SPANISH FORT, Alabama  – The method of engineering that is being considered as a solution to stormwater issues on upper Joe’s Branch is not faultless or time-tested, according to two people who have implemented “regenerative step-pool storm conveyance” (SPSC) as a watershed management technique in Maryland. Yet, in the struggle to control runoff in an area that has experienced rapid development on top of highly erodible soil, the public works department of Anne Arundel County believes SPSC is both cost effective and reliable.

SPSC involves converting free-flowing imperiled streams to filtering systems using alternating shallow pools, riffle weir grade controls and native vegetation to convey stormwater. The channel is only slightly altered and lined with sand and sawdust. The technique has been under development in areas where the severity of erosion prohibits more traditional methods.

On Joe’s Branch, a single culvert has gnawed a nearly 20-foot deep head-cut to within a couple of car-lengths of U.S. Highway 31. Beyond that, several hundred feet of stream has collapsed into a wide gully, which eventually narrows and spills out into a wetland area that is buried under more than a foot of nutrient stripped, sherbet orange sediment. Cypress, magnolia and other native canopy trees in the wetland have perished under the conditions. The stormwater eventually flows into D’Olive Creek, west of Lake Forest Dam.

The Mobile Bay National Estuary Program is considering using $770,000 in grants to construct a SPSC to stabilize the banks of the head-cut on Joe’s Branch. It isn’t known whether the grants will provide sufficient funding to rehabilitate the wetlands or other areas downstream, but it is expected to be a benchmark project as a part of the D’Olive Watershed Management Plan, which was adopted in 2010.

SPSC was pioneered in areas around Annapolis, Md., where coastal outfalls flowing to Chesapeake Bay have similar geology to the D’Olive Watershed. According to Rob Bowen, an engineer who has supervised watershed restoration projects as the public works director for Anne Arundel County, unchecked development over the past five decades increased erosion there “exponentially.” 2012 is expected to be the first year that his county has exceeded limits for Total Maximum Daily Load defined by section 303(d) of the Clean Water Act into the Chesapeake.

“We recognized years ago that we had to decrease nitrogen, phosphorous and sediment loads,” Bowen said. “An individual in our county was the innovator of [the SPSC], and we’ve worked with that individual and developed the technique to create general design guidelines.”

SPSCs are designed to contain a 100-year storm event, and in the 10-or-so years they have been under development in Anne Arundel County, they have been tested more than once. Watershed, Ecosystem and Restoration Services Administrator Ginger Ellis said there was an incident this year in which one area of the county was soaked by four inches of rain in 20 minutes.

“A few of the weirs were slightly undermined but I think they performed better than expected,” Ellis said. She added, “in traditional rain water events they have fared favorably.”

Bowen agreed, saying the 15-20 SPSCs the county has in place are “holding up very well,” and the process “has evolved” as the department has observed their performance.

“There have been some weir failures. And it’s been a journey with contractors, I can tell you that,” Bowen said. “But we’re learning and adapting and creating best practices.”

Ellis said she had not spoken with anyone from this area about the effectiveness of SPSCs in the Chesapeake Bay watershed but private developers, the state highway department and various academic institutions have begun to study and apply the concept.

In Anne Arundel County, at an average of $500 per linear foot, it is considered cost-effective. But Bowen also said permitting some of the wetland rehabilitation components at the federal level has been difficult and time consuming .

“There needs to be a cultural shift federally to recognize existing conditions,” Bowen said. He said in some cases federal regulation prevent adding non-native fill in areas that have lost most if not all resemblances to native wetland.

MBNEP Director Roberta Swann said last month the organization hoped to begin engineering the Joe’s Branch project by Spring and would aim for some time after the 2012 hurricane season to break ground on construction.