Flexamat Erosion Control Gallery

18 rolls of 15.5'x62' installed in two days (17,298 SF)

A transformation was needed for a former coal mine, county dump site and impaired state water body. A multimillion-dollar project was started in 2013 for a 178-acre fishing hole in the Midwest that was plagued by erosion from unregulated urban runoff and invasive species. To begin the transformation, the lake needed to be dredged and drained. The lake was constructed in 1965 out of a former coal mine and county dump. Since its construction, sediment from tributaries that feed the lake, along with sediment from shoreline erosion clouded the water and accumulated on the lakebed. The lake lost hundreds of thousands of cubic meters of potential volume due to shoreline erosion. In 1967, the lake's deepest point as 28 feet, according to the state DNR. Sediment reduced the maximum water depth to 21 feet by 2003, an equivalent of 317,035 cubic meters of water. Once the lake was made shallow by the increased sediment load from erosion, problems soon developed. The lake had poor water quality and suffered from large blue-green algae blooms, high bacteria concentrations and low oxygen levels. It was on the state's impaired waters list for years. No longer could people safely fish, swim or kayak in it's waters. Crews dredged 678,000 cubic feet of silt from the lake bottom - the equivalent of 20,545 dump trucks. They also removed more than 500 tires and a pickup truck that had been stolen in 1994 before being dumped into the lake. After the dredging, the lake was drained for lakebed restoration and shoreline stabilization The lakebed restoration was required due to site's past as the county's last operating coal mining site and it had large swaths of leftover waste. Crews neutralized the waste by adding lime to the surface, acting as a buffer for new soil on the lake bottom. The new lake bed helped improve algae problems created by river runoff that was high in nutrients, especially phosphorous, which clung to sediment. Over 20,000 feet of shoreline was rehabilitated, almost 4 miles! A vegetated armor was sought for the shoreline stabilization to improve water quality by reducing sediment loading into the lake. It was also important to increase recreational uses, such as fishing kayaking. The DNR planned to do controlled burns for vegetation management. For these reasons, the flame resistant Flexamat® Plus-FR was specified for the shoreline armor. 8' wide rolls were used for the vegetated shoreline armor. After nearly two decades of planning and six years of construction work, the lake was open again for swimming, kayaking and fishing. People enjoying these recreational activities are able to safely enter & exit the water, and fish over the vegetated shoreline armor. Now game fish such as bluegill, walleye, bass, catfish and crappie thrive in the waters that were once polluted. The now beautiful lake is surrounded by a 12-foot wide, 10-kilmeter recreation path. After the lake improvements, the park now attracts more than 1.5 million visitors a year!

This project was a tidal wetland enhancement that involved multiple agencies including US Fish and Wildlife, Valley Water, San Francisco Bay Bird Observatory, and Santa Clara County Parks. Along the edges of San Francisco Bay, tidal marshes provide refuge for sensitive and endangered species during high tides. These species include the American Avocet, Black-necked Stilt, California Clapper Rail, Salt Marsh Harvest Mouse, Snowy Plover, and the Western Sandpiper. The marshes also perform as a flood control zone for the South Bay watershed. The area situated between the lower marsh plains and higher elevation is the upland transition zone. Tidal salt marshes are vital for a healthy Bay. They are biologically productive ecosystems. The cyclic flow of tides continually injects fresh sea water containing food and oxygen, into the ecosystem while it flushes out waste products. Shallow marsh waters also produce vast amounts of macroscopic nourishment for wildlife and enrich the muddy soils through the breakdown of dead organisms. The engineers on this project needed an alternative to 24" rip rap for levee protection on the water side of the levee. Rip rap is not readily available in the Bay Area, but more importantly, US Fish and Wildlife goal was to restore the upland transition zone by planting native perennials such as California Buckwheat, Salt Grass, Cordgrass, and Pickleweed while also removing invasive plants. The design team specified Tied Concrete Block Mat, Flexamat® UV-T-10-NW. This concrete mat had a non-woven geotextile as underlayment to protect the shoreline from wave attack immediately upon installation. Each truckload of Flexamat® concrete mats saved 32 dump trucks from hauling rip rap through the Bay Area, a massive cost savings and reduction in the carbon footprint. Overall, the use of Flexamat® cut installation time by over 60% in comparison to 24" rock rip rap.

The Birmingham-Shuttlesworth International Airport (BHM) covers 2,170 acres. Within this space the airport has two asphalt runways: 150 feet x 12,007 feet and 150 feet x 7,099, terminals, concourses, taxiways, and a number of additional impervious surfaces. All of these impervious surfaces contribute to significant storm water runoff. The airport has Village Creek extending through the facility, running parallel with Taxiway A. Village Creek was once a pure stream that attracted settlers to the Birmingham area. As the industrial age advanced, Village Creek changed dramatically and became a prime example of how uncontrolled urban growth can change native landscapes. Village Creek's water flow increases rapidly during storm events due to the large urban watershed flowing into it. In 2016, the BHM Airport Authority moved forward with armoring a severely eroded section of Village Creek that was encroaching Taxiway A. The engineering firm tasked with designing this project specified Tied Concrete Block Slope Protection (Flexamat). Flexamat was specified as the erosion solution for a number of reasons. The flashy stream system required a robust armor with high performance in the high flow environment. Flexamat meets FAA height restrictions in the Obstacle Free Area (OFA) with it's low profile height of 2.25 inches. Additionally, Flexamat is maintainable and helps mitigate wildlife concerns associated with airports.

Denver International Airport sought a permanent solution to stabilize an area where significant erosion was occurring along a taxiway. The solution had to meet several challenges at the site, including being heavy enough to withstand jet blast while having a low profile to meet FAA standards. Flexamat Plus was selected and utilized because it provided a flexible, vegetated solution that would control erosion, improve stormwater quality and could be installed quickly to minimize disruption to the active taxiway.

This project was performed in conjunction with the US Army Corps of Engineers along with several state agencies. The armoring was required to be environmentally friendly, without any plastic components, and safe for wildlife, including endangered snakes inhabiting the site. Nearly 7 miles or 36,000 linear feet of the water side of levee was armored with Flexamat. Mats were unrolled from the the top of the levee to the toe, in continuous sections. The each mat had an overlapping extension for the next adjacent mat to be installed over, tying the entire system together. The contractor had 4, 4-person crews operating at the same time. Each crew installed 50,000 square feet per day, for a total of 200,000 square feet installed per workday. The vegetation seen in the video is all native growth, the site has not yet been seeded with the site specific seed mix. Flexamat will protect the levee during flood events, when it will be exposed to wave action and water flow.

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