County officials said they are conducting an environmental assessment of the property surrounding Nassau Coliseum in advance of an Aug. 1 vote on whether to build a new arena for the New York Islanders.

The environmental assessment, mandated by New York's State Environmental Quality Review Act, will examine the proposed $400 million development's possible impact on area traffic, air, water and noise quality, visual aesthetics and human health.

The assessment, known as a SEQRA review, is essentially a detailed checklist identifying potential concerns that could arise from the project, such as the addition of thousands more vehicles to the area, said Michael Sahn, an environmental attorney with the Uniondale law firm of Sahn Ward Coschignano & Baker.

"Traffic is one of those areas that could require further study because of the potential impact on roadways and traffic patterns in the area," Sahn said.

For example, the average attendance at Islanders home games during the 2010-2011 season was 10,650. A report commissioned by the county analyzing revenue projections for the arena anticipates attendance growing to 14,650 per game.

In addition, Sahn suggested that issues regarding groundwater, as well as sanitary and septic disposal, could require additional study.

The demolition of the existing Coliseum, which the county concedes contains asbestos, will also require careful disposal.

advertisement | advertise on newsday

The SEQRA review, begun several weeks ago by planners and engineers from the Department of Public Works, is expected to be completed after the Aug. 1 vote.

If the public approves the measure, the assessment and supporting documentation will be submitted to the County Legislature before it casts its final vote on whether to proceed with the project, said Deputy County Attorney Jane Houdek.

If the Legislature determines there are significant environmental concerns associated with the development, it could require the county to perform a draft environmental impact statement. This step involves a more thorough environmental review along with a plan to mitigate those concerns, Houdek said.

The Legislature would then determine if it wants the Nassau County Planning Commission to advise lawmakers in their analysis. But, Democrats argue, the administration of County Executive Edward Mangano should have kept the commission involved from the get-go to ensure that SEQRA was performed correctly.

"By improperly excluding the Nassau County Planning Commission, the Mangano administration may have made a serious blunder," Minority Leader Diane Yatauro (D-Glen Cove) said. "They should have used the commission's expertise, as we Democrats did with the Environmental Bond Acts in 2004 and 2006."