Rockland braces for increased rainfall in warmer climate

By Stephen Betts | Feb 06, 2020
Photo by: Stephen Betts Increased rainfall is expected to strain the city's drainage systems.

Communities are preparing for more severe rainstorms which will put a strain on roads, drainage systems, and wastewater plants.

The issue of expected increases in storm water runoff was one of the themes raised at the Jan. 22 meeting of the Rockland City Council during a discussion on making changes to residential zoning regulations in an effort to encourage the construction of more homes.

Donald Robishaw said if his neighborhood on Melrose Circle gets more than a half inch of rain, he could kayak between his house and the neighbor to the back because of poor drainage.

Former Rockland Community Development Director Rodney Lynch said the combination of increased rainfall from climate change and the proposed increases in residential development would put a strain on the city's storm water system.

Lynch said more catch basins would be needed, new and larger culverts, and larger underground lines to handle the additional runoff. He said the increased construction would also add to the carbon footprint.

In the wastewater treatment plant budget submitted last year, the director noted in his budget message that "it is strongly recommended that the City embark on establishing a storm water master plan to establish storm water relief for all City streets. With looming seawater rise, modification in storm water management may be required."

The city has been spending millions of dollars to separate storm water and sewer lines so that the wastewater plant is not needlessly treatment storm water. There are many more miles of lines, however, that are in need of repair and separation.

Rockland residents approved in November 2016, a $10.4 million bond referendum for upgrades to the sewer plant and the storm water collection system. Wastewater plant director Terry Pinto said in 2016 that the actual need was $19.8 million  but projects would be prioritized.

He estimated the storm water in the system costs sewer users $600,000 per year to have it treated at the plant. When there is excessive rainfall, the plant can be overloaded and the water is not treated as thoroughly as it should.

Contract planner Donna Larsen of Sebago Technics of South Portland said there are ways to manage storm water flowing off small lots if the city were to decrease minimum lot sizes and allow for additional residential development.

City Manager Tom Luttrell said the city is working with the engineering firm of Wright Pierce to come up with a citywide storm water management plan. He said one goal is to require house lots to handle the first inch of rain on their own property in order to reduce runoff.

A review of more than 100 years of rainfall records maintained by the local water company show that more water is falling from the skies.

Five monthly records for greatest amounts of rainfall have all been achieved in the past 15 years.

And the rainfall at Mirror Lake in West Rockport has exceeded the annual average every year but one since 2004.

The water company has compiled the precipitation figures since 1913.

The average annual rainfall or melted precipitation at Mirror Lake is 49 inches. The record was set in 2005 when 77.5 inches was recorded. The rainiest individual month also came that year when 17.5 inches fell in October.

The National Oceanic and Atmospheric Administration stated in 2019 that "In the Midwest and northeastern states, the frequency of heavy downpours has increased. In many regions, floods and water quality problems are likely to be worse because of climate change."

A warming atmosphere causes more evaporation, meaning more water is available for precipitation. For every 1°F increase in temperature, the atmosphere can hold around 4 percent more water vapor, which leads to heavier rain and increases the risk of flooding of rivers and streams.

In 2016, the city won an appeal with the Federal Emergency Management Agency to prevent the federal agency from classifying several sections of the waterfront in areas listed as at extreme risk of flooding from storms. Even without those changes, however, a significant portion of the city waterfront is in areas at risk of flooding during major storms, according to FEMA.

Comments (7)
Posted by: Debby Hansen | Feb 09, 2020 11:39

Advertise and promote  rain gardens,  any made would help. I believe nickels make dime etc.

https://www.motherearthliving.com/gardening/singing-in-the-runoff



Posted by: Deborah Clarisse Morrison | Feb 09, 2020 10:19

Let's hire the same engineers that put trees on Main street....right where you open car doors!



Posted by: Alison S McKellar | Feb 08, 2020 23:53

Really well done article and relevant far beyond Rockland.



Posted by: Jeff Grinnell | Feb 08, 2020 20:17

When Don gets in the Kayak to do that ...I want to be there with popcorn and life ring...:) :) :)....



Posted by: Kendall Merriam | Feb 06, 2020 10:52

Rodney Lynch has a great deal of expertise to offer city council. Yet, the council continues to ignore his knowledge and carry on with their non-planning practices which will negatively impact Rockland's residents.



Posted by: Stephen K Carroll | Feb 06, 2020 06:29

Anyone considering retaining ponds ?  Cheaper than storm water system and could make the city more appealing. Everyone loves duck ponds and fountains



Posted by: Richard McKusic, Sr. | Feb 06, 2020 04:21

"Climate change? What climate change? False news!"



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