when it rains it pours—stormwater flooding
Like every community in western Pennsylvania, Mt. Lebanon needs to come to terms with stormwater management.
What are Pittsburgh’s four seasons? Snow, snow-rain, rain and rain-snow.
We’ve all heard the jokes. We get it. It rains and snows a lot here.
Because of its climate and topography, Pennsylvania is one of the most flood-prone states in the country. Despite Seattle’s international reputation as a rain magnet, it often runs neck and neck with Pittsburgh in annual precipitation and number of rainy days per year.
All that water has to find somewhere to go. Back into the ground is the ideal place, but more and more of the ground has an added layer of concrete or asphalt. About 14 percent of Mt. Lebanon’s 3,891 acres is covered by streets, driveways, patios, parking lots, swimming pools and other structures that do not allow rain or snowmelt to infiltrate at the same rate as natural surfaces such as grass or dirt. The excess water runs off into an already overburdened storm water overflow system, often causing flooding and carrying litter and other forms of pollution into streams and rivers.
In 2011, the Mt. Lebanon Commission voted to establish a storm water fund by collecting a small monthly fee from property owners based on their amount of “impervious property”—property covered with asphalt or other materials that will not absorb rainwater.
Single-family households are assessed a monthly fee of $8. The fee is collected three times a year in $32 installments, with a 2 percent discount for paying the entire year’s worth in a lump sum. The fee provides funding for operations and maintenance of the storm water infrastructure, administration of Mt. Lebanon’s federally mandated municipal permit requirements, engineering and technical review staff, and design and construction of capital improvements. It also will pay for water quality monitoring and management systems required by the federal government under the National Pollution Discharge Elimination System (NPDES), an unfunded federal mandate.
Under NPDES, Mt. Lebanon is responsible for testing outfalls—all of the places where the storm water flows into creeks—for contaminants. If the testing reveals any illicit discharges, it is Mt. Lebanon’s responsibility to track down and stop the discharge. Mt. Lebanon uses money from the storm water utility to pay for the cost of testing, and to comply with other federal requirements. To date, Mt. Lebanon has completed testing on more than 85 percent of the municipality’s outfalls.
Since implementing the utility fund, Mt. Lebanon has spent more than $2.41 million on storm sewer upgrades, and another $1.72 million on reconstruction projects, mostly of curbs, which are instrumental in directing the flow of storm water. Curbs contain and direct storm water flowing from driveways and roof drains into inlets along the street and storm water pipes that flow into streams.
Each year Municipal Engineer Dan Deiseroth of Gateway Engineering works with Mt. Lebanon’s public works department and inspection office to compile a list of recommended projects, which they submit to the municipal commission for final approval.
This year’s sewer work includes the following areas:
Woodhaven and Forest Glen drives—To mitigate flooding, the project will include the installation of new inlets along Woodhaven and a new storm sewer on Forest Glen.
Altoona Place and Mapleton Avenue—New storm and sanitary sewer lines are being installed, starting on Rae (near Jayson) and extending down Altoona to approximately Cochran Road. This project will help mitigate flooding on Mapleton.
Lindendale Drive—A stream stabilization project will consist of installing a pre-cast concrete wall near the intersection of Lindendale Drive and Cedar Boulevard to shore up the eroded hillside and roadway.
Arden Lane—An inlet will be installed to stop a large water channel that flows to a home there, causing flooding.
Dillon, Jefferson, Twin Hills drives and Osage Road—New storm sewers were installed to remedy icing issues.
Mt. Lebanon repairs and removes debris from more than 75 miles of storm sewers and more than 5,000 catch basins throughout the municipality. Because most of Mt. Lebanon’s housing stock is 80 or 90 years old, Deiseroth says incorporating green infrastructure—rain gardens, green roofs and other building initiatives that promote stormwater drainage—is difficult here.
“We’re looking for any opportunities to incorporate (green infrastructure). We mostly try to add additional capacity, to the system” he says.
That means replacing old, cracked storm water pipes with new, larger ones, so the system can move more water faster. Catch basins double the size of the ones installed in the 1920s and ‘30s, are being placed closer together to further collect the drainage after a storm.
“Catch basins used to be spaced about 1,000 feet apart,” says Deiseroth. “Now we’re locating them 400 feet apart. We’re trying to incorporate 2015 design standards into a 1920s community.”
A recent success story happened on Morrison Drive, where after a storm, water would flow through several properties and accumulate in the yard of the house with the lowest elevation. Mt. Lebanon installed a new catch basin on a municipal sewer on the side of the house and eliminated the accumulation of water.
“A relatively inexpensive fix ($5,000) solved the problem, with minor disruption to the property,” says Deiseroth.
New construction that disturbs one acre or more of land requires an NPDES permit, and a storm water management plan. Mt. Lebanon spent more than $100,000 in stormwater management improvements for the Middle and Wildcat field project.
In addition to the things Mt. Lebanon is doing to upgrade the sewers, there are some small things homeowners can do to counteract the growing amount of impervious surface that water cannot drain into.
INSTALL A RAIN BARREL and receive a one-time $50 credit on your stormwater utility bill. Kits are available at Rollier’s and through the Nine Mile Run Watershed Association.
USE A COMMERCIAL CARWASH instead of washing your car in your driveway. This can use less water and will keep the rinse water, which can contain residue from exhaust fumes, gasoline, metals from car rust and other pollutants, from finding its way into a catch basin. Commercial car washes send the wastewater directly to a treatment system. Car wash fundraisers, usually held in a parking lot, can be a big contributor to washing pollutants into the system.
DRAIN YOUR SWIMMING POOL PROPERLY Turn off the pool chlorination system at least three days before draining your pool at the end of the season. Drain the water onto a landscaped area of your property, away from storm drains. Don’t drain it if there has been a recent application of pesticides or herbicides on your lawn. And when you’re draining, be considerate of your neighbors and keep all of the water on your property.
Despite all of the work that’s been done on sewers in the Pittsburgh area and all the work to come, the sad truth is that there are some properties that, because of topography, construction and location, always will be prone to flooding—and this is something prospective homebuyers should ask about and consider. Says Deiseroth: “If you live at the bottom of an 80-acre watershed, you really don’t have too many options.”