Subsurface Study. Faulk Assisted Living Facility Boca Raton, Florida. George E. Mueller West Palm Beach, Florida

Transcription

1 Subsurface Study Faulk Assisted Living Facility Boca Raton, Florida April 24, 2014 Terracon Project No.: HD Prepared for: George E. Mueller West Palm Beach, Florida Prepared by: Dunkelberger Engineering & Testing, a Terracon Company West Palm Beach, Florida

2 Mainsail Healthcare Development 901 North Flagler Drive, Suite 3 West Palm Beach, Florida Attn: Mr. George E. Mueller Subject: Subsurface Study Faulk Assisted Living Facilty 2245 Boca Rio Road Boca Raton, Florida Terracon Project No.: HD Gentlemen: We have completed the subsurface study for the referenced project. It was performed in general accordance with the scope of work described in our proposal dated February 6, This report presents the findings of the subsurface exploration and provides geotechnical engineering recommendations regarding foundation design and related construction. We appreciate the opportunity to be of service during this phase of the project. If you have any questions concerning the report, please feel free to contact us. Sincerely, Dunkelberger Engineering & Testing, a Terracon Company Kevin E. Aubry, P.E. Thomas J. Tepper, P.E. Geotechnical Services Manager Senior Engineer FL Registration No FL License No Terracon Consultants, Inc NW 33 rd Avenue, Suite 204 Fort Lauderdale, Florida P [954] F [954]

3 TABLE OF CONTENTS Page No. EXECUTIVE SUMMARY... I 1.0 INTRODUCTION PROJECT INFORMATION REVIEW OF EXISTING INFORMATION Topographic and Vegetation Information Soil Survey Information SUBSURFACE CONDITIONS Stratigraphy Groundwater BOREHOLE PERMEABILITY TEST ENGINEERING EVALUATION AND RECOMMENDATION Site Geotechnical Suitability Clearing, Grubbing and Stripping Soil Densification Engineered Fill Foundation Design and Construction Ground Floor Slab Pavement Considerations LIMITATIONS OF STUDY...7 APPENDICES APPENDIX A Sheet 1 Boring Location Plan Sheets 2A through 2C Subsurface Profiles Sheets 3A and 3B Field Permeability Test Results

4 Faulk Assisted Living Facility 2245 Boca Rio Road Boca Raton, Florida April 24, 2014 Terracon Project No. HD EXECUTIVE SUMMARY Subsurface conditions at the site were explored with eight 30-foot deep Standard Penetration Test borings and five 6-foot deep auger profile borings. The borings disclosed the property to be mantled by two to five feet of loose to very loose clean, clayey and silty fine sands (i.e. topsoil). At most boring locations the surficial soil is followed by weakly to moderately well cemented silty to sandy limestone that continues to depths of 6 to 8.5 feet below grade. Over the remaining depths the borings penetrated loose to medium dense sands. Groundwater levels were measured in the borings. The depth to the free water surface during the period of field exploration (March 25 to March 31, 2014) varied from 2.5 to 3.7 and averaged 3.2 feet. The site is considered suitable for the planned construction when viewed from a geotechnical engineering perspective. Following normal site preparation that includes clearing, grubbing, stripping and soil densification from the stripped grade, the building may be supported on shallow spread footings designed for an allowable bearing capacity of 2,500 pounds per square foot. Responsive Resourceful Reliable i

