GEOTECHNICAL ENGINEERING SERVICES REPORT
For the
MOTON ELEMENTARY SCHOOL KITCHEN COOLER ADDITION
7175 EMERSON ROAD BROOKSVILLE, FLORIDA
Prepared for
HOFFMAN ARCHITECTS, P.A. 29 WEST ORANGE STREET
TARPON SPRINGS, FLORIDA 34689
Prepared by
PROFESSIONAL SERVICE INDUSTRIES, INC. 5801 BENJAMIN CENTER DRIVE
SUITE 112 TAMPA, FLORIDA 33634
TELEPHONE (813) 886‐1075 FAX (813) 249‐4916
PSI PROJECT NO. 07752886
DECEMBER 20, 2019
www.intertek.com/building
5801 Benjamin Center Drive, Suite 112 Tampa, Florida 33634 phone: 813.886.1075
fax: 813.249.4916 intertek.com/building
psiusa.com
December 20, 2019
Mr. Todd Willsie, AIA Hoffman Architects, P.A. 29 West Orange Street Tarpon Springs, Florida 34689 Re: Geotechnical Engineering Services Report
Moton Elementary School – Kitchen Cooler Addition 7175 Emerson Road
Brooksville, Florida PSI Project No. 07752886
Dear Mr. Willsie: Professional Service Industries, Inc. (PSI), an Intertek company, is pleased to submit our geotechnical engineering services report for the proposed Moton Elementary School – Kitchen Cooler Addition project in Brooksville, Florida. This report presents the results of our field exploration program and includes geotechnical recommendations to guide design and construction of the project. Should there be any questions, please do not hesitate to contact our office at (813) 886‐1075. PSI would be pleased to continue providing geotechnical services or construction materials testing throughout the implementation of the project. We look forward to working with you and your organization on this and future projects. Respectfully submitted, Professional Service Industries, Inc. Engineering Certificate of Authorization 3684 Matthew Mooney, P.E. Nayan Saha, P.E. Geotechnical Engineer Senior Geotechnical Engineer Florida License No. 81208 Florida License No. 81635
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TABLE OF CONTENTS
1.0 PROJECT INFORMATION ............................................................................................................... 1 1.1 PROJECT AUTHORIZATION ................................................................................................................... 1 1.2 PROJECT DESCRIPTION ........................................................................................................................ 1 1.3 PURPOSE AND SCOPE OF SERVICES ........................................................................................................ 1
2.0 SITE AND SUBSURFACE CONDITIONS ............................................................................................ 2 2.1 SITE LOCATION AND DESCRIPTION ......................................................................................................... 2 2.2 SUBSURFACE CONDITIONS ................................................................................................................... 2 2.3 GROUNDWATER INFORMATION ............................................................................................................ 2
3.0 EVALUATION AND RECOMMENDATIONS ...................................................................................... 3 3.1 GENERAL .......................................................................................................................................... 3 3.2 SITE PREPARATION ............................................................................................................................. 3 3.3 SHALLOW FOUNDATION RECOMMENDATIONS ........................................................................................ 4 3.4 SETTLEMENT ..................................................................................................................................... 5 3.5 FLOOR SLAB RECOMMENDATIONS ........................................................................................................ 5 3.6 PERIMETER UNDERDRAIN .................................................................................................................... 5
4.0 CONSTRUCTION CONSIDERATIONS ............................................................................................... 5 4.1 GENERAL .......................................................................................................................................... 5 4.2 DRAINAGE AND GROUNDWATER CONCERNS ........................................................................................... 6 4.3 UTILITY EXCAVATIONS ......................................................................................................................... 6 4.4 EXCAVATIONS .................................................................................................................................... 6
5.0 REPORT LIMITATIONS ................................................................................................................... 7
APPENDIX
BORING LOCATION PLAN AND SOIL PROFILES ......................................................................................................... SHEET 1
