Published on July 29th, 2019 | by Carolyn Fortuna0
Practical Tools For Managing Stormwater Runoff
July 29th, 2019 by Carolyn Fortuna
The superintendent of Marblehead, Massachusetts’ Water & Sewer Department needs the public’s help. Amy McHugh is renewing the town’s Municipal Separate Storm Sewer System permit. The first step is to test each of the town’s 250 outfall locations — the areas where stormwater discharges into collection areas and/or public waterways.
McHugh said if a larger outfall doesn’t pass muster, her team will have to track backwards, testing every smaller area where stormwater enters the system to figure out where the problem originates. The problem could be anything from a leaky sewer pipe, “we do have an older sewer system,” or a failed septic system, she said.
Stormwater is really all of our responsibility.
What is Stormwater, and Why Should I Care?
Stormwater is rainwater or melted snow that runs off streets, lawns, driveways, and other human-built sites. When stormwater is absorbed into soil, it can become filtered, replenish aquifers, and even flow into streams and rivers.
However, much stormwater runs through developed areas that have impervious surfaces such as pavement and roofs. These surfaces prevent precipitation from soaking into the ground. According to the EPA, impervious surfaces direct water to run into storm drains, sewer systems, and drainage ditches and can have many negative consequences:
- Downstream flooding
- Stream bank erosion
- Increased turbidity (muddiness created by stirred up sediment) from erosion
- Habitat destruction
- Combined storm and sanitary sewer system overflows
- Infrastructure damage
- Contaminated streams, rivers, and coastal water
Each year more than one million acres of land in the US are converted to urban use, according to the Rhode Island Department of Environmental Management. These land use changes produce sediment that pollutes our streams, rivers, lakes, and reservoirs. Even on developing land (land that’s been disturbed for just a year or less), erosion is usually in the form of gully erosion. Disturbed land associated with development often has relatively short but steep slopes, with much of the vegetative cover removed. Excavation, filling, and stockpiling operations result in soil that lacks compacting, which is subject to the erosive action of concentrated surface flows.
Then there’s erosion on agricultural land from sheet and rill erosion over a period usually measurable in years. Sheet and rill erosion involves shallow, low energy flows, which transport soil particles comparatively short distances, with soil usually remaining on site. Gully erosion is the result of concentrated flows of surface runoff. These high-energy flows increase the cutting action and transport of soil as sediment. Both conditions result in a lower quality soil resource.
What Green Infrastructure Can Do to Help with Soil Degradation and Stormwater Runoff
But there’s hope with “green infrastructure.” Green infrastructure — green roofs, permeable pavement, bioswales, rainwater harvesting, green streets, stormwater parks, and conservation areas– can effectively address stormwater pollution and mitigate flooding, while at the same time providing open space for recreation, habitat, improved air quality, climate resiliency, and aesthetic benefits.
As the pictures in this slideshow below taken adjacent to Smith & Sayles Reservoir in Rhode Island demonstrate, simply redirecting water flow isn’t enough to provide a long-term solution.
Central to these efforts are approaches and technologies to infiltrate, evapotranspire, capture, and reuse stormwater to maintain or restore natural hydrologies.
A document created by the EPA describes how, in the face of climate change, it is increasingly important that communities reevaluate how best to make use of their water resources and treat rain and stormwater as the resource they are. Instead of communities that overlook stormwater laden with trash, metals, and pollutants that contaminate local waters, best management practices (BMPs) can effectively control stormwater while simultaneously building vibrant, attractive communities. These innovative practices also help to revitalize community economies by supporting sustainable local jobs, improving community assets, and reducing blight.
The correct use of soil erosion and sediment control BMPs ensures public safety, keeps local water clean, and prevents flooding, soil loss, and other long-term consequences of erosion. The following examples demonstrate ways to maintain soil integrity and enhance landscape aesthetics.
(Editor’s note: by mitigating storm runoff threats through this type of mitigation, communities spend less responding to flood emergencies and recovering from them. This leads to not only better public safety, but significant cost savings over time.)
Pervious Pavement Gains Popularity
According to Market Research Future (MRFR), the global pervious pavement market should garner a significant growth by 2022, registering an impressive compound annual growth rate (CAGR). Pervious pavement, sometimes also referred as permeable pavement or porous concrete, offers an alternative paving surface with a high porosity that allows stormwater to pass through voids into the ground below. The idea of permeable pavements basically proposes reducing floods, raising water tables, and replenishing aquifers. It focuses on tackling the increasing concerns of flooding in urban areas and controlling the stormwater runoff.
It is extensively used in structures such as driveways, sidewalks, commercial and multi-acre spaces, parking lots, and low-traffic streets. Due to its high porosity, pervious pavement makes an efficacious choice for developing green parking lots, rain gardens, solar covers, and other creative elements. The European region dominates the global pervious pavement market, with substantial investments made in infrastructure redevelopment projects by public and private organizations, which, as a result, drive the regional market.
Rain Garden Maintenance
What can a home or small business owner do to offset stormwater runoff? Rain gardens are a fairly easy way to capture water and to retain it in a vegetative area so the plants can absorb the water. Rain gardens actually have both regulatory and environmental functions.
Some areas to consider when planting a rain garden include a vegetated waterfowl buffer, waterfowl buffer planting plan, and a plants photo plan to help maintain the rain garden over time. So, too, is understanding which plants to include and which to leave out. The National Park Service defines an invasive species as a non-native organism whose introduction causes or is likely to cause economic or environmental harm, or harm to human, animal, or plant health. When constructing a rain garden to offset stormwater damage, it is important to differentiate between native and invasive species.
We care about invasive plants because they crowd out native species, which then affect the bees and insects that depend upon these plants for survival. Rhode Island’s “In the Weeds: The Guide” — which is also available in a mobile form — is split into 4 categories: Trees, Shrubs, Herbaceous/Grasses, and Vines. Under each category the plants are alphabetized by the common names that they share.
It is easiest to control invasive species through frequent inspection and weeding before they get firmly established, so many of the photos in this guide show seedlings and young plants. Other photos were chosen to emphasize distinctive plant features, such as large flowers, fruits, seedpods, leaf shape, and different bark textures.
Many states like Rhode Island are taking steps to help citizens understand their roles in stormwater managements, such as in the Rhode Island Stormwater Solutions.
Communities are developing comprehensive long-term community stormwater plans that integrate with economic development, infrastructure investment, and environmental compliance. Through this approach, communities can prioritize actions related to stormwater management as part of capital improvement plans, integrated plans, master plans, or other planning efforts.
Proper soil erosion and sediment control is critical to minimizing impacts to water resources and the environment during land disturbing activities. Proper soil erosion and sediment control techniques protect water quality, cultural and natural resources, and private properties.
Unless otherwise cited, photos by author Carolyn Fortuna
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