As heavy rains continue to carry pollutants into local waterways, the city of Greenville is launching a series of stormwater management projects in downtown that could provide a much-needed boost to Richland Creek’s water quality.
The first project will begin in mid-August on a portion of the creek that flows through one of the city’s oldest and most popular green spaces — McPherson Park.
Lisa Wells, a senior engineer with the city, said the new stormwater management project is designed to improve the overall water quality of the creek and will include work both in the stream and throughout the 12.5-acre park.
The city has hired North Carolina-based construction firm River Works Inc. to oversee the $700,000 project, which is funded in part by the U.S. Environmental Protection Agency under a Section 319 grant through the S.C. Department of Health and Environmental Control, according to Wells.
To prepare the site, River Works will first remove three trees that have been identified as potential safety issues due to their age and health. Additionally, the banks of the stream will be cleared of non-native and invasive plants.
The company will then remove rubble and debris from a 500-foot portion of the stream to stabilize its bank to prevent erosion. Crews will also place structures in the stream to create pools and direct the flow of water, and plant native vegetation along the streambank to increase the soil’s capacity to store rainwater.
Wells said the project scope also includes removing the concrete swale — channels that collect surface runoff — and pipes around the park’s tennis courts and demolishing the existing asphalt parking lot, which allows stormwater to carry oil, grease, trash, and other pollutants into the stream.
River Works plans to replace the concrete swale and pipes with a bioswale, a landscaped depression, to capture, treat, and infiltrate stormwater. The company will then replace the parking lot with a new surface consisting of gravel and interlocking grids.
During that time, the city will temporarily close the park’s tennis courts and parking lot, according to Wells. Parking will be available only in the small surface lot across the street from the Sears Recreation Center.
The park’s shelter, playground, and bandstand will remain open throughout much of the project, Wells said. The miniature golf course, however, will be closed to the public during construction. It will be replaced with a new course later this year.
Additionally, the park’s bridges will be closed and a portion of the parking lot near the stream will be used to stage equipment.
Weather permitting, the project should be complete by September or October, with final plantings along the stream bed to take place in November, she said.
Keeping floodwaters at bay
Wells said the upcoming project in McPherson Park marks the beginning of the city’s new approach to stormwater management, which has evolved from a focus solely on flood management to an additional focus on water-quality management.
Traditional approaches to managing urban stormwater runoff have utilized so-called “gray infrastructure,” such as concrete and debris from construction projects, to fortify stream banks against erosion, Wells said.
“The problem with that approach is that you’re destroying the natural function of the channel,” she explained. “It can create bigger problems downstream.”
Wells said stormwater runoff is one of the city’s biggest environmental threats, especially as urbanization throughout the downtown area continues to decrease the number of natural spaces capable of trapping stormwater when it rains.
The city, however, uses a “municipal separate storm sewer system” that carries stormwater runoff away from buildings, roads, and other developments and dumps it into local waterways, such as Richland Creek, to alleviate flooding.
Since 2005, the city has spent more than $15 million on several stormwater projects in flood-prone areas of the city: the Henderson basin in the Parkins Mill area, Chick Springs, White Oaks, Broad Street, and near McAlister Square.
More recently, though, interest has grown in green infrastructure technologies, such as bioswales, which use or mimic natural processes to infiltrate or reuse stormwater runoff on the site where it is generated, Wells said.
These practices keep rainwater out of the sewer system, thus preventing sewer overflows and reducing the amount of untreated runoff discharged to surface waters, she said.
The city is currently implementing a new, multimillion-dollar stormwater management improvement plan, dubbed “Stormwater 2.0,” a move that will substantially reduce the amount of pollution that runs off of city streets and construction sites.
As a part of the improvement plan, the city is modeling Richland Creek and other waterways throughout the city to determine how stormwater flows and at what volume into the city’s streams and rivers, according to Wells.
In 2015, for instance, the city developed the Richland Creek Water Quality Master Plan, which aims to reduce stormwater runoff throughout the creek’s approximately 8.6 square miles of watershed by fortifying streams with green infrastructure.
“It really is part of a bigger shift in how we’re handling stormwater runoff and how we’re impacting water quality by leveraging our public spaces and bringing them in line with the latest management trends,” Wells said.
She added that Richland Creek’s watershed is listed by the state as “impaired,” meaning its water quality is potentially harmful to aquatic life and public health.
Most of the development throughout the watershed occurred before proper stormwater control measures were in place, allowing large amounts of sediment and nutrients to pollute area streams when their banks eroded during heavy rainfall.
The city’s master plan for the Richland Creek watershed looks to remedy that issue with three stream restoration projects, including the work in McPherson Park.
That project will remove an estimated 64,000 pounds of total suspended solids per year upon completion, according to the city documents.
Total suspended solids can include a variety of material, such as silt, decaying plant and animal matter, industrial wastes, and sewage.
Preparing for future floods
Once the McPherson Park project is complete, the city plans to restore a small channel behind the TD Convention Center by installing a regenerative stormwater conveyance, which creates step-pools that filter water as it flows downstream, Wells said.
The city will then launch the master plan’s final project to restore a 500-foot reach of the creek that’s immediately upstream of Cleveland Park and East Washington Street.
That project aims to protect the stream “against erosion by regrading the stream banks to a stable angle and geometry and installing native plantings and using biodegradable materials to stabilize the banks,” according to city documents.
Wells said the city’s restoration efforts in the Richland Creek watershed would not only improve water quality but also create opportunities for educational outreach efforts.
The city, for instance, is partnering with local conservation groups Friends of the Reedy River, Trees Greenville, and Upstate Forever to develop events, workshops, permanent signage, and educational materials on topics like streambank restoration.
Upstate Forever is also partnering with the Greenville Zoo to organize training events for individuals who are interested in joining a voluntary water quality monitoring program at three locations throughout the Richland Creek watershed.
Erika Hollis, Clean Water program director at Upstate Forever, said the conservation nonprofit “appreciates the opportunity to provide input into the development of this stream restoration project, and we are looking forward to seeing water quality improvements in Richland Creek.”
The Richland Creek Water Quality Master Plan is expected to cost an estimated $10 million to fully implement, Wells said.
The city won’t be able to undertake every project listed immediately, but by including the proposals in the draft plan, it is eligible for grant funding from the state.
Wells said development of the city’s new Stormwater 2.0 program is still underway with watershed monitoring and modeling work. It should be complete by fall.
For more information, visit greenville.sc.gov.