The Maryland State Highway Administration (MSHA) Stormwater Management (SWM) Program was developed under the National Pollutant Discharge Elimination System (NPDES) program. Under the SWM Program MSHA developed and implemented strategies and processes for identification, inspection, maintenance and remediation of best management practices (BMPs). The primary goals are to improve performance, safety and the visual quality of SWM facilities statewide. This approach provides compliance with MSHA’s NPDES permit, but also meets MSHA’s business goals of environmental stewardship. The program consists of four major components:
- Inventory and inspection;
- Maintenance;
- Functional and visual quality enhancement; and
- Research and development.
The SWM Program initially concentrated on the inventory, but current focus has shifted to maintenance and functional retrofits. MSHA developed a classification system to aid in identifying the remedial activities that restore performance and pioneered new technologies for visual and functional enhancements. The overall process tracks inspection and remediation information to monitor the SWM facilities’ conditions and provides support data for long-term performance research. This in turn requires continuous inspection process improvement as well as the development of tools to track information such as performance data, remedial activities and associated costs. The data resides in various formats including digital images, relational databases and geographic information system (GIS) coverages. New technologies play a critical role in data processing to develop inspection reports, create work orders and schedule remedial activities. Data management tools for both office and field data collection were developed with the objective to combine GIS and database functionalities to facilitate rapid data management.
Graded on it
Inventory of SWM facilities consists of office processing, field investigation and data integration. The key data are attribute information, SWM facility outline, drainage areas and relevant drainage structures discharging into or out of a SWM facility.
Resources such as as-built plans, design reports, utility maps, GIS coverage and aerial photography are used during office inventory. Office processing includes identifying, characterizing and labeling drainage features and SWM facilities, while field investigation verifies locations and attributes. Collected data are compiled into databases and GIS models. Roadway data is verified at each level before being integrated into the database and GIS model per MSHA’s NPDES GIS Standard Procedures.
Field Inspection
MSHA developed a SWM Facility Field Inspection Manual to assess SWM facilities and collect data in a consistent fashion. To systematically evaluate each facility, a two-tier rating system was developed: performance-based and action/response.
The performance-based rating focuses on the facility function and integrity. Field inspection evaluates 45 individual parameters that are scored on a scale of 1 to 5 and relate to site conditions, functional performance and structural integrity. The inspections include digital field photos to document overall site condition and key elements such as inflows, risers, etc. These parameters are assessed collectively to provide an overall facility condition rating (A-E):
- —No Issues and SWM facility functioning as designed;
- —Minor problems, but SWM facility is functioning as designed;
- —Moderate problems and SWM facility performance is compromised;
- —Major problems; SWM facility is not functioning as designed and has potential for failure; and
- —Severe problems exist, and SWM facility is not functioning and has failed.
The inspection rating results provide the basis for the response ratings that aid in making remedial decisions. All inspection data are stored in a relational database table that is linked to the GIS model.
Staying in shape
The goal is to keep SWM facilities operating as designed and to strategically enhance their function to meet today’s water quality and safety standards. Remedial responses were developed to meet these objectives and are separated into re-inspection, maintenance, enhancement and retirement.
The response rating system is based on an overall inspection rating, as well as the scope and complexity of the remedial work:
- —No response required, schedule for multiyear inspection;
- —Minor maintenance required to sustain SWM facility performance;
- —Major maintenance is needed to restore functionality within the existing site;
- —Retrofit and functional enhancement required, because SWM facility cannot be returned to its original functionality within existing site; and
- —Immediate response is mandatory to address safety hazards regardless of SWM facility functionality.
Using this schema, individual SWM facilities can be targeted through a streamlined and systematic process for specific remediation.
Maintenance
Maintenance ranges from minor to major remediation with the objective to maintain performance and integrity. MSHA developed a response process that includes a comprehensive field assessment and recommendations. Maintenance action reports include a “punch list” for MSHA’s contractor to perform the required remediation. MSHA is tracking the costs for the assessments and remedial actions to gain perspective on the overall costs for long-term operation and maintenance and the cost-effectiveness of the remedial actions.
Routine maintenance applies to facilities with Response Rating II and addresses minor issues such as debris removal, vegetation management, minor erosion stabilization, etc. Major maintenance is required for ratings of III and addresses more complex issues, such as structural integrity, functional performance, public safety and visual appearance. The initial inspection is followed up by a detailed assessment that includes review of the original design, field verification of existing conditions, construction access and public safety. MSHA compares the cost versus the benefit of the water quality improvements to ensure the remediation is viable.
