The Town of Babylon is bonding for additional funds after costs for a new animal shelter increased by $4 million over original estimates.

When town officials began planning for the shelter more than three years ago, officials offered an estimate of $6 million for a new facility and said they hoped to have it open last year. The new total cost now exceeds $10 million with the earliest completion date of 2017. To pay for the shelter, the town has bonded for $9.85 million in increments since 2013, most recently for $2.5 million.

Officials said a new building is needed because the existing West Babylon shelter has become inefficient and is running out of space. Cats sit in cages in the lobby and food preparation, laundry and medical services are all conducted in one small room. Officials want to build a more modern facility on a town-owned parcel in North Amityville. The shelter houses an average of 100 cats and dogs.

The cost and time estimate increased because of the complex nature of the building, said shelter director Chris Elton.

“This is one of the most complicated types of buildings that can be built,” he said. “It is by far the most complicated building the town has ever undertaken.”

A large part of the price tag and complexity is the building’s planned heating, ventilation and air conditioning, or HVAC, system, which is estimated to cost nearly $1 million. While the current shelter has two and a half HVAC systems, Elton said, the new building will have 12 separate systems, designed for disease control and sound isolation.

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“The cats in the building won’t know there are dogs in the building,” Elton said. “They won’t smell them, they won’t hear them, which will greatly reduce the stress on the cats and greatly increase their adoptability.”

Additionally, dehumidification and cleaning systems will be built into the HVAC system. “Your initial costs are high,” Elton said. “But the time saved and the effectiveness of the cleaning down the line will gain those costs back.”

Another large expense is the purchase of a generator, which Elton said officials realized they needed during Superstorm Sandy.

The new facility will be about 13,000 square feet, an increase of 4,000 square feet. “We scratched off every single square inch that we could,” Elton said. “We started with floor plan A and we’re now up to floor plan R.”

In addition to separate rooms for food preparation and other activities, the shelter will have a room for training and education where workers can properly evaluate a dog’s behavior without it being affected by dogs or cats.

“Right now we don’t have a square foot in this building that we can do that,” he said.

Including the recent animal shelter money, so far this year the town has bonded for nearly $20 million for various projects. The highest amounts include $4.5 million for road reconstruction; $1.8 million for dock upgrades at Gilgo Beach; $1.5 million for work on the town hall annex; $1.2 million for the acquisition of construction and maintenance equipment; and $1 million for the acquisition and construction of a recycling building.