National Academies Press: OpenBook
« Previous: Section 6 - BMP Sizing and Design
Page 94
Suggested Citation:"Section 7 - Maintenance and Monitoring." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas. Washington, DC: The National Academies Press. doi: 10.17226/22031.
×
Page 94
Page 95
Suggested Citation:"Section 7 - Maintenance and Monitoring." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas. Washington, DC: The National Academies Press. doi: 10.17226/22031.
×
Page 95
Page 96
Suggested Citation:"Section 7 - Maintenance and Monitoring." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas. Washington, DC: The National Academies Press. doi: 10.17226/22031.
×
Page 96
Page 97
Suggested Citation:"Section 7 - Maintenance and Monitoring." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas. Washington, DC: The National Academies Press. doi: 10.17226/22031.
×
Page 97
Page 98
Suggested Citation:"Section 7 - Maintenance and Monitoring." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas. Washington, DC: The National Academies Press. doi: 10.17226/22031.
×
Page 98
Page 99
Suggested Citation:"Section 7 - Maintenance and Monitoring." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas. Washington, DC: The National Academies Press. doi: 10.17226/22031.
×
Page 99
Page 100
Suggested Citation:"Section 7 - Maintenance and Monitoring." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas. Washington, DC: The National Academies Press. doi: 10.17226/22031.
×
Page 100
Page 101
Suggested Citation:"Section 7 - Maintenance and Monitoring." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas. Washington, DC: The National Academies Press. doi: 10.17226/22031.
×
Page 101
Page 102
Suggested Citation:"Section 7 - Maintenance and Monitoring." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas. Washington, DC: The National Academies Press. doi: 10.17226/22031.
×
Page 102
Page 103
Suggested Citation:"Section 7 - Maintenance and Monitoring." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas. Washington, DC: The National Academies Press. doi: 10.17226/22031.
×
Page 103

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

94 Post-construction activities include BMP operation and maintenance, and BMP testing and monitoring. Maintenance is essential for design-level performance. BMP testing and monitoring is a means for evaluating and gaining operational information of BMPs. Developing and successfully conduct- ing post-construction activities requires upfront planning and coordination. This section describes recommended BMP maintenance and monitoring practices. 7.1 Types of Maintenance DOT maintenance crews and departments routinely address three types of BMP maintenance categories: • Routine inspection and maintenance: Regular and sched- uled BMP inspections and maintenance practices to ensure design-level performance, for example, mowing and vegeta- tion clearing, sediment clearing, and trash and litter pickup. • Major maintenance activities: Longer-term, periodic maintenance practices to remediate worn-out components (for example, media bed replacement and major sediment clearing) or to correct BMP deficiencies. • Emergency maintenance practices: Unscheduled and unanticipated maintenance in emergencies, for example, the repair of malfunctioning stormwater pumps or emer- gency actions to address spills of toxic materials. 7.2 Maintenance Factors That Affect Performance BMP maintenance issues and problems that commonly affect BMP performance include the following: • Sediment and debris buildup: Insufficient maintenance can allow sediments, trash, and debris to accumulate in settling basins, underground sumps and vaults, pipes and outlet, and detention and sedimentation facilities (Figure 7.1A). Buildup of solids can cause reduced treatment perfor- mance and poor effluent quality due to resuspension and washout and reduction of capacity. Sediment and debris clearing is among the most common BMP maintenance practices. Underground BMPs that have limited storage capacity require more frequent inspection and cleaning to maintain design capacity. • Clogging: Clogging occurs when trash, debris, sediment, or ice accumulates at inlets, weirs, pipes, outlets, or screens or on surface media beds, blocking or restricting the flow of water (Figure 7.1B). Clogging may occur gradually due to general BMP operation (e.g., media beds and infiltration facilities) or due to inadequate maintenance. Clogging may also occur rapidly from large storm events that transport large amounts of debris and/or sediment. Problems due to clogging include increased bypassing, diminished or ineffective treatment, ponding and safety concerns, and erosion. The assessment of sediment and debris accumula- tion and potential blockages is a primary task during BMP inspections. Inspection of underground BMPs, however, are more difficult and rigorous, and the effects of clogging may not be apparent and can go undetected. • Mechanical and structural failures: Mechanical equip- ment and structural facilities such as pumps, gates, valves, and conveyances can fail due to wear, corrosion, vandalism, clogging, and lack of maintenance. Underground BMPs that require pumping due to high head requirements, grade separation, and/or flat terrains may be subject to significant pump maintenance requirements. • Vegetation: Poor vegetation maintenance can result in improper type and/or inadequate or excessive growth of veg- etation (Figure 7.1D). Potential problems due to vegetation management include poor treatment performance, clogging of conveyances, lack of visual access for inspections, habitat for rodents and vectors, and aesthetic concerns. In space- limited settings, equipment access will be a key issue for vegetation management. S e c t i o n 7 Maintenance and Monitoring

