Stormwater Forum and Discussion - Aug 14th, 2018

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Held in the Lyons hearing room at town hall. Town engineer Wayne Chouinard let the forum.

Congress passed the clean water act in the 1970's but regulations on stormwater pollution were not passed in 2003. Now we have something called an MS4 permit, which stands for Municipal Separate Storm Sewer System. Basically, cities have to take responsibility for pollutants carried by stormwater runoff, including sanitary sewer overflows (SSOs).

Arlington's first sewers were installed in 1896. Now, 120 years later, some of those pipes are cracked and leaking effluent. This leaches into the ground, and into cracked stormwater drains.

IDDE stands for Illicit Discharge Detection and Elimination. It's a program that towns will have to adopt. It involves finding and fixing sources of contamination (which can involve tricky detective work), along with enforcement measures.

Sedimentation runoff from construction is also a concern. Wayne would like to incorporate a sedimentation control step into the building permit and inspection process. For example, our building cards require framing and insulation inspections before walls are covered; they also require trench inspections before footings are poured. They should also require sedimentation controls before excavation begins.

The town's made an effort to map out our stormwater infrastructure. The mapping effort identified 20% more catch basins than were on the town inventory.

The town will need to produce an annual report, to demonstrate that storm water system maintenance is taking place. (I think this is part of IDDE, but I'm not sure.)

What would be the town's metrics for success? Metrics could include reduced bacterial contamination and improved EPA scores.

Mill Brook is the worst water body in the town. The EPA gives it a grade of D-.

The town is looking at large projects that were permitted in the past, specifically those that involved a lot of paving or installation of catch basins. The town may add maintenance requirements to such projects. For example, regular sweeping of parking lots to prevent runoff, and periodic cleaning of catch basins.

One attendee talks about stormwater runoff from a construction project on the 300 block of Summer street. This leads to a discussion about stormwater runoff from roads. Wayne informs us that public roads have traditionally been designed designed to handle runoff from a 25-year storm. Those storms are happening much more frequently now, meaning that storm drains are overtaxed.

Private ways are another issue. Many are in a state of disrepair, and lack catch basins. Often, runoff from private ways makes its way onto public ways.

The town has 120 miles of roadways. Private ways account for 20 of these 120 miles.

The town has to reduce the amount of phosphorus in stormwater runoff, roughly by 50%. Where does the phosphorous come from? It's mostly organic waste: poop, grass clippings that were blown into the street, cars washed in the driveway, and so forth.

The town has a set of stormwater bylaws, which require stormwater mitigation if a house has more than 350 square feet of impervious paving. I noted that our parking requirements don't help here: our ZBL requires parking behind the front foundation wall, and the front foundation wall has to be set back 20--25 feet (depending on the zoning district). Given a 10 foot wide driveway, that's 200--250 square feet of paving right there.

The town now requires designers (architects?) to provide a stamped certification that driveways were built according to submitted plans.

An attendee shows a set of pictures showing stormwater runoff from the Sons of Italy on Prentis street. Over time, the runoff has deposited a lot of sediment, and he's concerned about what might be in the sediment.

The meeting ends with a go-round, where attendees state what their priorities are:

  • Green infrastructure (land treatment that absorbs water, and reduces runoff).
  • A stormwater enterprise fund (similar to our water and sewer enterprise fund)
  • Coordination of permitting bodies
  • A review of the Environmental Design Review process, and how it addresses stormwater runoff.
  • Incentives to install catch basins on private ways.
  • Conversion of private ways to public ways
  • Sampling of storm water, for contaminants.