Montana Department of Transportation

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Stormwater Information

Program Overview

Small Municipal Separate Storm Sewer Systems Permits

In January 2005, the Montana Department of Environmental Quality (DEQ) issued a new general permit known as the Small Municipal Separate Storm Sewer System (MS4) permit. The permit is required for urban areas within the state of Montana that have storm sewer systems that serve a population of at least 10,000 people. Areas included in the permit are Billings, Missoula, Great Falls, Butte, Helena, Kalispell, and Bozeman. Cities, counties, universities, military bases, and the Montana Department of Transportation (MDT) are some of the entities required to obtain the permit for these areas.

Several entities are working together within each of the urban areas to cooperate in undertaking the program. Under the permit, they are required to regulate the discharge of potential pollutants in stormwater runoff within the storm sewer system.

Each permit holder must develop, implement, and enforce a Storm Water Management Program (SWMP). This SWMP must address the following six "minimum control measures:"

  1. Public education and outreach on stormwater impacts;
  2. Public involvement/participation;
  3. Illicit discharge detection and elimination;
  4. Construction site stormwater runoff control;
  5. Post-construction stormwater management in new development and redevelopment; and,
  6. Pollution prevention and good housekeeping for municipal operations.

To comply with the Permit requirements and address stormwater pollution related to highway planning, design, construction, and maintenance activities, MDT has developed and is working to implement a Storm Water Management Program (SWMP) within each of the seven areas designated by DEQ.

Erosion and Sediment Control Best Management Practices: Reference Manual and Field Manual

The MDT Erosion and Sediment Control Best Management Practices Manuals were completed in May 2004. The Reference Manual version was developed to assist in the design, construction, and post-construction phases of MDT projects. This manual provides a background of state and federal regulations associated with erosion and sediment control practices including a general overview of the erosion and sediment processes. Best Management Practices (BMPs) are listed within the manual based on application categories. Each BMP is described; its applications and limitations are listed, as well as its design criteria. A condensed Field Manual version was also completed, and both are available on-line from MDT's internal and external websites.

Stormwater Runoff Control and Environmental Compliance

Erosion and sediment control, water pollution control, and stream preservation are required for MDT construction and maintenance projects by MDT Standard Specifications, MPDES and NPDES General Permits for Storm Water Discharges Associated with Construction Activity and by various other permits, authorizations, and regulations. In addition, MDT implements various processes and control measures for construction projects, including site plan reviews, stormwater permitting, preconstruction reviews, environmental checklists, contractor installation reviews, Storm Water Pollution Prevention Plans, erosion and sediment control inspections and maintenance, and contractor site requirements.

Refer to DNRC's Guide to Required Permits for additional information on the various permits, authorizations, and notifications (aka "permits") that could apply to MDT construction projects or maintenance activities.

Post-Construction Stormwater Management

Compliance with the General Permit for Stormwater Discharges after MDT Projects Have Been Completed

Final stabilization

The General Permit requires that areas disturbed by construction reach "final stabilization" before permit coverage can be terminated. Final stabilization is typically initiated as part of the project by applying topsoil or compost, planting a mix of grass and forb seeds, and fertilizing areas of bare soil that resulted from project construction activities. The seeds must germinate and grow, and eventually establish a "permanent" cover of desirable vegetation that's at least 70% as dense as the pre-disturbed vegetative cover to be considered "final stabilization". In Montana this can take two or more years. After construction of the project is completed, rather than requiring the contractor to continue being responsible for General Permit compliance, BMP monitoring, site maintenance and reporting for what could be years until final stabilization, the authorization and compliance responsibilities under the General Permit are transferred from the contractor to MDT Maintenance or, if applicable, to a City or County government.

The process for transferring the General Permit authorization and compliance responsibilities involves a "final" inspection, which includes field verification that the contractor has implemented and maintained BMPs to minimize potential pollutants in stormwater discharges as identified in the Storm Water Pollution Prevention Plan (SWPPP), and an evaluation of the adequacy and effectiveness of the erosion and sediment control measures and BMPs. Results or findings of the inspection are documented on the project close-out checklist or MDT SWPPP Inspection Report form.

The General Permit responsibilities will not be transferred until the BMPs are inspected and accepted and all pertinent records and inspection reports are furnished to the appropriate entity (MDT, County or City). MDT may require certain BMP's be replaced by another type of BMP prior to the transfer. More specific descriptions of the transfer processes can be found on-line by following the Manuals/Guides link.

Permanent Erosion and Sediment Control Design Guidelines:
The purpose of the Permanent Erosion and Sediment Control Design Guidelines is to describe procedures and methods to address long-term erosion and pollutantn transport that could potentially result from highway construction, and sedimentation resulting from highway-related stormwater runoff.

The guidelines include procedures for evaluating the need for permanent erosion and sediment control (PESC) measures during the project development process and determining what PESC measures can practicably be incorporated into the design. The guidelines also provide design details that address specific erosion and sediment control issues and discussions of construction issues and maintenance considerations.

