Engineered Stormwater Treatment Devices at 4th …cwsec-sc.org/wp-content/uploads/2013/08/SitesNotVisited-final.pdf · Engineered Stormwater Treatment Devices at 4th Ave N, ... (Not

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Engineered Stormwater Treatment Devices at 4th Ave N, 6th Ave N, and 44th Ave N Oceanfront Street Ends of Each Ave, Myrtle Beach, SC 29577 (Not Visited)

PROJECT/SITE DESCRIPTION Stormwater Best Management Prac ces (BMPs) are o en im-plemented in a “treatment train” approach, meaning you capture and treat stormwater at various stages along its path-way from when it hits the ground to when it makes its way to a receiving body of water. If capturing and trea ng it up-stream is not feasible, there are op ons for end-of-the-line treatments that help remove pollutants before water is dis-charged. Myrtle Beach has installed several engineered de-vices at the street ends of 4th Ave N, 6th Ave N, and 44th Ave N. Without removing the covers it is difficult to see them, but you can visit the sites and see the diagrams below.

CrystalStreamTM Technologies (CST) Water Quality Device 44th Avenue North Street End, Myrtle Beach, SC 29577

CST units are essen ally pre-manufactured, engineered boxes with a pipe flowing in and a pipe flowing out. This flow is adjusted based on site-specific condi ons, and mul ple units can be used in tandem depending on the amount of water that is being treated. Other adjustments are made depending on engineering specs and needs for a given site. CST units can be used as stand-alone treatment, or they can be combined with other measures as part of a treatment train approach. Stormwater flows through a series of chambers, bas-kets, screens, and filters where a variety of stormwater pollutants are removed, including trash, vegeta ve debris, sediment, nitrogen, and phosphorous. FOR MORE INFORMATION www.crystalstream.com City of Myrtle Beach Department of Public Works, Streets & Drainage Division

View of CST Boxes at 44th Ave N street end.

First chamber of filter screens. Second chamber of filter screens.

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Engineered Stormwater Treatment Devices, Storm Flo® Screen (Not Visited) 4th Avenue and 6th Avenue North Street Ends, Myrtle Beach, SC 29577

Top Le : Storm Flo tube schema c Top Right: Open screen hatch for easy cleaning Bo om Le : Mul ple screen installa on in Myrtle Beach Bo om Right: Accumula on of debris inside tube. Images courtesy of Kevin McGillicuddy, Roscoe Moss Company.

Storm Flo® Screens are cylindrical tubes that capture li er and debris. As stormwater enters the device, debris is captured within the screen’s interior and water exits outward through the screen openings. These devices can be installed as in-line or end-of-pipe treatment prac ces. Maintenance involves opening the hatches on the top and removing the accumulated debris with a vacuum truck. FOR MORE INFORMATION www.roscoemoss.com City of Myrtle Beach Department of Public Works, Streets & Drainage Division

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Infiltra on System (Not Visited) Ocean Lakes Family Campground, 6001 S Kings Hwy, Myrtle Beach, SC 29575

PROJECT/SITE DESCRIPTION The purpose of this project was to get stormwater runoff off of the beach and control flooding at Ocean Lakes Family Campground. Following a study of beach ou alls in 2008, the first Phase began in 2009 north of the snack shack on Seaside Drive. Four ou all pipes were removed, with one remaining for overflow. Given the nature of the campground, and the loca on of the flooding issues immediately adjacent to the beach, an op-portunity presented itself to install an innova ve infiltra on sys-tem, the Atlan s® D-Raintank® Tank Modules. Pictured to the le , second from top, these are highly durable, high-load bearing structural modules with an open void structure that is ideal for subsurface infiltra on and reten on—2000 of these tanks were installed underneath Seaside Drive, where bacteria have become established and process pollutants that enter the system. Ini ally, water was directed into the system through drop inlets in the road that were equipped with filter baskets and junc on boxes to help intercept solids and floa ng debris. But grass clippings and other debris con nued to clogged the system filters and rain tanks, so flooding issues persisted and frequent cleaning was required. To address this issue, the site was retro-fi ed (see images below) with a strip of pervious pavers that s ll allows water to infiltrate into the rain tank systems, but keeps out other debris. FOR MORE INFORMATION Horry County Stormwater Department www.atlan swatermanagement.com

