Originally published Saturday, Aug. 26, 2006
Rocky Branch begins with millions of raindrops rolling off grassy yards, shingled rooftops and asphalt roads into hundreds of storm drains in the Millwood Avenue corridor.
It's an unromantic beginning - nothing like bubbling up from a pristine underground spring - but somehow fitting. For Rocky Branch is a troubled stream that routinely bursts out of its human-mangled boundaries and floods Five Points businesses, floats cars in USC parking lots and leaves behind debris for the length of its four-mile course.
Like a tempestuous child ignored except when it misbehaves, Rocky Branch on Aug. 20 threw the type of fit that gets real attention. Its timing was good.
Before 2.7 inches of rain in 71 minutes swamped businesses and about 60 cars along Rocky Branch , Columbia already was working on an engineering study to determine how to fix the flooding problems. The study's findings should be presented to City Council in September.
"It seems every couple of years, we get a couple of floods down there," Mayor Bob Coble said. "Then we go a few years without any."
Sunday's flood "will add emphasis" to the engineering study, Coble said.
Twice in the past five years, the River Alliance has applied for Environmental Protection Agency Watershed Initiative grants to study Rocky Branch . In grant documents, the city, Richland County and USC agreed to work together on a greenway project with flood-control side benefits. The EPA didn't approve the grant, but River Alliance executive director Mike Dawson pledged to try again.
"Every time Five Points floods, it's a good object lesson that it all goes downstream and we ought to fix it," Dawson said.
A couple of projects already in the works should help.
The city is spending nearly $1 million to install a new pipe running from the intersection ofSaluda Avenue and Blossom Street to Maxcy Gregg Park, said Steve Gantt, Columbia's assistant city manager for development. That bypasses one bottleneck for water moving out of Five Points, but does little to solve the systemwide problem.
Gantt expects a federal project to remove railroad crossings on Assembly Street - which still needs millions in funding - will be more helpful. Rocky Branch now squeezes into a twin concrete culvert under Assembly just before a rail crossing.
In removing the rail crossing, a larger passage could be added for the water at the last of the dangerous bottlenecks.
The modern Rocky Branch first rears its ugly head in Martin Luther King Park, rushing out of two metal culverts from a series of groundwater collection pipes that stretches past Millwood Avenue.
It first floods a few feet later.
Carolyn Revere, director of the park, said the section that runs through the park floods any time hard rain falls for a couple of hours. The park was designed to handle the floods. Water never reaches the gym, but often pools several feet deep around the statue at the other end of the park.
Sunday's flood left a row of sticks about 50 feet from the creek's center line. King Park was the only place along the four-mile route where the banks weren't covered with trash.
After about 100 yards in the open, Rocky Branch goes back underground through one culvert at Pavilion Avenue for its piped trip under Five Points.
A 1905 map of Columbia shows an untamed Rocky Branch taking a meandering route from near Senate and Laurens streets, down Harden and then a right turn past Blossom. The map was part of a city plan commissioned by the Civic League. It noted the "practically undeveloped" lowlands where Harden met Blossom and suggested it be converted into Rocky Branch Park as part of a greenway along the entire waterway.
That portion of the plan was ignored. A decade later, the city funneled Rocky Branch into a pipe under a new business area called Five Points. Rocky Branch has been getting its revenge ever since, with the worst flooding in the business district coming in the past few decades.
The problem isn't just that Five Points was built over a swamp. The 20th-century rush of commercial and suburban building throughout the 2.4-square-mile Rocky Branch drainage basin meant more rain runoff with each passing year.
"At a time in history when they were making their best determination about road design and culverts, the timing of the flow was different," said Paul Conrads, a hydrologist with the U.S. Geological Survey.
Water that used to seep through soil and slowly flow down Rocky Branch now rushes into the skinny waterway and overwhelms culverts not only at King Park but also at Pickens, Wheat, Sumter, Whaley , Assembly, Old Bluff and Olympia streets and through two railroad berms.