5 SUBSURFACE STUDY FAULK ASSITED LIVING FACILITY BOCA RATON, FLORIDA Dunkelberger Project No.: HD April 24, INTRODUCTION This firm has completed the subsurface study in connection with the Faulk Assisted Living Facility to be constructed on the west side of Boca Rio Road slightly north of S.W. 8 th street in Boca Raton, Florida. This site has the physical address of 2245 Boca Rio Road. The study involved the drilling and sampling of Standard Penetration Test and auger profile borings to evaluate the nature, sequencing and condition of the profile components and performance of borehole permeability tests to assess the hydraulic conductivity characteristics of the near surface profile components. The purpose of the work was to provide recommendations and professional advice regarding site preparation, foundation design and related aspects of the project in consideration of the subsurface conditions that exist at the property. 2.0 PROJECT INFORMATION The project will involve the design and construction of a three story assisted living facility which will have an x-shaped configuration in plan and a footprint area of 57,147 square feet, which includes a 3,308 square foot entrance canopy. For foundation evaluation purposes, we have assumed that the structure will be built of reinforced concrete and unit masonry and that its elevated slabs will be supported on a combination of load bearing wells and columns which transmit maximum loads of 12 kips per foot and 300 kips, respectively, to their foundations. We have also assumed that the building area will receive no more than two feet of fill. Areas around the building will be paved to provide access to the structure and parking stalls for visitors and employees. We expect that the paving will be of the flexible type (i.e. asphalt concrete over aggregate base course. 1

6 Faulk Assisted Living Facility 2245 Boca Rio Road Boca Raton, Florida April 24, 2014 Terracon Project No. HD REVIEW OF EXISTING INFORMATION 3.1 Topographic and Vegetation Information Topographic information for the site gathered by Michael B. Schorah & Associates, Inc. shows that ground surface elevations on the property vary from about 14.5 to 16.5 feet with respect to the National Geodetic Vertical Datum of 1929 (NGVD). Most ground surface elevations are somewhat more than 15 feet NGVD. Vegetation on the property consists of low growing grass and weeds, scattered pine trees, seagrape plants and moderately dense clusters of cypress trees. The cypress trees exist in the southwest corner of the property. 3.2 Soil Survey Information Reference to the Soil Survey of Palm Beach County Area, Florida prepared by the U.S. Department of Agriculture Soil Conservation Service of 1978 shows most of the site to be mantled by the Boca fine sand soil association. Riviera sand depressional soils exist in the area covered by the cypress trees. Both taxonomic units are described as loamy (i.e. silty to clayey) sands that are same 20 to 40 inches thick. In the case of the Boca fine sand, limestone underlies the overburden material at depths of 20 to 40 inches below grade. 4.0 SUBSURFACE CONDITIONS 4.1 Stratigraphy Subsurface conditions at the site were explored with eight 30 foot deep Standard Penetration Test (SPT) borings and five 6 foot deep auger profile borings arranged as shown on Sheet 1. The SPT borings were accomplished with a Central Mine Equipment Company Model 45B drill rig using mud rotary methods. The auger borings were also performed with this same drilling rig but by turning a six-inch diameter helical auger. Logs of the borings are furnished on Sheets 2A through 2C. 2

7 Faulk Assisted Living Facility 2245 Boca Rio Road Boca Raton, Florida April 24, 2014 Terracon Project No. HD With minor variations, the borings disclosed the stratigraphy described hereafter. Item Topsoil Upper Sands Limestone Lower Sands Description Topsoil consisting of organic sands with roots covers a majority of the site in thicknesses that vary from 0.4 to 1 foot Very loose to medium dense clean to clayey fine sands exist next in the profile and persist to depths of 1.8 to 5.0 feet below. A formation of weakly to moderately well cemented limestone underlies the upper sands at most boring locations and continues to depths of 6 to 8.5 feet beneath the ground surface. The limestone has suffered erosion in past geologic times. This condition is typified by the variable depth to the carbonate rock formation and the absence of limestone at the location of Boring TB-3 Over the remaining depths of exploration the borings penetrated slightly silty to clean fine sands. These soils typically range from loose to medium dense in terms of relative density. 4.2 Groundwater Groundwater levels were measured in the borings when the free water surface was initially intercepted. The depth to the water table varied from 2.5 to 3.7 feet beneath the surface grades and averaged 3.2 feet during the period of the field exploration (March 28 through March 31, 2014). Given that the borings were drilled near the end of the dry hydroperiod, we estimate that the groundwater level could rise as much as two feet during the wet season of the hydrologic year. 5.0 BOREHOLE PERMEABILITY TEST Two borehole permeability test (denoted BHP-1 and BHP-2) were performed at the site to assess the hydraulic conductivity of the upper six feet of the profile components. Their locations are depicted on Sheet 1. 3