95 • Groundwater: Shallow groundwater can affect the sit- ing and capacity of infiltration BMPs, and groundwater flows into surface and underground BMPs may dimin- ish the treatment effectiveness, cause excessive bypass, or require additional flow control and pumping. Main- tenance activities due to high groundwater may include temporary or permanent pumping, more frequent rou- tine and vegetation maintenance, and structural repairs or modifications. • Vectors: Burrowing rodents and animals can damage veg- etation and embankments, diminishing treatment per- formance and potentially affecting structural integrity. Standing water in BMPs that do not fully drain is a poten- tial breeding habitat for mosquitoes, which can prompt concerns by public health officials and require the use of vector control methods. 7.3 Maintenance Considerations for Ultra-Urban Highways Without proper and consistent maintenance, BMPs will not perform at their capacity. This is particularly valid for many ultra-urban BMPs that have limited storage capacity for accumulated solids, and proprietary filtration systems that are susceptible to clogging. Neglected maintenance can ultimately lead to significant costs for major cleaning, repairs, or emergency actions. On the other hand, DOT maintenance departments are very concerned about potentially burden- some requirements and high costs of maintaining ultra- urban BMPs due to the following conditions: • Space and access limitations: Space limitations in ultra- urban settings potentially constrain maintenance access, Figure 7.1. Four examples of BMP conditions requiring maintenance: (A) excessive accumulation of sediments in underground detention; (B) clogged pipe; (C) accumulation of trash and debris in a GSRD; and (D) excessive vegetation near an outlet.

