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Hurricane Flooding Nutrient Reduction Rooftop Reuse Airport Drainage 18 Path to resiliency 20 Innovative practices 25 Citizen science 29 Kraków expands

Volume 6 / Issue 3 Autumn 2018

The Official Publication of the WEF Institute MANAGEMENT

Stream restoration Nutrient Reduction Nontraditional solutions GHOLYHUPXOWLSOHEHQHƮWV for municipalities restoration and shoreline stabilization provide valuable results for municipalities required to meet assigned waste load allocations for phosphorus, nitrogen, and . Ashley Hall, Daniel Proctor, Karen Hall, Josh Running, and Travis Crayosky RI6WDQWHF,QFH[SODLQWKHHQYLURQPHQWDOƮQDQFLDODQGSUDFWLFDOEHQHƮWVRIHPSOR\LQJWKHVH two nontraditional stormwater practices in the Commonwealth of Virginia, .

Localities with Municipal Separate Many MS4s initially struggled Ideal projects would ideally have plants, etc.) and can be traded Storm Sewer System (MS4) Per- to find enough projects to meet easy support from all stakeholders as a nutrient credit among point mits in the state of Virginia, United the reductions and then quickly and have clear environmental sources and nutrient bankers. States (US), have been pushed fit them into long-term funding benefits with a low cost relative to The success of a project can hard to meet their assigned Waste plans to be approved by elected the amount of pollutants removed. be measured, to an extent, by the Load Allocations (WLAs) given officials who were surprised by In Virginia, phosphorus has tradi- pounds of phosphorus removed in Total Maximum Daily Loads the financial consequences of the tionally been marked as a unique along with the overall cost of the (TMDLs). MS4s are named in MS4 permits. As a result, a search type of currency for benchmarking project, providing a data point TMDLs that have been developed led by local government officials stormwater practices. In the most in terms of dollars per pound of for hundreds of impaired water- (with support from contracted general terms, the presence of removed phosphorus ($/lb-P). sheds. These local TMDLs have consultants) ensued for innovative phosphorus represents stormwater While this figure represents a challenging reductions, but the practices that would bring multiple pollution from multiple sources gross estimate, not accounting for TMDL-related pressure visual benefits to the public. (construction sites, treatment maintenance costs, community point for Virginia MS4s is the Chesapeake Bay TMDL, which assigns WLAs for phosphorous, nitrogen, and sediment. The Chesapeake Bay has its own Special Condition in Vir- ginia’s MS4 permits, with a firm deadline to meet the WLAs for nutrient and sediment reductions by 2028, as detailed in the General Virginia Pollutant Elim- ination System Permit (VPDES) for Discharges of Stormwater from Small Municipal Separate Storm Sewer Systems, Section 1.C: Spe- cial condition for the Chesapeake Bay TMDL. This objective is also integrated into Virginia’s com- mitments to the Environmental Protection Agency (EPA) to clean up the Chesapeake Bay. The financials for meeting these goals started off dire as cost estimates returned were higher than anticipated and there were no dedicated funds for TMDL implementation at the time. The above image shows Dead Run before the stream restoration project began. Photo by Stantec