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Regional Stormwater Pond with Trash Screens (Not Visited) Behind Surfside Bowling and Billiard, 510 Hwy 17 North, Surfside Beach, SC 29575

PROJECT/SITE DESCRIPTION

The driving factors behind the development of a regional stormwater pond were to limit upstream flooding by increasing storage capacity and to filter trash and pollutants before the runoff enters the Town of Surfside Beach. Trash guards and a trash sock were ineffec ve. In winter 2008-2009, a weir and 3mm mesh size trash/debris screens were installed on the pond. Since this area receives drainage from a significant drainage basin, the pond was expanded in 2009 to address volume and flow capacity issues. The power line access in be-tween the two pond bays was lowered to add storage capacity while con nuing to provide needed access to the overhead lines. The peninsula floods during heavy rains but is dry at other mes. Debris is cleaned from the trash screens with a vacuum truck. Water quality sampling both before and a er installa on showed a significant decrease in pollutants exi ng the pond, par cularly bacteria which is a concern for the Town’s beaches.

FOR MORE INFORMATION Horry County Stormwater Department

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Compost Sock/Living Shoreline (Not Visited) Magnolia Lake, 14th Ave North, Surfside Beach, SC 29575

PROJECT/SITE DESCRIPTION Magnolia Lake in Surfside Beach has an access point on 14th Ave North that was used for access when the Town’s lakes were dredged in 2008. A er the dredging was complete, the lake edge was rapidly eroding without any vegeta on to hold it in place. Originally, a bulkhead was going to be constructed as a shoreline stabiliza on approach, but the Town decided instead to use a low impact approach and install compost socks. Com-post socks are essen ally long, flexible fabric or synthe c tubes that are filled with compost. The sock is made of a loose weave that allows plants to grow from within the tube if the compost has been mixed with seed, or it can be cut and plugs and plants installed directly into the tube where they take root in the com-post. The socks can be stacked on top of each other and an-chored into place, and can even be stacked to make a 90° ver -cal wall. This prac ce benefits stormwater by crea ng a vegetat-

ed buffer that filters stormwater as it flows through the buffer, trapping sediments and debris and removing nutrients. Wetland plants that establish themselves at the bo om of the living shoreline also help to take up nutrients from the water. Finally, compost has a high absorp on capability so more rainwater is captured and absorbed rather than running off the surface of the land as stormwater runoff.

In addi on, the Town used this site as a beau fica on project and installed a gazebo with golf cart parking, pervious pavers, and na ve vegeta on for landscaping.

FOR MORE INFORMATION www.ecoexpressllc.com

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Murrells Inlet Watershed-Based Plan

PROJECT/SITE DESCRIPTION Sponsored by Murrells Inlet 2020, local water resource management agencies including Horry and Georgetown Coun es, Coastal Carolina University, and Earthworks Group LLC are collabora ng to develop a watershed-based plan for Murrells Inlet. The main focus of the plan is to address fecal coliform impairments in the Shellfish Harves ng Areas of the watershed. The project facilitator, Waccamaw Regional Council of Governments, was awarded a Sec on 319 Grant from South Carolina Department of Health and Environmen-tal Control (SCDHEC) last year to lead this process. The final plan will review historical water quality trends in Murrells Inlet and set forth a list of recommended best management prac ces to meet the outlined water quality goals. An evalua on of poten al funding op ons and a meframe for implementa on will also be key components of this plan. Addi onally, the plan will aim to address future monitoring and public outreach needs to ensure success. It is expected that this plan will posi on the Murrells Inlet community to be eligible for future 319 grant implementa on projects and other worthwhile long-term water quality ini a ves spon-sored by state and federal agencies. The final plan is due for submission to SCDHEC in mid-November 2013.

FOR MORE INFORMATION Waccamaw Regional Council of Governments, Murrells Inlet 2020

Top: Murrells Inlet map with blue lines delinea ng sub watersheds and the green dots are SCDHEC sam-pling sta ons. Bo om Right: Murrells Inlet watershed plan stake-holder mee ng par cipants use watershed maps to iden fy poten al hot spots.