96 necessitate expensive lane closures and traffic-control pro- cedures, and prompt safety concerns. • Uncommon requirements: Underground proprietary BMPs are more difficult to inspect and maintain than surface BMPs. Routine maintenance of proprietary under- ground BMPs potentially requires costly proprietary com- ponents (e.g., filter cartridges), specialized or expensive equipment, uncommon procedures, and/or specific train- ing such as confined-entry practices. • Higher frequency: Ultra-urban highways can have higher loadings of sediment, trash, and debris. Small-footprint or undersized BMPs are more likely to require frequent inspec- tion and maintenance to remove accumulated solids to maintain capacity and/or filtering/infiltration performance. To address these maintenance department concerns, plan- ning and coordination is necessary to select BMPs that will have acceptable and achievable maintenance requirements, as well as to design BMPs that will facilitate maintenance activities. Specific guidance and recommendations include the following: • Understand and evaluate maintenance requirements: BMP maintenance requirements must be an essential part of the BMP evaluation and selection process. This requires an understanding and evaluation of the specific maintenance practices, materials, equipment, and training for the candi- date BMPs. Consider implementing pilot testing programs to evaluate maintenance requirements and to address main- tenance department concerns for promising but untested BMPs. For example, Section 10.6 describes a pilot test of construction and design practices for bioretention systems conducted by the District of Columbia DOT. As part of this pilot study, monitoring is conducted to evaluate construc- tion impacts on maintenance, in particular, the need for soil stabilization as part of finalizing the project construction. • Coordinate with maintenance personnel. The mainte- nance evaluation must be fully coordinated with appro- priate maintenance personnel throughout the retrofit planning process. Maintenance departments should have approval authority on BMP selection and design elements. • Design for maintenance: Planning for maintenance dur- ing the design stage of retrofit projects can simplify long- term inspection and maintenance requirements. – Lane closures: Locate BMPs and BMP access points to avoid lane closures for BMP inspection and mainte- nance. Site underground BMPs to limit lane closure requirements, if unavoidable. – Access roads: Provide maintenance access for required equipment and practices. Access roads must have ade- quate width and slope to ensure that heavy equipment can safely reach and exit the BMP site under its own power (Hunt et al., 2008). – Internal access of underground BMPs: It is essential that there is safe access to all internal components and spaces of underground BMPs to facilitate inspections, long-term cleaning, and repairs (Scott, 2008). Hunt et al. (2008) note that many chambers within the under- ground manufactured BMPs are not accessible or are very difficult to access. Ability to visually inspect and clean components of the BMP must be factored into the design. Most manufacturers are aware of BMP mainte- nance issues and typically provide detailed maintenance specifications that can be reviewed, evaluated, and tai- lored for the actual design. Some manufacturers are including design components to address maintenance issues, such as providing more access options for easier inspection and clean-out, and the use of baskets for sediment storage and easy cleaning. – Structural design: Underground BMPs must be struc- turally designed for vertical and horizontal AASHTO H-20 loadings to ensure that heavy maintenance equip- ment can access the site. – Manhole design: Locate access manholes to under- ground BMPs no more than 5 m (15 ft) from access roads, as the boom of typical vacuum trucks can only reach 5 m (15 ft). Access manholes should have a mini- mum diameter of 75 cm (30 in.) to facilitate cleaning and confined-space entry, as well as all required appur- tenances such as hoses and booms. Filter boxes and cer- tain hydrodynamic devices may require larger openings, as some components may not be able to fit through a 75 cm (30 in.) opening. There must also be sufficient manhole access to ensure that high-pressure spray washers operated by persons or remotely operated can reach all areas and surfaces in the underground facilities to remove all collected sediment and debris (Hunt et al., 2008). Ideally, underground BMPs should have at least two access manholes. – Conveyance design: To minimize scouring and erosion in surface conveyances, make sure there is sufficient energy dissipation at inlets and outlets. Consider hard armoring or stabilization fabric as needed. To mini- mize maintenance problems of pipes, coordinate with geotechnical engineers, structural engineers, and/or manufacturers in pipe material selection and design. Consider clogging potential and maintenance access in the design of outlets, orifices, and trash racks. Design considerations may include reverse slope pipes, gravel or filter blankets around perforated pipes, and properly designed trash racks. – Cold weather design: Retrofit designs in cold weather regions require adaptations to mitigate cold weather problems and associated maintenance requirements. This may include over-sizing BMPs and conveyances,