8 Faulk Assisted Living Facility 2245 Boca Rio Road Boca Raton, Florida April 24, 2014 Terracon Project No. HD The tests were conducted in six inch diameter by six foot deep boreholes whose sidewalls were stabilized with a two inch diameter No. 20 slot well casing and 6/20 silica sand. Usual open hole, constant head methodology was used for each test. Results of the tests are furnished on Sheets 3A and 3B along with pertinent stratigraphic, geometric and hydraulic conditions information. Reference to the test results shows that the average hydraulic conductivity of the materials was 1.35 x 10-5 cubic foot per second per square foot- foot head (cfs/sf-ft) for BHP-1 and 9.77 x 10-3 (cfs/sf-ft) for BHP-2. Because of these low values, the civil engineer responsible for stormwater drainage may wish to consider over excavation of the limestone along the exfiltration trenches alignments and backfilling the overexcavated part of the trenches with open graded crushed rock enveloped with a geotextile fabric designed for drainage. This measure is intended to provide connectivity with the lower sands to improve the hydraulic efficiency of the trenches. 6.0 ENGINEERING EVALUATION AND RECOMMENDATIONS 6.1 Site Geotechnical Suitability Results of this study confirm that the site is suitable for the proposed construction when viewed from a geotechnical engineering perspective. Following normal site preparation that includes intensive densification of the surficial soils, the building may be supported on shallow spread footings and employ a slab-on-grade floor system. 6.2 Clearing, Grubbing and Stripping The proposed building and pavement areas should be cleared of all vegetation at the onset of construction. Clearing and grubbing should include the complete removal and disposal of asphalt concrete, timber, stumps, grass, roots, rubbish, debris and all other obstructions resting on or protruding through the surface of the existing ground. All roots greater than one inch in diameter, or high concentrations of smaller diameter roots exposed by clearing and grubbing, should be removed to a depth of not less than 12 inches. We anticipate the average depth of stripping will range from nil to 12 inches in most areas. Deeper stripping may be needed in the area where the cypress trees now exist. 4

9 Faulk Assisted Living Facility 2245 Boca Rio Road Boca Raton, Florida April 24, 2014 Terracon Project No. HD Soil Densification The sandy soils which cover the site should be thoroughly compacted to create a uniform density condition. Improvement of the soils in this fashion should be carried out throughout the structural footprint including a five foot wide perimeter which extends beyond the maximum outside lines of the superstructure. It should be accomplished from a stripped grade that is at least 24 inches above the ambient water table using a heavy vibratory roller which imparts a dynamic drum force of not less than 44,000 pounds. Each section of subgrade should be subjected to multiple, overlapping (minimum of 20 percent overlap) coverages of the compactor as it operates at its highest vibrational frequency and a travel speed of no more than 1.5 miles per hour (normal walking speed). Rolling should be continued until no further settlement can be visually discerned at the ground surface. In no case, however, should any section of subgrade receive less than ten roller coverages, with five made in the longitudinal direction and five in the transverse direction. The densification activities should be carefully monitored to identify signs of subgrade instability such as pumping, weaving and / or shoving. This type of subgrade response will indicate that weak and potentially compressible materials exist within the influence depth of the roller. Correction of the instability may require removal of the weak soils and replacement of them with well compacted granular fill. Density control should be exercised in the upper 12 inches of the subgrade soils. Soils in this interval should be compacted to not less than 95 percent of the ASTM D 1557 maximum dry density. 6.4 Engineered Fill Fill required for the building pad and site grading should consist of clean, granular materials that are free of debris, cinders, combustibles, roots, sod, wood, cellulose and organic material. The fill should have no particle size larger than three inches and not more than 10 percent passing the U.S. Standard Number 200 Sieve (dry weight basis). It should also have an organic content less than three percent. The fill should be placed at a water content within three percent of optimum and thoroughly and uniformly compacted to not less than 95 percent of the ASTM D 1557 maximum dry density. Subgrades receiving fill should be densified to an equivalent relative compaction. 6.5 Foundation Design and Construction Following implementation of the ground modification procedures described earlier in the report, the structure may be supported on shallow foundations that are based in the improved profile components and designed for a net allowable bearing pressure of 2,500 pounds per foot. To 5

