HomeMy WebLinkAboutCorrespondence - 45 BRIDGES LANE 11/23/2004 ENGINEERING NEW ENGLAND i
INC
November 23, 2004
By Fax and Mail
Attention Clair Golden
Department of Environmental Protection 1
Division of Water Pollution Control
1 Winter Street f t
Boston, MA 02108
RE: 45 Bridges Lane, North Andover
Dear Clair:
Thank you for your call today regarding the above referenced property. The specific issue
which needs clarification is the"doubling" of different reductions allowed by different
alternative leaching and treatment systems in one subsurface sewage system repair
design.
The specific question regarding the above referenced property is the use of a Fast
pretreatment system to lower the required offset between the bottom of the leaching
system and the water table from 4 feet to 2 feet combined with the use of the Infiltrator
chamber system to reduce the required area for the leach system. It is the opinion of the
review engineer for the Town of North Andover that the systems can not be combined to
take multiple reductions without first applying to DEP for a variance. I am specifically
asking for your interpretation of the matter and it is my belief that a variance should not
be required. My reasoning is as follows.
The Fast pretreatment system is being used to pre-treat the effluent prior to distribution in
the'leach field. The fact that the effluent is cleaner and therefore needs less treatment
prior to corning in contact with the water table is the basis for DEP having granted the
approval of the Fast system for this type of reduction. The science behind the granting of
the approval of this system is separate from the science behind the granting of the
Infiltrator system approval. The infiltrator system approval for a reduced leach field size
is based upon the fact that there is more surface area to treat the effluent at the bottom of
the trench than that of a stone trench. By combining these two approvals there is no loss
of the ability of each system to work as designed. The infiltrator field will work as
designed to treat the effluent in the same manner as a system without the Fast
pretreatment unit.
60 BEECHWOOD DRIVE-NORTH ANDOVER, MA 01845-(978)686-1768-(888)359-7645- FAX(978)685-1099
This same question has been raised before by the same review engineer but the
combination of reductions was different. In those instances I asked for reductions in leach
area size for the use of pretreatment, pressure dosing, and the equivalent size of the leach
chambers. In that instance I agreed that the proposal coupled reductions in a manner that
was not allowed. This present request however does not couple the same type of
reduction and in my opinion should be viewed separately and therefore allowed.
Thank you for your expedient review of my question. If you need any additional
information please do not hesitate to contact me at the office number or at my cell phone
number which is 508-328-4633..
Sincerely,
Benjamin C. Osgood, r.,PE
President
CC Susan Sawyer, RS
North Andover board of Health Agent