97 burying pipes, increasing pipe slopes, and selection of salt-tolerant vegetation. Caraco and Claytor (1997) pro- vide specific design recommendations for cold weather BMP applications. – Groundwater elevation: Consider the elevation of sea- sonal high groundwater levels and the potential impacts on the operation, performance, and maintenance of BMPs. Design underground BMPs to limit ground- water intrusion and select materials to mitigate poten- tial groundwater impacts. – Vegetation design: Coordinate with biologists, land- scape personnel, and maintenance crews to select native and natural vegetation that will be easy to estab- lish, will not contribute to invasive-species issues, and will not hinder BMP inspection and maintenance. Coordinate the design of vegetated BMPs with main- tenance crews to evaluate maintenance requirements and capabilities. – Vandalism design: Consider design components to dis- courage vandalism, such as fencing and gates to limit site access, locking manholes, and locking hand wheels and gates. – Vector control design: Coordinate BMP designs with health official and maintenance crews as needed to eval- uate potential vector issues. Mitigation measures may include active vector control or design modifications to reduce vector attraction such as vegetation selection and location, selection of BMPs that fully drain, and inclusion of screens on manhole covers. • Ensure construction management and quality control: Detailed BMP design specifications and good quality con- trol during construction can reduce or eliminate BMP problems and maintenance requirements. Inspectors should have sufficient background and training to ensure that BMP materials meet specifications (e.g., plant palettes and media properties); that specified inverts and slopes are constructed; and that specified construction practices such as proper compaction of backfill, proper installation of conveyances, and manufacturers’ specifications for instal- lation of proprietary BMPs are followed. • Confirm construction erosion control: Sediment loadings from inadequate sediment control during and immediately following construction can damage or overload BMPs dur- ing initial operations and may cause early maintenance issues. Planners should coordinate with construction per- sonnel to evaluate potential sediment sources and to ensure adequate sediment control during and immediately fol- lowing construction. Construction specifications should require that newly constructed BMPs are transferred to DOTs in a clean and operating condition. • Increase early inspection schedules: Newly constructed BMPs should be inspected frequently (quarterly, monthly, or more often as needed) to assess one or more of the following: – Proper function: Ideally, newly constructed BMPs will be inspected during and immediately following storm conditions to determine that they are functioning as designed (e.g., flow patterns and drawdown rates) and that there is no excessive sediment accumulation or ero- sion issues due to improper site stabilization. – Vegetation establishment: Vegetated BMPs should be inspected frequently during the establishment period to ensure the vegetation is establishing as expected, that there are no or minimal invasive plants, and that there is no erosion or washout issues from storm flows. – Sediment loading: Pollutant loadings vary both seasonally and spatially and are likely to deviate from anticipated design loadings (Brzozowski, 2004). Newly constructed BMPs should be inspected frequently (quarterly, monthly, or more often as needed) to establish loading rates and seasonal factors and to assess if planned maintenance frequencies are appropriate. Increased frequencies should be considered for areas with heavy sanding or other sediment/debris loadings. • Develop maintenance triggers/indicators: To ensure adequate BMP maintenance, BMPs should have clearly defined maintenance indicators and triggers; for examples, see the indicators developed for the Caltrans retrofit pro- gram (Caltrans, 2002a). Section 7.4 presents general main- tenance triggers of selected retrofit BMPs. • Determine responsible parties for maintenance and training: DOTs typically assume maintenance responsi- bilities for BMPs in the ROW and have well-established and -equipped maintenance departments. However, underground proprietary BMPs can have specialized practices, equipment requirements, and components that are not agreeable with maintenance departments. The use of properly trained maintenance contractors should be considered during BMP evaluation and selec- tion when DOTs lack adequate maintenance capabil- ity. Hunt et al. (2008) recommend that specific training should be provided by the BMP manufacturer and, in the absence of training films, detailed maintenance man- uals specific to the BMP must be provided by the BMP manufacturer. • Maintain documentation: Comprehensive documenta- tion of ongoing BMP maintenance practices supports periodic review and assessment of BMP maintenance requirements and costs, as well as BMP evaluations and potential refinements. Maintenance documentation includes maintenance logs, checklists, and digital photo- graphic records.