10 Faulk Assisted Living Facility 2245 Boca Rio Road Boca Raton, Florida April 24, 2014 Terracon Project No. HD provide an adequate factor of safety against a shearing failure in the subsoils: (1) all foundations should be based not less than 24 inches below the lowest adjacent grade, (2) continuous footings should be at least 24 inches wide, and (3) isolated footings should have a width not less than 30 inches. The recommended bearing pressure refers to dead plus normal live loads and reflects a net increase in pressure over and above that due to the overburden soils. It may be increased by 25 percent for total loads, including wind forces. Foundations subjected to lateral forces will resist those forces through earth pressure mobilized on the vertical faces of the footings located at righ angles to the direction of load application and shearing forces acting at the footing-subgrade interface. Earth pressure resistance may be determined using an equivalent fluid pressure of 180 pounds per square foot depth (psf/ft) for well compacted moist granular soils above the water table. Base shearing resistance may be computed using a coefficient of friction of The design of the footings against sliding should include a factor of safety of not less than 1.5. Individual footing areas should be excavated, formed and maintained in a dry condition until placement of the substructure concrete. The excavation bottoms should be tamped with a hand-held or walk-behind compactor prior to placement of reinforcing steel. The compactive effort should achieve a relative compaction of 95 percent (ASTM D 1557) for a minimum depth of 12 inches below the excavation bottom. Foundations designed and constructed in the recommended manner are estimated to sustain a maximum total settlement of about one inch provided the wall and column loads for the structure do not exceed those presented earlier in the report. Differential settlements that occur between adjacent foundations are not expected to exceed one-half inch. Angular distortions along wall footings due to differential settlement should not be more than 1 in 650. Because the subsurface materials of the iste are granular in texture, foundation settlements should occur as rapidly as the loads are applied and be nearly complete by the end of the construction period. 6.6 Ground Floor Slab Slab-on-grade construction may be used for the ground floor of the structure. The slab concrete should be cast upon granular engineered fill compacted to 95 percent of the ASTM D 1557 maximum dry density. 6

11 Faulk Assisted Living Facility 2245 Boca Rio Road Boca Raton, Florida April 24, 2014 Terracon Project No. HD A vapor barrier should be installed beneath the bottom of the floor slab to prevent moisture intrusion from the subgrade. Ordinarily a 10-mil thick film of polyethylene is suitable for this purpose. However, floor coverings which are particularly sensitive to moisture flux may require a thicker membrane and/or one of alternative composition. 6.7 Pavement Considerations We believe that conventional flexible (asphalt concrete surfaced) pavement sections can be used for the drive aisles and parking areas of the facility. The sections provided below are typically used in the geographic area for heavy and light duty pavements. Heavy Duty Pavement Component Wearing Course Base Course Subbase Component Wearing Couse Base Course Subbase Thickness and Composition 1.5 inches of structural asphaltic concrete 8 inches of crushed aggregate (LBR = 100 minimum) 12 inches of stabilized subgrade material (LBR = 40 minimum) Light Duty Pavement Thickness and Composition 1 inch of structural asphaltic concrete 6 inches of crushed aggregate (LBR = 100 minimum) 12 inches of stabilized subgrade material (LBR = 40 minimum) 7.0 LIMITATIONS OF STUDY Dunkelberger warrants that the conclusions, recommendations and professional advice provided in this report have been promulgated based on recognized practice in soil mechanics and foundation engineering within this geographic area. No other warranties are expressed or implied. 7

12 APPENDIX A SHEET 1 BORING LOCATION PLAN SHEETS 2A THROUGH 2C SUBSURFACE PROFILES SHEET 3A AND 3B FIELD PERMEABILITY TEST RESULTS

