HomeMy WebLinkAbout2418 French Ave - #198 (1987) (STRETCHES CAR WASH) DOCUMENTSJAM MAL & ASSOCIATES, INC. Consulting Engineers
July 10, 1987
Project No. 87-02218
TO: Mr. Jim Sterchi
105A Springwood Circle
Longwood, Florida 32750
SUBJECT: Foundation Soil Investigation, Proposed Car Wash,
Lots 2-6 and 15-19, U.S. Highway 17-92, Sanford,
Florida
Dear Mr. Sterchi:
Per your request, we have completed a foundation soil
investigation at the subject site (see vicinity map Sheet 1).
Preliminary findings and opinions have previously been
discussed with you in meetings on May 27 and 29, 1987 at our
offices.
BACKGROUND
Initially, the purpose of our investigation was to determine
the subsoil conditions at the subject lots and advise you as to
the suitability of the lots for construction of a lightly
loaded car wash building and adjacent pavement areas on the
southern one-half of the property. Results of test borings
TB-1 through TB-6 (see Sheet 1) were presented and our opinions
concerning the encountered. soil conditions were verbally given
to you on May 27, 1987. In that meeting, we informed you that
the southern lots (Lots 1-4 and 17-19) were underlain by
relatively thick layers of fibrous peat and organic sand.
Geotechnical Engineers, Hydrogeologic Consultants Er Materials Testing Engineers
1.675 Lee Road, 32789 P.O. Box 339, Winter Park, Florida 32790 i Telephone (305) 645-5560
Regional Offices: West Palm Beach, Ormond Beach, Tampa, Ocala, Florida
Mr. Jim Sterchi
Project No. 87-02218 -2-
We indicated to you that conventional construction on these
soils would include use of deep pile supported foundations. We
also indicated that a somewhat riskier development approach
could consist of utilizing a heavily reinforced slab/mat
foundation design to mitigate the effects of the anticipated
long term differential settlement.
At the close of that meeting, we recommended and you authorized
four (4) additional borings be performed to check for secondary
layers of organics beneath the proposed car wash building and
to determine the vertical extent of the buried peat on the
northern one-half of the property (Lots 5-6 and 15-16).
In our meeting on May 29, 1987, we discussed the results of
borings TB-7, TB-8, AB-1 and AB-2 (see Sheet 1) with respect to
the above foundation options.
Initial estimates showed that a 40 foot by 82 foot building
might be supported on about 28 piles driven to 50 foot depth.
Assuming that 1,400 LF of piling could be installed for about
21,000 and that additional foundation modifications might cost
about $5,000 to $9,000, we roughly estimated that a deep pile
supported foundation system might cost about $25,000 to $30,000
in addition to the cost of a normal slab -on -grade foundation.
In view of the light commercial use you intended for this
structure, such an investigation for foundations did not appear
economically feasible to you.
In light of the above discussion, we began evaluating the
second alternative, which included a brief preloading of the
building area with fill for 30 to 60 days followed by
construction of a masonry block building on a heavily
reinforced monolithic slab with an integral waffle grade beam
system.
We suggested that the building area be preloaded with 2 to 4
feet of fill above the proposed finished grade for as long as
your construction schedule would permit. We understand this
initial filling was completed the first week in June and that
about 4 feet of fill was placed over the entire building area.
Current plans call for about 2 feet of the preload material to
be removed prior to construction.
Mr. Jim Sterchi
Project No. 87-02218 -3-
Currently, we understand you are having a local engineer
develop site grading plans and you desire specific
recommendations for use in the design of the reinforced slab
foundation. The following sections provide comments pertaining
to that ongoing design.
EVALUATION AND RECOMMENDATIONS
General
Based on the test borings performed and our experience with
similar subsoil conditions, we are of the opinion that the
proposed car wash structure can be supported on a shallow,
heavily reinforced slab foundation system without undergoing
significant or potentially dangerous structural distress.
By selecting to utilize a shallow foundation system on this
site which is underlain by compressible peat, you have elected
to significantly minimize initial foundation costs in the hope
that the cost of periodic cosmetic repairs over the life of the
structure will be of a lesser magnitude.
6nticipated Settlement
We anticipate that the 10 to 20 feet of peat underlying the
building area beneath 7 to 12 feet of clean sand fill will
continue to undergo long term compression due to the weight of
the fill and superimposed building loads. Depending on
seasonal water fluctuations or any outside influence that might
cause temporary or permanent dewatering of the peat layer, we
estimate future settlements may be on the order to 3 to 9
inches over a 10 to 20 year period. Because the peat has been
preloaded for many years by the 7 to 12 feet of near surface
fill and the underlying peat is relatively uniform in
thickness, we anticipate very little of the settlement
predicted above will be in the form of differential settlement.
Mr. Jim Sterchi
Project No. 87-02218
Slab Reinforcement
4-
In order to mitigate any differential settlement that might
occur over the service life of the proposed structure (20 years
or less), we recommend additional top and bottom reinforcement
be added to the foundations. The purpose of this reinforcement
would not be to reduce the total settlements predicted above
but to minimize most of the harmful effects of wracking and
cracking of the foundations.
Typically for a small, lightly loaded structure such as this,
we recommend the structural engineer establish a system of
shallow grade beams with a drop down section about 12 inches
below a 6 inch thick floor slab, having a bottom width of about
18 inches. The grade beams would normally be configured to
form a waffle or grid pattern on 12 to 15 foot centers beneath
the entire building. Typically, the floor slab would be
reinforced with #4 reinforcing bars at 12 to 18 inches on
center top and bottom each way and the grade beams might
contain 3 to 4 #5 rebars top and bottom with #3 stirrups at 18
to 24 inches on center surrounding the #5 rebars. Specific
details of the slab and footing reinforcement are the
responsibility of the projects structural engineer of record.
Superstructure Modifications
In the masonry block superstructure, we recommend providing a
5 rebar in a filled cell at all windows, door openings and at
a maximum of 6 feet on center around the perimeter of the
structure. Durawall added between block courses at 24 inches
on center vertically would also aid in stiffening the
structure. As recommended verbally, we recommend the exterior
facia be a flexible material such as rough sawn cedar,
aluminum, etc. in order to minimize exposing any minor cosmetic
cracking that might occur in the future. Use of brick or
stucco exterior finishes would tend to accentuate any minor
cracking due to settlements.
Other Considerations
As mentioned to you previously, we recommend the use of a
flexible pavement with limerock base course on sites prone to
long term settlement. Should premature resurfacing be
necessary, we have found the task easier and more cost
Mr. Jim Sterchi
Project No. 87-02218 -5-
effective using a limerock base course material. This type of
pavement typically has fewer surface cracks to allow water
infiltration than does a pavement section with soil -cement base
course.
As your civil engineer is setting grades for this site, we wish
to suggest that slopes toward drainage inlets be exaggerated
slightly in the initial construction so that long term
settlements will not tend to create low spots or poor drainage
in the future.
Once site grades have been set and preliminary structural
drawings have been prepared, we would be pleased to review them
to ensure they meet the general intent of our recommendations.
In the meantime, we trust the information contained herein is
sufficient for your immediate needs. Should you or your
civil/structural engineer have questions, please contact our
office.
Sincerely,
JAMMAL & ASSOCIATES, INC.
T.Obert T Goehring, P.E.
Sex"iia- Frd'ect -Ma a_ger
Fls:' Rp9i'str,ation -No, . 34127
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