Managing Stormwater Runoff from Large Highway Construction Projects

Introduction

The last decade has been challenging for drivers on Interstate Highway 35 in the San Antonio and Austin area. First, the region has seen almost explosive growth in population. The Austin metropolitan area grew from about 850,000 in 1990 to over 1.2 million in 2000 — a 48 percent increase. While less dramatic than Austin, population growth in the San Antonio increased by 19 percent during that same period — from 1.3 million to 1.6 million. Much of this population growth has occurred along the IH 35 “corridor” connecting the cities within unincorporated areas and in communities such as Round Rock, San Marcos, and New Braunfels. Now, with about three million people residing in this area, IH 35 has become the major thoroughfare for both inter- and intra-city traffic.

In addition to the demand on highway resources created by a burgeoning population, truck traffic on IH 35 has also increased dramatically. In 1994, the North American Free Trade Agreement (NAFTA) created the world’s largest free trade area and led to the construction or expansion of scores of “Maquiladora” plants in Mexico. These plants are primarily engaged in the manufacture or assembly of products bound for US markets, and these products are transported to market primarily by truck. The majority of trucks carrying goods from Maquiladora plants in Nuevo Laredo, Monterrey, and other Mexican cities enter the United States at Laredo, making it the busiest port of entry on the Texas/Mexico border. The trucks then travel north on IH 35 to the heartland of the United States.

This combination of increased private vehicular and commercial truck traffic has resulted in an unusually high degree of traffic congestion, particularly in the Austin area, which the Texas Transportation Institute has stated has the worst traffic congestion of any mid-sized city in the United States. In an attempt to relieve this situation, the Texas Department of Transportation (TxDOT) is building State Highway (SH) 130.

SH 130 will be a toll road approximately 90 miles in length from IH 35 north of Georgetown to IH 10 east of Seguin. TxDOT has chosen to construct the northern segment of the tollroad as a design-build project in order to reduce construction time. The first portion, about 49 miles from the terminus at IH 35 north of Georgetown to US Highway 183 southeast of Austin, is currently being built by Lone Star Infrastructure (Developer) under contract to TxDOT.

Most of this portion of SH 130 will be located on previously undeveloped land. Since so much land must be disturbed within the 600-foot wide right-of-way, control of pollutants entrained in stormwater is an environmental compliance issue of particular importance. TxDOT and the Developer have established a program to ensure that the project stays in compliance with the regulatory requirements of the State of Texas regarding control of stormwater from construction sites.

Stormwater Protection Programs for Highway Construction Projects

Standard Design-Bid-Build Project

In terms of stormwater protection, TxDOT’s standard design-bid-build highway project consists of the following:

1. Highway and stormwater protection plans are prepared by TxDOT or by engineers under contract to TxDOT.
2. Construction contractors not affiliated with the engineers bid the project based on the plans and material quantity estimates prepared by the engineers.
3. During construction, stormwater controls (best management practices or BMPs) are inspected by TxDOT or by a consulting engineering firm under contract for services to TxDOT; however, TxDOT maintains approval authority with regards to BMP selection, installation, and maintenance. The engineer determines whether the controls have been installed in accordance with the stormwater pollution prevention plan (SWP3) and are being maintained in accordance with TxDOT specifications and standard practice. TxDOT will also recommend modifications to types and locations of BMPs, if conditions so warrant.
4. The contractor is required to install and maintain the BMPs as depicted on the original SWP3 plan sheets under its existing contract with TxDOT. In addition, any modifications to the controls (e.g., location, upgrades) could be additions to the contract. All BMP installation and maintenance is paid based on unit rates provided during bidding.

SH 130 Design-Build Project

The Developer has a lump-sum contract with TxDOT to provide right-of-way acquisition services, design, and construction of SH 130. This includes preparation of the SWP3, installation and maintenance of BMPs, and inspection of the BMPs for regulatory compliance. The contract requires that the Developer hire an independent construction quality assurance (CQA) firm whose duties are, in part, to inspect the BMPs. The inspections are conducted to verify compliance with the Texas Commission on Environmental Quality (TCEQ) General Permit to discharge stormwater from construction sites (TXR150000) and conformance with the SWP3. BMP modifications and upgrades necessary to maintain compliance are also noted in the inspection reports.

In addition to the CQA firm, two more entities are contracted to provide environmental compliance inspection services on the project. The second entity, the environmental compliance (EC) firm, is under contract to LSI to monitor the compliance of the project with the various environmental programs to which it is subject (i.e. air quality regulations, National Environmental Policy Act - NEPA), including the TCEQ General Stormwater Permit.

The third entity with contracted environmental compliance oversight responsibilities is the Owner Verification (OVT) firm under contract to TxDOT. The OVT firm provides oversight of the activities of the Developer and its subcontractors, including the CQA and EC firms.
Finally, TxDOT itself has a direct role in the oversight of the Developer’s activities. A portion of their responsibility is to ensure that the Developer complies with provisions of the contract with TxDOT including compliance with applicable environmental programs.