13 NORTH AB-1 AB-2 BHP-1 TB-1 TB-2 AB-3 TB-3 TB-4 AB-4 TB-5 TB-6 AB-5 TB-7 TB-8 BHP-2 SOURCE: URBAN DESIGN KILDAY STUDIOS 0' 50' 100' 200' LEGEND TB-1 STANDARD PENETRATION TEST BORING LOCATION AND NUMBER BHP-1 BOREHOLE PERMEABILITY TEST LOCATION AND NUMBER AB-1 AUGER BORING LOCATION AND NUMBER Locations are approximate. JJ BORING LOCATION PLAN DM FAULK ASSISTED LIVING FACILITY BOCA RIO ROAD KA BOCA RATON, FLORIDA SEE SCALE BAR HD

14 BORING NO. TB-1 TB-2 TB-3 TB-4 LEGEND Dark brown silty organic SAND with roots, grass, some lenses gravel (SM) Gray to dark brown fine to medium SAND, trace silt to slightly silty, trace to some roots and gravel, some lenses with finely divided organic matter (SP, SP-SM) Light gray to light brown fine to medium SAND, some lenses with small roots less than 1/4-inch in diameter (SP) Light brown clayey fine SAND, some fibrous roots less than 1/4-inch in diameter, some silty lenses (SP-SC, SC, SM) Light gray to light brown silty, sandy LIMESTONE Light brown fine to medium SAND with shell fragments, trace silt to slightly silty, some cemented fragments (SP, SP-SM) Dark brown slightly silty fine SAND, some organic staining (SP-SM) DEPTH IN FEET DEPTH IN FEET SP N Light brown to brown fine to medium SAND (SP) Unified Soil Classification System Group Symbol (ASTM D 2487) Indicates the number of blows of a 140 pound hammer, freely falling a distance of 30 inches, required to drive a 2-inch diameter sampler 12 inches (ASTM D 1586) TB-1 Standard Penetration Test (SPT) boring and number Depth of groundwater (feet) & date measured (1) (2) (3) NOTES Borings were drilled on March 28 and 31, 2014 using a Central Mine Equipment Model 45B (CME 45B) drilling rig. Strata boundaries are approximate and represent soil strata at each test hole location only. Soil transitions may be more gradual than implied. Groundwater depths shown on the subsurface profiles represent groundwater surfaces on the dates shown. Groundwater level fluctuations should be anticipated throughout the year. JJ DM KA 1" = 5' SUBSURFACE PROFILES FAULK ASSISTED LIVING FACILITY BOCA RIO ROAD BOCA RATON, FLORIDA HD A

15 BORING NO. TB-5 TB-6 TB-7 TB-8 LEGEND Dark brown silty organic SAND with roots, grass, some lenses gravel (SM) Gray to dark brown fine to medium SAND, trace silt to slightly silty, trace to some roots and gravel, some lenses with finely divided organic matter (SP, SP-SM) Light gray to light brown fine to medium SAND, some lenses with small roots less than 1/4-inch in diameter (SP) Light brown clayey fine SAND, some fibrous roots less than 1/4-inch in diameter, some silty lenses (SP-SC, SC, SM) Light gray to light brown silty, sandy LIMESTONE Light brown fine to medium SAND with shell fragments, trace silt to slightly silty, some cemented fragments (SP, SP-SM) Dark brown slightly silty fine SAND, some organic staining (SP-SM) DEPTH IN FEET DEPTH IN FEET SP N Light brown to brown fine to medium SAND (SP) Unified Soil Classification System Group Symbol (ASTM D 2487) Indicates the number of blows of a 140 pound hammer, freely falling a distance of 30 inches, required to drive a 2-inch diameter sampler 12 inches (ASTM D 1586) TB-5 Standard Penetration Test (SPT) boring and number Depth of groundwater (feet) & date measured (1) (2) (3) NOTES Borings were drilled on March 28 and 31, 2014 using a Central Mine Equipment Model 45B (CME 45B) drilling rig. Strata boundaries are approximate and represent soil strata at each test hole location only. Soil transitions may be more gradual than implied. Groundwater depths shown on the subsurface profiles represent groundwater surfaces on the dates shown. Groundwater level fluctuations should be anticipated throughout the year. JJ DM KA 1" = 5' SUBSURFACE PROFILES FAULK ASSISTED LIVING FACILITY BOCA RIO ROAD BOCA RATON, FLORIDA HD B

