Urban Stormwater Controls Operation and Maintenance

By Water Environment Federation

The effectiveness of stormwater management programs depends largely on how well and how safely stormwater control measures (SCMs) perform over time. This manual provides best practices for the continued operation of SCMs, with a target audience of designers, utility managers, and O&M staff.

• Language: English
• Publisher: Water Environment Federation
• Release date: Dec 14, 2022
• ISBN: 9781572784260

Book preview

Preface

The effectiveness of stormwater management programs depends largely on how well and how safely stormwater control measures (SCMs) perform over time. Nationwide, the largest challenge of stormwater programs is ensuring long-term performance of SCMs and stormwater systems. In addition, as these programs evolve, the number of SCMs is increasing rapidly. In fact, some communities and utilities in urban areas have tens of thousands of SCMs that have been constructed as part of land development projects or to solve flooding and water quality problems. Many SCMs are also built to address stormwater and combined sewer system regulatory compliance requirements.

The importance of maintenance and the significant numbers of SCMs have created the need for guidance on how stormwater programs must adapt to address evolving SCM design and maintenance requirements, climate change and resilience, and integration of asset management concepts to reduce long-term program costs. Furthermore, successful implementation of SCMs requires good design, proper construction, and perhaps more importantly long-term maintenance. There are several manuals and publications that provide information on maintenance needs in specific geographies or for specific SCMs, but the intent of this publication is to create one comprehensive manual.

The manual was developed as a companion to Design of Urban Stormwater Controls (WEF et al., 2012). Urban Stormwater Controls Operation and Maintenance describes the importance of incorporating maintenance considerations to the design and construction of SCMs, as well as sharing best practices on the implementation of maintenance programs. The manual also addresses program and regulatory requirements and includes a description of the elements of an inspection and maintenance program, as well as the skill sets needed in modern maintenance crews. Within this manual, users will find a compendium of best practices for inspection and maintenance (protocols), as well as forms and checklists, stormwater asset management considerations, and information on maintenance personnel, equipment, scheduling, and cost considerations. Case studies are presented to illustrate these concepts in large and small utilities/municipalities. You will find all you need to know about stormwater maintenance in this manual.

The manual is targeted to designers of stormwater controls (designing with maintenance in mind) as well as operations and maintenance staff. Senior managers of utilities and municipalities will also benefit from information on program development, costs, staffing and equipment considerations, and funding for operations and maintenance. Manual users will understand the need to take a long-term view of maintenance.

Authors’ and reviewers’ efforts were supported by the following organizations:

Arcadis U.S., Inc.

Burns & McDonnell

City of Lancaster Department of Public Works

Office of Water Programs at California State University, Sacramento Philadelphia Water Department

1

Introduction

1.0THE IMPORTANCE OF STORMWATER CONTROL MEASURE MAINTENANCE

2.0MANUAL OVERVIEW

3.0HOW TO USE THIS MANUAL

4.0FUNDING OPERATIONS AND MAINTENANCE ACTIVITIES

5.0TERMINOLOGY

6.0REFERENCES

1.0THE IMPORTANCE OF STORMWATER CONTROL MEASURE MAINTENANCE

Stormwater runoff is one of the fastest growing sources of pollution in many waterways across the United States (Water Environment Federation Stormwater Institute [WEF SWI], 2021), and stormwater management remains one of the greatest challenges to meeting water quality standards (U.S. EPA, 2021). The pollution consists of nutrients, sediments, metals, motor oil, lawn and garden care products, trash, and anything else that washes from streets and developed parcels into local streams and lakes, and eventually into bays, estuaries, and oceans. In addition, unmanaged stormwater also causes significant flooding and erosion. Stormwater control measures (SCMs; sometimes known as best management practices, BMPs, or green infrastructure) help address the stormwater quality and quantity challenges and provide the following benefits:

SCMs play a critical role in reducing pollution and protecting the nation’s waterways, as well as protecting downstream areas from flooding, erosion, and water quality degradation.

SCMs are used to manage combined sewer systems (CSSs), and the information in this manual will help in addressing the requirements of the first of the nine minimum controls, Proper Operation and Regular Maintenance Programs, to reduce the effects of combined sewer overflows (CSOs) on receiving waters, and prevent flooding and sewer backups.

