mtec REPORT OF GEOTECHNICAL EXPLORATION FTFA Construct Bin Wall at HERD Eglin AFB, Florida

Transcription

1 mtec REPORT OF GEOTECHNICAL EXPLORATION FTFA Construct Bin Wall at HERD Eglin AFB, Florida MTEC Project Number November 10, 2014 Revised: January 5, 2015 Prepared For: Peterson Engineering, Inc. 75 South F Street Pensacola, Florida MTEC Innovations, Inc. 216 East Government Street, Pensacola, Florida (850)

2 216 E. Government Street Pensacola, Florida November 10, 2014 Revised: January 5, 2015 Peterson Engineering, Inc. 75 South F Street Pensacola, Florida Attention: Subject: Mr. Greg Peterson, P.E. Report of Geotechnical Exploration FTFA Construct Bin Wall at HERD Eglin AFB, Florida MTEC Project No Mr. Peterson, MTEC Innovations, Inc. (MTEC) is pleased to provide you with this report detailing the results of our subsurface exploration for the proposed FTFA , Construct Bin Wall at HERD on Eglin AFB, FL. These services were provided in general accordance with our Proposal Number G, dated September 5, This report presents the findings of our subsurface exploration and provides geotechnical recommendations with respect to our understanding to our understanding of the proposed development. We appreciate the opportunity to have worked with you on this project. We hope this report meets your needs and addresses the geotechnical issues concerning the proposed construction. If you have any questions, or if we can be of further assistance, please feel free to call us. Sincerely, MTEC Innovations, Inc. Jeff McCarthy, P.E., LEED AP Principal Engineer Josh Lindstrom, P.E. Senior Geotechnical Engineer

3 TABLE OF CONTENTS 1.0 INTRODUCTION PROJECT INFORMATION Project Description Field Exploration Laboratory Testing FINDINGS Surface Conditions Subsurface Conditions RECOMMENDATIONS General Groundwater Control Foundation Design Site Preparation Construction Related Services... 5 Appendix Site Location Map Boring Location Plan Boring Logs Field Procedures

4 January 5, 2015 FTFA Construct Bin Wall Revetment MTEC Project Number INTRODUCTION This report provides the results of our geotechnical exploration for the installation of new bin walls at the existing HERD facility on Eglin Air Force Base, Florida. Our exploration was substantially performed as outlined in our proposal dated September 5, As outlined in the proposal, this report includes: Our understanding of the scope of work for the project as it relates to the Geotechnical exploration. A description of the site as well as field and laboratory work performed. A description of the soil conditions and the depth to groundwater encountered during our field exploration. A discussion of any potential design and/or construction related issues indicated by the exploration that could impact the proposed development, such as weak organic laden soils, a shallow groundwater table, etc. An estimate of total and differential settlements of foundation based on available structural loading data. Recommendations for subgrade preparation requirements including control of groundwater during construction. Recommendations for foundation design and construction including foundation type, allowable bearing capacity, bearing depth, and quality control during construction. An assessment of the suitability of on-site soils for re-use as structural fill and backfill. Additionally, the criteria for suitable fill materials will be provided. 2.0 PROJECT INFORMATION 2.1 Project Description Based on this information we understand that a new, pre-engineered steel bin wall is planned at the existing HERD facility. The bins will reportedly be used to replace the existing earthen berms as a blast barrier. We understand that the proposed steel bins are 10 wide and will be erected to a maximum height of 32 feet above current grades. An approximately 800 long section of bin wall will is proposed along the north side of the existing asphalt road north of Buildings 1221, 1227, and A U-shaped section of Bin Walls will be placed to east, south, and west of the three above mentioned Buildings. Additionally, an approximately 72 foot section will be placed across the existing pavement to the east Building We understand that material from the existing earthen berms will be used to backfill the steel bins. We understand that the bin wall manufacturer will likely be Conntech and have had several phone conversations with their local sales representative regarding the bin wall installation. We understand that the bin wall will likely be embedded 3 feet below final grades. Additionally, we understand that the bin wall infill material Specification will consist of a clean coarse material with 10% fines, or less and that bin wall backfill requirements will likely consist of compacting 8- inch loose lifts to 90% of the materials Standard Proctor density (ASTM 698). -1-