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1.0 PROJECT INFORMATION 1.1 PROJECT AUTHORIZATION Professional Service Industries, Inc. (PSI), an Intertek company, has completed a geotechnical exploration for the proposed kitchen cooler addition to the existing Moton Elementary School located at 7175 Emerson Road in Brooksville, Florida. This study has been performed in general accordance with our Proposal for Geotechnical Exploration No. 0775‐297272, issued December 6, 2019. Our services were authorized by Mr. Edward Hoffman, Jr. with Hoffman Architects by executing acceptance of our proposal on December 11, 2019. 1.2 PROJECT DESCRIPTION We understand that the proposed project will consist of the construction of a one‐story kitchen cooler addition to the existing Moton Elementary School located at 7175 Emerson Road in Brooksville, Florida. Based on the Construction Documents by Hoffman Architects dated September 13, 2019 provided to PSI, we understand the proposed cooler addition will have a plan area of approximately 500 square feet and it is planned for the southern portion of the existing facility. The proposed cooler will be a pre‐engineered metal structure supported on a thickened edge slab foundation system. The slab will be 5‐inches thick and the thickened edges will be 1‐foot wide. A generalized plan view of the project site is shown on Sheet 1. Proposed grading and structural loading information has not been provided. We assume maximum wall loads will not exceed 2 kips per lineal foot and maximum floor slab loads will not exceed 150 psf. Existing grades are believed to be at or near proposed. Should any of the above information or assumptions made by PSI be inconsistent with the planned construction, we request that you contact us promptly to allow us to make any necessary modifications to the recommendations in this report. 1.3 PURPOSE AND SCOPE OF SERVICES The purpose of our exploration was to provide geotechnical engineering recommendations to guide the design and construction of the proposed development. Subsurface conditions at the site were explored by performing 2 Standard Penetration Test (SPT) borings in the proposed addition area to depths of approximately 15 feet below existing grade. The number of borings, boring locations, and boring depths were selected in accordance with the contract between Hoffman Architects and PSI. The borings were located in the field by estimating distances from known site reference points identified on the site plan provided to PSI. The boring locations shown on the Boring Location Plan presented on Sheet 1 should be considered approximate. The SPT borings were advanced utilizing mud rotary drilling methods. In each boring, samples were collected and SPT resistances were measured virtually continuously from 4 to 10 feet and on intervals of 5 feet thereafter to boring termination. The top 4 feet of the borings were manually augered to check for utilities. Drilling and sampling techniques were accomplished in general accordance with ASTM standards. The borings were backfilled with soil cuttings and bentonite upon completion.
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Representative portions of each sample were returned to our Tampa, Florida office where they were subjected to laboratory testing and visual classification by a geotechnical engineer. Classifications were primarily performed in general accordance with the Unified Soil Classification System (USCS). The laboratory testing program included gradation analysis, Atterberg limits, and natural moisture content testing on select soil samples. A soil profile was prepared for each borehole indicating lithological materials encountered and any additional pertinent information. At the conclusion of our field and laboratory work, the data was evaluated by an experienced geotechnical engineer to develop appropriate engineering recommendations.
2.0 SITE AND SUBSURFACE CONDITIONS 2.1 SITE LOCATION AND DESCRIPTION The existing Moton Elementary School consists of a one‐story building, pavements, and other associated infrastructure. The proposed cooler addition is being considered for the southern side of the school in an area that was previously an asphalt driveway. At the time of our fieldwork, the pavement section within the approximate addition limits had been demolished and removed from the site, and the area had been excavated approximately 6 to 12 inches below the surrounding pavement surface elevation. An overhead canopy extended from the existing building over a portion of the addition area. The addition area is bordered to the northeast and northwest by the school building, to the southeast by a driveway, and to the southwest by a grass slope that slopes up approximately 20 feet from the school facility to a wooded area. 2.2 SUBSURFACE CONDITIONS Borings B‐1 and B‐2 generally encountered medium dense to dense clayey sandy (SC) and medium stiff to very stiff sandy clay (CH). The upper approximately ½ to 1 feet of material appeared to be disturbed or previously placed fill material likely associated with the previous site development. The boring profiles presented on Sheet 1 include soil descriptions and stratifications. Variations may occur and should be expected between the widely spaced boring locations. The stratifications represent the approximate boundary between subsurface materials and the actual transition may be gradual. 2.3 GROUNDWATER INFORMATION The static groundwater level was not apparent in the borings performed. It should be noted that water is introduced into the borehole during the mud rotary drilling process which can obscure natural groundwater levels. In addition, groundwater levels tend to fluctuate during periods of prolonged drought and extended rainfall and may be affected by man‐made influences. A seasonal effect will also occur in which higher groundwater levels are normally recorded during rainy seasons. It is likely groundwater will temporarily perch/pond above the clayey soils encountered at the surface of the borings following heavy rain events. We recommend the contractor determine the groundwater level prior to construction and assess any potential impacts.