20 World Water: Stormwater Management Autumn 2018 Nutrient Reduction

benefit, improved , shear stresses that cause , the stream restoration project may etc., it provides a tangible starting incision, and overall initially be undertaken for ero- point that allows for consistent FACED WITH THE degradation of the natural stream sion concerns, but then it may be tracking of results. INSURMOUNTABLE system. While upland stormwater further enhanced to endure future During the search for innovative CHALLENGE OF practices can alleviate some of considerations such as recurrent practices, Virginia MS4s col- INSTALLING SUCH these symptoms through flow flooding or upcoming development. lectively found that conventional controls, are still vulner- All aspects of the stream and stormwater structural practices A HIGH NUMBER able to impacts from urbanization its watershed are reviewed prior – detention basins, constructed OF PRACTICES IN A and stormwater discharges. to designing a stream restoration wetlands, , and SHORT TIMEFRAME, Stream channel erosion releases project. Key considerations include permeable pavement, for example sediment into waterways, along topography and , along – posed a challenge as far as cost MANY MS4S WERE with the associated nutrients with constraints such as bedrock. and scale was concerned. They CONSIDERING BUYING bonded to the soil particles. Ad- Existing utilities – sewer mains and discovered that these traditional CREDITS AND WALKING ditionally, urbanization’s effects laterals, fiber optics, and electrical practices would have to number in on streams have caused discon- – are also frequent constraints the hundreds in order to meet their AWAY FROM THE nection from as well that must be considered and WLAs, would eventually become MAINTENANCE AND as decreased contact time and addressed as part of the design. a maintenance nightmare, and LOGISTICS. a reduced ability for nutrient analysis is also a would have a very high dollar-per- uptake by streams and ripar- major consideration. The design pound removal rate. Faced with ian vegetation. These sediment of a stream restoration project the insurmountable challenge of and nutrient loads were noted has the ability to impact the installing such a high number of contributors to the degradation of mapped zones and thereby practices in a short timeframe, the Chesapeake Bay and its many influence Federal Emergency many MS4s were considering buy- . Sediment can impair Management Agency (FEMA) ing credits and walking away from benthic communities that rely on mapping, insurance rates, and the maintenance and logistics. stable stream cobble and gravel property values. Sourcing of However, Virginia’s MS4s substrates for colonization. materials for these projects is soon identified two nontraditional Excess nutrients, coupled with also a key project consideration. practices that had the potential warm temperatures, create algae Local, state, and federal regulatory to achieve similar quantities of blooms and the resultant hypoxic agencies typically prefer to see pollutant reductions as numerous conditions currently found within onsite materials used where structural stormwater practices in parts of the Chesapeake Bay. possible such as root balls from one project at a more cost-effective for resiliency, reducing The practice of trees, native soils, and harvested removal rate: stream restoration flooding impacts, protecting exist- restoration seeks to reduce the loss streambed materials. Large and shoreline management. In ing infrastructure, and increasing of sediment and associated nutri- rock structures are typically both practices, sediment and public access to green spaces. ents from the stream channel while installed to help direct flows associated nutrients are directly stabilizing the stream channel to and provide for grade controls. prevented from entering waterbod- Stream restoration withstand new watershed condi- Visits to quarries to view boulder ies, with additional ecological Urbanization has significantly tions and other environmental choices are common, and hauling uplift added through natural affected waterways, with increases factors. A stream restoration project costs need to be considered. processes that can be designed in impervious areas spiking storm- can vary greatly depending on the Many MS4s have successfully into the project. Addressing the water discharges and peak flows. existing conditions and the desired restored stream channels and stream and shoreline erosion also These stormwater discharges outcome. In some instances, reported the amount of sediment improves other conditions for MS4 are conveyed to receiving chan- erosion reduction is all that is war- and nutrients (nitrogen and phos- permit holders, such as designing nels with high velocities and ranted for a project. In other cases, phorus) effectively removed from downstream receiving waters, and ultimately from the Chesapeake Bay. The amount of sediment and nutrients that is credited to the project for purposes of the Chesa- peake Bay TMDL is determined using the Chesapeake Bay Pro- gram’s assembled Expert Panel guidance document, which describes the practice, recomm- ends removal rates, and outlines qualifying criteria. Projects are credited using four primary protocols. The majority of a stream restoration project’s credit comes from the prevented mass of sediment and nutrients that is annually lost from erod- ing streambanks. This figure is estimated using a predictive model that considers susceptibility to erosion and dimensions of the stream, and it may be verified with pin measurements. Other The Dead Run stream restoration project, currently underway in Virginia, is protocols account for reductions expected to result in the environment depicted in the above rendering after achieved through nutrient process- restoration and stabilization are complete. Image by Stantec ing by denitrification and nutrient