The Geological Survey in 1984 installed a gauge in Maxcy Gregg Park to measure the flow of Rocky Branch . On a normal day, the water might trickle up to the one-foot mark, but it rises quickly with heavy rains.
The water peaked at 9.06 feet in 1997 and routinely topped seven feet each year before the gauge stopped operating in 2004. Based on the debris line on the bank this week, Sunday's flood neared that 1997 storm, with a water flow of more than 1,000 cubic feet per second.
PROBLEMS AT USC
Through most of its one-mile journey through the USC campus, Rocky Branch is hemmed in by banks of concrete, riprap or wooden pilings installed as buildings and parking lots were built near the water in the 1960s and 1970s.
During Sunday's storm, the water ran through the parking lot behind the Naval ROTC building on Pickens Street, another parking lot behind the Blatt Physical Education Center and another behind the College of Engineering and Information Technology building on Catawba Street. (Don't blame the engineers for that one; USC bought the building from SCE&G.)
Nearly 50 motorists in the USC area needed help during Sunday's floods.
"We plan to completely evaluate the effect (Sunday's flood) had on campus and what, if anything, we need to do about it," said USC spokesman Russ McKinney.
The root of the USC flooding is the twin concrete culvert under the intersection of Whaley and Main streets. It can't handle the volume of water in a mildly heavy rain storm. A few hundred feet later, Rocky Branch goes through a culvert under the railroad bridge, then and additional 100 feet later under Assembly Street.
Pavement along Whaley and in the parking lot behind the 100 Assembly shopping center collapsed during Sunday's flood. Sand that flushed down the creek covered deep vegetation 40 feet from the main stream bed.
Coble and McKinney said fixing the Whaley and Main intersection should be a priority, either before or in tandem with the Assembly Street railroad work.
After crossing under Assembly, Rocky Branch runs through an undeveloped block covered in kudzu, takes a tunnel through an old railroad berm and dumps into Olympia Park. Sunday's flooding undermined a park picnic table near the water and left debris on top of other tables nearly 15 feet above normal water levels.
After the water flows under Olympia Avenue, it rolls behind the old mills and for about a mile through the Granby community along the boundary of the Vulcan quarry before plopping into the Congaree River, creating a large sandbar.
That sandbar used to be a popular swimming area for Granby residents, said neighborhood advocate Bob Guild. Taking a dip there, or anywhere in Rocky Branch , wouldn't be a good idea these days.
The rain that runs into Rocky Branch rolls off roofs covered with bird manure, roads fouled by oil and yards filled with pet wastes and fertilizer. It creates a toxic stew.
Rocky Branch isn't large enough to warrant monitoring by the S.C. Department of Health and Environmental Control. But USC student Allison Albert measured fecal coliform levels nearly three times what's considered safe as part of a senior honors thesis. Albert also found high levels of benzene, tolulene and methyl tert-butyl ether, all dangerous pollutants.
The S.C. Department of Natural Resources survey of fish in Rocky Branch in 1993 found about 20 percent of the redbreast had external tumors, a likely product of living in a heavily polluted waterway.
Other pollution concerns are more evident to the naked eye. Plastic bags, beer cans and shreds of paper lined banks from Maxcy Gregg Park through Olympia after Sunday's flood. Near the culvert in Maxcy Gregg, a sleeping bag, a pair of blue jeans and one white sock hung from branches . The top of an Apex DVD player stuck out of the mud.
As if to show the resilience of nature, a turtle plopped into the water near that Maxcy Gregg culvert when disturbed from his sun bath. Later, a great blue heron awkwardly flapped out of the culvert under Assembly Street.
Despite those signs of life, it's hard to imagine Rocky Branch will ever again be a pristine waterway. But if City Council acts on the engineering study, the River Alliance gets grant money, and the rail-moving project helps with flow, it might one day just be a benign waterway that runs through Columbia.
Reach Holleman at (803) 771-8366.