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3.0 EVALUATION AND RECOMMENDATIONS 3.1 GENERAL The borings encountered moisture‐sensitive fine‐grained highly plastic clayey sands and sandy clays, which could prevent proper compaction and could also exhibit vertical movement (heave) with changes in moisture content. We understand the existing school building and floor slabs have previously experienced cracking/distress possibly associated with the shallow clayey soils. We recommend providing a minimum 4‐foot separation between any clay (CL, CH) or clayey sand (SC) materials and the bottom of the slab/slab thickened edge. This will require over‐excavating the existing clayey soils to allow for the minimum 4‐foot separation of suitable material in the addition area. The over‐excavation should extend at least 5 feet, horizontally, beyond the addition perimeter, where possible and the separation material should consist of engineered fill. We also recommend a perimeter underdrain system be designed and constructed by others to intercept and divert groundwater and surface runoff (particularly from the adjacent grass slope) from perching atop the clayey soils. The structural drawings provided indicate a portion of the slab thickened edge adjacent to the existing building is planned to partially bear on an existing footing, which is not recommended by PSI. We recommend the new slab and existing footings must be structurally separated. Once final design plans and specifications are available, a general review by PSI is strongly recommended as a means to check that the evaluations made in preparation of this report are correct and that earthwork and foundation recommendations are properly interpreted and implemented. 3.2 SITE PREPARATION The following are our recommendations for general site preparation. These recommendations should be used as a guideline for the project general specifications prepared by the design engineer. 1. We recommend the addition area be over‐excavated to allow for a minimum 4‐foot separation
between the existing soils and the bottom of the slab/slab thickened edges. At a minimum, it is recommended that the over‐excavation extend at least 5 feet horizontally beyond the proposed addition perimeter, where possible.
2. Following the over‐excavation operations, the exposed subgrade should be evaluated by a representative of PSI. the exposed subgrade soils should be compacted to at least 95 percent of the maximum dry density in accordance with ASTM D‐1557, modified Proctor method. Any soft or unsuitable materials identified during the initial compaction should be removed and replaced with approved structural fill.
3. Following subgrade preparation, a layer of separation fabric should be placed on the exposed
subgrade. The development area may then be brought up to finished subgrade levels, using structural fill. Fill soils should be tested and approved by PSI prior to import and placement. Imported fill should consist of fine sand with less than 12 percent passing the No. 200 sieve, free of significant rocks/rubble, organics, clay, debris and other unsuitable material. Approved sand fill should be placed in loose lifts not exceeding 12 inches in thickness and should be compacted to at least 95 percent of
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the maximum dry density in accordance with ASTM D‐1557, modified Proctor method. Density tests to confirm compaction should be performed in each fill lift before the next lift is placed.
4. Prior to beginning compaction, soil moisture contents may need to be controlled in order to facilitate
proper compaction. If additional moisture is necessary to achieve compaction objectives, then water should be applied in such a way that it will not cause erosion or removal of the subgrade soils. A moisture content within the percentage range needed to achieve compaction (typically +/‐ 3 percent) is recommended prior to compaction of the natural ground and fill.
