Tierra is a full service consulting geotechnical, environmental and construction materials testing engineering firm with 18 years of experience servicing governmental agencies and the private sector. Tierra has capabilities to provide drilling, field sampling, laboratory testing, inspection, asbestos and lead based paint surveys, site assessments and remediation, hazardous materials management, engineering analysis and reporting for this contract. We utilize MicroStation and AutoCAD for site maps and roadway drawing plan sheets and are fully integrated with GPS and GIS mapping for self locating field borings and sample locations.
A majority of Tierra’s workload includes transporation projects for the Florida Department of Transportation (FDOT) and City and County governments throughout Florida. In addition, Tierra has provided support services for general site development, industrial facilities, wastewater treatment plants, pipelines and structures. The diversity of Tierra’s project expience is demonstrated in the project profiles presented below.
Project: I-4 / Crosstown Connector Segment 3C, Hillsborough County, Florida
Owner: FDOT District VII
Florida Department of Transportation District VII designed an elevated limited-access, freeway-freeway system Interchange that extended from the Lee Roy Selmon Crosstown Expressway along the west side of 31st Street to Interstate 4. The project has commonly been referred to as “the I-4/Crosstown Connector" or “the Connector.” The design and construction budget is over $666,000,000.
Tierra was responsible for geotechnical engineering design recommendations for three (3) different superstructure alternatives. The scope of services included recommendations for 5,000 lineal feet of new elevated roadway, architectural gateways, bridge structures including foundation alternatives and a tolling facility supported on Mechanically Stabilized Earth (MSE) walls. In addition, Tierra wrote a Technical Special Provision (TSP) for Settlement Monitoring required for recommending two-stage wall construction.
Tierra managed a $999,000 geotechnical budget for a portion of the Connector including over 7,875 feet of Standard Penetration Test (SPT) borings, rock coring and laboratory testing on selected samples. The project was on schedule and within budget for the 4 year duration of the project.
Project: Suncoast Parkway 2 (SR 589), from North of US 98 to US 19/98 Hernando and Citrus Counties, Florida
Owner : Florida’s Turnpike Enterprise
Florida’s Turnpike Enterprise proposes to extend the existing Suncoast Parkway (Suncoast 1) northward from its existing terminus at US 98 in Hernando County to US 19 near the small community of Red Level in Citrus County, a distance of approximately 26 miles. The Suncoast extension (designated as Suncoast 2) has been divided into three (3) sections – Sections 1, 2 and 3.
Section 1 – Suncoast Parkway 2, from US 98 to North of Cardinal Street
Section 2 – Suncoast Parkway 2, from N of Cardinal Street to N of CR 486
Section 3 – Suncoast Parkway 2, from North of C.R. 486 to U.S. 19
The proposed alignment is privately owned property and is currently utilized as commercial, residential and/or undeveloped. Some of the undeveloped property was not accessible to Tierra’s standard drilling equipment. Tierra used handheld Global Positioning System (GPS) equipment and portable tripod drill rigs to make these remote areas accessible. The use of handheld GPS equipment allows Tierra to prepare geotechnical exploration programs from site plans and lay the exploration program out in the field without survey support.
Nineteen (19) pond locations were selected from the Pond Siting Report (PSR) phase as final pond locations associated with the project. Tierra completed a field exploration of these 19 pond locations. The field exploration program consisted of borings, geophysical testing, and infiltration/hydraulic conductivity testing. Tierra performed near-surface infiltration testing at locations identified by the client to support the design of the project conveyance ditches and for modeling of pre-development drainage and field hydraulic conductivity tests within the selected pond sites for pond modeling.
The 60% design plans for structures, roadway and stormwater retention areas were completed on schedule and within budget for all three (3) Sections. Since Tierra began services in 2007 on these projects, the project scopes and budgets have not changed.
Project: Mid-Bay Bridge Connector Phases II and III, Okaloosa County, Florida
Owner: Mid-Bay Bridge Authority
The Mid-Bay Bridge is a 3.6 mile, two (2)-lane toll bridge spanning the Choctawhachee Bay, in Okaloosa County. The existing bridge begins in Niceville, Florida and ends in Destin, Florida. The Mid-Bay Bridge Connector Phase II and III, consists of a new limited access toll facility connecting the existing Mid-Bay Bridge to SR 85 bypassing the city of Niceville. The overall length of the project is approximately 8.3 miles and includes an additional 5.8 miles of new ramps and connector road improvements. The project alignment for Phases II and III are located primarily on property owned by Eglin Air Force Base. Land use along the alignment generally consists of rural undeveloped land and natural forests. In addition, naturally occurring streams, creeks and swamps are located at several locations. The proposed improvements consist of the design and construction of a new 2-lane rural road (4-lane ultimate), a new tolling facility, three (3) interchange/bridge structures at Range Road, SR 285 and SR 85 and five (5) bridge structures located at Rocky Bayou, East Turkey Creek, Swift Creek, Fox Head Branch and Mill Creek.
