Discussions centered on road safety, structural integrity, and water protection Wednesday as the Mason Planning Board spent two hours deliberating a proposed sand and gravel excavation operation on Brookline Road.
Following the discussion, the board voted unanimously to continue the public hearing to Sept. 16.
The proposal by Onyx Corp. calls for a phased gravel excavation business. Under the site plan, excavation would proceed in sections no larger than 3 acres at a time, with each area reclaimed before moving to the next.
Road impacts and increased truck traffic remained major points of concern. Planning Board Chair Dane Rota asked Mason Road Agent Dave Morrison about local road maintenance costs to frame potential impacts.
Morrison noted that the town’s annual repair budget is approximately $130,000, most of which will be used this year to reclaim and pave six-tenths of a mile on Greenville Road. Upgrading the more than 4 miles of road along the proposed trucking route would cost roughly $2 million, Morrison estimated.
The board reviewed a road impact study submitted by the neighboring town of Brookline, an abutter to the project. Members discussed potential mitigations, such as lowering speed limits or reducing vehicle weight limits. However, the board noted that weight and speed limits fall under the jurisdiction of the Select Board or the state, though the Planning Board can offer recommendations.
Onyx Corp. has agreed to several road-related accommodations, including reconfiguring a corner of the property to improve sightlines at the Brookline Road intersection and providing up to $2,000 for signage or brush clearing. Although Mason does not assess developer impact fees, Onyx representatives indicated a willingness to discuss road maintenance reserves with the Select Board.
The board also evaluated an independent engineering review commissioned by the town, specifically addressing Onyx’s request to waive a local regulation prohibiting excavation below the seasonal high-water table. Onyx requested the waiver to construct permanent ponds for dust-control water supplies. Studies submitted with the application indicate the planned water extraction would not deplete the water table.
Select Board ex-officio member Antje Skorupan questioned whether permanent ponds were necessary, while board member Chris Jones suggested drilling a well as an alternative.
Addressing concerns that surface runoff could contaminate the ponds and surrounding groundwater, project engineer Jeffrey Brem proposed constructing containment berms around the basins. Brem said the feature would require revising the stormwater management plan but was feasible. Jones indicated that berms would resolve his environmental concerns regarding the ponds.
The board will resume the hearing on the excavation plan at an off-schedule meeting set for 7 p.m. Sept. 16 at Mason Elementary School.