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CLIENT: MACTEC, Inc.
MARCH/APRIL 2007: Stormwater
Sophistication and implementation
The new millennium has effected change in many arenas, not the least of which is stormwater management. Minimum compliance is no longer the standard, and stormwater is no longer an afterthought for community planning. For example:
This article is the first of a three-part series addressing the current state of stormwater management in the Atlanta area. Part 1 covers stormwater management issues, part 2 will look at redevelopment and professional certification, and part 3 will examine the Endangered Species Act as it relates to stormwater management.
The series focuses on causes, effects, and remedies leading to the establishment and refinement of administrative procedures, professional trust, proactive approaches, and the elimination of plan implementation obstacles. As a community, we must pool our resources to help enable a positive return on our endeavors. The goal is not only to continually improve the protection and restoration of our streams and watershed but also to improve the process.
Even though issues such as BMP validation, professional certification, resource availability, acquisition of homes in floodplains, and land redevelopment are not new to stormwater management in general, these issues have moved to the forefront in terms of importance.
|A newly constructed storm drain allows runoff to flow beneath the road.|
Stormwater management is valuable and necessary. Based on each community’s environmental and economic needs, many state and local governments are going beyond the minimal stormwater management requirements set by the federal government. In addition, protection, stewardship, sustainable growth, and quality of life have become more important and valuable among a wider variety of stakeholders.
As a result, better methods are evolving to quantify progress. Stormwater management implementation must take place sooner and show tangible results. We cannot wait for technical certainty and guidance that would leave no question unanswered. Instead, our actions must be bolder based on confidence gained by more sophisticated approaches.
Below are brief synopses of explicit and sophisticated requirements and issues that the Atlanta area and other rapidly developing areas of Georgia are experiencing.
Floodplain Management: The MNGWPD model ordinances require that floodplains be developed for all streams. By expanding the mapping of floodplains from Federal Emergency Management Agency (FEMA)—regulated streams to the headwaters, two distinct results occur: Firstly, because we are required to map future land use, conditions of the floodplains are conservatively wide, and secondly, because we are mapping streams that were not studied by FEMA, there are more identified floodplains.
The general intent and benefits are clear: We can update our current situation and more effectively plan for the future. For example, with more accurate floodplain information (i.e., models) at our disposal, more potential flooding problems (i.e., maps) can be identified. This not only can change the way floodplain issues are managed but also can serve as the basis for finding solutions to flooding problems. There is less speculation now that more “engineering evidence” is available. The mandated implementation timeline varies, but definitive actions must be taken swiftly because we now know the problems and which solutions will be most beneficial.
Stream Buffer Protection: Minimum stream buffer control measures maintain tree canopies that reduce temperatures and provide vegetative cover that reduces pollutant loads. Many undeveloped sites do not have enough available space to deal with the larger buffers economically. Therefore, communities are faced with identifying alternatives (e.g., variance procedures) that preserve one’s right to develop the land but don’t let the process become overly subjective and arbitrary.
Field Sampling and Inventory: Field sampling and inventory requirements are necessary to make sure that each community understands the health of its watersheds and when corrective actions are required. Field data provide proof of what is occurring, whether it is pollutant discharges or deteriorating infrastructure. The question is, what do you do when the actual requirements of the investigations are extensive and threaten to use the resources that could begin to resolve the noted concerns? Which do you address first: the big ones, regardless of their location, or only those in the right of way?
|Reviewing water-quality samples taken near a storm drain collection location|
Redevelopment Versus New Development Standards: Even though the GSMM has been adopted by the communities in the MNGWPD, the techniques it promotes are most applicable to new sites. Although the GSMM and formal training strongly emphasize better site design practices for new development, what do you do for redevelopment where sites can be well constrained—even beyond what the smaller, undeveloped lots experience? These sites may be landlocked and may have zoning restrictions, but extensive retrofitting can be cost prohibitive. In such cases, you may not be able to meet the targeted pollutant reduction goals (80% of total suspended solids), resulting in the argument that any improvement to a previously developed site (not meeting the current stormwater regulations) is an improvement. Hands may be tied relative to ordinances and policies that do not distinguish between new site development and redevelopment. How can a variance procedure help without being viewed as arbitrary, unfair, and leaving the community in a state of non-compliance?