A representative of PSI should be retained to provide full time, on‐site observation of earthwork and excavation activities. It is important that PSI be retained to observe that the subsurface conditions are as we have discussed herein, and that fill placement is in accordance with our recommendations. The contractor should take care during site preparation activities including demolition, excavation or compaction to not damage the existing structure or foundations. Shoring or protection of the existing structure should be made the responsibility of the contractor and designed by a professional engineer licensed in the State of Florida. During compaction operations, thinner lifts and/or operating compaction equipment in the static mode may be necessary. Due to access constraints, a smaller roller or other manually guided compaction equipment such as a plate vibrator or “jumping jack” may be necessary. 3.3 SHALLOW FOUNDATION RECOMMENDATIONS With proper subgrade preparation, shallow foundations can be designed for a net allowable soil bearing capacity of 1,500 pounds per square foot, based on dead load plus design live load. The thickened edge foundations should bear at a depth of at least 6 inches below the final exterior grade and be at least 12 inches in width, and should be designed per Building Code Requirements.
The foundation excavations should be observed by a representative of PSI prior to steel or concrete placement to confirm that the compacted fill foundation materials are capable of supporting the design loads and are consistent with the materials discussed in this report. If the foundation excavations appear suitable as load bearing materials, the bottom of the foundation excavations should be compacted to at least 95 percent of the maximum dry density in accordance with ASTM D‐1557, modified Proctor method, for a minimum depth of one foot below the bottom of the foundation depth, as determined by field density compaction tests. Foundations that are constructed for the addition could induce settlement of the existing building, possibly causing minor cracking and cosmetic distress. To minimize this effect, we recommend the new slab and existing footings be structurally separated to the extent possible to allow for differential movement. Soils located within the zone of influence of existing footings should not be removed during new slab excavation. New bottom of slab elevations should be the same as existing bottom of footing elevations and rigid connections between new and existing footings should be avoided. A construction joint should also be considered to allow for some differential movement. When constructing the slab near existing structures the excavations should be limited to relatively short (less than eight‐foot) segments. After opening, slab excavations should be observed and concrete placed as quickly as possible to avoid exposure of the slab bottoms to wetting and drying. Surface run‐off water
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should be drained away from the excavations and not be allowed to pond. The foundation concrete should be placed promptly after the excavation is made. 3.4 SETTLEMENT Provided the recommended subgrade preparation operations presented herein are properly performed, total settlement should be on the order of one inch or less. Differential settlements should be approximately 50 percent of the total movements. These estimates are based on the foundation loads being relatively lightly loaded. The settlement of shallow foundations supported on sandy soils should occur relatively quickly after initial loading. Thus, the majority of expected settlement should occur during construction as dead loads are imposed. 3.5 FLOOR SLAB RECOMMENDATIONS Slab‐on‐grade construction should be supported on soils compacted to at least 95 percent of the maximum dry density in accordance with ASTM D‐1557, modified Proctor method. We have assumed no extraordinary floor slab performance requirements such as very low allowable deflections or smoothness requirements are necessary. Any cuts that are made in the building pad for utility installation should be backfilled with clean granular materials that are compacted to at least 95 percent of the maximum dry density in accordance with ASTM D‐1557, modified Proctor method. Material to be placed within 12 inches of the bottom of the slab should have no single particle greater than 3 inches in size, and should meet the requirements of approved structural fill. The floor slab should be adequately reinforced to reduce the risk of cracking due to differential settlement. An impervious membrane should be installed between the soil subgrade and bottom of floor slabs to be overlain with moisture sensitive coverings to avoid slab moisture problems. Floor slab design should conform to American Concrete Institute (ACI) design standards and practices. 3.6 PERIMETER UNDERDRAIN A perimeter underdrain system circling the new addition should be designed and constructed to intercept and divert groundwater and surface runoff from perching atop the clayey soils. Surface runoff from the adjacent grass slope should be considered in the design. PSI does not perform design of dewatering systems. We recommend a civil/drainage engineer be consulted for design of the system.
4.0 CONSTRUCTION CONSIDERATIONS 4.1 GENERAL It is recommended that PSI be retained to provide observation and testing of construction activities involved in the foundation, earthwork, and related activities of this project. This will promote project continuity and will reduce the potential for misinterpretation of our recommendations.