Tierra performed extensive subsurface explorations including over 15,000 feet of SPT borings and over 9,000 feet of auger borings along the project alignment. A large muck/peat pocket was identified at the Rocky Bayou Bridge crossing. SPT borings using manual “tri-pod” methods were utilized to develop deep foundation recommendations and construction considerations for the proposed Rocky Bayou Bridge Structure to account for the muck/peat soils of up to 30 feet in depth. Laboratory testing was performed on selected soil samples to develop the project soil legend using both the AASHTO and USCS classification systems. Geotechnical engineering recommendations for the proposed roadway, bridge structures, retaining walls, sign structures and pond design were provided in formal engineering reports in accordance with FDOT guidelines. In addition, engineering recommendations were developed for slope stability of the proposed roadway in areas where “steepheads” were identified during our explorations.
Project: Citrus Park Drive Extension, Hillsborough County, Florida
Owner: Hillsborough County
The project consisted of creating design and construction plans for improvements to and the extension of the existing Citrus Park Drive from Countryway Boulevard to Sheldon Road, approximately 2.8 miles. Tierra performed a subsurface exploration plan including 163 SPT borings, 438 hand auger borings, muck delineation, infiltration testing and pavement cores. Laboratory testing was performed on selected samples. Due to the site conditions, Tierra utilized amphibious and track-mounted drilling equipment. Along with geotechnical recommendations for roadway, stormwater retention, walls, culverts, and bridge structures, a Technical Special Provision (TSP) was prepared. The TSP addressed geogrid reinforcement under a surcharge embankment and a system of settlement plates to enable the Engineer to observe, monitor and determine the magnitude and rate of ground settlement as a result of the surcharge and embankment construction over soft soils.
Project: I-75 (SR 93), from North of River Road to North of SR 681, Sarasota County, Florida
Owner: FDOT District I
The project consisted of widening and partial realignment of the existing mainline I-75 and associated ramps and cross streets. The roadway alignment traverses wetlands, low areas and elevated roadway embankments. Tierra provided geotechnical input to the design team to assist in the design of exit and entrance ramps located at the intersections of River Road, Jacaranda Boulevard, Laurel Road and SR 681; overpasses located at North River Road, North Jackson Road, North Havana Road and Jacaranda Boulevard; underpasses located at Border Road, Laurel Road and SR 681; and bridges crossing Curry Creek, Salt Creek, Cow Pen Slough and Fox Creek.
Tierra executed a subsurface exploration program consisting of borings, subsurface sampling and field-testing. A total of 11,145 feet of Standard Penetration Test (SPT) borings, 6,075 feet of hand auger borings, pavement coring and laboratory testing on selected samples was performed. Geotechnical recommendations for roadway, stormwater retention areas, walls, culverts, signs/signals and bridge structures were provided to guide the project design and construction.
Project: East-West Connector, Polk County, Florida
Owner: City of Lakeland
Tierra is providing geotechnical engineering services for the proposed East-West Road (aka Edgewood Drive Extension) as part of the Kimmins Contracting Design/Build Team. The project includes the design and construction of a new roadway embankment from Harden Boulevard to South Lincoln Avenue within the City of Lakeland in Polk County, Florida. The proposed roadway alignment traverses reclaimed phosphate mine land. Mine-cast soils and highly plastic waste phosphatic clays (slime) are present along the roadway alignment. These soils are considered unsuitable for roadway support unless the soils are improved to increase soil strengths and decrease settlement potential. The potential adverse impacts associated with roadway construction through mined land include instability of roadway embankments and drainage swales, overall settlement and differential settlement. The adverse impacts associated with constructability include handling and managing slimes, unpredictable settlement and long term soil behavior properties, and disposal requirements associated with the slimes.
Tierra performed several Standard Penetration Test (SPT) borings along the proposed alignment to evaluate the extent of the slime. In addition, laboratory testing was performed on samples obtained from the borings for further characterization.
Due to time constraints for construction of the proposed improvements, an alternative to typical soil surcharging was required to improve the slime soils that were present at the site. A system consisting of embankment supported by a load transfer platform was proposed to transfer the embankment loads to competent soils underlying the very weak/very soft slimes. Tierra is currently working with the project team to refine the design layout, testing procedures and subsequent production of the proposed load transfer system.
Project: Sawgrass Lake Restoration, Pinellas County, Florida
Owner: Southwest Florida Water Management District
The project site is located at the Sawgrass Lake Park, situated in the area west of Sawgrass Lake and east of the Skyway Shooting Club in Pinellas County, Florida. The project consisted of remediation/restoration of the wetland areas around Sawgrass Lake east of the Skyway Shooting Club. The proposed remediation/restoration consisted of constructing an approximate 2,500 lineal feet long containment berm. The berm will form the southern, eastern, and northern boundaries of the wetland remediation/restoration area. Using amphibious drilling equipment, Tierra executed a subsurface exploration plan including Standard Penetration Test (SPT) borings within the proposed berm. General subsurface soil conditions, geotechnical recommendations and construction considerations with respect to the proposed berm were provided to guide the design and construction of the project. The project includes the design and construction of earthen berms that will be constructed with geosynthetic (geogrid) reinforcement due to poor subsurface conditions including soft organic muck and peat soils.