The SCMs are also key components of resilience and flood risk management strategies and can be a catalyst for climate change adaptation and economic development in urban areas.

Therefore, it is important that SCMs continue to perform over time, and the only way to ensure long-term performance is to have a well-established stormwater maintenance component in a utility’s or community’s stormwater program. The following are needs and issues that can be addressed by proper operation and maintenance of SCMs:

Aging Stormwater Infrastructure Needs. The Water Environment Federation (WEF) Stormwater Institute conducted in 2020 the second National Municipal Separate Storm Sewer System (MS4) Needs Assessment Survey (WEF SWI, 2021). In this survey, Aging Infrastructure was the top program challenge and the top driver for planning and investment decisions. The maintenance approach, protocols, and tools described in this manual will assist in improving the performance and longevity of SCMs and ultimately the effectiveness of stormwater management programs that depend primarily on how well and how safely SCMs perform.

Evolving SCM Design and Maintenance Needs. Maintenance of SCMs has changed considerably as the design of traditional SCMs (e.g., basins or ponds, infiltration trenches, etc.) has changed, and newer SCMs (e.g., green infrastructure practices, such as bioretention and green roofs, and manufactured devices, such as screens, nets, and swirls concentrators) are implemented. For example, in the past most basins had trickle ditches to concentrate flow from small storms, had short grass as the main vegetative component, and in most cases, had no sediment forebays. Now, most basins have diverse vegetative components, multiple flow paths for the inflow to reach the outfall structure, and sediment forebays, or other pretreatment devices to facilitate maintenance. In addition, new SCMs such as green infrastructure and manufactured devices have been used for the last 25 years, and their design continues to change because of failures, design improvements, and new technologies.

Finally, real-time controls have been introduced in the last 5 to 10 years creating new components (e.g., valves and gates that are activated remotely, solar panels, or electric components, etc.) that require even new maintenance procedures. As the type and design of SCMs evolve, stormwater programs also must evolve, creating a need for guidance on how these programs need to adapt to address new maintenance requirements and incorporate asset management concepts to reduce long-term program costs.

Stormwater MS4 Permits Maintenance Requirements. The effectiveness of a stormwater management program depends largely on how well and how safely stormwater controls perform over time. In addition, the long-term performance of SCMs is linked to the frequency of inspections and proactive maintenance. As a result, stormwater MS4 permit conditions for industrial, construction, and municipal permittees require that pollution prevention, construction, and postconstruction SCMs be adequately inspected and maintained (NRC, 2008). Stormwater programs with effective tracking systems will typically be able to ensure that SCMs and the stormwater system are inspected periodically, and maintenance is conducted by responsible public or private entities. Communities and utilities or any state or local entity (e.g., Department of Public Works, Department of Transportation, Department of Environmental Engineering, Drainage Department, etc.) conducting SCM maintenance activities are responsible through their MS4 permits to ensure that SCMs are maintained properly to facilitate their continued function and performance over time.

SCM Ownership and Private and Public Maintenance. Most SCMs are simple to operate and maintain if there are appropriate maintenance protocols and funding to conduct inspections and maintenance. However, SCMs are becoming more complex, and special skills and knowledge are required to properly maintain them. Regardless of the complexity of the operation and maintenance requirements, all SCMs are part of the local stormwater infrastructure, and this implies that ideally SCMs should be owned and maintained by the public agency responsible for the stormwater system. However, this is seldom true (Watershed Management Institute, 1997).

Many local governments and utilities rely on private property owners or homeowner associations for the maintenance of SCMs and associated assets mainly because of cost. A large portion of the stormwater infrastructure is constructed by developers to comply with development regulations, and local public works or stormwater departments are not ready or do not have adequate funding to take on operations and maintenance responsibilities for that infrastructure. However, as stormwater infrastructure grows and ages, many private owners and entities are also not ready or do not have funds for maintenance, and unfortunately often maintenance is not a priority for them, and SCMs fail. Some communities (e.g., Prince William County, VA, Montgomery County, MD, etc.) have taken over maintenance of selected SCMs as part of the implementation of stormwater utilities. Some cities, like Austin and Seattle, assume responsibility for long-term maintenance of SCMs in residential areas (NRC, 2008). The use of maintenance agreements to ensure that private property owners maintain SCMs in their properties has been standardized for newer SCMs, and this will enhance long-term performance.

