Section 4: Contamination Factors and Considerations during Construction
During the design phase, it is necessary to determine how preventive action will be accomplished during construction and delegate responsibility for the various activities.
Many construction-related considerations and factors should be analyzed to determine the most efficient and cost-effective design.
Anchor: #i1014502Contamination Factors during Construction
When the preventive action for the contaminated materials cannot reasonably be accomplished by a separate contract prior to construction, several factors should be analyzed to determine the best method for incorporating the preventive action into the PS&E. These factors include:
- Anchor: #XVIJTBGQ
- Type and severity of contamination Anchor: #QVBBMUIV
- Area of contamination as related to project size and sequencing Anchor: #WFKCTFWA
- Time and traffic constraints Anchor: #NGPRHOSL
- Possible reuse of contaminated soil Anchor: #IFQEWQSN
- Estimated cost of preventive action.
Contamination Considerations during the Construction Design Phase
During the design phase, several construction considerations should be addressed in areas where the environmental site assessment and/or investigations indicate the possibility of contamination. The district should work closely with the divisions to determine the most cost-effective, efficient manner of handling contamination on a project. The following options for handling contamination are available; any one or a combination thereof may be used:
- Anchor: #TMIRDXPB
- Prior to Construction: Preventive action occurs prior to roadway construction by the owner, operator or party responsible for causing the contamination, or by a specialty contractor via TxDOT contract or prearranged purchase order Anchor: #VMAOGLGO
- Emergency Contract: Preventive action occurs during construction after an emergency contract is issued for a TxDOT specialty contractor Anchor: #QNJAUULX
- Prearranged Purchase Order: Preventive action occurs during construction via a prearranged purchase order for a state specialty contractor Anchor: #CJQFFRFP
- Change Order: Preventive action is performed during construction by the prime construction contractor or subcontractor using a change order Anchor: #RWLEOAVX
- Prime Construction Contractor: Preventive action occurs during construction when the prime construction contractor or specialty subcontractor is required to perform work; Anchor: #PDADRAGT
- Responsible Party: Preventive action occurs during construction by those responsible for causing the contamination.
Option 1 - Prior to Construction: Option 1 is the preferred choice for sites known to be contaminated. This option provides for cleanup prior to roadway construction and allows normal construction activities to be conducted by the prime construction contractor without delay or additional costs. Option 1 is best suited for contaminated sites within the proposed right-of-way that can be cleaned up with little or no disruption to traffic. However, if redundant excavation will occur when using two separate contracts, other options may need to be considered.
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Option 2 - Emergency Contract: Option 2 requires TxDOT to suspend construction in the area of the contamination in order for the emergency contractor to perform preventive action activities. To reduce delays and associated costs, coordinate with CST, ENV and PRO if an emergency contract is required. Working with PRO early in construction phases when an emergency contract is needed will help to ensure a smooth transition from the prime construction contractor's work to the specialty contractor's work with minimal delays. The disadvantage of Option 2 is the inherent conflict of having two firms, both on contract to TxDOT, working on the same job site at the same time.
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Option 3 - Prearranged Purchase Order: Option 3 can be useful for certain types of recurring contamination, such as those encountered by large urban districts. District blanket purchase orders may also be useful when advance notification of known contamination is made. This option allows a specialty contractor to be available on short notice when contamination is encountered; prices for different work activities have already been competitively bid and are charged for each project as needed. ENV maintains Master Blanket Purchase Orders with specialty contractors to provide rapid response to contamination issues. Option 3 may still require TxDOT to suspend construction activities in the area of contamination so the specialty contractor may perform preventive action activities. However, delays should be minimized since a contract already has been approved for the preventive action work. Option 3 is especially useful in addressing soil only LPST contamination that may have migrated into the project limits from an off-site source. For many soil only LPST sites, the construction activity may be viewed as an extension of a site investigation. As long as the prime construction contractor knows to discontinue work if/when contamination is encountered, the transition back and forth between the prime construction contractor and specialty contractor can proceed smoothly and efficiently without the need for an expensive preconstruction environmental site investigation. Groundwater contamination in general requires additional protective measures that are likely outside of this option.
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Option 4 – Change Order: Option 4 may be used in accordance with Item 4 (4.0, Scope of Work) of the Standard Specifications for Construction of Highways, Streets and Bridges. Option 4 may be useful when a reasonable cost can be negotiated with the prime construction contractor to perform the preventive action work. In most cases, the prime construction contractor must subcontract for this work; it may be more cost-effective to use Options 2 or 3. However, there are advantages to this method. The prime construction contractor has more control of the work activities, delays are reduced, and reductions in work conflicts due to outside contractors are avoided. The prime construction contractor can also employ an industrial hygienist to monitor permissible exposure limits (PELs) on the project site. The district should coordinate with CST and ENV when negotiating for change orders to ensure the cost effectiveness of the prime construction contractor's offer.
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Option 5 - Prime Construction Contractor: When requiring the prime construction contractor to perform preventive action, typically through the use of an SGMP included in the PS&E, Option 5 should be used only in exceptional cases. Option 5 may be necessary when it is not feasible to clean up contamination prior to starting the roadway project. Option 5 also minimizes the number of independent contractors working in the same location, reducing the potential for conflicts. When contamination is located under the proposed roadway, an effective way to minimize traffic flow interruption is to coordinate the preventive action and construction schedules. The designs should also be coordinated to eliminate redundant excavation. For example, the standard preventive action philosophy is to return a contaminated area to its original condition. Without coordination, the possibility exists that the preventive action contractor will excavate and dispose of the contaminated soil and replace it with clean soil. If the site is in a cut section, the prime construction contractor would then haul away the fill that had just been brought to the site. When the prime construction contractor is responsible for performing the preventive action or by subcontracting with a specialty contractor, this coordination is easier to ensure.
While in some situations it may be necessary for the prime construction contractor to be responsible for all aspects of the preventive action, in other situations it may be appropriate to limit the prime construction contractor's responsibility to on-site activities only. For instance, the prime construction contractor would be responsible for conducting (either with his own forces or those of a specialty subcontractor) on-site work in contaminated areas of a project, including moving materials to a TxDOT-designated storage area or incorporating the materials into the project. In this case, the prime construction contractor would not be responsible for any off-site related work. TxDOT or the local entity would procure the services of a specialty contractor to load, haul and dispose of materials at an off-site disposal facility.
Approval from the TxDOT Administration is necessary before preventive action work can be incorporated into the PS&E. The district should work closely with ENV, DES, and CST during the early stages of project development when Option 5 is considered. The district is encouraged to consult with DES for development and review of plans, requirements and specifications.
Typically, the mitigation for this option is paid through a force account that is setup prior to letting the construction project. A force account is a fund that is setup to pay for mitigation work and is not competitively bid by prospective bidders. The force account amount is determined by an Engineer’s estimate that is developed by estimating the costs to perform the mitigation work, the contractor’s health and safety requirements, and increased construction costs caused by the mitigation work.
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Option 6 - Responsible Party during Construction: Option 6 is feasible only when the responsible party is willing and able to perform the preventive action. Prior to finalizing the PS&E, arrangements with the responsible parties should be made. These arrangements can be incorporated into the acquisition process when additional right-of-way is required. This option may also be used when unanticipated contamination is encountered during construction. With this option, the need for cost recovery is avoided or minimized. Significant coordination between the prime construction contractor and the responsible party's specialty contractors will be necessary to prevent or limit the prime contractor’s downtime. Note the in some industrial or commercial areas it may be difficult to identify the responsible party, or there may be several contamination plumes which have commingled.
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