MARBLEHEAD – After seven months of hearings the Conservation Commission has approved the reconstruction and enlargement of a seawall at 15 Spray Ave., and, after one hearing, green-lighted a town demolition and contamination clean-up project on Stony Brook Road.Groom Construction, which is renovating the ocean-side house at 15 Spray Ave., will be making the house?s seawall higher to fend off the waves. Attorney Paul Lynch represented Groom, but neighbors feared that the new seawall would divert the waves to their property and hired Attorney Carl King to represent them.?We would have preferred no change at all at the Bass Rocks end,” King said Friday. “The final plans do minimize any increased risk of storm damage for the immediate neighbors.”Commission Chairman Walter Haug said Friday that two independent consultants provided evidence that the wall design would not affect neighboring properties. A revised seawall design did not require backfilling and Peter Ogren and the project consultants said workmen would fill and seal gaps at the base of the wall to add support.With that in mind, Haug said commissioners issued an order of conditions for the work.The Stony Brook Road clean-up affects properties that were contaminated by run-off from the former town landfill. The town has arranged to purchase properties at 55, 56 and 57 Stony Brook Road and is taking an eight-month easement on property at 52 Stony Brook Road by eminent domain.Since a brook which locals refer to as Babbling Brook runs through the contaminated area the Conservation Commission had to sign off on the project and, after reviewing the town?s plans, they did, Haug said.