow foundations will bear on compacted fill material, the compacted fill shall comply with the provisions of an approved geotechnical report, as set forth in Section 1803.”
From the first submittal of this project there has been a disconnect between the geotechnical report and the design drawings. The design drawings have not followed the clear wording in the geotechnical report.
The August 20, 2013 letter from the geotechnical engineer Maria Kampsen resolves the disconnect. Please note, however, her letter was not a “clarification” as indicated. It was a revision of her prior recommendation. Her letter now states that it is okay to reuse existing fill below the water table.
Ron Wilde
Plan Review Engineer
343-8371
5. 08-02-2013 Comment Resolved.
STATEMENT OF SPECIAL INSPECTION
Please provide a Statement of Special Inspection detailing the special inspector’s responsibilities as per AMC 23.105.115.4, IBC 1704.7, and IBC Table 1704.7. This can be shown on the drawings or submitted separately. IBC Table should be used as the basis for the statement of special inspection. Attach a copy of this to the Special Inspection and Testing Agreement. See comment 7.
7-11-2013. This was not provided.
08-02-2013. Provided
6. 08-02-2013 Comment Resolved
LETTER INDICATING WHO IS HIRING THE SPECIAL INPECTOR
Please provide an email, or letter stating who is hiring the special inspector and what his relationship is to the project. See IBC, 1704.1, paragraph 1.
Please do not submit a letter stating that the special inspector has been hired “on behalf” of the owner. Such wording does not say who has hired the special inspector. Be specific.
7-11-2013. The letter does not say who has hired the special inspector. It says on behalf of… We want to know who the special inspector has a contract with. Be specific.
08-02-2013 The letter was revised.
7. 08-02-2013 Comment Resolved
SPECIAL INSPECTION AND TESTING AGREEMENT
Please fill out and submit a signed copy of the Special Inspection and Testing Agreement. The Statement of Special Inspection (Table 1704.7) needs to be attached to this agreement before it is signed. The purpose of this agreement is so that all who are involved know the extent of the special inspection. This agreement can be found beginning on page 7 of the Special Inspection Program Requirements http://www.muni.org/Departments/OCPD/development/BSD/BSDDocuments/SpecialInspectionGuidelines.pdf
7-11-2013. Not provided.
8. 08-02-2013 Comment resolved.
PRECONSTRUCTION MEETING
This project requires a preconstruction meeting at the beginning of the project to outline coordination between the contractor, special inspectors, and Building Safety. To set up this meeting please contact the Lead Structural Inspector, Jim Stubbs at 343-8325.
9. 08-02-2013 Comment resolved.
BOTTOM-OF-HOLE INSPECTION BY BUILDING SAFETY
One of the required inspections by Building Safety is to verify the bottom of hole.
