Downtown Columbia, MD
The Crescent is a new mixed-use neighborhood with 2,300 residences; several parking garages; a 250-room hotel; 1.475 million square feet of office space; 313,000 square feet of retail and 225,000 square feet of civic and cultural uses spread throughout four development areas in Columbia, Maryland. The Crescent will become a live-work-play location as well as an employment center with buildings that will frame the Merriweather-Symphony Woods neighborhood in a distinctive curving arc. The neighborhood will have many distinctive features including its natural setting amidst preserved and enhanced woodlands and tributaries to Symphony Stream and the Little Patuxent River.
The neighborhood will include an ultimate buildout of over 20 buildings ranging from 2 to 16 levels. Some of the buildings are to be podium style, with above grade parking, and others with two (2) to four (4) levels of parking below grade. The buildings range from wood framed, to precast concrete, to steel framed with precast concrete cladding.
Significant site development was required including mass grading, rock excavation, infrastructure, new roads, bridges, pathways, water features and ponds, and culverts. Additionally, hundreds of stormwater management facilities are required at the site, each of which needed to be integrated into the site features and structures.
The Robert B. Balter Company (Balter) is providing Geotechnical Engineering, Subsurface Explorations, Materials Testing and Quality Assurance (QA), and Site Inspections (SI) at this project. Balter also performed a multitude of Environmental Site Assessments throughout the project, and performed chemical testing of imported fill soils for heavy metals and contaminants.
To obtain the necessary geotechnical information, Balter performed field exploration programs consisting of a review of available geologic information, soil borings, rock coring, in-situ permeability testing, and geophysical analyses.
Geotechnical Engineering Services
Our Geotechnical Reports include the resulting boring logs, rock coring logs, test results, geophysical analysis and laboratory soil test results. The geophysical analysis consisted of seismic refraction testing which is used in conjunction with the soil borings to further define the depths of the soil, weathered zones, and rock surface. Our Geotechnical Reports also include recommendations for design and construction of various building types and include recommendations for shallow (conventional spread footings), intermediate (stone column supported footings) and deep foundations (micropiles) of the proposed bridges, culverts and buildings. The reports also address design and construction, and cost issues related to earthwork, rock removal, pavement design, and stormwater management. Balter worked closely with the Owner to limit site development costs based on the soil, rock, and groundwater conditions at the site. Rock excavation costs were reduced by Balter’s recommendation to raise building elevations or to delete basement levels. Balter also worked closely with the design team, reviewing foundation plans and delegated designs for conformance with the geotechnical reports, and the project requirements, and to control construction costs.
Site Development Inspections
As the QA/SI firm for the project, Balter has been on site since 2006, performing testing on the site development phases of construction. Testing includes earthwork, utilities, roadways, culverts and bridges. Precast prestressed concrete beams, up to 135 feet in length, were inspected a the precast concrete plant, as well as during and after installation within the roadway bridges. Balter is performing field visits, construction recommendations, materials testing and review of inspection reports to ensure project is constructed in accordance with the County requirements and project plans and specifications. Inspections included stormwater management facilities, ranging from biofiltration trenches to massive underground precast stormwater storage units. Roadway subgrades were tested to meet the County pavement requirements, and soil-cement was required to stabilize portions of the roadway subgrades.
This project includes a new, 12-story mixed-use office building at the Crescent Development in Columbia, MD. The building includes 340,000 square feet of floor area. Building amenities include ground floor retail on three sides of the building, a fitness center, rooftop amenity with a conferencing center and exterior terrace. This steel framed building was founded on a concrete basement level and included a unique rock anchor tie down system to resist overturning loads.
This is a special inspection project, and inspections performed during construction included significant variable subsurface conditions at the footing subgrade elevations. Rock excavation was required on the eastern half of the building, and Highly Weathered Rock and dense soils were encountered at the west end. Inspections of the post-tensioned rock anchor system required close inspections of the subcontractors, and close contact with the structural engineer to discuss field modifications
Juniper Multi-Family Building
This project consists of a new, 7-story mixed-use residential and retail building, with 687,000 square feet of floor area. The building includes two ground floor levels of concrete podium style retail area, supporting 5 levels of wood framed residential units. The center of the building includes a precast parking garage, extending from the ground level to the roof level. This is a special inspection project. The building’s architecture resulted in heavy loads, which exceeded the settlement capacity of the onsite soils. Balter’s solution was to include reduced size spread footings, supported on the natural soils improved with cost-effective stone columns. Balter mapped the underlying rock surface and worked closely with the design team to reduce the amount of rock excavation, while providing a cost-effective foundation system. Balter reviewed the delegated design and inspected the installation of the stone columns to ensure that the project requirements were met.
Area 3 Garage
This project was designing a new, 10-story precast concrete parking garage and emergency response building. The precast elements are to be supported on a shallow foundation system consisting of large reinforced concrete rafts supported by rock or stone column improved soils. The steeply sloping rock surface, which extended from grade to 100 feet below grade, presented a challenging geotechnical profile. Our senior Special Inspectors provided the required inspections in order to ensure the site development, associated retaining walls, crane pads, and foundations were constructed in accordance with the project plans, specifications, the schedule of Special Inspections, the geotechnical engineering report, and the applicable code. Inspections during the installation of the stone columns were critical, as the contractor could not get the stone columns to depth, and our field inspectors worked closely with Balter’s geotechnical engineers to keep the project moving forward.
Area 3 Hotel
This project involved geotechnical design related to a new, 15-story Hotel at Valencia Land and Mango Tree Road including four (4) levels of concrete podium construction and 11 levels of steel framing. Geotechnical Engineering was provided to supplement Balter’s earlier studies to define rock surface based on final grading, increase bearing pressures, estimate settlements, and establish earthwork and rock site development parameters. Special Inspections were provided to ensure the site development, associated retaining walls, crane pads, and foundations were constructed in accordance with the project plans, specifications, the schedule of Special Inspections, the geotechnical engineering report, and the applicable code.
Marlow Multi-Family Building
Designed to mirror Juniper, this 7-story mixed-use residential and retail building, with 687,000 square feet of floor area, includes two ground floor levels of concrete podium style retail area, supporting 5 levels of wood framed residential units. The center of the building includes a precast parking garage, extending from the ground level to the roof level. This is a special inspection project. The building’s architecture resulted in heavy loads, which exceeded the settlement capacity of the onsite soils. Balter’s solution was to include reduced size spread footings, supported on the natural soils improved with cost-effective stone columns. Balter mapped the underlying rock surface and worked closely with the design team to reduce the amount of rock excavation, while providing a cost-effective foundation system. Balter reviewed the delegated design and inspected the installation of the stone columns to ensure that the project requirements were met.
The Crescent Development is an excellent example of how the Robert B. Balter Company can become an integral part of the design and construction inspection phases of a project. Balter’s Special Inspections have been essential to ensure the quality of construction of these multi-story buildings. Engineering support, including pavement design, bridge/culvert geotechnical explorations, foundation designs, rock surface mapping, and stormwater management analysises. QA testing included onsite testing of soils, concrete, reinforcing steel and asphalt pavements. Our proactive chemical testing prevented contaminated soils from being delivered to the site. Field representatives are supported by the engineering staff to prevent site delays and construction cost implications such as existing fill soils, wet soils, and the reuse of excavated rock. Balter’s team works closely with the owner, design team, and construction contractors to ensure that the requirements of the project documents are met, while limiting construction costs.