The different models of SCM ownership and maintenance responsibilities described above require a good tracking system and clear inspection and maintenance protocols to ensure that SCMs are properly maintained. All SCMs require active routine and nonroutine maintenance to continue to provide stormwater quantity/volume control and water quality benefits.

2.0MANUAL OVERVIEW

The purpose of this manual is to present best practices that will facilitate development of maintenance programs and incorporation of maintenance consideration in the design and construction of SCMs. This manual also provides stormwater maintenance protocols, forms, reporting, and asset management tools, as well as information on personnel, equipment, and costs to assist in the planning of maintenance activities. In addition, this manual provides maintenance guidance needed by maintenance agency staff (state, municipal, or utility) to adapt to evolving maintenance requirements for SCMs and climate change. Last, this manual presents several case studies that illustrate the evolving nature of stormwater operations and maintenance programs.

This manual responds to the need to address program and regulatory requirements, and includes a description of the elements of an inspection and maintenance program, as well as the skill sets needed in modern maintenance crews. The manual includes information useful to communities and utilities, and any state or local entity conducting maintenance activities of SCMs.

This manual was written by a dedicated group of volunteer authors with experience in government, academia, maintenance contracting, and consulting. The authors gathered information from a multitude of sources (e.g., federal, state, regional, and local) in the attempt to provide a national resource that is useful in all regions of the United States and beyond. It is the authors’ hope that this manual fills the gap for a consistent and succinct source of information on the evolving operation and maintenance needs of SCMs. This manual uses the same nomenclature as and complements the publication titled Design of Urban Stormwater Controls (WEF et al., 2012).

This manual is divided into ten chapters, each of which addresses important topics regarding operations and maintenance of stormwater control measures as follows:

Chapter 1, Introduction. Describes the importance of stormwater maintenance and provides an overview of this manual and suggestions on how to use it. In addition, this chapter presents information on funding for maintenance and the terminology used to help standardize the multitude of terms currently used in the stormwater sector.

Chapter 2, Program Development and Regulatory Framework. Provides information of the regulatory context that, in many instances, drives the development of stormwater programs and, more specifically, the operations and maintenance roles and components of those programs. In addition, this chapter provides considerations on how to integrate resilience and future climate change programs in operations and maintenance (O&M) programs and how to make SCMs more resilient through maintenance activities.

Chapter 3, Design and Construction Maintenance Considerations. Describes the need to design SCMs with maintenance in mind and presents key design issues that affect long-term maintenance. The chapter also describes maintenance needs during construction to minimize the effects of erosion and sediment on SCMs, as well as the importance of communications during the design and construction phases.

Chapter 4, Conventional SCMs and Green Infrastructure Maintenance. Presents maintenance goals applicable to SCM O&M programs and key processes found on SCMs that need to be sustained. This chapter also summarizes maintenance activities that are needed to optimize SCM performance and provides special considerations to preserve functions of infiltrating systems, slow-release systems, and proprietary/manufactured devices. The chapter ends with a maintenance summary for each type of surface and subsurface SCMs, including routine maintenance activities and common problems.

Chapter 5, Inspection and Maintenance During and After Construction (Protocols). This chapter provides general protocols for inspection and maintenance procedures and practices of SCMs, and describes the different types of SCMs and their components that require maintenance. This chapter also presents guidance on activities to be considered before inspection and maintenance commences. Detailed maintenance routine and nonroutine protocols to be used during construction and postconstruction, as well as checklists to guide maintenance activities, are provided. In addition, this chapter provides guidance on prioritizing corrective actions and thresholds that trigger maintenance. The chapter ends with checklists, equipment, and tools needed for the inspection and maintenance of SCMs.

Chapter 6, Asset Management and Tools. Provides an overview of stormwater asset management and guidance on how to evaluate the current state of assets, as well as identification of levels of service and evaluation of critical assets. The chapter also describes evaluation of investment strategies and long-term funding options. The chapter ends with an overview of adaptive management concepts for maintenance.