Tierra managed a $60,000 geotechnical budget including over 400 feet of Standard Penetration Test (SPT) borings and laboratory testing on selected samples. The project was completed on schedule and within budget.
Project: Lake Carroll at 3009 Samara Drive, Hillsborough County, Florida
Owner: Hillsborough County
The County planned to demolish and replace the existing seawall structure located at 3009 Samara Drive in Tampa, Florida. Tierra conducted an Asbestos Containing Materials (ACM) survey of the seawall. The seawall components were surveyed and homogeneous areas of suspect ACM were visually identified and documented by a Certified Asbestos Inspector. Suspect ACM samples were collected in general accordance with the sampling protocols outlined in EPA regulation 40 CFR 763 (AHERA). Samples were delivered to an accredited laboratory for analysis by polarized light microscopy. Tierra provided appropriate worker safety and waste disposal practices which should be followed when handling ACM during the demolition activities.
Project: NE 38th Street and Dixie Highway Parcels A & C, Broward County, Florida
Owner: City of Oakland Park
Prior to the City of Oakland Park acquiring right-of-way (ROW), Tierra managed the Level II screening at four (4) locations to evaluate whether hazardous substances or petroleum products had impacted the existing or proposed ROW. The general scope of the Level II field screening consisted of the following activities: review of previous assessments, site safety and health plan preparation, drilling and soil sampling, monitoring well installation, laboratory analysis of soil and groundwater samples, data analysis and interpretation and report preparation.
Project: FDOT District VII Materials Testing Contract Hillsborough, Pinellas, Pasco, Hernando and Citrus Counties, Florida.
Owner: FDOT District VII
Since 1994 Tierra has been involved in the FDOT District VII Materials Testing contract. Until June 2010, Tierra was assisting Mactec to verify and inspect all phases of construction of pre-stressed piles and beams for various projects throughout Florida. The project includes set-up and maintaining current verification data files for up to thirty (30) on-going FDOT projects in various stages of pre-stress construction. The contract also consisted of verification laboratory testing including compression testing of concrete and soil tests such as standard and modified Proctor tests, LBR tests, chemical tests to determine soil corrosiveness, organic content, liquid and plastic limits, grain size analysis and soil classification. Data entry into the LIMS system is required.
In June 2010, Tierra was awarded a five (5) year contract as the prime consultant for FDOT District VII materials testing services. Our duties as the prime consultant remain as stated above plus additional duties involving administration of the contract and management of subconsultants.
Project: Clearwater Reclaimed Water Distribution Systems Design, Pinellas County, Florida
Owner: City of Clearwater
The project consisted of providing subsurface soil conditions along a grid of proposed pipeline alignment that totals approximately 10 miles in length. The proposed reclaimed water line will be located in two (2) areas within Clearwater, Florida. The North Region area, also named Chautauqua, will consist of approximately 23,500 feet of 4 to 6 inch diameter distribution line and 3,500 feet of 12 inch diameter force main. The Chautauqua area is located west of CR 611 and south of SR 580. The South Region, also known as Coachman Ridge, will consist of approximately 22,000 feet of 4 to 6 inch diameter distribution line and 6,000 feet of 12 inch diameter force main. The Coachman Ridge area is located west of US 19 and south of CR 576. The pipeline is anticipated to be installed via directional drilling methods.
Tierra provided subsurface soil conditions and relevant geotechnical engineering properties, as well as, to geotechnical recommendations to guide project design and construction.
Project: City of Tarpon Springs Public Service Building Expansion, Pinellas County, Florida
Owner: City of Tarpon Springs
The project consisted of a 2,000 square feet building expansion to the existing City of Tarpon Springs Public Services Building located at 325 East Pine Street. In addition, a stormwater management facility (pond) was proposed at the project site. Tierra performed subsurface explorations and testing at the project site consisting of Standard Penetration Test (SPT) borings, auger borings and field hydraulic conductivity testing. Representative portions of the soil samples obtained were collected and brought back to Tierra’s Tampa laboratory for confirmation of the field classifications by a geotechnical engineer. The borings were stratified and soil profiles plotted for use in the engineering analyses performed to formulate the geotechnical recommendations to support the design and construction of the proposed improvements.
Geotechnical recommendations were provided in formal engineering reports for the proposed shallow foundations and stormwater pond design. The foundation recommendations included allowable bearing capacity, minimum foundation dimensions, recommended foundation levels, settlement estimates, floor slab recommendations and construction considerations including site preparation recommendations, recommended fill types and compaction criteria. The pond design recommendations included horizontal and vertical hydraulic conductivity rates for the near surface soils encountered within the proposed pond area, recommended values for the effective porosity of the near surface soils within the proposed pond area and an estimation of the seasonal high groundwater table level within the proposed pond area. Signed and sealed reports were provided to the design engineer for use in developing the project construction plans and for design and permitting of the proposed stormwater pond.