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Murrells Inlet Volunteer Water Quality Monitoring


Since June 2008, four teams of volunteers have been measuring water quality biweekly at eight sites in the Murrells Inlet watershed. As of 2006, the federal Clean Water Act requires the coun es and ci es in the Grand Strand to reduce polluted stormwater runoff by developing and implemen ng their own stormwater management plans. The US EPA recognizes volunteer monitoring as an important component of these local efforts. For this reason, the town of Surfside Beach, Georgetown and Horry coun es are jointly funding the Murrells Inlet volunteer monitoring program.

The science plan for the Murrells Inlet monitoring program has the following goals: (1) Iden fy hot spots on land that are significant sources of polluted runoff to the Inlet and (2) Provide baseline data that will docu-ment improvements in water quality as stormwater management ac vi es are implemented. The program is currently being conducted by 15 trained volunteers who are measuring dissolved oxygen, temperature, salin-ity, conduc vity, pH, nutrients, turbidity, and E. Coli. Most of these pollutants have water quality standards promulgated by SC DHEC.

In addi on to Murrells Inlet monitoring, the Consor um also supports volunteer water quality monitoring taking place on sites in Surfside Beach, on CCU’s campus, and on the Waccamaw River beginning in NC and con nuing to Winyah Bay. FOR MORE INFORMATION Visit Website at h p://bccmws.coastal.edu/volunteermonitoring/

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Waccamaw Neck Bikeway

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Bioreten on Basins & Pond Retrofits (Not Visited) Horry County Government & Jus ce Building, 1301 Second Ave, Conway, SC 29526


When the Horry County Administra on and Court-house Building on 2nd Avenue and Laurel Street in Conway was constructed, large, dry stormwater deten on ponds were built to control runoff from the parking lots and roo ops. These ponds, how-ever, were not designed to address water quality. Horry County Stormwater has converted one of the dry deten on ponds into a large-scale rain garden (1/3 acre) to improve the quality of storm-water before it reaches the Waccamaw River.

This bioreten on area appears like a landscaped area with na ve shrubs, flowers, and ornamental grasses. Beneath the surface, however, is a sys-tem to treat and transport runoff before it drains to the Waccamaw River, which suffers from low dissolved oxygen and higher bacterial levels dur-ing rain events. The rain garden consists of 6-inch perforated underdrains and 8 inches of coarse gravel, a 3-foot sand/soil mix, and a layer of mulch. Water enters the rain garden through curb-cuts and flumes from the parking lot. The over-flow pipe was set at 12 inches to limit ponding in the rain garden, so that it does not generate mos-quitoes and does not drown the plants. Standing water drains from the rain garden in less than 24 hours.

FOR MORE INFORMATION Horry County Stormwater Department

Top Le : Gravel and perforated underdrains were installed. Middle Le : Sand and compost were added and mixed. Bo om Le : Monitoring equipment added to cell. Bo om Right: Bioreten on cell a er rain event.

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Wetland Carpet Installa on and Floodplain Restora on

Crabtree Canal, Intersec on of Oak Street and Mill Pond Road, Conway, SC 29526


Crabtree Swamp drains about 60% of the City of Conway before discharging into the Waccamaw River at the City’s restored River-front Park. A major collabora ve effort involving federal, state, and local partners advised by university research scien sts and staff has set goals for protec ng and restoring water quality and habitat in this watershed. The watershed suffers from bank and channel erosion and water quality degrada on a ributed to urban stormwater flows into a system originally designed for agricultural runoff. Restora on projects have been implemented to stabilize the banks, provide more storage capacity for floodwaters, slow the velocity of water during high water events, and restore the flood-plain by reintroducing na ve floodplain species for water quality filtra on and wildlife habitat. Two one-half mile phases have been completed with funding and staff support from the City of Conway, Horry County, and the US Fish and Wildlife Service. Project design was informed by hydrodynamic modeling conducted by Clemson University.