Chapter 7, Personnel, Equipment, and Cost Considerations. Provides information on personnel and equipment requirements, and typical crew requirements for routine surface, subsurface, and permeable pavement SCMs. The chapter also provides brief information on nonroutine crew, equipment, and materials requirements. The chapter includes budgeting considerations for O&M programs, including budget components, estimating program costs, in-house vs. contracted labor, tracking of O&M costs, and development of a maintenance capital improvement program.

Chapter 8, Maintenance Scheduling. Describes the importance of scheduling and provides information on maintenance scheduling scenarios. The chapter also presents considerations, priorities, and tools for scheduling maintenance. In addition, the chapter describes an adaptive management process to optimize scheduling and suggestions on when to engage design professionals to address or improve SCMs and reduce maintenance burdens.

Chapter 9, O&M Forms, Logs, and Reporting. Presents information on tracking and reporting inspections and maintenance along with sample maintenance forms and logs. The chapter also includes consideration for developing inspection forms and examples of inspections and reporting forms.

Chapter 10, Case Studies. Four case studies are presented representing large, midsize, and small communities at different stages of implementation.

3.0HOW TO USE THIS MANUAL

Audience and Intent. This manual is targeted to designers of SCMs and O&M staff in charge of developing and implementing maintenance programs. In addition, maintenance crews conducting inspection and maintenance activities can use the checklists, fact sheets, and inspections forms and logs provided in Chapters 5 and 9 of this manual.

The manual’s intent is to assist designers by providing information and considerations that facilitate design and construction of SCMs by keeping maintenance in mind. The manual also provides program-level insights to assist municipal and utility leaders in the development and implementation of O&M programs. The manual summarizes best O&M practices to support practitioners who are conducting O&M activities in the field and processing data in the office.

4.0FUNDING OPERATIONS AND MAINTENANCE ACTIVITIES

Obtaining funding for O&M activities can be a significant problem for public agencies because of the competing demands for limited funds. In addition, according to the National Research Council, one of the weakest parts of most stormwater management programs is the lack of information about, and funding to support, the long-term maintenance of SCMs (NRC, 2008). Furthermore, the majority of municipal stormwater programs do not have adequate plans or resources in place for the long-term maintenance of SCMs (NRC, 2008). To overcome these problems, a dedicated source of revenue for the stormwater program, including maintenance of stormwater systems and SCMs, is recommended. WEF has resources on methods to develop and implement funding mechanisms, including the following publications:

User-Fee-Funded Stormwater Programs (WEF, 2013) provides details for the establishment of stormwater utilities.

Green Infrastructure Implementation (WEF, 2014) provides information on program development and overcoming implementation barriers. This publication also includes a chapter on financing strategies that describes the different funding mechanisms that are available for green infrastructure and stormwater programs in general.

Maintenance of private SCMs in commercial or industrial sites is generally not a problem if the stormwater program has clear policies and maintenance procedures, as well as enforcement procedures. Commercial/industrial property owners typically have a maintenance budget and staff or contractors who can conduct maintenance activities. However, finding funds to maintain SCMs for residential property owners and homeowner associations can be problematic. Grants and assistance programs can facilitate funding of maintenance activities in residential areas, but ownership and maintenance by the local municipality or agency (with or without contractor support) will always be the preferred alternative to ensure that O&M activities are conducted in a professional manner. Additional information on O&M program funding is provided in Chapter 2 and long-term funding options in Chapter 6. A high-level discussion on maintenance cost considerations is presented in Chapter 7.

TABLE 1.1 SCM Categories and Types

5.0TERMINOLOGY

This manual uses the term SCMs to describe BMPs, stormwater facilities, low-impact development, green infrastructure, and manufactured devices, such as screens, nets, and swirls concentrators. The use of SCMs is consistent to the recommended terminology of the National Research Council report (NRC, 2008) and the terminology and nomenclature used in the companion manual, Design of Urban Stormwater Controls (WEF et al., 2012). There are many other names and terminology used in the stormwater sector to describe stormwater infrastructure. WEF and ASCE/EWRI continue to use SCMs as the preferred term, and the authors hope that this manual will contribute to the standardization of the use of this term.

Table 1.1. SCM Categories and Types, presents the nomenclature used in this manual. It has been adapted from the Design of Urban Stormwater Controls (WEF et al., 2012).

6.0REFERENCES

National Research Council. (2008). Urban stormwater management in the United States. The National Academies Press.

