WINDHAM – When Windham residents head to the polls Nov. 6 to decide local, state and federal elections, they’re going to have a lot of information stored in their heads. Not only are they deciding major issues and officeholders but, on the local level, the sewer referendum will no doubt add another set of data to be crunched and considered.

While opinions vary widely regarding the need for sewer and many questions remain pending further design, a number of facts and figures have arisen in the two years since town leaders enlisted the help of Portland-based engineering firm Woodard & Curran to design a wastewater system for North Windham and Windham Center.

As envisioned by the firm’s Barry Sheff, who has designed about a dozen large wastewater systems and a myriad of smaller systems in his 19-year career, the Windham sewer has a set of knowns and unknowns, along with another category of maybes and yet-to-be-determineds, when it comes to project details and timelines.

Schematic designs

The sewer network would consist of a collection system and a transport system. The collection system, located north of the route 302/202 rotary, would allow connections from neighboring homes and businesses. The transport system, a forced main running at high pressure south on Route 302 from the rotary to the Westbrook pump station at the corner of East Bridge Street, would not allow connections from neighboring homes and businesses since the sewerage is traveling at a flow rate that feeder pipes couldn’t overcome, Sheff said.

Sewerage flow through the system is produced mostly by gravity. The route from the Windham/Raymond line to Westbrook is mostly downhill, so there is less need for pump stations than it would be for a mostly uphill sewer system.

To encourage flow, Sheff has incorporated six pump stations. The stations are one-story tall, no bigger than 20 feet by 20 feet and built to mimic surrounding architecture. The pipes would run underground in the “wet well” but electrical equipment would reside aboveground.

The six stations would be located by Enterprise Drive, Whites Bridge Road, on Route 115 near Mill Pond Drive, near the North Windham fire station, at the school complex in Windham Center and by the rotary. No stations are located south of the rotary.

“Unless you absolutely need a pump station, we prefer to go by gravity, so you’re balancing upfront cost with operations and lifecycle costs,” Sheff said, explaining that he is budgeting about $300,000 annually for operations and maintenance. “It’s much less expensive to maintain a gravity system than it is to maintain a pumped system.”

The Town Council has worked with Sheff since 2010 to refine the scope of the sewer project and is now at the point of presenting the project to voters. So far, Sheff has created two sets of plans. The initial plan, at a cost of about $68 million, would have brought a wastewater collection system to most neighborhoods in North Windham and Windham Center. The initial cost – more than $100 million with debt service factored in – was met with alarm by the public, and the council, focusing on the need to remove pollutants leeching into the North Windham aquifer from faulty septic systems, scaled back the plan.

What is now referred to as a “spine” project would limit sewer to the commercial Route 302 corridor as well as some off-shoot segments along Route 115 to Collins Pond, Route 35 to the Basin Road area, and Route 202 west to the school complex. That scaled-back vision is estimated to cost $37.8 million ($62 million with debt) and heads to voters Nov. 6. The council has talked about the possibility that the sewer system could be expanded in the future to resemble the first design plans that would connect more homes, but leaders would need to seek a second public vote to do so.

According to Windham Town Manager Tony Plante, the $37.8 million spine project could be scaled back another $4.6 million to $33.2 million if upgrades to the Portland Water District’s sewage treatment facility in Westbrook aren’t needed, which Plante said last week is likely since the district recently informed Windham that the added sewage could likely be accommodated with no upgrades.

The numbers are far from set in stone. Debt payments, which are dependent on interest rates, could rise or fall, adjusting the overall costs significantly. Project overruns could also occur, or the water district could require upgrades. On the other hand, expenses could run less expensive than budgeted.

Another unknown cost driver, according to Sheff, is a built-in construction contingency of 15 percent. That contingency would go to pay for “change orders” if the project runs over budget during the construction phase. Unexpected costs incurred from having to blast through bedrock to install the sewer pipe and the presence of underground utilities could affect the project’s final cost. Sheff said he has budgeted $2 million for blasting alone. More or less blasting would affect the final figure.

During the second design phase, Sheff was able to be more detailed than the first. He designed the layout of the pipe route, sized pipes according to diameter (they range from 4 inches to 27 inches), placed access manholes and determined where the pump stations would need to be located. The planning took about six months and was completed earlier this year.

“Rather than being at the 50,000-foot level, now we’re down at about the 10,000-foot level,” Sheff said.

