7/2/1987 CONSERVATION COMMISSION Minutes

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MASHPEE ONSE AT1DN COMMISSION MEETING E JULY , 1987 COMMISSIONERS PRESENT: V. Louise Behr man, Gertrude Ferriday, Heathen Urquhart, hoary Marsters, Carol Jacobson, Elliot oenbury, Joseph Burns Also present: John Va konda, Conservation Officer. This meeting was called to order by Chairman, V. Louise Behrman at 7:30 p.m. 7:30 - New Sea�bury Corporation (lot 1346 Seanest Drive) - Continued from prior hearing of June 4, 1987 Nor. Jack Brown,, Engineer and her. James Pablick were in attendance representing New Seabury Corp. Mr, Brown stated h-e has revised the pians as requested by the board at the previous meeting. He stated he has placed gasoline traps at each of the catch basins and have formed a 10x10x12 inch PVCT which will be added to each catch basin. Mr. Brown stated he could not locate 15 inch perforated piping and and stated what we are proposing to use is reinforced concrete pipe, open joint. He stated bedding the pipe will be 3 11/2 cement gravel and will be using a filter cloth over the pipe to prevent the inflow of sand. [fir. Brown explained the gravel bedding underneath is to let the water flow freely through the gap and spread out for; a soaking. Mr. Brown stated they do intend to use 10 inch boulders on a 12 inch bed of select gravel and stated the idea is for the boulders to break the fail and the gravel would prevent washout of sand underneath. 1r. Brown stated another question raised at the prior meeting was the effect on the pond on high vo lure rainfall . He stated according to the National Rain Service, with a ton year rain fall , 4.85 inches in 24 hours will add the equivalent of 210,0 00 gallons of water to the water shed area. Mr. Brown commented that the area of the pond, which is 9 acres will re- sult in a total of 8.6 inch rise in pond water and explained in a 100 ,year storm 7 inches over a 24 hour period will add 12.5 inches to the pond. He stated the normal pond elevation i s at 5.5 feet, overf1o with 8.3 feet and stated we could increase that overflow to 10 feet by the addition of an 80 foot, 1 .7 foot high berm and connect the two 10 foot contour lines (shown to the Board) , 1r. Burns commented that if there is an overflow -it will be self- contained. Ir. Brown stated questions were also raised, at the prior meeting, as to Septic System #3 and its profile and breakout on it. 1r. Brown explained breakout calculations were made in accordance with Title v, which required. 15 feet, and stated we took the conservative approach and