A river runs under it: the Star City’s stormwater woes
Stormwater drains @ Roanoke River
This second post in our Star City Series at SCH–”The Roanoke Valley’s Framework for the Future”–addresses a major concern across all neighborhoods in the City of Roanoke: stormwater drainage.
Most of Roanoke’s stormwater drainage problems, according to Roanoke’s City Engineer Phil Schirmer, stem from a pipe system that is too small or too overloaded with debris to adequately handle the volume of water in a heavy downpour.
Schirmer describes the standing water around Star City street corners, torrents gushing down alleys, and run-off pooling in cul-de-sacs as “nuisance flooding.” Not since 1985 has the City of Roanoke experienced a devastating flood:
Heavy rainfall from October 31 through November 6, 1985, caused record-breaking floods over a large region, including western and northern Virginia. Most of the rain fell on November 4 and 5 and was indirectly related to Hurricane Juan. New maximum peak discharges were recorded at 63 streamgaging stations during this flood. In the Roanoke area, 10 people died as a result of the flood, 22 in Virginia. The cost of this flood for the Roanoke-Salem area was estimated to be $440 million (USGS report).
As the mid-Atlantic region enters a hurricane season with a 25% chance of above-normal activity (NOAA), Roanokers may not need to be anxious about another 100 year flood like 1985; however, despite hard economic times, the Star City’s stormwater infrastructure could use some serious attention.
In June of 2008, the City of Roanoke prepared its Capital Improvement Program for the next several years. According to that report, Roanoke identified 168 stormwater related projects totaling over “$59 million in unfunded capital drainage projects which have been identified with preliminary design and cost estimates.”
The current budget for those projects is only $3.5 million through fiscal year 2012.
The problem with Roanoke’s stormwater system
Floods are ranked based on what is called a recurrence interval, explains Schirmer. “Think of it like this, a 100 year flood has a 1% chance of happening in any given year . . . a two year flood has a 50% chance of occurring. The 1985 flood was a 100 year flood.”
The accepted engineering standard for most stormwater discharge system designs is a 10 year flood standard. “That is the standard the Virginia Department of Transportation uses,” adds Schirmer.
Roanoke’s stormwater system is over 100 years old by some estimates and has the capacity to adequately manage somewhere between a 2 year and a 10 year flood recurrence interval. “It works” for the moment, says Schirmer, but improvements are sorely needed to address a “city-wide phenomenon” of nuisance flooding that disrupts traffic and creates health hazards. Moreover, Roanoke must face the possibility of another major storm event.
City Council to consider stormwater management fee
From their beginnings in the headwaters near Lafayette in Montgomery County, Virginia, the North and South Forks of the Roanoke River combine and flow as one waterway along the border of Floyd County before crossing the Roanoke Valley into Salem, Virginia, and eventually Roanoke.
The Roanoke River is fed in the heart of the Star City by two “runs” that combine beneath the City in aging sewer pipes and water courses. On a quiet morning at certain spots downtown, one can hear the dull gurgling of the confluence of Trout Run and Lick Run as it passes beneath the City.
Scientific American reported that “[t]he water in brooks, streams and creeks from Michigan to Puerto Rico carries a heavy load of pollutants, particularly nitrates from fertilizers. These nitrogen and oxygen molecules that crops need to grow eventually make their way into rivers, lakes and oceans, fertilizing blooms of algae that deplete oxygen” and extinguish aquatic life.
According to the Environmental Protection Agency, most of those pollutants come from stormwater runoff:
Every single day, especially when it rains, sewage pours into our waterways. Shocking but true: Overflows of pollution from our nation’s crumbling sewer systems dump 850 billion gallons of sewage annually. It is simply unacceptable to allow raw or poorly treated human waste, laden with potentially-deadly pathogens, to enter our rivers, streams and lakes (Act for Healthy Rivers).
The National Research Council has found that “about 29 million gallons of oil enter the oceans around North America each year as a result of human activities. Of that, the largest share, 15.6 million gallons, comes from rivers and runoff, largely from such things as street runoff, industrial waste, municipal wastewater and wastewater from refineries” (emphasis added).
Soon, Roanoke City Council will take up the question of whether to adopt the stormwater management fee proposed by City Administration. The fee will be proportional to the amount of run-off produced. To determine this amount, the City survey nearly all of Roanoke’s 45, 000 parcels of land via GIS and made its estimates based on an impervious surface area averaging 2000 square feet. Residential units will pay a flat fee from $3 to $8 per month. Commercial properties will pay a fee based on dividing the total area of impervious space by 2000 square feet. The commercial fee has yet to be decided.
The proposed stormwater management fee will be used to rebuild the City’s aging stormwater infrastructure as well as to implement best practices, notes Schirmer, that will help Roanoke contribute to the overall health of the Roanoke River downstream.
SCH VIDEO EXTRA
Cross-posted from Star City Harbinger.