98 7.4 Maintenance Practices To support initial development and evaluation of retrofit options, Table 7.1 shows general maintenance practices and maintenance indicators by retrofit categories. Example main- tenance practices are illustrated in Figure 7.2. Detailed and site-specific maintenance indicators and maintenance practices should be developed during retro- fit design and may be refined based upon the experience gained from ongoing post-construction maintenance and monitoring efforts. Sources of maintenance information include: • DOT manuals and guidance documents, • Manufacturer specifications and manuals, • DOT maintenance crews and personnel, and • BMP handbooks and maintenance guidance documents. 7.5 BMP Monitoring and Performance Assessment DOTs commonly conduct BMP pilot testing and BMP per- formance monitoring to evaluate and gain operational expe- rience of promising and/or innovative BMPs. Such efforts are especially suitable for ultra-urban retrofit situations where BMP options likely include proprietary BMPs and BMPs that are unfamiliar to DOTs, BMPs or BMP treatment trains with limited performance information, and underground BMPs that have high installation costs and unique and/or costly maintenance practices. The objectives of BMP monitoring programs may include: • Evaluating BMP construction specifications and construc- tion practices; • Determining BMP hydraulic performance (flow patterns, effective sizing, volume reduction); • Establishing BMP treatment performance and effluent quality for various highway POCs and comparing perfor- mance to other BMPs; • Assessing factors that affect performance (climate, operat- ing conditions, maintenance); • Evaluating maintenance practices; • Determining construction and maintenance costs; and • Complying with regulatory or legal requirements. 7.5.1 Information Sources BMP monitoring practices are specific to particular site conditions and objectives, and thus only general information is included herein. The following documents provide detailed guidance and information to support the development of site-specific BMP monitoring and performance assessments: • FHWA Guidance Manual for Monitoring Highway Runoff Water Quality (FHWA, 2001). This manual describes pro- cedures for developing highway monitoring programs, for selecting specific equipment and monitoring methods, and for installing and operating monitoring equipment. • FHWA Guidance Manual of Stormwater Best Manage- ment Practices in an Ultra-Urban Setting (Shoemaker et al., 2002). Details a process for implementing BMP per- formance monitoring programs in ultra-urban settings, and presents a number of case study examples for a variety of BMPs. • Caltrans BMP Pilot Study Guidance Manual (Caltrans, 2009). This planning document presents detailed guidance for developing and implementing BMP pilot tests in highway settings and additionally for managing and interpreting monitoring data results. • WERF and USEPA Urban Stormwater BMP Performance Monitoring (Geosyntec and Wright Water, 2009). This guidance document was developed in support of the Inter- national BMP Monitoring Database Program. It presents detailed procedures for developing monitoring plans for BMP performance monitoring, for selecting and installing monitoring equipment, and for analyzing and interpret- ing monitoring results. It is also one of the few manuals that address monitoring the performance of distributed/ LID BMPs. 7.5.2 Monitoring Plan Design Designing an effective pilot testing and BMP monitoring plan requires detailed planning and quality control. The WERF and USEPA manual presents a detailed systematic approach for developing and implementing urban BMP monitoring plans and for interpreting the monitoring results. The follow- ing steps summarize the main principles of this approach: 1. Define study objectives/state the problem: The first step is explicitly defining the objectives and scope of the moni- toring study. This entails: • A concise description of the problem being investigated and the monitoring objectives; • A clear understanding of the BMP operation and site conditions, including key parameters for evaluation; and • A summary of resources including budget, staff, equip- ment, schedule. 2. Define the study goals: Step 2 further defines the study objectives by developing detailed study questions and determining key measurement parameters. The products of this step are (1) well-defined study principles, (2) a list of alternative outcomes, and (3) a decision statement indi- cating how the study findings will be used.

