Correspondence (40) CITY OF TIGARD
OREGON
February 8, 2001
Vince Loftus, P.E.
J -U -B Engineers, Inc.
2810 Clearwater Avenue. Suite 201
Kennewick, WA 99336
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Re: Alternate Methods of Construction
Lowe;s Hardware
Permit # SIT98 -00048
Dear Mr. Loftus,
This letter responds to your request for approval of alternate methods of construction
regarding the plumbing utilities work at 12615 SW 72 Ave, Tigard, OR under permit
number SIT98- 00048. The request includes not using flexible connectors between the
storm piping and the manholes and not using tracer wire for the storm piping, both of
which are required under the Oregon State Plumbing Specialty Code.
It is simplest to address the tracer wire issue. You stated that the tracer wire was not
installed because of the different requirements of Washington State vs those in Oregon
and that much of the system was already installed without the tracer wire when it was
brought to your attention. The alternate proposed is that all of the storm piping is
installed in a straight line of sight between manholes, thereby making location of the
storm piping simple and straight forward. The approved plans and the modified as-
builts in fact, support this. The videotape of the installed system also reflects this.
The more important issue, the omission of flexible connectors between the storm piping
and the manholes, requires a more comprehensive proposal for an alternate method of
construction. Your reasoning, and thereby your proposal for alternate methods of
construction, was that 1) these fittings are not available for this type and size of piping
and 2) that all of the trenches and backfill were compacted to a level of 95 %, the same
as required for a new structure. The second item is your proposal to mitigate the
potential for differential settlement.
13125 SW Hall Blvd., Tigard, OR 97223 (503) 639 -4171 TDD (503) 684 -2772
Normally this issue would have been dealt with and an alternate approved prior to
installation. The purpose of these fittings is to allow for differential settlement between
the lengths of piping and the manholes resulting in possible separation and failure of the
storm drainage system.
We have ascertained that these fittings are not, in fact, available for the size and type of
approved piping you used. We are also in receipt of extensive soil compaction reports
verifying that the bedding and backfill were compacted to a minimum of 95% of optimal
density. We feel with this type of documented compaction reports, the storm system
has very little chance for settlement, and meets the intent of the code which states in
Section 301.2.2 of the State of Oregon Plumbing Specialty Code, "The Administrative
Authority may approve any such alternate provided that the Administrative Authority
finds that the proposed design is satisfactory and complies with the intent of the Code
and the material offered is for the purpose intended, at least the equivalent of that
prescribed in this Code, in quality, strength, durability, and safety or that the methods of
installation proposed conform to other acceptable nationally recognized standards." The
code also goes further in Sections 301.2.3, 301.2.4, 301.2.5, and 301.2.6 that proof
and /or tests shall be submitted to substantiate the method of construction. It also states
that the Administrative Authority can require additional tests to ascertain that is still
conforms to the requirement on which its approval was given.
The alternate to installing tracer wire is hereby approved. The straight line construction
between manholes is an acceptable method of locating the direction of storm piping and
is deemed to comply with Section 301.2.2 of the plumbing code. This alternate meets
the intent and provides equivalence to the purpose of the code requirement.
The alternate to installing flexible joints between the storm piping and the manholes is
hereby approved. The soil compaction, being equal to that for a new structure, is an
acceptable alternate for flexible connections to prevent separation and failure of joints in
the storm piping system and is deemed to comply with Section 301.2.2 of the plumbing
code. This altemate meets the intent and provides equivalence to the purpose of the
code requirement.
These two approvals are conditioned upon our receipt of an executed copy of
agreement by Continental Dirt Contractors, Inc. and /or Lowe's Hardware to conduct a
video camera inspection of the storm system in one year and at any future time that is
deemed necessary by the City of Tigard (Section 301.2.6 OSPSC).
These conditions are also conditioned upon receipt of an executed document stating
that Lowe's Hardware provide the City of Tigard with indemnification in the event of
deterioration or failure of the storm system in relation to these approvals.
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If I may be of further assistance, call me at (503) 639 -4171 ext. 311 or you may e-mail
me at garv@ci.tiaard.or.us
Sincerely,
Gary Lampella
Building Official
Cc Continental Dirt Contractors, Inc., 1340 M Street SE, Suite A, Auburn, WA 98002 -5744
Bill Crocker, Lowe's Hardware, 1530 Faraday Ave, Suite 140, Carlsbad, CA 92008
Jim Hendryx, Community Development Director
Bill Monahan, City Manager
City Inspectors
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