Section 3: TxDOT Decisions and Communication

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Decision-Making Process

Regardless of the stage at which a hazardous substance or petroleum contamination is identified, a decision must be made to revise the location of the project, delay the project, or terminate the project. This decision should be based on cost/benefit evaluations and risk assessments, which depend upon the types of contaminants present, level of health risk, contaminant fate and mobility, and feasible treatment options.

FHWA guidance is steering TxDOT toward the proactive policy of conducting site assessments during the project planning phase to avoid, minimize and recover costs. If a hazardous materials site cannot be avoided, then the project should be designed to minimize hazardous materials impacts. To minimize the impact most effectively, the environmental site assessments and investigations must be comprehensive to determine the extent and severity of the contamination of concern. The level of investigation should correlate to the amount of information the department needs to determine the following:

  1. Can the contamination be effectively remediated prior to letting without causing undue traffic flow interruption or redundant excavation?
  2. Can the construction contractor work in the contaminated areas without exceeding the permissible exposure limits (PEL) for the chemical of concern? In other words, is the construction site safe for the contractor?

Decision-making during the construction phase of the project is usually limited to unanticipated hazardous materials/waste sites encountered during ongoing construction activity. In cases of anticipated site(s) where there is a strong certainty that hazardous materials/wastes are present, project-specific action should already have been sequenced in the plans.

If hazardous materials are discovered in a work zone, the first determination the Engineer must make is the impact, if any, a work stoppage might have on construction site safety. For example, could stopping the work have a disastrous effect on the project, such as the collapse of an earth wall or retaining structure? Once that determination is made and a stage has been reached at which the work can be safely stopped, the contaminants must be identified and concentrations determined to assess whether the exposure level is above that permitted by the Occupational Safety and Health Act (OSHA). The next decision the Engineer must make is whether the project should be terminated, suspended or altered to avoid or mitigate the effects of the hazardous materials/waste. The contract(s) may be amended to accommodate whatever decision is made. If the decision is made to continue with the project, a careful investigation must follow to examine the possibility of concurrently executing both clean-up and construction activities and to establish the sequence offering optimum accomplishment of both objectives.

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Communication between districts and divisions is essential in determining the most effective and economic method of proceeding with project development. Figure 1-1 depicts the communication flow that should occur during project development between advanced planning, right-of-way, design and construction functional areas.

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Figure 1-1.

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