CA/Tastrophe In Our Future?
Construction materials from the Central Artery / Tunnel demolition and excavation from the early days of the nationís largest public works project may prove central to the Big Digís construction problems. Recycled into project concrete, could the contaminated dirt cause multi-million gallon tunnel leaks and 3-ton concrete slabs suspended overhead to crash to the ground less than 3 years after tunnel and connector opening events? Will the uncompressed Boston Blue Clay from the harbor tunnel prove too corrosive for the steel infrastructure? The slump test of the CA/T concrete might have been too little and too late, similar to the political maneuvers of Governor Mitt Romney to oust Mass Turnpike Chairman Matt Amorello.
Boston visitors and travelers should avoid using the $14.6 billion dollar Boston CA/T Tunnels until a full federal investigation occurs. Significant scrutiny of project decisions, including the opinions of project engineers unrelated to the project or any of its major players should certify the safety of the tunnel structures first. The Central Artery/Tunnel (CA/T) Project, now the property of the Massachusetts Turnpike Authority, needs to reassure the public. We expect answers to these questions about what $14.6 billion dollars of federal and state taxpayer money bought for the people of Massachusetts before our students, commuters, visitors to Boston and the millions of travelers who use the Interstate Highways each year continue to travel the tunnels.
1. Was a contamination clearance analysis for concrete corrosives and expansion properties established prior to using the stored 4,000 miles and over 11 million cubic yards of excavated construction materials destined to be recycled within the projectís concrete and other state projects?
2. Were the standards for recycling concrete aggregate systematically and uniformly applied to all materials recycled into this project?
3. Can the process of application of those standards be substantiated by contracts established with contractors that document review of the requirements for contamination? Was testing of concrete mix for strength and temperature performed by the Joint venture on materials supplied by contractors the only measure required?
We possess memos that outline the Massachusetts Highway Department and Department of Environmental Protection testing procedure of contaminated soil that was excavated during the Big Dig and stored at Suburu Pier and Massport. The agreement and memos stipulate which truck loads of material will be tested, the first of every 5 trucks. This process practically assured that questionable materials could easily pass through the first line of defensive inspection if that was desired by the Joint Venture. Bechtel and the state (the Joint Venture) were the people charged with recycling or disposing of all of the dirt and excavate.
Key Contaminants Affecting Humans and Wildlife
The Department of Environmental Protection storage criteria for Big Dig excavated materials is contained in documents we possess. If the excavated material was highly corrosive (pH1.5), reactive, ignitable (flashpoint<140 degrees F) or if it exceeded the threshold level for waste subject to TCLP, a test for soil and groundwater clearance was required prior to storage. This test was to determine if the excavated materials had to be contained in areas with or without a protective liner for months or years before eventual disposition to cap landfills or to be recycled back into constructing the artery as backfill and concrete aggregate.
Testing was done on CA/T demolition materials. The following list shows which contaminants the DEP was testing on recycled construction material. This test was used by the Massachusetts Highway Department and the Department of Environmental Protection in the mid 1990s to determine the levels of contamination acceptable for storage in unlined facilities at Mass Port sites. Some material was destined for use in capping landfills and for use in recreational parks. Other dirt was recycled into the 3.8 million cubic feet of concrete that is the Big Dig. While I am not a chemical engineer, I would like to know if the DEP or the Joint Venture tested for other elements.
Contaminant Criteria (mg/kg)
PCB - 10ppm
TPH - 3,000
PAH - 300
Arsenic - 40
Chromium - 500
Lead - 500
Mercury - 10
The test used was the often questionable TCLP.
If a truckload of dirt (excavated materials from the tunnel preparation) tested positive, DEP permission to store the materials was required. The DEP employees in charge of the permission process were salaried by the CA/T Joint Venture of Bechtel/Parsons Brinkerhoff and the Mass Highway Department. Memos show that, "At MHD ' s request, DEP will allow Non-Clearance excavate to be placed directly into the disposal area without the requirement of a liner, even though the requisite risk assessment has not been completed..."
These storage contamination tests were for corrosives and metals listed above that are harmful to people and wildlife.
1. Were the same tests applicable to determine suitability of soil beyond storage when materials were recycled as concrete aggregate (soil, sand, gravel)?
2. Could these or other untested contaminants effect the structure, strength and durability of concrete?
What Are Key Contaminants Affecting Strength, Durability and Properties of Concrete?
A review of Central Artery Tunnel video footage of Boston's Big Dig documentary series and corresponding documents shows that testing for chemical contamination in recycled construction materials was both lax in application and highly questionable in efficacy. For example, Joint Venture (Massachusetts Highway Department and Bechtel/Parsons Brinkerhoff) concrete testers were called in by the contractors during on-site pours of already mixed concrete to conduct random strength tests. Any on-site inspections of the contractor mixing facilities took place on a weekly scheduled basis according to our sources who were state and federally licensed concrete testers with the CA/T. Pours with insufficient strength were held for 28 days and 56 days to see if their strength would improve. Someone needs to review this testing process and determine what happened to the concrete that did not make the cut. I don't recall hearing of instances where concrete was deemed inadequate or where contractors were asked to remove and replace concrete after 56 days of testing.
Long before contaminated aggregate was ever mixed into the concrete, standards and tests for corrosion and concrete expansion should have been available or developed. Don't forget, we are talking about $14.6 billion dollars. A research grant for a small fraction of that amount at MIT might have yielded the answers in the 1990s that are becoming available today, ten years too late. Our investigation shows that construction standards for recycled concrete aggregate are still in a development stage and standards were not recognized internationally in the 1990s. So what criteria are independent investigators planning to use to determine if this project is sound or a public health hazard?
We could find no evidence of standards for reuse of any excavated materials as a recycled concrete aggregate similar to the ones used to safely store the contaminated materials. There seems to have been no analysis of roadway and harbor contaminants that could affect the performance of the 3.8 million cubic yards of concrete mixed from the recycled aggregate used to construct all of the Big Dig Tunnels. Web searches show International standards for acceptable levels of contaminants in concrete made from recycled aggregate seem to still be in development. Bechtelís on site VP discussed the experimental nature of Bechtel's use of Bostonís Blue Clay from the harbor floor in the construction mix in a company promotional tape for Bechtel that we obtained privately.
Excavated materials used as aggregate concrete mix that can have a potentially negative effect on the performance and strength of concrete properties include chlorides (accelerating steel corrosion) found in marine demolition (Boston Blue Clay?), sulphates (effecting expansion), alkali reactive material (glass that can expand dangerously when wet), organic components such as wood and polymeric materials that become unstable. This list is under development by K. Sagoe-Crentsil and T. Brown as a Guide for Specification of Recycled Concrete Aggregates(RCA) for Concrete Production- Final Report for CSIRO, Victoria.
If the CA/T had standards for testing aggregate reused in concrete in this project or if it can show substantial testing of contaminants prior to use in this project that served as a basis for guiding the concrete testing, they should be forthcoming with those standards. In the absence of this information and given the lax application of testing procedures for contaminants harmful to humans and wildlife, the public must avoid the tunnels until appropriate tests are conducted.
©2006, Dale Orlando
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