(continued on next page) Maintenance Objective Frequency and Maintenance Indications Typical Maintenance Activitie s Comments C a t c h B a s i n R e t r o f i t G S R D R e t r o f i t s H y d r o d y n a m i c S y s t e m s O i l - W a t e r S e p a r a t o r s A b o v e g r o u n d D e t e n t i o n U n d e r g r o u n d D e t e n t i o n M e d i a F i l t r a t i o n V e g e t a t e d F i l t r a t i o n I n f i l t r a t i o n F a c i l i t i e s P o r o u s P a v e m e n t s Site inspection • As scheduled per DOT or manufacturer guidance • Following major storms • As needed to address emergency, safety, and maintenance issues • Measure accumulated sediment, debris, and floatables and oil accumulation in sumps, forebays, basins, and vaults by visual inspection, with calibrated dipsticks, or by video inspection. • Check for visible signs of clogging at inlets, racks, outlets, and pipes. Look for bypassing, erosion, channeling, and standing water. • For media filtration and infiltration BMPs, look for signs of clogging, bypassing, poor drainage through media, standing water, accumulation of fine sediments, and cake on the surface. • For vegetated BMPs, check vegetation health, type, and distribution. Look for poor or excessive growth, blockages, unwanted vegetation. • Check water levels of BMPs with permanent pools. • Check for oil accumulation and gummy deposits in oil- water separators, coalescing plates, and devices w ith oil-adsorbent pads. • Look for signs of windblown transport of trash. • Inspect for structural problems, corrosion, undercutting, cracks, and vandalism. • Inspect for vector issues (mosquitoes, burrowing rodents). • Essential activity for all BMPs. • Catch basin retrofits and small vault BMPs (hy drodynamic sy st ems, oil-water separators) require more frequent inspections to identify and address maintenance and clogging issues in a timely manner. • Inspections of underground BMPs are more likely to be neglected because the y are out of sight and more difficult to inspect. Neglected or incomplete inspections can delay the identification of maintenance needs. R R R R R R R R R R Minor removal of sediment, trash, and debris • Per DOT or manufacturer guidance • Visible accumulation or potential clogging at key locations • Aesthetic concerns • Remove minor accumulations of sediment, trash, and debris from inlets, outlets, and other locations as needed to ensure operation. • Routine sweeping and trash pickup to reduce sources, reduce potential clogging of porous asphalts, and address aesthetics. • Routine activity applicable to all BMPs. • Routine minor clearing activities are more challenging in underground BMPs with poor access. Maintenance activities ma y be delayed until major cleaning is warranted. R R P P R P R R R R R = routine or common maintenance activity; P = periodic maintenance activity as needed Table 7.1. Common maintenance practices and indicators for retrofit categories.

Maintenance Objective Frequency and Maintenance Indications Typical Maintenance Activitie s Comments C a t c h B a s i n R e t r o f i t G S R D R e t r o f i t s H y d r o d y n a m i c S y s t e m s O i l - W a t e r S e p a r a t o r s A b o v e g r o u n d D e t e n t i o n U n d e r g r o u n d D e t e n t i o n M e d i a F i l t r a t i o n V e g e t a t e d F i l t r a t i o n I n f i l t r a t i o n F a c i l i t i e s P o r o u s P a v e m e n t s Major clearing of sediment, trash, and debris • Prescribed clean-out schedule • Accumulated levels exceed threshold • Visual clogging • Accumulated levels affect BMP performance • Remove sediments for forebays, basins, and vaults of surface BMPs with backhoes or vactor equipment. • For underground BMPs, vactor sediments, debris, and water from sumps and chambers per DOT or manufacturer guidance. Use high-pressure jets to flush sediments to sumps and access locations as needed or per manufacturer guidance. • Remove trash and debris from sumps, screens, and vaults. Remove and replace trash nets in accordance with O&M and/or manufacturer procedures. • Pressure wash (capturing and managing wash waters) screens to remove accumulation (e.g., CDS units). • Properly transport and dispose of all sediments, trash, debris, and water. • One of most common maintenance activities. • Major cleaning of underground BMPs can be difficult, may require specialized procedures or confined-space entry practices , and can be costly. Underground BMPs with small storage volumes may require frequent cleaning (more than once per year) to maintain design treatment capacity. • If jetting is required to wash solids to collection areas , use care to not cause and/or minimize flushing to outlets. • Accurate estimation of accumulation is important for establishing maintenance schedule and costs (Gulliver et al., 2008). R R R R R R R R R Vegetation maintenance • Prescribed schedule • Poor growth, type, or distribution of vegetation • Excessive growth or blockages • Routine grass and turf maintenance • Vegetation pruning, clearing, thinning, and harvesting • Planting and reestablishment of bare areas • Fertilizer, pesticide, herbicide application • DOTs have reported that vegetation maintenance for wet basins, wetlands, and bioretention can require significant staff time (Gulliver et al., 2008; Caltrans, 2004). R R P Media replacement and infiltration system maintenance • Per DOT schedule or manufacturer guidance • As needed to address observed clogging or reduced infiltration capacity • For non-proprietary sy st ems, scrape, remove, and replace top inches or entire media bed as needed • For proprietary systems, remove cartridges and/or replace media in accordance with manufacturer instructions • Rototill upper layers of filter media • Proprietary cartridges are potentially costly and may require regular and frequent replacement (Caltrans, 2004). • Maintenance of underground sy st ems ma y require confined-space entry procedures. P R R = routine or common maintenance activity; P = periodic maintenance activity as needed Table 7.1. (Continued).

