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Section 3: Design Considerations and Factors

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Avoidance and Minimization

TxDOT should analyze each alternative carefully; the goal is to select the most cost-effective option that is least likely to impact the environment and best serves the purpose of the project. Several factors must be considered in the decision to avoid or minimize involvement with hazardous materials including health and safety concerns, design feasibility, maintenance after construction, liability, costs and other environmental issues.

If contamination is encountered and cannot be avoided, TxDOT should make every effort to have the owner, operator and/or responsible party investigate and clean up the contamination prior to acquisition. If it cannot be cleaned up prior to construction, the project designer should find ways to minimize involvement or impacts with hazardous materials by redesigning the project or properly handling the concern prior to or during construction. It may be necessary to develop procedures, plan notes, specifications and/or plan details to address contamination concurrently with construction. In some cases, requirements for proper management of hazardous materials or special considerations for post-construction maintenance activities may also apply.

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Design Considerations

When there is a strong degree of certainty that hazardous material contamination exists within the project limits, coordination with affected divisions should begin early in the project development process. Each TxDOT district should develop its own procedures based on the information in this document and designate responsible persons for determining and coordinating project development activities when there is a possibility of encountering hazardous material contamination during construction. Project designers should coordinate with TxDOT divisions through designated district personnel. If needed, Chapter 6: Hazardous Materials Services Contracts provides detailed instructions to acquire consultant and contractor services with the assistance of ENV and the Purchasing Section of GSD.

All design and construction activities involving hazardous material contamination should comply with state and federal rules and regulations. Coordination with the TCEQ throughout project development and construction may be necessary. Consultants may be needed to develop the preventive action plan and provide coordination with other agencies, depending upon the district staff’s level of training and experience. The preventive action plan details the plans and specifications for monitoring and testing, health and safety plans, waste management and other items that may be needed. The cost-effective project design should also:

  • determine who will accomplish the work activities in the contaminated areas
  • determine how and when construction sequencing should occur
  • determine how costs associated with contamination will be taken into account
  • assign responsibilities to the parties involved in the construction contract.

If possible, preventive action should be accomplished prior to construction on the roadway project. When contamination is located within the proposed right-of-way limits, the best way to minimize traffic flow interruption is to coordinate the preventive action and construction plans. When preventive action and roadway construction plans are let as separate contracts, the designs should be coordinated to eliminate redundant excavation.

Design Factors: When contaminated materials or wastes are involved, analyzing the following and other factors will help determine the most efficient and cost effective procedures for handling preventive action activities:

  • type of contamination
  • severity of contamination
  • location of contamination
  • design, construction and traffic delays
  • right-of-way acquisition
  • utility adjustments
  • design requirements (for example: reconsider storm sewer placement to avoid or minimize excavation in contaminated areas, elevated rather than depressed roadway sections, and de-watering requirements)
  • costs associated with preventive action.
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