5 January 5, 2015 FTFA Construct Bin Wall Revetment MTEC Project Number Our recommendations are based upon the above information. If any of this information is incorrect, any changes are anticipated, please inform MTEC Innovations, Inc. so that we may evaluate our recommendations. 2.2 Field Exploration Our field exploration was performed on October 20, 2014 and consisted of three (3) standard penetration test (SPT) borings drilled to a depth of 30 feet below grade. Additionally, a composite sample was collected from the existing berms for classification and index testing. The location of the boring is provided on the Boring Location Plan and the Boring Logs are provided in the Appendix of this report. 2.3 Laboratory Testing Representative soil samples obtained during our field exploration were examined by a geotechnical engineer. The samples were visually classified in general accordance with ASTM D 2488 (Unified Soil Classification System). Additionally, one (1) fines content test was performed on a bulk sample collected from the existing berm material to determine. The fines content was performed in general accordance with ASTM D1140 (Amount of Material finer than No. 200 Sieve). The results of the fines content test are included below: Laboratory Test Results Sample Location Sample Depth % Finer than No. 200 Sieve Top of berm at southeast corner of Building ft. below grade USCS Soil Classification 4.5 SP 3.0 FINDINGS 3.1 Surface Conditions The portion of the site that will contain the two sections of bin wall placed north of Buildings 1221, 1227, and 1233 appears to be relatively free of surface impediments. Those two areas are vegetated primarily with sparse grasses and shrubs. Existing earthen berms and pipe racks are present along the perimeter of the three Buildings. Small pine trees and shrubs are present along the south side of Building Subsurface Conditions Beneath a thin layer of topsoil, the borings generally encountered loose to medium dense sand (SP) soils to the bottom depth of 30 feet below existing grade. The material encountered in the berms appeared to be native sandy soils from previous construction activities. -2-

6 January 5, 2015 FTFA Construct Bin Wall Revetment MTEC Project Number RECOMMENDATIONS 4.1 General This section of the report provides our recommendations for groundwater control, foundation design, site preparation, and construction related services. The following recommendations are made based upon a review of the attached soil test data, our understanding of the proposed construction, and experience with similar projects and subsurface conditions. If the proposed grades, dimensions, construction methodology and/or materials change significantly from those previously discussed, we request the opportunity to review and possibly amend our recommendations with respect to any changes. The discovery of any subsurface conditions during construction which deviate from those encountered in the boring should be reported to us immediately for observation, evaluation and recommendations. 4.2 Groundwater Control Groundwater was not encountered at the time of our field exploration. We do not anticipate that groundwater control measures will be necessary for the proposed construction. It should be noted that the groundwater table will fluctuate seasonally depending upon local rainfall. The rainy season in Northwest Florida is normally between June and September. 4.3 Foundation Design Based on the results of our field exploration, we consider the subsurface conditions at the site adaptable for support of the proposed bin walls. Provided the site preparation and earthwork construction recommendations outlined in Section 4.4 of this report are performed, the following parameters may be used for bin wall design Bearing Capacity Based upon our discussions with the bin wall manufacturer, we have assumed that the proposed bin wall foundation will be designed for the load applied to the subgrade by the weight of the bin wall plus 32 feet of compacted infill with a Factor of Safety for bearing capacity of 2.0. We have based our settlement estimates and Site Preparation recommendations upon this information Bearing Material We recommend that the bottom of the bin walls be seated on a Graded Aggregate Base (GAB) bearing pad with minimum dimensions of 3-feet wide by 12-inches deep. The GAB material should be compacted to at least 98 percent of the Modified Proctor maximum dry density (ASTM D 1557) Settlement Estimates Our settlement estimates for the proposed bin wall are based on the use of site preparation/earthwork construction techniques as recommended in Section 4.4 of this report. -3-

7 January 5, 2015 FTFA Construct Bin Wall Revetment MTEC Project Number Any deviation from these recommendations could result in an increase in the estimated postconstruction settlement. Using the existing soil conditions, the assumed maximum structural loads and the field data which we have correlated to geotechnical strength and compressibility characteristics of the subsurface soils, we estimate that total settlement could be on the order of one to two inches or less. It is important to note that this settlement estimate does not include settlement of the infill material placed inside the bin wall. The infill should be placed and compacted per the bin wall manufacturer s recommendations. Because of the general uniformity of the subsurface conditions and the recommended site preparation and earthwork construction techniques outlined in Section 4.4 we anticipate that differential settlement should be on the order of 1 inch or less. 4.4 Site Preparation Due to the high bearing stresses which will be imparted to the subgrade soils, we recommend that the Contractor engage MTEC to develop and implement a Quality Control program to ensure that the bin walls are placed upon a suitable subgrade and the intent of the design is achieved in the field. We recommend that, at a minimum, the following items be included in the Site Preparation portion of the construction of the proposed structure: Prior to construction, the location of any existing underground utility lines within the construction area should be established. Provisions should then be made to relocate interfering utilities to appropriate locations. The bin wall manufacturer recommends that the bin wall be embedded a minimum of 3 feet below finished grades; we anticipate that excavation depths on the order of 10 feet will be required to reach the final bearing depths. The excavations required to install the bin walls shall be sloped, shored, braced, etc. as necessary to provide safe access as described in applicable OSHA standards. Upon completion of the excavation, the exposed subgrade soils will need to be densified via a smooth drum vibratory roller making a minimum of eight (8) overlapping passes. The vibratory roller should capable of imparting a dynamic drum force of not less than 44,000 pounds. The subgrade should be closely observed by the Geotechnical Engineer of Record during rolling operations to detect signs of pumping, yielding, and shoving. Any deficient areas detected during the rolling should be corrected. Correction of these areas could include undercutting unsuitable soils and replacing with compacted granular fill. However, actual remedial measures can best be determined in the field by the Geotechnical Engineer at the time of construction -4-

