Alewife Study Group > wetlands and flooding > community feedback > Dec. 20 1999, Conservation Commission Search 

Oaktree Development
and the Cambridge Conservation Commission

(This page created Jan. 14 2000)

Letter from members of the Alewife Study Group,
sent in anticipation of Cambridge Conservation Commission meeting on Dec. 20 1999
regarding the Oaktree development at 30 CambridgePark Drive.

to Cambridge Conservation Commission

December 20, 1999

Albe Simenas
Cambridge Conservation Commission

Dear Mr. Simenas:

Enclosed below are comments for the hearing of December 20, 1999 for Oaktree Development's proposal for 30 CambridgePark Drive. Please distribute these comments to the Board members prior to the discussion.

This is our response to the legal opinion rendered by Donald D. Cooper of Hutchins, Wheeler & Dittmar, the attorney retained by Oaktree, on the matter of compensatory storage on the site, as provided to us by Gwen Noyes.

His legal opinion was based on two main arguments. It attempted to show that the 'incremental' requirements of the Regulations (310 CMR 10.00) can be met by creating compensatory flood storage equaling the cumulative volumes at each elevation rather than the respective incremental volumes between elevations and that compensatory flood storage could be excavated from soils that are already in the flood plain.

The Regulations do not indicate that incremental volumes are allowed to be measured cumulatively. Mr. Cooper states his opinion is the "plain English" interpretation but this is not so. If the Regulations had called for cumulative volumes there would have been no need to specifically add the word "incrementally" to 310 C.M.R. 10.57(4)(a)(1) which requires,

Compensatory storage shall mean a volume not previously used for flood storage and shall be incrementally equal to the theoretical volume of floodwater at each elevation, .(emphasis added)

Indeed it makes perfect sense for the Regulations to be referring to increments of flood storage between each elevation as this would provide a level of protection from floods that would not be provided by a cumulative determination.

For example take two situations. In one a cumulative model of flood storage has been employed that allows a developer to excavate all of their flood storage from the bottom of a pit and in the second an incremental model has been employed requiring compensatory flood storage between many elevations. There are several ways in which the second model would produce a better result in the event of a flood. First, the pit at the bottom of the excavation would be filled at lower groundwater elevations than the incremental excavations of the second model. Second, even if the pit only filled up with flood waters it would be more likely to keep them around longer in the flood than the incremental excavations which would send early flood waters out of the area at a time when the riverway had the capacity to move water out of the area.

At the very least the second type of excavation would most closely recreate the type of flood storage that existed prior on the site and thus would be most in line with the spirit of the Regulations to recreate lost flood capacity.

The documents provided by Mr. Cooper support this interpretation. In the case entitled IN THE MATTER OF NEPONSET ASSOCIATES, the DEP representative is shown to be calculating increments between elevations and not cumulatively. In section III B 2 of the narrative it states that, ".the number he gives for total storage volume at elevation 102 -- is shown in Ms. Sabounjian's (DEP rep) calculations as the number of cubic feet of flood storage that will be provided between elevations 101 and 102", indicating that the DEP views the actual volumes between two elevations to be important.

The GUIDE TO UNDERSTANDING AND ADMINISTERING THE MASSACHUSETTS WETLANDS PROTECTION ACT, was introduced by Mr. Cooper to make the argument that flood storage can occur within a flood plain. Although we do not dispute that compensatory storage can occur within a flood plain under certain conditions, it is interesting to note that the passages cited provide conclusive proof that although flood storage can be taken out of an existing flood plain it must be done in such a manner that new flood capacity occurs within each foot increment.

In the example shown on page 276, 1900 square feet of fill are proposed within the 100-year floodplain and an incorrect and a corrected example of compensatory flood storage are shown. In the first example labeled 'Incorrect Compensatory Flood Storage' a total volume of 2000 square feet of compensatory storage has been achieved by excavating a hole, but it does not meet the requirements of the Regulations because it does not provide sufficient flood storage at each of the two one-foot increments that are involved. These increments are clearly labeled as 'difference in elevation' of one foot between elevation 85 and 86 and then again 'difference in elevation' of one foot between elevation 86 and 87. Between the 85 and 86 elevations the site has lost 300 square feet of flood storage volume and the 'incorrect flood storage' has not created any new flood storage between those increments. Despite the fact that the total flood volume created exceeds the 1900 lost this plan does not meet the Regulations.

In the 'Corrected Compensatory Storage' on page 278, the Regulations are met by providing 400 square feet of storage between the 85 and 86 elevations.

It should also be noted that the 'Corrected Compensatory Storage' is shown being excavated from soils that are both below and above the 100 year flood elevation. This is common sense as the only way to compensate for lost flood storage right up to the level of the 100-year flood is to excavate from areas that are at the same elevation or higher than the 100-year flood elevation. However, while some compensation occurred within the flood plain, it should be also noted that compensation was required outside the flood plain. This is particularly relevant to the site at 30 CambridgePark Drive where there is no location on the site that is equal to the final one foot increment below the 100-year flood elevation. The kind of compensatory storage excavation that is illustrated in the Guide cannot be achieved on this site.

We agree that it is legal under the Regulations to create flood storage from within a flood plain, but only if all other conditions are met. It would have to be proven to the satisfaction of the authority overseeing a compensatory storage plan that indeed this type of compensatory flood storage would work and would not in fact add to flooding. In making this judgment many factors would have to be taken into consideration for example if there were already groundwater in the areas to be used as compensatory storage these areas would certainly not serve to add compensatory flood storage as they would already be filled with water. The Regulations allow the Conservation Commission to make a judgment as to the efficacy of an compensatory storage plan

This discretion is built into the language used in the General Performance Standards of the Regulations which state that,

Compensatory storage shall be provided for all flood storage volume that will be lost as the result of a proposed project within Bordering Land Subject to Flooding, when in the judgment of the issuing authority said loss will cause an increase or will contribute incrementally to an increase in the horizontal extent and level of flood waters during peak flows. (emphasis added)

In summary, although compensatory flood storage can be achieved within the floodplain it is up to the judgment of the Conservation Commission as to whether this storage would be effective. And even were it judged to be effective it would still have to meet the incremental requirements of new flood storage at each one foot increment at which it is lost. We don't see how these requirements could possibly be met on a site that is wholly below the 100-year flood elevation as is the site at 30 CambridgePark Drive.


Lew Weitzman, Montgomery Street
Michael Nakagawa, Madison Avenue

Julia Bowdoin, Director, Cambridge Conservation Commission
Gwen Noyes, Oaktree Development

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