Eight core investigation holes will be drilled at the bush site of the proposed Northern Regional Prison on Birralee Road north of Westbury, starting from Monday.
Ten nearby land owners were informed of the plans on Tuesday, which are planned to enable soil and rock testing as part of geotechnical investigations.
The works involve the use of a drilling rig, water truck and other equipment and will last two weeks.
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The Brushy Rivulet land contains extensive dolerite rock.
The notice to land owners noted that "increased activity on the site" would be noticed, and pointed out that "no work will be undertaken within the 500-metre no disturbance zone that is in place for the duration of the wedge-tailed eagle breeding season".
Westbury Region Against the Prison secretary Linda Poulton said the group held concerns that the works would still interrupt the eagle breeding season.
"We are absolutely outraged that it's happening in the middle of breeding season when it could've been done well and truly before now," she said.
"We think its a provocative and divisive step to take, we will consider what action we'll take."
A Department of Justice spokesperson said it was using the advice of consultants to determine when the drilling could occur.
"An independent environmental consultant has been advising the department and coordinating with the geotechnical consultant regarding the degree of investigative work on site, including this drilling," the spokesperson said.
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"Core testing advises the composition of soil, clay and rock and is an important element of the due diligence work."
The prison footprint is proposed to cover 16 hectares, but last month the government could not say whether that would need to be increased to include a bushfire buffer zone. The government stated "investigations" were being undertaken to determine bushfire risk.
Work is also ongoing for "master planning and site development options", and the government could not say if the Tasmanian Planning Scheme required a 200-metre setback from neighbouring agricultural properties.