Functional Enhancement and Retrofit
Sites rated IV do not perform as designed and are selected for functional enhancement or retrofit. Most enhancement projects are in the environmentally sensitive watersheds of metropolitan counties where urbanization and transportation infrastructure grew rapidly. The sites provide control and treatment of highway runoff, but are based on older design standards and have marginal water-quality treatment. The enhancements focus on maximizing pollutant removal efficiency and improving functionality by upgrading facilities to today’s standards. Upgrades are more cost-effective than constructing new facilities that may need right-of-way acquisition.
In addition, more effective and multifunctional management of storm water runoff will minimize possible impacts to public and private properties, reduce negative effects of highway runoff and enhance the aesthetic quality of communities. Improving water quality by implementing new and updated techniques will result in environmental benefits in the surrounding communities and through the Chesapeake Bay Critical Areas by offsetting the adverse impacts of urbanization.
Retirement
Typically less than 2% of SWM facilities are retired due to failed performance. MSHA will only abandon a facility as a last resort when site conditions severely restrict access and no remediation options are feasible. To mitigate for this loss, off-site SWM projects are initiated within the same watershed.
MSHA is active in researching SWM facilities to further the understanding of long-term performance. The results will aid MSHA in future decisions on remedial actions and ways to improve the inspection protocol.
Because infiltration trenches are historically the most commonly used BMP for treating highway runoff and statewide inspection efforts revealed that they have the highest failure rate, an Infiltration Trench Study was performed to investigate their functionality. Gauges were installed inside the monitoring wells to collect water levels over several seasons. This information and rainfall data were processed and analyzed and site conditions and design information were reviewed to assess functionality and trench life expectancy.
A follow-up study, Infiltration Trench Forensic Analysis, was performed to determine the reasons for failure. The results justified the need for enhancements including runoff pretreatment to ensure sediment capture.
Sharp Tools
Data management is essential to streamline information relating to SWM facility features and performance. Through the inventory, inspection and construction of new SWM facilities, MSHA continues to generate large amounts of data. Currently the data repository is composed of Microsoft access databases and mapping stored in ESRI ArcView GIS Shapefile format. There also are media files such as digital photos, scanned plans and voice inspection recordings. MSHA developed data management tools that aid in collecting field inspections as well as editing and reviewing data in the office. These applications were developed to be user-friendly to accommodate a variety of data users.
Field Data Collection
A powerful tool for the inventory and initial inspection phases is ESRI’s ArcPad field application. ArcPad includes customized utilities to edit inventory attributes and spatial elements and to enter inspection results. MSHA also is deploying a custom field application, NPDES Field Inspector, on PDA devices. This tool provides consistency in data collection, especially for follow-up inspections when inventory data has already been established.
Office Management—Current
To manage the overwhelming data, MSHA required an effective office tool to enter, review and edit information. The BMPviewer application was developed to minimize complexity so that the casual user can access the inventory and inspection data. The primary functions include export, query and printing of SWM facility information. The application allows the user to add different mapping coverages to enhance the viewing from various levels such as a highway corridor, MSHA district, county or watershed.
The biggest benefit is the flexibility to query data, which can be done by pull-down list, SQL query or spatially. The latest inspection data is auto-selected, but a pull-down menu allows for selection of historical results. Another key function is the reporting features, such as output to customizable Microsoft Excel spreadsheet or to a pre-specified Crystal Report-style format.
For assigning remedial actions, MSHA relies on BMPviewer to quickly select sites to develop maintenance work orders. These are selected by querying inspection ratings and specific condition parameters; SWM facility type; roadway; etc., to tailor the list. The spreadsheet option allows for further enhancing to create work orders that include a detailed “punch list” for maintenance requests.
Responding Well
MSHA worked diligently to develop sound protocols for inventorying and inspecting SWM facilities. This led to the development of a responsive maintenance program that includes functional and visual enhancements. MSHA also progressively researches SWM facility performance. MSHA utilized data management technology to manage SWM facility data. These help to make timely decisions on remedial actions, and meet and exceed MSHA’s NPDES permit requirements.
In the coming years, MSHA also will have reliable information on the costs of operation and maintenance to quantify benefits and costs on SWM facility performance. MSHA’s Stormwater Facilities Program was recognized on a national level by being awarded the Federal Highway Administration’s 2003 Environmental Excellence Award in water quality. The program components collectively have laid a solid foundation of a systematic and strategic approach not only to meet the NPDES permit requirements but also to optimize and enhance the performance of MSHA SWM facilities.
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