To reach that lower aerial perspective, Sheff met with Portland Water District officials as well as nine local site contractors, such as Grondin and Shaw Bros., to solicit their knowledge of the proposed sewer route. The water district, Sheff said, was especially helpful since water-pipe route maps showed the pipe located along much of the Route 302 corridor, except for a section below the rotary that is slightly less than a mile long, district spokeswoman Michelle Clements confirmed. The district’s water pipe, Sheff said, is located 5 feet deep, while the sewer pipe, which would run in the same general area as the water pipe, ranges in depth from 4 to 16 feet to accommodate undulating terrain, Sheff said.

More detailed cost estimates would be available in the next stage, should residents vote to go ahead with the project Nov. 6. That would include an even more thorough schematic design, at a design cost of $450,000-$600,000. The final design would include boring test holes to determine more precisely what is underground in the corridor. It would then allow the town to request bids on the project.

Paying for the project

According to Sheff, the payment options available with the Windham project are commonly used in similar sewer projects around Maine and the country.

When voters are confronted with bond questions on ballots, they are usually paid for with a combination of state and federal money. Not so with the Windham sewer project. Although the town has discussed teaming up with Raymond and Westbrook to cover some costs, there are few funding sources and grants available. Instead, the sewer would be paid for primarily by users and Windham taxpayers.

Sheff and town councilors came up with various methods to incorporate users and non-users, determining, in the end, that taxpayers would need to pay a major share – about two-thirds of the annual $2.3 million bond payment – since the costs far exceed the amount the projected 218 sewer users could afford. Users, which are those homes and businesses along the route, would pay betterment fees, ready-to-serve fees and/or user rates based on how much sewage they produce. The estimated payments would likely total about $600,000-$700,000 a year and cover a third of the cost. To increase the amount of users, Windham is requiring all businesses to hook into the system the first year. Residents can decide whether to opt in to use the sewer and avoid the ready-to-serve fees, but all landowners along the route must pay the one-time betterment fee, and those who opt out must pay the annual ready-to-serve fee. All connection fees are the responsibility of the user.

The three user-based fees are as follows:

• Betterment fees: Since access to a sewer is believed to increase, or “better,” the value of one’s property, the council has imposed a one-time betterment fee of $12.30 per frontage foot. Someone with a lot 200 feet wide would pay about $2,500, for example. Farmland would be exempt. The amount can be paid off over a five-year period.

• Ready-to-serve fee: Those residents not wanting to connect can remain on their septic systems but must pay $285 a year, the same amount the town charges non-users who choose not to hook into the sewer in South Windham. “That’s a fixed cost. In 2050, it would still be $285 unless the council changes it,” Sheff said.

• User fees: The bulk of the user fees come from annual sewer rate fees. Both residents and businesses will be charged according to how much sewerage they produce. Since sewer meters won’t be installed as a norm and some households will remain on wells, the council and Sheff have determined a set price per equivalent dwelling unit (EDU), which is estimated at 500 cubic feet of water usage per month. To make it simple for households, all residences using the sewer will see a sewer bill of $696 per year. Businesses, on the other hand, will pay depending on their specific water usage. The water district already has meters installed on most businesses along the route so the town would piggyback on water usage rates to determine sewer rates. Sheff said a business, which doesn’t flush as much water as it uses (for example, a coffee shop), could petition the town to install a sewer submeter. “The professional norm is that for most businesses most of the water goes down the drain. You don’t meter unless someone requests it,” Sheff said.

Taxes will pick up the remaining balance of the $2.3 million annual sewer-related debt payment. Taxpayers throughout town, whether they are paying sewer bills in South Windham or paying user fees for the proposed sewer, will also be paying for the sewer through their property taxes, as well.

The first year of sewer service, which would likely occur in 2016 when the project is scheduled for completion, taxpayers would see a maximum $1.01 increase per $1,000 of valuation on the property tax rate. That would generate $1.7 million assuming the town’s taxable property stays the same as it is today. Sheff points out that the tax rate impact could change depending on whether more businesses move to Windham as a result of the sewer. On the flip side, and unlikely if North Windham’s recent growth is any indication, businesses could move out of Windham as well, which would decrease the user revenue and require more residential tax revenue.

Sheff said Windham could be lucky and receive a no-interest bond similar to what the town of Chatham, Mass., recently received from the state of Massachusetts. Something like that would change everything for the Windham taxpayer.

If Windham didn’t have to pay a projected 3.5 percent interest, its annual payments would decrease from $2.3 million to $1.3 million. User fees would remain constant at about $600,000, meaning taxpayers’ contribution would would be cut by two-thirds.

“There are many unknowns,” Sheff said citing the possibility of a second stimulus package should President Barack Obama get re-elected as well as the massive greenhouse project slated for North Windham. “A lot of things could change the tax picture.”