Test laboratory Smithers Viscient LLC is planning a two-phase expansion of its Wareham facility that the company says would result in the creation of more than 100 permanent new jobs.

Located at 790 Main St., just north of Decas Elementary School, Smithers currently employs 143 people, many of them scientists, to do contract research for the pharmaceutical, chemical and consumer products industries.

Having outgrown its current space, Smithers is seeking permission to build two additions – one now, one at an undetermined future date. At full expansion, officials say the company will employ 250 people.

Because the structure that Smithers has occupied for 40 years is a “pre-existing, non-conforming” use in a non-commercial/industrial zone and borders a wetland, the company needs special permits from the Zoning Board of Appeals and the Conservation Commission before plans can proceed.

On Monday night, Smithers representatives spoke to the Planning Board, seeking – and receiving -- at least conceptual approval of their plans in advance of an April 9 ZBA hearing.

As explained on Monday, plans are to construct a two-story, 7,000 square-foot addition to the current facility this summer. A larger, 20,000-square-foot second addition would follow as further expansion of the business merits.

Questions and discussion focused on parking, hours of operation, the impact on neighbors and emissions from Smithers’ many ventilation stacks.

Company representatives Attorney Lawrence Winokur, Facilities Manager Joseph Sousa and accompanying landscape and building architects assured the board that trees would adequately buffer the expanded building from the few nearby homes on Fearing Hill Road, that expansion would not significantly increase traffic in the area and that the ventilation stacks emit nothing hazardous.

Smithers’ next stop in the permitting process will be an April 2 visit to the Conservation Commission, followed by the April 5 ZBA hearing.