Maintenance Objective Frequency and Maintenance Indications Typical Maintenance Activitie s Comments C a t c h B a s i n R e t r o f i t G S R D R e t r o f i t s H y d r o d y n a m i c S y s t e m s O i l - W a t e r S e p a r a t o r s A b o v e g r o u n d D e t e n t i o n U n d e r g r o u n d D e t e n t i o n M e d i a F i l t r a t i o n V e g e t a t e d F i l t r a t i o n I n f i l t r a t i o n F a c i l i t i e s P o r o u s P a v e m e n t s Remove oil • Per DOT schedule or manufacturer guidance • Oil-adsorbent pads are discolored or saturated • Oil accumulation in oil-water separators exceeds threshold (e.g. 1 to 2 in.) • Coalescing plates have oil deposits • Vactor oil and water from chamber and dispose in accordance with regulations • Remove and pressure wash plates. Properly dispose of rise water • Replace oil-adsorbent pads in accordance with manufacturer instructions • Design and system dependent. • Pads are generally low cost and easy to replace. R R R Structural repairs • Observed structural problems • To correct/improve design • Fix/replace pipes, inlets/outlets, pumps, and other control devices as needed • Repair/stabilize eroded embankments and other erosion problems • Work with manufacturers and contractors to repair facilities • Infrequent. P P P P P P P P P P Vector control • Scheduled • As needed to address problems • Routine mosquito abatement practices • Pest control for burrowing rodents • Mosquito control is a potential issue for all BMPs with permanent wet pools or BMPs with a potential to create standing water. • Burrowing rodents can potentially damage embankments and vegetation. P P P P P P P P P R = routine or common maintenance activity; P = periodic maintenance activity as needed Table 7.1. (Continued).

102 3. Identify information inputs: The purpose of this step is to identify the specific types of information and data needed to meet the study objectives. The key activities are: • Determining the types and potential sources of infor- mation needed, for example, the types of precipitation measurements, water quality monitoring samples and parameters, and cost and labor-hour data. • Determining the basis for specifying performance cri- teria for the collected data. This includes an assessment of the number of samples required to achieve statisti- cal confidence, and the laboratory protocols, detection limits, and acceptance criteria. • Verifying the availability of appropriate sampling equipment. In this key task, the team evaluates and selects the monitoring approaches and equipment. This requires an understanding and familiarity with the many types of monitoring approaches and equipment that are available, including assessment of the benefits and limitations of equipment options. 4. Define the study area and parameters: In this step, the moni- toring team conducts site investigations and field recon- naissance to fully characterize the site conditions including the precipitation characteristics, tributary and drainage characteristics, and physical constraints. The team decides the location of monitoring stations and defines the specific parameters to be measured, the monitoring protocols, and the timeframes and frequency of measurements. 5. Develop the analytical approach: In this step, the team establishes how the collected data will be analyzed. For example, BMP treatment performance monitoring may utilize mean or median EMCs, or may require the estima- tion of annual loads from EMC and flow data. Other types Figure 7.2. Four examples of BMP maintenance activities: (A) vactoring solids from underground sumps; (B) removing sediments from surface BMPs; (C) replacing media in filtration BMPs; (D) replacing proprietary media cartridges.

