WASHINGTON SUBURBAN SANITARY COMMISSION (WSSC)
Throughout our history, Balter has provided our services to WSSC over a variety of projects. These projects have included Wastewater Treatment Plants (WWTP), force main alignments, and elevated tank rehabilitation. Our services have included Geotechnical Engineering, specialized consultations, and assistance with asset management. A sampling of our work with WSSC is provided below, and will continue to grow with our steady involvement at WSSC.
Piscataway WWTP
Balter has performed multiple geotechnical studies for projects at the Piscataway WWTP including existing pipeline evaluation of the soil corrosion, geotechnical evaluations for the new Bio-Energy facility consisting of a new FOG facility, a side stream treatment facility, a CHP facility which will include new generators, new above-ground anaerobic digesters, gas treatment and storage, a flare structure and boilers, a THP facility, a new odor control station, bio-energy substations, and a blending/distribution box.
All projects at the Piscataway WWTP require significant coordination with plant personnel to perform all field work. The plant has implemented a detail procedure for working within the facility Balter is intimently familiar with. For all geotechnical operations, Balter worked closely with the Plant and the Client to develop an appropriate boring plan that did not disturb plant operations or the existing infrastructure. Following site specific meetings with the plant, plant approval of the boring plans, and receiving background checks of all site crews, all boring locations were cleared for utilities by numerous methods including standard Miss Utility clearance, ground penetrating radar (GPR) and vacuum test pits. In our experience, GPR is not an effective utility clearance method at the plant due to shallow fine-grained soils and a dense underground utility network both which masked the deeper utilities. Vacuum test pitting are usually performed at select locations where utility conflicts were of most concern.
Historically, Balter has performed new subsurface borings, installed ground water monitoring wells, performed continuous SPT sampling and testing, and collected Shelby tubes. The properly permitted ground water monitoring wells were installed under MDE requirements to evaluate long-term stabilized water levels. These wells were also developed for future use at the plant. For all projects, a Balter geotechnical engineer has been onsite full time to direct the drill crews and oversee all field operations, to correspond with WSSC site personnel, to visually log the excavation of the site soils by the methods being performed (vacuum test pits, backhoe test pits, borings, etc.) and to collect the selected soil samples for laboratory testing.
The selected soil samples were tested in Balter’s AASHTO accredited and Corps of Engineers validated laboratory and included standard engineering index testing (Natural Moistures, Gradations, Atterberg Limits), proctors, CBRs, flex-wall permeability tests, direct shears, and consolidation tests. Soil samples have also been subjected to corrostion testing. All collected subsurface data is inputted into WSSC’s gINT format and used to assess the site conditions relative to the proposed development.
Our evaluations result in developing a geotechnical report that has addressed the site conditions recommending the design of foundations, retaining structures, open cut excavations, temporary slopes, and reuse of the site soils. The reports also have addressed site excavations near the existing infrastructure that would typcially be sensitive to construction vibrations (ie, utilities, building foundations, existing clarifier tanks, etc.).
PCCP Rehabilitation
The Washington Suburban Sanitary Commission (WSSC) has commenced a new initiative which will ultimately replace all PCCP water transmission mains within its water transmission system due to the inherent shortcomings of the pipe material.
As part of the Asset Management Program, WSSC has requested preliminary design services in order to develop alternative alignments, evaluate pipe materials, and construction methods for preliminary design of transmission main replacements.
Balter’s work under this task has involved preliminary evaluations of possible alignments for several tasks. As part of this work, we studied existing documents in order to identify potential risks to each alignment. This features include, historical topographic maps, environmental databases, Soil Surveys, Geologic Maps, existing Geotechnical Data, and the presence of right-of-way or permitting issues (rail, State Highways, etc.).
Once our prelimnary work was compelted, the alignments were than narrowed down to several options. Using the information obtained from our previous work, borings could be selected along the alignments at areas of greater interest. This information was then comiled into preliminary Geotechnical Reports to allow for further design of the alignments.
Projects under this task have included:
Pumpkin Hill Force Main
Hill Road Force Main
Carsondale Force Main
Pointer Ridge Elevated Tank
Pointer Ridge Elevated Tank (ET) is a two million gallon elevated steel tank owned and operated by the Washington Suburban Sanitary Commission (WSSC). Design Documents have been generated which include recommendations for repainting the storage tank, and replacing the existing altitude valve vault. As part of this task, we have been requested to review the existing documents, relative to Geotechnical issues and constructability, and to perform additional site investigations and evaluations to update the existing plans to be bid ready documents.
This task is part of a larger Tank Rehabilitation conract where Balter will perform a similar scope of services throughout the WSSC jurisdiction.