Design Freedom and Technical Innovation: New development requires innovative techniques and products to meet the intended use while complying with water-quality standards. Balancing reliable and predictable performance with increased performance to offset available space requirements is an important issue. Even though there are many new products and techniques available, it is important to understand what works best, is easiest to design, and can get approved. Technical innovation can be risky. For developers, innovation can be costly due to multiple design concepts, and for communities, a failed BMP project for watershed restoration can be a political nightmare. However, there are instances where the reward outweighs the risks, such as finding ways to control the risks while capitalizing on the potential rewards of new innovation.
Professional Certification: The procedures were followed, the proper control measures were applied, and a good post-development stormwater management plan was developed, but who can certify it? For MNGWPD requirements, professional engineers can certify the plan, and other professionals can certify only portions of the plan. Certification can be fairly complicated, depending which side you are on. A highly debated subject, certification will continue to be discussed as additional insight is gleaned from other programs.
|Top: Scientists from MACTEC conduct macroinvertebrate sampling and stream habitat assessment of a storm drain. Bottom: A geologist programs two flow meters to evaluate watershed loading of potential pollutants.|
Knowing the available options is imperative to understanding the myriad issues and the resulting changes that either are taking place or still needed. Below is one attempt at connecting those dots to provide an overview of the options we have to move ahead:
Venturing Into the Watershed
Think of the flexibility in design options that could be gained if involved parties would go beyond their site or public right-of-way limits. Most projects are not conceived to handle the time involved and money required to coordinate activities such as access and easements with property owners. However, following are examples of how this approach could be applied.
Offsite Mitigation: From a private site development perspective, offsite mitigation has been used when wetlands and streams are impacted and the effects cannot be mitigated onsite by other measures (e.g., BMPs). In addition, offsite mitigation can be useful when the site is small and heavily encroached upon by restricted areas, such as stream buffers that exceed the minimum state widths. The result is that a new site is developed as planned and impacts are addressed by mitigating the effects through control measures, either onsite or offsite. This is not to suggest that wetland, streambank, or stream buffer “banking” is easy to do or always an option, but it is a general mechanism that can allow development and provide an acceptable level of watershed protection.
From a redevelopment perspective, where a vacant parcel exists but there is no feasible way to meet the current stormwater standards, do you scrap the idea and allow the property to remain unusable? Or do you identify another undeveloped site further downstream with enough room for BMPs that you could use to treat the pollutant load from the upstream redevelopment site? For developers and local plan reviewers, this is not a new or easy concept but definitely worth investigating.
Land Acquisition: From the government’s perspective, there are homes in the FEMA floodplain that have been damaged by flooding, often because they were built before FEMA had mapped floodplains or before there were local regulations for stormwater detention. The properties aren’t worth much money, and the owners aren’t asking much. Communities have purchased some of these properties and turned them into useful sites, such as recreation areas, which ultimately benefit the communities by reducing claims and flood insurance premiums.
Extensive future floodplain mapping is good, but it comes with potential tradeoffs. For example, floodplain mapping has legitimized claims and concerns of floods and/or threats of floods. However, there may not be sufficient available funds to meet the public’s demands, making it unclear as to which projects are most worthy of the funds. The situation is complicated because emotions and people’s homes are involved, so we should be sophisticated in identifying and prioritizing the most deserving projects to receive the designated funds.
Field Inventory/Operations and Maintenance: Outside the right-of-way area, who is responsible for field inventory as well as operating and maintaining stormwater systems? Communities are ultimately responsible for ensuring that the stormwater systems are functioning and that proper maintenance is scheduled and funded.
