Laserfiche WebLink
TOWN OF MASHPEE PLANNING 130ARD <br /> DEFINITIVE SUBDIVISION PLAN REVIEW <br /> FLAT POND, NEW SEABURY <br /> To: Town of Mashpee Planning Board <br /> From:Charles L. Rowley, PE, RLS <br /> Engineering Consultant to Planning Board <br /> Date:August 18, 1993 <br /> Plan Oats: 8/4/93 <br /> 1.Definitive Plan: <br /> Sheet 3 of 4 <br /> Lot 48-- make drainage easement line dashed across 20 foot width. <br /> Lot 67-- Identify how the 217 Access Easement across this lot will be protected <br /> from being blocked by the lot owner. A notation on the plan as well as a <br /> restriction on the deed would be best. <br /> Sheet 4 of 4 <br /> Show drainage easements on Lots 48, 55, 56 and 58. <br /> Reserve Lot 69 has no frontage. Is this to be combined with other land of New <br /> Seabury? A notation as to id's status as a non-building lot should be added to the <br /> plan. <br /> 2. Drainage Calculations: <br /> Drainage calculations state that they have been done in accordance with Town of <br /> Mashpee Regulations. However the Rules and Regulations call for runoff coefficients of 1.0 and <br /> 0.4 and not 0.9 and 0.3 as used to calculate runoff rates. This will Increase the total runoff In all <br /> Of the calculations. Leaching areas may need to be resized accordingly. <br /> 3. Drainage Design: <br /> i <br /> The design has changed from a combined leaching pit/free outlet system to one of all <br /> leaching pits. In some cases where the bottom of the leaching pit Is at or near ground water, <br /> � I <br /> only the sides of the pit have been used for percolation of drainage water. This still means that <br /> the water discharged from the leaching pits will be in close contact with the ground water in the <br /> area. <br /> This has been done in areas of the plan which were once free outfalls near defined <br /> wetlands. <br /> I recommend that storm drainage systems in these areas be designed in accordance <br /> with the least impact on the water source which feeds Flat Pond. If there is an Indication from <br /> the ground water studies of the applicant and others that fresh water accesses the pond from <br /> below, then I would recommend that leaching pits In Gose proximity to the ground water not be <br /> used and that a direct surface outfall with appropriate diffusion devices be used instead. The <br /> areas of greatest concem are in the west and southwesterly portions of the project. <br />