Differences Between Design-Bid-Build and Design-Build

The major differences between a standard TxDOT design-bid-build project and the SH 130 design-build project are presented in the table below.

The SH 130 Erosion Control Experience

Erosion Control Organization

The Developer employs three full-time erosion-control crews, each crew consisting of three laborers and a foreman, to install and maintain the BMPs. The activities of the crews are overseen by the Developer’s three construction area managers. In addition, outside contractors are periodically used to install BMPs. The Developer has estimated that during the height of construction when almost all of the 49-mile SH 130 right-of-way was actively under construction, approximately 3,500 BMPs were present on the project. These included such diverse elements as silt fences, rock filter dams, sedimentation ponds, diversion berms, and mulch socks.

In accordance with General Permit requirements, periodic inspections of all BMPs are conducted by the CQA firm. Initially, inspectors conducted BMP inspections every 14 days and within 24 hours after a rainfall event of ½ inch or more as stipulated in the General Permit. However, this often resulted in two or more inspections within a seven-day period during rainy weather, so the inspection frequency was modified to once every seven days - another option allowed under the General Permit. Each inspection results in a report listing BMPs requiring maintenance and recommendations for additional or upgraded BMPs. The report is signed by the responsible inspector and the erosion-control foreman. The Developer then has seven days to address the list items or risk non-compliance with the General Permit. The major exception to the seven-day requirement was inaccessibility to BMPs which was a common condition after significant rainfall events.

The EC firm and the IE inspectors also review the compliance status of BMPs. However, their observations are communicated to the erosion-control inspectors informally rather than in a report in order to reduce the number of parties interacting with the erosion-control crews.

Because five entities (Developer, TxDOT, CQA firm, EC firm, and OVT) are involved in the stormwater compliance program, a procedure was put into place to allow for any of these entities to challenge recommendations and actions taken. Four levels of escalation were included in the procedure from inspector (Level 1) to senior management (Level 4). Generally most escalated issues were resolved at Level 2 with a few being elevated to Level 3. To date, no issues have been escalated to Level 4.

In order to keep all parties informed of BMP status, the CQA firm implemented a system, using the weekly inspection reports, to concisely summarize:

1. The number of disabled BMPs in each section of the project;
2. The number of disabled BMPs that were inaccessible
3. Designations and locations of disabled BMPs

The summary is distributed weekly and is used by Developer management to assess the allocation of personnel performing erosion control and by all parties as a means to determine the compliance of the project with the General Permit.

Erosion Control Implementation

Each erosion-control crew was presented with considerable challenges in maintaining the hundreds of BMPs present in its assigned project segment. Rainfall events in central Texas are generally intense resulting in a large number of BMPs requiring maintenance. Furthermore, BMPs are often displaced or inadvertently disabled during construction activities requiring the need to replace the structures. During dry weather, each crew may have to service and install one hundred or more BMPs, and after rainfall events this number could be several hundred.

The CQA firm inspection report is generally available one day after the inspection. At that time, the Developer erosion-control foreman signs the report acknowledging the list of deficiencies and then has seven days to complete the deficiency list or the project can potentially be non-compliant with the General Permit. If the foreman disagreed with any of the inspector’s recommendations, the foreman can request that the escalation process be used to resolve the issue.

During the course of the week, inspectors from the CQA firm, EC firm, IE, and TxDOT conduct informal reviews of progress. If other areas of concern are noted by the EC firm, IE, or TxDOT, they notify the CQA firm inspector who, if he was in agreement with the evaluation, would either relay the information to the Developer or include the area in his next inspection report. If he disagrees with another inspector’s evaluation, he can escalate the issue.

The escalation process has been used several times, primarily during the early phases of the project while the most appropriate types of BMPs for the variety of conditions on the site (i.e. adjacent to streams, within ditch lines) were experimented with and evaluated.

In order to provide better coordination among the various parties involved in the erosion-control program, the CQA firm created the position of Corridor-Wide Stormwater Coordinator. The Coordinator’s responsibilities included the following:

• Ensuring that the escalation process was followed and completed when one of the parties requested it
• Achieving consistency in report format and evaluation of BMPs by the erosion-control inspectors
• Evaluation of the effectiveness of BMPs recommended by the erosion-control inspectors
• Providing summary reports of weekly inspections to Developer management and TxDOT

As discussed above, compliance of the project with the General Permit is based on the Developer addressing accessible BMPs noted on the weekly inspection reports within seven days. This is generally not a concern until after significant rainfall events, as a result of which, hundreds of BMPs might be disabled or require maintenance. After these events, BMP maintenance was discussed at joint bi-weekly meetings between the Developer, TxDOT, and the monitoring firms in order to quickly resolve potential accessibility and priority issues rather than deferring them to the more linear escalation process.