U.S. Environmental Protection Agency. (2021). Stormwater management and green infrastructure research. https://www.epa.gov/water-research/stormwater-management-and-green-infrastructure-research

Water Environment Federation. (2013). User-fee-funded stormwater programs.

Water Environment Federation. (2014). Green infrastructure implementation. Water Environment Federation Stormwater Institute. (2021). 2020 National municipal separate storm sewer system (MS4) needs assessment survey results.

Water Environment Federation, American Society of Civil Engineers, & Environmental & Water Resources Institute. (2012). Design of urban stormwater controls (WEF Manual of Practice No. 23, ASCE/EWRI Manuals and Reports on Engineering Practice No. 87).

Water Environment Federation. Watershed Management Institute. (1997). Institutional aspects of urban runoff management: A guide for program development and implementation.

2

Program Development and Regulatory Framework

1.0INTRODUCTION

2.0MAINTENANCE DRIVERS

2.1Regulatory Drivers

2.2Land Development

2.3Performance

3.0ROLES OF REGULATORY AGENCIES

3.1Federal

3.2State

3.3Local

3.4Stormwater Control Measure Inspection During Construction

3.5Private and Public Parties

4.0PROGRAM DEVELOPMENT

4.1Overview

4.2Extent and Level of Service

4.3Program Models and Functions

4.3.1Program Components

4.3.2Scoping the Maintenance Program

4.4Program Organization

4.5Program Funding

4.5.1Stormwater Fees

4.5.2Loans Programs

4.5.3Grant Funding

4.6Training

5.0RESILIENCE CONSIDERATIONS IN OPERATIONS AND MAINTENANCE

6.0SAMPLE MAINTENANCE AGREEMENTS

7.0REFERENCES

1.0INTRODUCTION

Over the past 40 years, cities large and small have responded to development growth with various stormwater controls, and unfortunately most controls have gone without maintenance since their installation. Typically, anything that is constructed will need routine inspection and maintenance to ensure the useful life is met. Stormwater control measures (SCMs) are no different, and whether gray, green, or proprietary they need regular attention. The effect on the environment is dependent on the stormwater control’s ability to reduce the risk of flooding and effectively remove pollutants before releasing the stormwater back into the environment.

The maintenance of early generations of SCMs primarily involved keeping conveyance systems like storm sewers, culverts, and ditches open and flowing. As communities have grown, so has the need to inspect, maintain, and operate their SCMs. No matter how effective SCMs may be, none can be expected to continue functioning effectively without regular maintenance and inspections.

The new generation of SCMs have developed in response to extended detention for water quality; surface water impairment because of pollutant loading and regulations are main drivers for improving maintenance. Water quality treatment brought additional features to traditional practices such as stormwater control basins and an entirely new set of control measures such as bioretention, infiltration, permeable pavements, and flow-through practices (Northeast Ohio Storm Water Training Council, 2017).

The responsibility for operations and maintenance (O&M) of SCMs lies, in most cases, with the owner of the SCM. Typically, the owner of the property on which the SCM is constructed is the owner of the control measure and is legally obligated to operate and maintain the control measure. Inspection and maintenance programs are developed to provide owners a structure to identify who is responsible, what is entailed in the responsibility to maintain SCMs, how to inspect and maintain SCMs, and how to build resiliency into their program.

It takes a lot of time and great deal of effort to develop a stormwater maintenance program. It is not enough just to design and construct SCMs properly. Long-term maintenance is important to ensure that the SCM will perform as designed throughout its life. No maintenance or inadequate maintenance are the main deficiencies in most local stormwater programs, and the deferred maintenance may ultimately cause the SCM to fail, causing it to become a nuisance, pose safety concerns, or induce stress on the receiving stream. Therefore, developing and implementing an effective maintenance program is essential (Hirschman & Kosco, 2008).

2.0MAINTENANCE DRIVERS

The four areas that tend to drive the need for SCM maintenance are regulatory requirements, newly developed or redeveloped land, funding for local stormwater programs, and performance of SCMs.

While stormwater management has become popular over the past few decades, communities across the country are striving to build programs to effectively manage stormwater and meet regulatory requirements of the Clean Water Act (CWA), Phases I and II of the National Pollutant Discharge Elimination System (NPDES) municipal stormwater permit program (Hirschman & Kosco, 2008).