Construc on was conducted in 2009 and 2012. A maintenance plan has been put in place by project partners. Site performance has been assessed by Coastal Carolina University and Clemson Uni-versity, including water level loggers, sediment accumula on pro-files, plant condi on inventories, and rainfall gages.

FOR MORE INFORMATION Horry County Stormwater, City of Conway Public Works, Coastal Carolina University’s Waccamaw Watershed Academy, Clemson University’s Ins tute of Coastal Ecology and Forest Science

Top: Crabtree Canal a er construc on, and a er the installa on of the wetland carpet and plants. Middle: The exis ng bank of the canal was 8-10 feet above water level, and a spoil berm alongside the canal added another 4-6 feet of eleva on. The berm was removed and the slope of the bank was graded to a slope that is more natural for a floodplain. Bo om: Grading of the shoreline and prepara on for plan ng and installa on of the wetland carpet.

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Rain Garden at Waccamaw Elementary School (Not Visited) 251 Claridy Road, Conway, SC 29526


The installa on of a rain garden on the campus of Waccamaw Elementary School was a collabora ve effort with the overall mission to create a demon-stra on and educa onal site u lizing a stormwater BMP. Students and teachers from Waccamaw Ele-mentary, Wal-Mart employees, Coastal Waccamaw Stormwater Educa on Consor um members, and Horry County Stormwater Department employees worked together to install a rain garden in an ex-is ng bed in the front parking lot. This site was cho-sen by stormwater staff with input from the princi-pal and several faculty members because it is highly visible to staff, students and visitors while addi on-ally serving to remove pollutants from the parking lot. The garden collects excess rain water from the adjacent parking lot, where chemical, physical and biological proper es of soils, plants and microbes process the pollutants that come from the parking lot runoff.

The Waccamaw Elementary project was one of nine rain garden installa ons that was made possible through a partnership between the CWSEC, local Wal-Mart stores, and area schools. Some funds went to the construc on of the rain gardens, but many materials were donated, and the majority of the funding obtained from Wal-Mart was put to-ward the purchase of educa onal resources needed

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Pervious Concrete at University Suites (Not Visited) 2241 Technology Blvd, Conway, SC 29526


University Suites is a residen al apartment complex for students, located near Horry Georgetown Technical College and Coastal Carolina University. Sec ons of pervious concrete were used on site to provide some addi onal infiltra on on site and help reduce the size of the stormwater ponds that were planned for this site.

Pervious concrete is ideal for parking lots and areas that have slow-moving or light traffic. It is laid over addi onal layers of gravel to add storage and infiltra-

on capacity to the site, and o en is equipped with an under drain system that directs the water into a nearby storm system.

At University Suites, pervious concrete is used for the parking stalls, whereas the center drives of the com-plex are tradi onal asphalt. This is an ideal applica on because drippings from parked automobiles are then able to be processed by microbes as they infiltrate the pervious concrete, and also, since the parking stalls receive much slower and lighter traffic than center driving lanes, this will increase the lifespan of the per-vious concrete.

FOR MORE INFORMATION City of Conway Public Works Department

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Gravel Paving at UPS Center (Not Visited) 200 George Bishop Parkway Myrtle Beach, SC 29579


Gravel paving is another permeable paving op on that is ideal for parking lots or areas with slow moving traffic. The support needed to sustain vehicle traffic comes from a highly durable plas c ring and grid structure with a geotex le fabric layer molded to the underside. The grid comes as a large roll that is rolled out on site and cut to fit the area as needed, and is then top-dressed with gravel, which fills in the voids and provides addi onal structure as well as permeability. Unlike a regular gravel parking lot, the grid holds the gravel in place preven ng it from migra ng around the site with re traffic.

Gravel pave is installed in one sec on of the UPS distribu on center parking lot and is able to withstand the daily movement of many large trucks. The benefit of using permeable paving applica ons such as gravel pave in industrial areas and parking lots is that hydrocarbons and other pollutants from “vehicle drippings” are processed by the microbial processes that occur in soils (bioremedia on) and are cleaned out by the me the infiltrated stormwater reaches the water table.