The primary objective of this guidance document is to provide adequate information for the selection of the appropriate PESC measures to be included in the plans package. Those measures are intended to reduce soil erosion and sediment deposition into adjacent waterways and protect the highway facility. It is anticipated that including PESC measures in the plans will clarify MDT's expectations of contractors, reduce maintenance needs, improve erosion and sediment control efficiency, facilitate efficient permitting and reduce long-term erosion and sediment control costs.

The incorporation of PESC measures will typically be limited to projects with scopes related to rehabilitation or reconstruction and locations in proximity to sensitive resources such as impaired waterways or high quality aquatic habitat and spawning areas. PESC measures can also provide solutions for areas with a history of erosion or sedimentation problems.

Inclusion of PESC measures into project plans are evaluated on a project-by-project, site-specific basis. Inclusion of PESC measures into the project plans should be coupled with proactive management of basic design considerations such as limiting the area exposed to construction, maximizing use of vegetative cover, minimizing sliver cuts and fills, weighing appropriateness of flat-bottomed channels as opposed to v-ditches, and using natural topographic features to the best advantage. All of which could reduce the need for PESC design measures.

MDT's Adopt A Highway Program

MDT operates an "Adopt A Highway" Program in each of MDT's 5 Districts. The program promotes and encourages public participation in litter pick up and highway cleanups throughout the state. Individuals or groups "adopt" a stretch of highway. Participants sign a contract agreeing to adopt 2 miles for a 2-year period and to pick up litter a minimum of three times a year. This program helps prevent litter and miscellaneous garbage from washing into the stormwater drainage systems and receiving waters.

For more information, please contact your area coordinators

Maintenance

Maintenance of Vegetation Adjacent to MDT Highways
Maintaining vegetation adjacent to our highways helps to prevent erosion and reduces the amount of sediment that's discharged with highway stormwater runoff. MDT Maintenance conducts ongoing vegetation management practices along its highways to restore sight distance, control noxious weeds, prevent snow drifting, reduce ice and to control or prevent slope failure. These practices include mechanical mowing, trimming, brush removal, spraying herbicide and re-seeding. MDT has developed and uses a variety of best management practices for maintenance activities related to vegetation management, which are documented in the Environmental Best Management Practices section of the MDT Maintenance Manual.

Roadside Cleanup Program
MDT's Roadside Cleanup Program includes activities such as: Removal of debris, litter, trash and large animal carcasses; clean up by sweeping traveled ways, shoulders and paved ditches, and involvement of Adopt-a-Highway. This improves safety, reduces the potential for pollutants to be discharged in stormwater runoff and addresses other environmental concerns.

snowplow clearing drifts
Clearing snow drifts

Winter Road Maintenance
Snow Plowing, Ice Removal and Sanding (sanding Material and liquid deicers) - MDT continually reviews its winter road management activities, including use of sanding materials, salt, and chemical deicer, in an effort to improve winter travel safety and cost effectiveness, and to reduce adverse environmental effects. MDT Maintenance develops winter management and operation plans that identify sensitive/critical areas and has developed Best Management Practices (BMPS) and guidelines for maintaining water quality in snow and ice operations that can be implemented to avoid or minimize adverse effects to these sensitive areas.

MDT Snow blower
MDT snow blower

Best management practices include:

  • Striving to reduce the overall amount of aggregates used through alternative treatment strategies.
  • Applying liquid deicers alone, or in combination with, abrasives at site-specific sensitive locations where appropriate and practical.
  • Adhering to the MDT/DEQ abrasive material specifications for PM-10 nonattainment areas, where applicable, to address air quality issues.
  • Placing barriers in site specific locations where appropriate and practical (such as along streams or direct drainages) to route abrasives/anti-icing material away from watercourses. If a culvert or catch basin could discharge sediment and impact waterways, sediment control measures should be implemented whenever possible to prevent excess abrasives run-off into the waterway.
  • When possible, stopping sidecast sweeping within 50 feet of structures over water and avoiding casting snow and/or ice into a waterway.
  • Cleaning of structures in the spring. Abrasives should be recovered from bridges and the highway shoulder when weather and road conditions allow. Cleanup should also include removing material from under the guardrail.
  • Hauling and disposing of removed snow in an appropriate manner away from sensitive sites.
  • Educating MDT Maintenance staff on water quality and fishery resource issues.

Materials Storage / Spill Prevention, Control, and Countermeasure (SPCC) Plans
MDT developed and maintains SPCC Plans for the MDT Maintenance Section facilities that store more than 1,320-gallons of petroleum product in aboveground containers, and that are located where a spill could reasonably be expected to discharge oil or fuel in harmful quantities into navigable waters of the U.S.. The SPCC Plans include measures such as secondary containment, facility drainage, containment dikes and barriers, sump and collection systems, retention ponds, curbing, tank corrosion protection systems, and liquid level devices.