World Water: Stormwater Management Autumn 2018 21 Nutrient Reduction

An aerial rendering of Jamaica Bay illustrates shoreline stabilization tactics in New York. Photo by Stantec absorption through floodplain re- ecosystems and vegetation. Shore- most substantial sediment and connection. Regenerative practices line management practices that nutrient reductions are achieved. used on intermittent and perennial incorporate benefits THE MAJORITY OF A Estimates of sediment and nutrient streams to slow flows and increase are often referred to as living shore- STREAM RESTORATION reductions are based on measured floodplain interaction are also cred- lines. A living shoreline practice PROJECT’S CREDIT erosion rates, bank heights, and ited as a stream restoration practice. incorporates nature-based designs COMES FROM THE soil conditions (bulk density and where feasible, with nonstructural chemical constituency). Depending Shoreline management features such as marsh creation, PREVENTED MASS on the project, further sediment The transport of sediment along , and vegetated OF SEDIMENT AND and nutrient removal may also be shorelines is an essential process banks. However, when hydrody- NUTRIENTS THAT quantifiable through the creation of in tidal environments, but in areas namic conditions warrant further tidal marsh due to such processes where erosion rates are more exces- protection to achieve stability, a IS ANNUALLY LOST as denitrification, nutrient uptake sive, it can also be detrimental. At hybrid design using structures (i.e., FROM ERODING from biomass production, and a natural rate, eroding shorelines breakwaters or rock sills) can be STREAMBANKS. sediment accretion (Protocols 2-4). provide tidal through ac- incorporated to adequately resist cretion of natural . On the wave erosion while maintaining goals such as TMDL WLAs. Like Disputed issues regarding other hand, the rate of shoreline ero- natural coastal processes. A shore- the one convened for stream res- credit sion can be dramatically increased line management project can also toration, the Chesapeake Bay Pro- In addition to setting technical due to sea level rise, increased be enhanced to accommodate rec- gram convened an Expert Panel standards on how to quantify frequency in storm events, shore- reational and resiliency benefits. to define the dominant methods sediment and nutrient reductions line development, and increased All aspects of the shoreline and in which shoreline management for stream restoration and shore- commercial and recreational the surrounding area are reviewed achieves sediment and nutrient line management practices, the activities. Areas of larger erosion when conceptualizing a shoreline reductions to waterways. For many respective Expert Panels also are problematic from a water qual- management project including the shoreline management projects, addressed various concerns raised ity perspective, where shoreline current rate of erosion of the shore- there are steep or rapidly eroding by opponents to using the practice sediments and accompanying line banks, existing geologic condi- banks that require immediate for meeting WLA requirements nutrients are deposited into the tions, wave heights, nearby infra- protection. The prevented loss of in addition to legitimate issues receiving waterbody. Considering structure, and construction access sediment (Protocol 1) is where the raised by unbiased parties. Among the sediment and nutrient issues (land and water). The presence within the Chesapeake Bay, the of migrating birds, submerged contribution of this source should aquatic vegetation, archaeological not be overlooked. In many of the sites, bald eagles, anadromous same ways as stream restoration, fish, other threatened and endan- stabilizing eroding tidal banks gered species, federal navigation can result in a beneficial sedi- channels, and leased oyster beds ment and nutrient reduction. are some of the common obstacles Several management practices noted for Virginia projects. Such can be used to address shoreline obstacles are surmountable but erosion and improve water quality. have unique restrictions that Traditionally, shoreline erosion has are incorporated into the design been approached using structural and construction for projects. practices, such as , bulk- The amount of sediment and heads, and , but nutrients prevented from entering these practices can create other a waterbody as the result of a and scour is- shoreline management activity can sues and can limit habitats for tidal be quantified toward water quality