However, the community does not own everything that collects and conveys stormwater or most of the land that generates the runoff. So, is the community responsible for all stormwater system features? Generally, the answer given by communities is no. Private property is private, and, as you can imagine, this creates challenges such as dealing with the political and public relations aspects. For example, what if portions of your stormwater system (e.g., a roadway culvert) depend on the function of a private system (e.g., a detention pond) to work? Who is ultimately responsible for operating and maintaining that private system?
In each of the examples above, there is a common theme: How does one move from a point of control (your site, the right of way, etc.) to one that requires cooperation, communication, and dependency on others? For the developer, there is the risk of time and money. For the community, how do you buy “some” houses in the floodplain or inventory and fix only “some” privately owned stormwater systems and not others? For both parties, failing to follow your instincts to the problem’s source and the solution may lead to a bigger problem than the one you are trying to avoid.
Flexibility and Liability
It is difficult to be flexible and conservative when dealing with rain and with land development: Both events consist of variations that are random and unpredictable. In contrast, engineering is a profession that traditionally relies on scientific techniques and the ability to quantify parameters and performance to solve problems. Because stormwater management is a well-regulated field of expertise, with federal, state, and local regulations that can lead to penalties, technical methods are used to manage stormwater plans based on conservative, logical, and reasonable assumptions that can lead to the necessary action plans. However, too much conservativeness and simplicity—to alleviate the fear of consequences—can limit our options and increase costs. On the other hand, too much flexibility with respect to more inventive methods can lead to inconsistent practices and standards.
Floodplains: Floodplain management is a balancing act. In many cases, the required detention facilities that control peak flows of heavy rainfall are not owned by the community, but the community is responsible for maintaining (or at least ensuring) flood control. The concern is that without proper maintenance, those ponds could fail and the watershed could behave as if the ponds did not exist. One remedy, or safety factor, applied by the MNGWPD is that if not owned by the regulating entity, detention facilities are not included in hydrologic studies. Models are run with increased imperviousness but with no additional detention to mitigate the additional runoff.
It is a reasonable approach intended to keep people safe from flooding while erring on the side of caution. However, in some cases the over-predicted floodplain limits will prevent land from being developed as intended. In other cases, improvement projects such as culvert and bridge upgrades could be ranked improperly (too high or too low) for implementation. Many of the more experienced decision makers look at the basis and ramifications of future floodplain limits and are able to put the information into the right context to make good decisions. On the other hand, those newer to the process will not find it as easy to make such judgments.
|Left: Newly constructed riprapped channels and culverts convey stormwater runoff along a major highway.
Right:A MACTEC technician services a remote telemetry stormwater unit after California wildfires.
How do you manage stormwater and watershed health without slowing or stopping a collaborative and flexible process? Stormwater initiatives often do not provide instant or obvious returns, and it is difficult to recognize their value. In some cases, doubts occur and questions arise. The deciding factor can be tied to confidence and/or comfort.
New BMPs: Validated BMP performance and new BMPs that haven’t been field-tested increase each year creating questions such as these:
Professional Certification: Assuming all of the methods and applied technologies have been proven with confidence, who provides the certification—an engineer, a landscape architect, or a surveyor? In Georgia, the discussion of professional certification of stormwater management plans has included the following arguments:
At this time, the latest revisions to the Post-Development Stormwater Management Model Ordinance states that only the following four (of 12) elements in the MNGWPD model ordinance for post-development stormwater management must be certified by a P.E.:
If this version is noted into acceptance, either a P.E. or an RLA can control the plan, while portions of it may be prepared and stamped by an RLS. Even though this can be considered progress or a compromise, the discussion will undoubtedly continue.
Part 2—Less Talking and More Walking
Part 2 of the three-part series will focus on a more detailed discussion on the complexities associated with redevelopment, offsite mitigation, and professional certification.
Return to: 2007 Feature Stories