A $915,000 shortfall created when Town Meeting voters agreed to cap sewer project fees in the Oakdale and Cromesett neighborhoods could rise by as much as $270,000.

Water Pollution Control Facility Director Guy Campinha asked Selectmen on Thursday to approve two sewer abatements for lots that were discovered to be unbuildable and thus inappropriately charged for the expansion of town sewer to those neighborhoods. Campinha's request led to a more general discussion about how many abatements the town could have to grant.

Here's the background on the situation.

When the town decides to expand the sewer system to a neighborhood, each homeowner is charged a "betterment fee" to pay for the cost of the project. Betterment fees are traditionally set by dividing the total cost of a project by the total number of properties in the neighborhoods in the contract.

But the betterment fee for the Oakdale and Cromesett neighborhoods — which are both part of one sewer expansion project — was capped at $18,000 at Town Meeting last fall, after residents argued that the process for assessing the betterment was flawed.

If voters hadn't OK'd the cap, the fee per property would be $21,339.

The cap created a $915,000 shortfall, which is apparently growing larger as the town finds that betterment fees were inappropriately assessed to unbuildable lots that by definition, will not be using town sewer.

"You go back a few years and things weren't done like they should have been," Campinha told the Selectmen.

According to Campinha, 10 abatements are in the pipeline, which would add $180,000 to the shortfall, and another five properties are in question. If those five properties are granted abatements, it would tack on a total of $270,000 to the shortfall.

Campinha told the board that 15 abatements was the worst case scenario.