16 BORING NO. AB-1 AB-2 AB-3 AB-4 AB-5 DEPTH IN FEET DEPTH IN FEET LEGEND Dark brown silty organic SAND with roots, grass, some lenses gravel (SM) Gray to dark brown fine to medium SAND, trace silt to slightly silty, trace to some roots and gravel, some lenses with finely divided organic matter (SP, SP-SM) Light gray to light brown fine to medium SAND, some lenses with small roots less than 1/4-inch in diameter (SP) Light brown clayey fine SAND, some fibrous roots less than 1/4-inch in diameter, some silty lenses (SP-SC, SC, SM) Light gray to light brown silty, sandy LIMESTONE Light brown fine to medium SAND with shell fragments, trace silt to slightly silty, some cemented fragments (SP, SP-SM) Dark brown slightly silty fine SAND, some organic staining (SP-SM) Light brown to brown fine to medium SAND (SP) SP AB-1 Unified Soil Classification System Group Symbol (ASTM D 2487) Auger boring and number Depth of groundwater (feet) & date measured (1) (2) (3) NOTES Borings were drilled on March 28 and 31, 2014 using a Central Mine Equipment Model 45B (CME 45B) drilling rig. Strata boundaries are approximate and represent soil strata at each test hole location only. Soil transitions may be more gradual than implied. Groundwater depths shown on the subsurface profiles represent groundwater surfaces on the dates shown. Groundwater level fluctuations should be anticipated throughout the year. JJ DM KA 1" = 5' SUBSURFACE PROFILES FAULK ASSISTED LIVING FACILITY BOCA RIO ROAD BOCA RATON, FLORIDA HD C

17 Field Permeability Test Project Name: Faulk Assisted Living Facility 2245 Boca Rio Road Boca Raton, Florida Project No. HD TEST NUMBER: BHP-1 TEST LOCATION: See Boring Location Plan SUBSURFACE PROFILE Depth (feet) Soil Description Gray brown fine SAND, trace organics Gray brown fine SAND with cobble to boulder size limestone fragments Brown fine to medium SAND Light brown silty LIMESTONE Water Table Depth: 3.2 feet below grade on 03/27/14 Constant Head Maintained at: At ground surface PERMEABILITY RESULTS Uncased (U) or Cased (C): C 6-inch Casing Depth (ft): 6.0 Casing Stick-up (ft): 0.0 Perforated length (ft): 6.0 Constant Head Falling Head Start Stop Volume Used (gallons) Start Stop Drop (Ft) 0 sec sec *K, Hydraulic Conductivity (CFS/Ft 2 - Ft Head) = 1.35 x 10-5 *(Reference: Equations in SFWMD Permit Information Manual, Volume IV) Sheet 3A

18 Field Permeability Test Project Name: Faulk Assisted Living Facility 2245 Boca Rio Road Boca Raton, Florida Project No. HD TEST NUMBER: BHP-2 TEST LOCATION: See Boring Location Plan SUBSURFACE PROFILE Depth (feet) Soil Description Dark brown fine SAND with small roots and organics Light brown aggregate base course Gray fine to medium SAND, trace small roots Brown and light brown fine to medium SAND Light brown silty fine SAND Gray brown to light brown clayey LIMESTONE Water Table Depth: 4.6 feet beneath the ground surface on 3/27/14 Constant Head Maintained at: At ground surface PERMEABILITY RESULTS Uncased (U) or Cased (C): C 6-inch Casing Depth (ft): 6.0 Casing Stick-up (ft): 0.0 Perforated length (ft): 6.0 Constant Head Falling Head Start Stop Volume Used (gallons) Start Stop Drop (Ft) 0 sec sec *K, Hydraulic Conductivity (CFS/Ft 2 - Ft Head) = 9.77 x 10-5 *(Reference: Equations in SFWMD Permit Information Manual, Volume IV) Sheet 3B