HomeMy WebLinkAboutYOUNG PEOPLES LEARNING CENTER - PDP W/ADDITION OF PERMITTED USE - PDP140012 - CORRESPONDENCE - (5)It is my opinion, as a civil engineer, that the increased load potential applied by the second floor addition will not
adversely affect the 8" clay line.
Please call if you have questions.
Sincerely,
Geoff Robinson, PE
Civil / Structural Engineer
Robinson Engineering, Inc (970) 217-4960
319 South Grant Avenue, Fort Collins, Colorado 880521 PO Box 2459, Fort Collins, Colorado 80522
January 30, 2015
City of Fort Collins
and
CJR Homes, LLC
124 Fishback Avenue
Fort Collins, CO 80521
Dear Sirs.
RE: Effect of adding second floor addition to east portion of building, 205 E. Plum Street, Fort Collins, CO
80521, REI Project # 13-093.
We have worked with CJR Construction and the Young Peoples Learning Center with a series of renovations and
changes to the existing structure in the past 2 years. We were asked by CJR Construction to comment on the effect
of adding a second floor addition to the east portion of the building with respect to an existing clay sanitation line 3'
below the existing buildings footings.
We understand that the sanitation line is 8" in diameter. We also understand that the contractor excavated just north
and south of the building and measured the distance from the footing base to the top of the clay pipe with a minimum
clearance of 3.07'. The clay sanitation line appears to have been installed decades prior to the addition being built.
The edition and the clay pipe have co-existed to this point without problem. Concern was raised as to whether the
added second floor addition load would jeopardize the existing clay line.
Prior to the addition, it is unknown whether there was a prior home or structure built over the line. The line is at
least 11.5' below the original grade. At 115 pcf, the estimated original equivalent fluid pressure on the 8" line would
be approximately 1325 psf or 9.2 psi on the pipe. The foundation under the addition appears to be a slab foundation
with the edges thickened to 8" deep. We assumed the slab was not reinforced (typical of residential construction in
the 1960's) and may only be thickened for about 18" in from the perimeter. For our calculations we assumed an 18"
effective footer width. We also assumed a soil load based on 115 pcf soil. Our estimate of the load on the 8" pipe
with 11.5' of soil cover is 1325 pcf or 9.2psi.
The structure was analyzed using a 40 psf occupancy load for the main floor and basement. A 50 psf occupancy load
was used assuming office space on the second floor.
As a summary, the maximum soil load on the 8" clay pipe given the existing structure is estimated at 1581 psf or
11.0 psi. With the addition of a second floor with 50 psf occupancy, a future maximum soil load would be 1922 psf
or 13.4 psi. The increased load potential is about 121.5% due to the second floor addition. The attached page
represents the summary of our calculations for the load on the pipe.
Inspection and comments are limited to the specific items listed in this letter and in no way implies a certification or complete inspection of the
structure, its systems or site work. No liability is assumed for future loss of value, marketability or any other loss claims.
CJR YPLC pipe 1-30-2015.doc January 30, 2015
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C Robinson Engineering, Inc.
319 S. Grant Avenue
Fort Collins, Colorado 80521
(970) 217-4960 office / (970) 797-2649 fax
RobEngInc@gmail.com
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