2.1Regulatory Drivers

Table 2.1 lists regulatory drivers that may influence postconstruction stormwater.

2.2Land Development

A result of unprecedented growth throughout the United States is stormwater runoff. The transition from pervious to impervious surfaces, combined with various pollutants in stormwater, have led to water quality degradation in virtually all urban streams.

As communities grow, there is a balancing act between maximizing the opportunities and benefits associated with growth while minimizing the environmental effects of development. A community’s geography, ecosystem, infrastructure, and the way a community grows is affected when decisions are made at an executive level with little discussion on how stormwater will be managed and how SCMs are going to be maintained.

Incorporating long-term stormwater maintenance in a community’s overall master plan can effectively help balance development decisions with environmental protection. The barrier, however, is where and how to engage in development decisions. If stormwater management and long-term maintenance are included in initial planning, managers of the stormwater program can influence what is in a master plan and how the plan can develop for the overall environmental health of a community.

2.3Performance

A great number of SCMs are installed throughout the country every year including wet ponds, constructed stormwater wetlands, bioretention, infiltration practices, permeable pavement, swales, and rainwater harvesting systems. Unfortunately, many of these SCMs fail as a result of lack of maintenance or even outright neglect. Probable reasons for neglect include lack of inventory, insufficient communication, unclear responsibilities, lack of knowledge, financial barriers, and decentralized measures.

TABLE 2.1 Other Regulatory Drivers That Influence Post-Construction Stormwater (Hirschman & Kosco, 2008)

3.0ROLES OF REGULATORY AGENCIES

3.1Federal

From a federal level, the CWA is the governing policy that institutes the NPDES permit directing municipalities throughout the country to meet water quality standards for stormwater. A municipal separate storm sewer system (MS4) is permitted authorization to discharge under the NPDES and remain in compliance with the Federal Water Pollution Control Act and their State Water Pollution Control Act.

3.2State

The role of the state, in delegated MS4 states, is to issue permits and enforce the requirements, including inspection and maintenance requirements. In states without delegation authority (Massachusetts, New Hampshire, New Mexico, District of Columbia, U.S. territories, and on federal and tribal lands), U.S. Environmental Protection Agency (U.S. EPA) issues and enforces the permit requirements. The MS4 community may declare regulations governing the quantity and quality of stormwater discharges from premises within the community’s corporation limits and where applicable, from premises outside of the corporation limits, which are tributary to the sewer system of the MS4. The MS4 community is regularly inspected by the U.S. EPA to ensure the O&M program for the SCMs are implemented as outlined in the issued permit.

3.3Local

Stormwater is challenging as municipalities expand, and it is important to focus on reducing the risk of flooding, streambank erosion, and water quality degradation that is caused by stormwater runoff in all watersheds. Local municipalities implement policy to design, construct, inspect, and maintain SCMs to address stormwater management concerns. To carry out the policies, municipalities can develop a process, which includes a design manual to ensure consistency with design standards, inspection, and maintenance requirements, which include as-built surveys, facility inspection and maintenance, and maintenance and access easement requirements to allow for maintenance in and around stormwater facilities. Also, consistency in the inspection procedures, requirements, and approvals is important for a local program to be successful.

3.4Stormwater Control Measure Inspection During Construction

SCMs for construction are designed to control runoff from construction sites during storm events before being discharged into watercourses, lakes, and/or wetlands. The requirements for construction best management practices (BMPs) are intended to adequately reduce sediment and related pollutants contained in construction stormwater runoff. In general, a Stormwater Pollution Prevention Plan (SWPPP or SWP3) is required for qualifying development sites and must be submitted with the construction plans as part of the development plan approval process (City of Columbus, 2012).

First and foremost, the local stormwater program needs to identify their inspection staff. There are a few different ways to achieve the proper staffing levels:

Existing inspectors in the building or utility department,

Dedicated postconstruction SCM inspectors,

Subconsultants or subcontractors retained by the local stormwater program, and

Subconsultants or subcontractors retained by the owner/developer.

The following is a good example of an inspection during the construction process presented in Managing Stormwater in Your Community: A Guide for Building an Effective Post-Construction Program (Hirschman & Kosco, 2008).

Before construction, the owner/developer must receive approved plans to construct the SCMs,