HomeMy WebLinkAbout1987_01_06 Coastal Zone Management Commission Minutes Town of Mamaroneck Village of La,Y1040
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MINUTES
A special meeting of the Coastal Zone Management Commission (CZMC) was held
on Tuesday, January 6, 1987, at the Town Center, 740 West Boston Post Road.
The meeting commenced at 8:15 P.M.
Members present: Shirley Tolley, acting Chairman
Elinor Fredston
Wallace Irwin, Jr.
Mary Anne Johnson
Arthur Katz
Lawrence Lowy
C. Alan Mason
Phyllis Wittner
0 Others present: Paul Kean, liaison, Village Board
Elaine Price, Joint Town-Village Planning Commission
Victor D'Ortona, Midland Construction, Inc.
Joseph F. Risoli, P.C. , Joseph F. Risoli, Co. ,
Consulting Engineers
Richard Zavesky, Joseph F. Risoli, Co. , Consulting
Engineers
Introduction
Mrs. Tolley opened the meeting, stating that the sole purpose of this
meeting was to consider the proposal of the Larchmont Professional Center by
Midland Construction, Inc. She turned the floor over to Mr. Risoli,
I principal of the consulting engineer company that created a stormwater
drainage and treatment plan for the proposed development.
Presentation of Drainage Treatment System
Mr. Risoli introduced his associate, Richard Zavesky, who gave a
simplified, but thorough description of the proposed system. Fundamentally,
surface water enters the grates into one of three catch basins which consists
I of a four foot sump to collect sediment and a bell trap (cast iron skirt) to
screen out flotage. The effluent would then pass through a pipe to a
distributor tank (which also serves as a manhole) with a baffle trap,
designed to hold back additional supernatant matter. Next, the water
percolates through layers of varying substrates in a filter tank. In this
Address Correspondence to CZM Commission, 740 West Boston Post Road, Mamaroneck, NY 10543 (Phone 914-381-6133)
CZMC minutes - 1/6/87
"rapid sand filter," much of any remaining sediment will be filtered out.
Percolation holes in the base of the filter tanks will allow some water to
seep into the ground. The rest will converge in another distributor tank to
be let out by a single larger pipe directly to East Creek. Mr. Zavesky noted
that all the parts and equipment for such a system are readily available in
the open market.
Questions and Answers
Maintenance - The engineers addressed several inquiries regarding future
maintenance of the system. They explained that the catch basins should be
cleaned out periodically (estimated twice a year) with any of several
machines as were listed in the appendix of their submittal. Filter tanks
should be cleaned out by vacuum process and refilled when necessary. The
time for refilling can be determined by observing if the water in the catch
basin has remained at the four foot mark for more than four hours. Although
the retention of fine materials in the filter can eventually block the
system, Mr. Zavesky remarked that proper maintenance of the catch basins
would prolong the life of the filter. The only other possibility that he
could think of off-hand that could cause a blockage to the filter system
would be growth of fungi or anaerobic organisms; however, the provision for a
vent in the filter tanks should hinder such growth. Pesticides could also be
employed, but it would require a State permit. The responsibility for
maintaining the system, Mr. D'Ortona added, would be included in the
condominium contract's operating procedures and the costs would be
incorporated into the maintenance fees.
Capacity - The system was designed to handle as much as a ten-year
frequency storm for the entire property (including the International House of
Pancakes area). There is also a provision for overflow, whereby a weir in
the upper portion of the filter tanks will allow excessive water to bypass
filtration. Mr. Katz entertained the alternative of closing off the weir
inside the filter tanks to protect against untreated overflow and to
encourage proper maintenance. The engineers felt that this would be an
unfeasible alternative, because flooding of the parking lot could occur.
Despite the bypass, the engineers expressed that the stormwater would be
sufficiently handled since the dirtiest water occurs with the "first flush"
which, therefore, could be treated before peak flow could overwhelm the
system. In answer to a concern over the possibility of high tides backing up
the system, Mr. Zavesky replied that the system would continue to function
with the creek as high as the level of the school parking lot.
Oil Pollution Concerns - Several CZMC members questioned the treatment
systems ability to handle oil discharges. Ninety-nine parking spaces for the
office condominiums and thirty for the Pancake House have been planned for
the property. Mr. Zavesky believes that their proposed system could
adequately take care of oil deposits from these automobiles, because,
according to recent studies, 60-96% of oil molecules adhere to granules
which, therefore, can be caught in the catch basin or filter tank. Gas-fired
furnaces will be used to heat the building instead of oil, Mr. D'Ortona
added. Some members felt that the conventional oil separation traps might
serve as a better precaution against oil contamination.
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CZMC minutes - 1/6/87
Other Comments
Although a community in Autumn Ridge, Connecticut, has approved a similar
stormwater drainage treatment system, it has not yet been installed and
tried. A discussion of the potential impact due to increased rate of runoff
arose. The engineers strongly discouraged the installation of a detention
basin, however, because the site, being close to the end of discharge, would
flood with the added inflow from the rest of the watershed. It was noted
that erosion control measures during construction have been provided for in
the plans and that there will be a retaining wall, terraced with plants on
the slope behind the proposed building. The development's sewer line will be
hooked up to the sewer servicing the Pancake House if it is adequate,
following inspection by Tom Leddy, Highway Superintendent, and Bill Paonessa,
Building Inspector. Otherwise, it will be connected to the county sewer
along the Boston Post Road.
Conclusion
The engineering consultants and Midland Construction, Inc. , were
commended on their efforts to provide protection for the environment. Mr.
Irwin cited Local Waterfront Revitalization Program policies #30, ##44, #14,
and /114A as relevant policies. CZMC concurred that the application for the
office conduminiums should be recommended to the Planning Board for approval,
but with the following suggestions included: (1) the addition of inspection/
sampling ports, one in the filter tank and the other in the discharge pipe;
(2) the retention of the authority to require the retrofitting of an oil
separation trap should the oil discharge exceed a specified standard; and (3)
a stipulation for owner maintenance obligation. Since the Local Consistency
Law allows the submission of additional comments, Mrs. Johnson will submit a
letter, following consultation with Professor William Niering of Connecticut
College, to inform the Planning Board of the adverse effects that may result
from excessive freshwater runoff into the nearby Hommocks salt marsh. Ms.
Price will try to contact DEC to get their advice regarding oil runoff from
parking lots and will report it to Mrs. Tolley.
The meeting was adjourned.
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