Section 3: Design Considerations and Factors
Avoidance and Minimization
TxDOT should analyze each project alternative carefully; the
goal being 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 acquisition and 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
(e.g. an SGMP). In some cases, requirements for proper management
of hazardous materials or special considerations for post-construction
maintenance activities may also apply.
Design Considerations
When there is a strong degree of certainty that hazardous
material contamination exists within the project limits, coordination
with affected TxDOT divisions should begin early in the project development
process. Each TxDOT district should develop its own procedures based
on the information found in this manual 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 instructions to acquire consultant
and contractor services with the assistance of ENV and PRO staff.
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 expertise 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 implementation of 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.
- 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