103 of monitoring objectives may require the use of decision rules, for example, maintenance triggers based on annual loadings or levels of accumulated sediments. 6. Specify performance or acceptance criteria: For BMP effec- tiveness studies, there must be a procedure for determining the level of confidence in the analysis. In this step, the team establishes the statistical hypothesis testing protocols for assessing BMP effectiveness. 7. Develop the plan for obtaining data: The next step is to develop a Quality Assurance Project Plan (QAPP) that describes the details of the sampling and analysis tech- niques. The elements of the QAPP include (1) project management procedures and a description of roles and responsibilities of team personnel, (2) description of data collection and analysis procedures, (3) quality assurance and quality control procedures to ensure the QAPP is properly implemented, and (4) data validation procedures. 8. Assess reasonableness of plan and refine: Developing a monitoring plan is an iterative process. In this key step, the team evaluates the monitoring plan to assess whether it can reasonably achieve the objectives within the physical and administrative constraints. Revision and refinements to the plan in order to improve outcomes and/or conform to constraints are likely. The WERF and EPA guidance report (Geosyntec and Wright Water, 2009) provides details for applying these prin- ciples to specific sites. 7.5.3 Monitoring Plan Implementation Successfully implementing the monitoring plan requires careful attention to details by the team personnel and a sys- tematic approach such as the following: • Prepare health and safety plan: The first step is to develop a monitoring health and safety plan. The goal of the plan is to fully define the potential hazards, safe working practices and protocols of work activities, the site-specific health and safety requirements, and emergency response procedures. • Train personnel: All personnel should be completely familiar with the monitoring and health and safety plans. All personnel should receive training and periodic refreshers on applicable monitoring activities, on quality control activities, and on the health and safety procedures. Training may include practice events and monitoring run-throughs. • Install equipment: All equipment must be properly installed and functioning in accordance with site-specific requirements. Upfront planning is needed. The team should prepare equipment preparation checklists and well-stocked and -organized field boxes that include tools, health and safety supplies, and equipment operation manuals. • Test and calibrate equipment: Once installed, all equip- ment should be thoroughly tested and calibrated. A dry run may be conducted to test equipment and train personnel. • Conduct monitoring: The monitoring is conducted in accordance with the established protocols for weather tracking, team mobilization, and monitoring activities. • Coordinate with laboratory: Mobilization protocols should include laboratory notification and coordination. Frequent and close coordination with the laboratory will help to minimize problems and improve quality assurance. All samples should be collected, packed, and shipped to the laboratory in accordance with laboratory and quality assurance protocols. 7.5.4 Data Management and Evaluation Monitoring Effective data management, validation, and reporting are fundamental components of an effective stormwater BMP monitoring study. Well-established protocols are described in the ASCE and USEPA guidance manual (Geosyntec and Wright Water, 2009). On the other hand, data evaluation can be challenging and complex. Procedures must suit the objectives and support interpretation and conclusions about the BMP’s effectiveness. Detailed descriptions of data analysis procedures are found in guidance documents listed in Section 7.5.1.

Next: Section 8 - Retrofit Costs »
Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

TRB’s National Cooperative Highway Research Program (NCHRP) Report 728: Guidelines for Evaluating and Selecting Modifications to Existing Roadway Drainage Infrastructure to Improve Water Quality in Ultra-Urban Areas provides guidelines to evaluate and select hydraulic modifications to existing drainage infrastructure that will help mitigate potential impacts of highway runoff on receiving waters.

The guidelines are directed specifically at roadway facilities in dense urban areas that can be particularly difficult and costly to retrofit because of space limitations, high pollutant loadings, hydrologic flashiness, hydraulic constraints, legacy contamination, utility conflicts, and other issues.

The guidelines are accompanied by a Microsoft® Excel-based design and sizing tool on a CD-ROM included with the print version of the report. The tool generates best management practice (BMP) performance curves that relate the performance and design criteria for selected BMP controls described in the guidelines for each of the 15 U.S. rain zones.

The excel spreadsheet that is content on the CD-ROM is available for download.

Excel Spreadsheet Disclaimer - This software is offered as is, without warranty or promise of support of any kind either expressed or implied. Under no circumstance will the National Academy of Sciences or the Transportation Research Board (collectively "TRB") be liable for any loss or damage caused by the installation or operation of this product. TRB makes no representation or warranty of any kind, expressed or implied, in fact or in law, including without limitation, the warranty of merchantability or the warranty of fitness for a particular purpose, and shall not in any case be liable for any consequential or special damages.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!