BUTLER TWP — Butler Area Sewer Authority will save more than $1 million through a timely bond refinancing that closes this week, officials said, and is laying the ground work for millions of dollars in sewer plant upgrades that will take place in 2016.

The refinancing of about $10 million of bonds issued by the authority in 2010 will save the organization between $80,000 and $85,000 each year through 2031.

The savings exceed the authority’s projections by about $150,000, said BASA executive director Thomas Rockovich.

The bonds, which totaled more than $20 million, were issued to finance work on wet weather diversion pump stations and other infrastructure the authority agreed to build as part of a 2006 consent order with the state Department of Environmental Protection.

In the agreement, which was fulfilled in 2013, the authority agreed to eliminate wet weather sewer overflows into various streams in the area. The work cost more than $40 million.

The refinancing doesn’t include some remaining 2010 bonds, which total about $1.5 million and weren’t refunded because including them would have lifted the refinancing amount over $10 million — a financial threshold which would have changed some rules governing the action.

In other financial news Tuesday authority officials said they are also preparing the issue at least $10 million in new bonds in 2016. The new money would finance infrastructure upgrades at the authority’s sewage treatment plant.

That bond issue is expected to be voted upon by board members at the authority’s December meeting.