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4.2 DRAINAGE AND GROUNDWATER CONCERNS If necessary, dewatering should maintain the groundwater level at least 2 feet below the lowest excavation. We recommend that the dewatering system be designed, constructed, and maintained by an experienced dewatering contractor. The effects of the proposed dewatering system on adjacent properties or nearby structures should also be considered in the design. Water should not be allowed to collect in the foundation excavations, on the floor slab areas, or on prepared subgrades of the construction area either during or after construction. Undercut or excavated areas should be sloped toward one corner to facilitate removal of any collected rainwater, groundwater, or surface runoff. Positive site drainage should be provided to reduce infiltration of surface water around the perimeter of the building and beneath the floor slabs. The grades should be sloped away from the building and surface drainage should be collected and discharged such that water is not permitted to infiltrate the backfill and floor slab areas of the building. 4.3 UTILITY EXCAVATIONS Utility trenches may be required for this project. We recommend all utility trench backfill comply to the gradation and requirements of structural fill, as described above and be placed and compacted to the recommendations contained in the site preparation section of this report. This fill should be compacted to at least 95 percent of the maximum dry density in accordance with ASTM D‐1557, modified Proctor method. 4.4 EXCAVATIONS In Federal Register, Volume 54, No. 209 (October 1989), the United States Department of Labor, Occupational Safety and Health Administration (OSHA) amended its “Construction Standards for Excavations, 29 CFR, Part 1926, Subpart P”. This document was issued to better insure the safety of workmen entering trenches or excavations. It is mandated by this federal regulation that excavations, whether they be utility trenches, basement excavations or footing excavations, be constructed in accordance with current OSHA guidelines. It is our understanding that these regulations are strictly enforced and if they are not closely followed, the owner and the contractor could be liable for substantial penalties. The contractor is solely responsible for designing and constructing stable, temporary excavations and should shore, slope, or bench the sides of the excavations as required to maintain stability of both the excavation sides and bottom. The contractors “responsible person”, as defined in 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as part of the contractor’s safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in all local, state, and federal safety regulations. We are providing this information solely as a service to our client. PSI does not assume responsibility for construction site safety or the contractor’s or other party’s compliance with local, state, and federal safety or other regulations. It is the policy of PSI not to provide recommendations regarding temporary slopes during construction which is the sole responsibility of the contractor as indicated above.
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5.0 REPORT LIMITATIONS The Geotechnical Engineer warrants that the findings, recommendations, specifications or professional advice contained herein have been made in accordance with generally accepted professional geotechnical engineering practices in the local area. No other warranties are implied or expressed. The services provided were conventional in nature and did not include any special services that may lessen the risk of conditions that can contribute to moisture, mold or other microbial contaminant growth in buildings. You may be aware that mold is abundant throughout nature and is comprised of a wide variety of microscopic fungi. Due to its nature, the potential for mold infestations cannot be completely eliminated. The scope of services also does not include an environmental assessment for determining the presence or absence of wetlands, or hazardous or toxic materials in the soil, bedrock, surface water, groundwater, or air on or below, or around this site. Any statements in this report or on the boring logs regarding odors, colors, and unusual or suspicious items or conditions are strictly for informational purposes. Florida is underlain by a soluble limestone formation, which can dissolve and result in surface subsidence and the formation of sinkholes. A comprehensive assessment of the potential for sinkhole development at this site was not included in our scope of services. Typically, such an assessment would include geophysical surveying methods and the extension of deeper soil borings into the underlying limestone formation. The recommendations submitted are based on the subsurface information obtained by PSI and design details furnished by Hoffman Architects for the proposed project. If there are any revisions to the plans for this project or if deviations from the subsurface conditions noted in this report are encountered during construction, PSI should be notified immediately to determine if changes in the recommendations are required. This report has been prepared for the exclusive use of Hoffman Architects and its consultants for the specific application to the proposed kitchen cooler addition to the existing Moton Elementary School located at 7175 Emerson Road in Brooksville, Florida.
APPENDIX