Results

Construction on SH 130 began three years ago (October 2003), and during that time over 25,000 BMPs have been installed along nearly 50 miles of right-of-way. LSI and TxDOT were careful to build an erosion-control program that would be effective and remain compliant with the Construction General Permit. Because of this care, the project has not received a single citation from either the TCEQ or EPA for violations of the permit.

In October 2006, the project was recommended by a TCEQ auditing team for recognition as an Environmental Leader within the TCEQ Clean Texas Program. This program recognizes businesses and organizations that are committed to making real environmental improvements as a part of their business activities. Due to the size of the SH 130 stormwater program and its public visibility, this aspect of the project environmental program received much attention from the auditing team.

Recommendations

Based on the SH 130 experience, the following procedures are recommended for erosion-control programs for future design-build highway construction projects.

1. Costs for SWP3 Preparation and Implementation
   The Developer of SH 130 submitted a lump-sum bid to TxDOT for all costs associated with constructing the highway including preparation and implementation of the SWP3. While it may be possible to estimate the engineering cost associated with SWP3 preparation, the number and types of BMPs that will initially be required, along with upgrades and modifications that may be needed as construction proceeds, cannot be reasonably anticipated.
   The following recommendations are made for future design-build projects:
   (1) Include preparation of the SWP3 as a cost to the Developer (see Recommendation 4).
   (2) The CQA firm should prepare the SWP3:
   i. The CQA firm is responsible for inspection of stormwater controls
   ii. The potential for conflict of interest is removed if the developer is not responsible for both preparing the plan and installing recommended controls.
   (3) Make costs for implementation and maintenance of the erosion-control system payable by TxDOT based on the initial plan and weekly inspections. This would preclude the necessity of bidders on future projects from putting contingency into their bids to account for erosion-control costs that cannot be anticipated.
2. Construction General Permit Permittee
   The Construction General Permit permittee for the SH 130 project is TxDOT. As such TxDOT is directly responsible for compliance with the permit. For future design-build projects, it is recommended that TxDOT and the Developer be co-permittees. This would accomplish two goals:
   (1) The Developer would be directly responsible for compliance with the permit and would thus have an additional incentive to avoid situations of potential non-compliance.
   (2) The OVT would not have to inspect BMPs on behalf of TxDOT as TxDOT would not have all the risk in General Permit.
3. Construction General Permit Notice of Intent (NOI)
   The Construction General Permit stipulates that the SWP3 must be “completed prior to obtaining authorization under this permit.” TxDOT was responsible for submitting a single authorization request (Notice of Intent or NOI) for the SH 130 right of way. This necessitated that the SWP3 for the entire right of way be prepared prior to submitting the NOI. However, as much of the details of construction were not known until immediately prior to beginning construction, the SWP3 prepared far in advance of construction could not have anticipated actual construction conditions.
   Therefore, it is recommended that individual NOIs be submitted for smaller areas immediately prior to commencing construction. This will allow the developer to prepare SWP3s (see Recommendation 4) that more closely reflect the actual sequence of construction and construction activities.
4. Preparation of SWP3
   As discussed above, a single NOI was obtained by TxDOT for the entire length of SH 130. Since the Construction General Permit requires that the SWP3 be prepared prior to authorization, the Developer prepared the SWP3 for the entire project right of way during the design phase. Because of this, it was necessary to significantly modify many of the plans prior to commencing construction as the SWP3 engineer could not have anticipated the sequence of construction when the SWP3 was prepared. This resulted in inefficient use of personnel who could have been used on other project requirements.
   For future design-build projects, it is recommended that the SWP3 be prepared for smaller sections of the project as those areas open up for construction. The SWP3 engineer will be able to consult with construction personnel as to the type and sequence of construction activities in order to prepare a plan that more closely reflects actual construction conditions.
   Preliminary plans could then be reviewed by the Developer and TxDOT during a walk-through of the area immediately prior to beginning construction. The SWP3 engineer would incorporate comments into the plans.

Conclusion

SH 130 is one of the largest design-build highway construction projects ever undertaken in the United States. During the course of construction, nearly 3,500 acres of land has been disturbed, and, by law, runoff from all of this disturbed area must be controlled to reduce the potential for release of pollutants to adjacent properties and surface water bodies. The TxDOT and Lone Star Infrastructure stormwater management program has not only resulted in zero violations of the Texas Construction General Permit to discharge stormwater from construction sites, but the project has also been recommended by TCEQ as an Environmental Leader in the TCEQ Clean Texas Program.

The SH 130 erosion-control program can serve as a model for future large highway construction projects and, with the recommended modifications, can be further optimized to benefit the state, the developer, and the tax-paying public.