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Home My WebLink About2418 French AveJAM 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 A t t a''rr ten t RLG : 9' m 1025S 140,