FOR MORE INFORMATION www.invisiblestructures.com

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Permeable Pavers, Living Shoreline, and Filterra Units (Not Visited) Marina Inn at Grande Dunes, 8121 Amalfi Place, Myrtle Beach, SC 29572


A variety of stormwater treatment and low impact develop-ment prac ces are implemented at this site. Permeable pavers are installed at several loca ons—in sec ons along the driveway, throughout the main entrance that leads up to the Marina Inn, and in the pool area. Filterra units are installed throughout the parking lot and along the drive-ways. These are bioreten on systems which use the proper-

es of plants and soils to filter stormwater runoff before it flows into a connec ng stormwater pipe system. A living shoreline was used along the Intracoastal Waterway as an alterna ve to rip rap, which does li le to support natural plant and animal communi es, or bulkheads which are not only expensive to build and maintain but provide no shore-line habitat. This prac ce s ll has structure underneath to provide the stabiliza on needed for a steep shoreline that supports development above and is subject to wake disturb-ance at the water’s edge. In addi on, the design allows plants to establish themselves, it supports other wildlife, and it promotes a more natural-looking shoreline.

FOR MORE INFORMATION Greg Duckworth, Environmental Concepts LLC James Coster, Carolina Paver & Wall Systems, LLC Russ Bri on, EcoExpress LLC

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Pervious Concrete, Concrete Grid Paver (Not Visited) 6th Ave South Beach Access Parking Lot & Sidewalk, North Myrtle Beach, SC 29582

PROJECT/SITE DESCRIPTION The City of North Myrtle Beach installed several pav-ing applica ons at the 6th Avenue South beach ac-cess. Pervious concrete parking stalls line both sides of the parking lot. The center of the parking lot is crowned to promote drainage of stormwater runoff onto the pervious side stalls. Block pavers are used for the sidewalks, but NOTE that these pavers are not permeable—the difference can be seen between this installa on and the pavers in the Our Lady Star of the Sea Catholic Church parking lot. An open-celled con-crete grid filled with sand and gravel is used as an apron to an adjacent parking garage and represents another op on for sa sfying structural paving needs while maintaining permeability of the site. FOR MORE INFORMATION City of North Myrtle Beach Department of Public Works Greg Duckworth, Environmental Concepts, LLC

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Pervious Paver Parking Lot, Our Lady Star of the Sea Catholic Church (Not Visited) 8th Avenue N., North Myrtle Beach, SC 29582


Pervious pavers were chosen to add a decora ve and func onal element to an upper parking area in the parking lot of the church. Special a en on was paid to the aesthe cs and layout of the pav-ers. The original plan called for a much smaller sec on of pavers, but was modified a er the church realized the stormwater and aesthe c benefits.

The difference between permeable and non-permeable pavers is apparent when comparing this site to pavers at other sites. Many pavers are ce-mented in, which add to the aesthe cs of a site with li le to no stormwater func onality. Open space between these interlocking pavers is filled with gravel, and is a visual cue of the permeability of this site.

FOR MORE INFORMATION Jim Coster, Carolina Paver & Wall Systems Greg Duckworth, Environmental Concepts

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Low Impact Neighborhood Design (Not Visited) Town of Briarcliffe Acres, SC 29572


The Town of Briarcliffe Acres represents several general low impact neighborhood design prac ces which have significant benefits for stormwater runoff quality and quan ty. Among them are grassy swales, lack of curb-and-gu er systems, preserva on of natural vegeta on, and mature trees. The Town also has an intact dune system and homes are set back from the beach. The benefits of these prac ces are that they allow a greater amount of stormwater to infiltrate into the ground and be intercepted and taken up by vegeta on.

Habitat Park—located on the corner of Pine Tree Lane and Cabana Road—exemplifies the use of na ve vege-ta on in community landscaping for the benefit of suppor ng na ve flora and fauna. Furthermore, the preserva on of natural vegeta on as a landscaping feature, or the use of na ve species reduces (and can even eliminate) the need for supplemental fer liza on, irriga on, and applica on of pes cides and herbi-cides. This is because na ve species are already well adapted to local soil condi ons, rainfall pa erns, and insects. The stormwater benefit is that because fewer chemicals are being added to landscaping, which means fewer chemicals and nutrients are being washed downstream by stormwater.

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