22 World Water: Stormwater Management Autumn 2018 Nutrient Reduction

others, these concerns included never actually be transported Summary The science and crediting proto- dissatisfaction in the location to the Chesapeake Bay. This Stream restoration and shoreline cols of these practices is also under of the obtained pollutant reduc- potential was addressed using management can be exceptional continuous review in Virginia and tions, the fear of taking reduction the EPA’s modeling tools for the practices that accomplish reduc- for the Chesapeake Bay Program. credit for sediment that would Chesapeake Bay TMDL and tions of sediment and nutrient The Expert Panels are subject to never be fully transported to the establishing delivery ratios for loadings to local waterbodies for reconvene and reassess recom- Chesapeake Bay, and indirectly various tributaries, along with relatively low cost compared to mendations if determined neces- supporting bank armoring under similar checks and balances, to other conventional stormwater sary. While it might be challenging the guise of environmental avoid over-counting sediment and practices. Accessible eroding to keep up with the Chesapeake restoration that could limit other nutrient reduction potentials. Since stream channels and shorelines Bay Program’s methodologies, the desirable natural processes. shoreline management practices on public lands may be limited science behind stream restoration The treatment processes are contained within the actual for some MS4s. In urban com- and shoreline management is described by the protocols are itself, the same concern munities, adjacent residents must fundamental. These practices not mechanisms contained within the was not applicable, but the need be willing stakeholders in the only improve water quality but stream channels or nearshore tidal to reconcile the allowable credits project. The disruption of natural also bring a suite of additional areas themselves versus within with respect to the EPA modeling areas in an already urbanized benefits to the community. As upland areas of the watershed, as was identified. Maximum achiev- community and the willingness communities are challenged to in other stormwater practices. For able sediment and nutrient reduc- to provide easements can be build with resilience and replace years, regulatory agencies had tion loads were established within sensitive issues; therefore, early aging infrastructure, stream resto- been encouraging the avoidance given segments of the contributing public outreach is essential in ration and shoreline management of placing stormwater facilities tributaries to avoid overestimation. having a project proceed without will continue to be the leading within jurisdictional areas, and the One of the largest points of major delays or cost escalation. options for multifaceted solutions. crediting of these practices seemed contention was that crediting these When implementing these to conflict with this objective. practices would indirectly encour- projects, the MS4 will be respon- Authors’ Note Furthermore, it was questioned age a vast hardening of natural sible for maintaining the project Stantec Senior Engineer Ashley whether it would be acceptable systems. Other environmental integrity. Maintenance of these Hall, located in Richmond, Virginia, to achieve the permit-mandated value is present within natural projects is anticipated to be low; specializes in water resources en- WLA well downstream from the stream and shoreline conditions however, every project is different, gineering including watershed point of discharge covered by the that should not be ignored for the and the use of these practices for analysis, stormwater management MS4 permit – or within a different sake of sediment and nutrient WLA compliance is still early. The planning and design, low impact hydrologic setting altogether. reduction. If a dangerously narrow initial guidance for monitoring and development, municipal separate Thanks to a diverse range of interpretation were applied, much verification of stream restoration storm sewer system permit sup- stakeholder involvement in the of the science behind the protocols projects was set at 5 years, and port, and TMDL implementation. Expert Panels, which included would suggest no difference be- the first general permit to require Stantec’s Water Resources regulatory agencies, these con- tween replacing an eroded stream Virginia MS4s to act on the Chesa- Manager Daniel Proctor, Water cerns were thoroughly discussed, with a fully restored system, peake Bay TMDL was issued in Resources Engineer Karen Hall, and a reasonable consensus was versus a concrete or riprap-lined 2013, so some projects are now ap- Associate and Senior Environmental achieved. This resolution was in channel. Likewise, it was ques- proaching the first 5-year window. Planner Josh Running, and Principal large part due to acknowledge- tioned whether or not replacing As time advances, it is thought Travis Crayosky work out of the ment that pollutant reductions an eroded shoreline with a riprap that the verification process may company’s Williamsburg, Virginia, would indeed be achieved, which or vertical bulkhead need to be more frequent and office. Proctor has more than a was the primary objective of the should be allowed. Unintended more prescriptive. The agencies decade of experience in planning, WLAs. The Chesapeake Bay was consequences could result in have the discretion to prolong designing, and managing complex widely indiscriminate as to where adverse effects to the same ecosys- the monitoring of these projects, environmental and engineering the pollutant reduction occurred. tems intended to be protected, so requesting resolution of issues projects. Karen Hall has experience But local waterways still had to be the protocols contain qualifying such as , vegeta- in multiple aspects of stormwater protected, too, so limitations were criteria and minimum standards tion die-off, scour at structures, management and water resources placed on the watershed locations to avoid such situations where or excessive sediment , engineering. Running has nearly 20 of the treatment practices with re- possible. To achieve sediment and among others. Having a knowl- years’ experience and serves as the spect to the credited MS4 location. nutrient reduction credits, stream edgeable consultant or other party firm’s national technical lead for eco- It was also understood that restoration is required to use natu- to review and defend a project can systems restoration. Crayosky has some of the eroded sediment from ral channel design methods, and be important in making sure that more than 20 years of experience stream banks might be deposited shoreline management must incor- the project is not monitored for specializing in ecosystem restora- along the downstream areas and porate living shoreline principles. an unnecessary period of time. tion projects that include stream and wetland assessment, restoration design, regulatory permitting, construction management, and monitoring and reporting activities.

(Left to right): The images show three stages -- before, during, and after -- of a stream restoration project in Fairfax &RXQW\9LUJLQLD6WDQWHFbSURYLGHG UHVWRUDWLRQVHUYLFHVIRUD3LQH\5XQ that extends from the Fairfax &RXQW\3DUN$XWKRULW\RZQHG%DQNV 3URSHUW\WR2OG7HOHJUDSK5RDGQHDU +D\ƮHOG5RDG6WDQWHFFRPSOHWHG YDULRXVDVVHVVPHQWVZHWODQGDQG HFRORJLFDOVXUYH\VPDFURLQYHUWHEUDWH VDPSOLQJFRQFHSWXDOGHVLJQGHWDLO design, permitting, and construction drawings. 3KRWRVE\6WDQWHF

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