8 January 5, 2015 FTFA Construct Bin Wall Revetment MTEC Project Number The upper 12 inches of the rolled subgrade should be density tested at a minimum frequency of one test per 50 lineal feet of bin wall. These materials should be compacted to at least of 98% of the Modified Proctor (ASTM D1557) maximum dry density. Place and compact a maximum 12-inch thick loose layer of graded aggregate base material and compact to a minimum of 98% of the Modified Proctor maximum dry density. Test the exposed GAB at a minimum of one test per 50 lineal feet of bin wall. Bin wall infill should be placed in accordance with the selected bin wall manufacturer s recommendations. Manufacturer s recommendations available at the time of this report consist of placing bin fill in thin horizontal loose lifts not exceeding 8 inches in thickness. Each lift should be compacted to a minimum of 95% of the Standard Proctor (ASTM D698) maximum dry density. We recommend that infill material be placed in horizontal lifts as long as practicable to avoid differentially loading the underlying materials. Each lift of bin fill be tested at a frequency of one test per 100 lineal feet, or as required by the bin wall manufacturer. 4.5 Construction Related Services We recommend that MTEC be retained to perform construction materials testing and observations on this project. Field tests and observations include verification of foundation subgrades by performing quality assurance tests on the placement of compacted structural fill courses and bin wall infill material. We can also provide concrete testing, structural inspections, and general construction observation services. The geotechnical engineering design does not end with the development of the construction documents. The design is an on-going process throughout construction. Because of our familiarity with the site conditions and the intent of the geotechnical engineering design and recommendations, we are most qualified to address problems that might arise during construction in a timely and cost-effective manner. -5-

9 APPENDIX

10 Project Location NOV. 07, 2014 mtec INNOVATIONS JL WEH JL 1 3

11 B-3 B-2 B-1 Bulk Sample Location NOV. 07, 2014 mtec INNOVATIONS JL WEH JL 2 3

12 mtec INNOVATIONS NOV. 07, 2014 JL WEH JL 3 3

13 FIELD AND LABORATORY PROCEDURES FIELD PROCEDURES Soil Test Borings The soil test borings were performed in general accordance with ASTM D 1586, "Penetration Test and SplitBarrel Sampling of Soils." A continuous flight auger was used to drill to the boring termination depth. At regular intervals, the auger was removed and soil samples were obtained with a standard 1.4inch I.D., 2.0inch O.D., splittube sampler. The sampler was first seated six inches and then driven an additional foot with blows of a 140pound hammer (manual ropecathead system) falling 30 inches. The number of hammer blows required to drive the sampler the final foot is designated the "Penetration Resistance." The penetration resistance, when properly interpreted, is an index to the soil strength and density. The completed boreholes were backfilled with native soil. Representative portions of the soil samples, obtained from the sampler, were placed in plastic bags and transported to our laboratory. The samples were then examined by a geotechnical engineer in order to confirm the field classifications. Auger Borings (Hand) Auger borings were advanced by hand with a soil auger. The soils encountered were identified, in the field, from cuttings brought to the surface by the augering process. Representative soil samples were placed in 3mil thick Ziploc bags and transported to our laboratory where they were examined by an engineer in order to confirm the field classifications. Field Permeability Test The borehole permeability test was conducted in order to determine the inplace permeability rate of the subsurface soils in the area of the planned retention pond. The results of the test are presented on the attached Field permeability Test Results sheet. To perform the field permeability test, a 2inch diameter solid section of PVC pipe was installed in a borehole augered to the required test depth. Water was added into the pipe and the volume of water required to maintain a constant head near the top of the pipe was recorded for time intervals until the flow rate had apparently stabilized. The permeability rate of estimated using the following formula. q k = 5.5rh Where k= coefficient of permeability

14 q= constant rate of flow into the test hole necessary to maintain a given head r= inside radius of the casing h= differential head of water NOTE: All measurement units (linear dimensions) should be consistent throughout the formula. LABORATORY TESTING Water Content The water content is the ratio, expressed as a percentage, of the weight of water in a given mass of soil to the weight of the solid particles. This test was conducted in general accordance with ASTM D2216. Fines Content In this test, the sample is dried and then washed over a No. 200 mesh sieve. The percentage of soil by weight passing the sieve is the percentage of fines or portion of the sample in the silt and clay size range. This test was conducted in general accordance with ASTM D1140. Grain Size Distribution The grain size test were performed to determine the particle size and distribution of the sample tested. The sample was dried, weighed, and washed over a No. 200 mesh sieve. The dried sample was then passed through a standard set of nested sieves to determine the grain size distribution of the soil particles coarser than the No. 200 sieve. This test is similar to that described by ASTM D422.