Picture from a Pine Brook area flood in 2002.

Report of Flood Conditions
on
Pine Brook Boulevard at Kilmer Road

Frank T. Griffin
Larchmont Village Engineer
November 15, 1954

Pine Brook drain is a natural water course that drains a portion of the City of New Rochelle, a portion of the Town of Mamaroneck, and a portion of the Village of Larchmont. Up until the year 1931, this was an open uncovered brook running through the western portion of the Village and emptying into Premium Creek, immediately south of the Boston Post Road.

This report was prepared at the request of the Board of Trustees of the Village of Larchmont, which body has been petitioned by the homeowners on Pine Brook Drive in the vicinity of Beverly Plan and Kilmer Road to alleviate flood conditions in times of heavy rains and high tides.

The Pine Brook Drainage Commission consisting of the City of new Rochelle, the Town of Mamaroneck and the Village of Larchmont, was formed in 1930, under the authority granted under the Laws of New York, Chapter 260. This commission improved and enclosed Pine Brook and the cost thereof was distributed, as follows: To the City 60%; to the Town 25% and the Village 15%. However, Section 7 of the law stated, as follows “Upon the completion of the project for the improvement of said Pine Brook and its tributary waters, the maintenance of said water course, whether enclosed or unenclosed, shall devolve upon the City of New Rochelle, the Town of Mamaroneck and the Village of Larchmont respectively, as to such part of the said water courses and drains as may be located respectively within the territorial confines of said City, Town and Village, in the same manner as though said water course shad been originally maintained and located within the said limits and with the same force and effect as though this improvement had not been made at the joint expense of the free municipalities cooperating to carry out this improvement.”

Most of the homes referred to above in the Kilmer Road, Beverly Place, Pine Brook Drive area have cellars, the elevations of which are approximately three to four feet above the mean high tide. We have had floods of a tidal nature in the last fifteen years which have reached elevations of seven foot above mean high tide, and more recently the tide cause by Hurricane Carol rose to an elevation of approximately 7 ½ feet above mean high tide. At times such as these, even with no rainfall, the tide will pour back into the drain in a reverse flow and come out through the catch basis, flood the street, and flood cellars of these low lying homes.

In order to prevent the encroachment of high tides into this low lying area, it is entirely possible to install a tidal gate at the outlet of Pine Brook drain, immediately south of the Boston Post Road. This gate would be constructed of timber and would be counter-balanced so that it would close when the tide waters start to flow up the drain and open at any time that rain water accumulates to a slightly higher elevation than the tidal waters in Premium Creek. Preliminary design sketches are being prepared for such an installation and it is estimated that such an installation would cost approximately $1,500. However, it must be pointed out that such a tidal gate would only alleviate the flood condition in this area by preventing the tide from backing up during periods of dry weather. It must be borne in mind that if we have the coincidence of a high tide and a heavy rainfall, that the rainfall will build up in the drain, eventually flood out onto the streets and into the basements, until it reaches an elevation slightly higher than the elevation of the tidal water. When this condition occurs, the tidal gate with then open and the elevation of the tide while it is receding will govern the elevation of the water in the Pine Brook Drive area as it does at the present time.

Furthermore, the drain itself has not been cleaned of sediment of many ears and I would recommend that this cleaning operation be carried out before the tidal gate would be installed. In addition, the sanitary sewers in this area are surcharged or flowing under pressure during times of heavy rainfall, and it is entirely possible that during the cleaning operation points of leakage in the Pine Brook drain and/or openings in the sanitary sewer may be discovered. It is extremely difficult to place an estimate on this phase of the work with the data now at hand. However a figure of approximately $5,000 might be considered.

At the present time, a four foot drain from Mayhew and Howard Avenues enters Pine Brook drain at a point just north of Kilmer Road. In order to prevent any flooding of the Pine Brook Drive area in this vicinity, it would be necessary to have Pine Brook drain and the four foot drain from Mayhew Avenue completely weather tight with no openings for catch basins in this low area. These drains would then operate as pressure conduits and the rainfall that would accumulate in the low lying area of Pine Brood Drive, because of the low elevation, would have to be raised up by a pumping operation and empty through a separate pipe into Premium Creek. This would be an extremely expensive operation and would entail a detained engineering survey to determine its feasibility. At the present time, because of the increasing development in the watershed area of Pine Brook, the present drain is inadequate to take care of rainfall flood flows. In fact, during the war years, a post-war planning project complied by the Office of the Village Engineer propose enlarging Pine Brook drain from a point approximately 120 feet north of Kilmer Road to a point approximately 100 feet south of Beverly Place, with provisions for the installation of a five foot six inch diameter drain pipe parallel to Pine Brook drain from that point to the outlet just South of Boston Post Road. Another project in 1947 proposed the installation of a five foot diameter intercepted drain to pick up the four foot drain from Mayhew Avenue and the drainage of all waters from the low lying Pine Brook drive area, so that all openings in the main Pine Brook drain could then be sealed off. However, neither of these projects, which, incidentally, were never carried out, would prevent the backflow of tidal waters, although tidal gates such as the ones now proposed could supplement either project.

CONCLUSIONS AND RECOMMENDATIONS

1. To afford protection at the present time against tidal flood waters, it is recommended that a tidal gate be installed at the outlet of Pine Brook drain and that the drain itself be cleaned of sediment and repaired where necessary. A preliminary estimate of the cost is $6,500, which in all probability , because of Section 7 of Chapter 260 of the Laws of New York, as quoted above, will have to be borne by the Village. An attempt might be made to reactivate the Pine Brook Drainage Commission since it is illogical that the Village of Larchmont should be saddled with the highest maintenance cost on the drain merely because our section happens to be at the outlet of the stream.
2. Any enlargement of Pine Brook drain proper should definitely be referred to the Pine Brook Drainage Commission since it affects all parties in the watershed area. It must be remembered that some of the waters from the New York-New England Thruway will, of course, flow into Pine Brook drain, although it does not appear that here will be any significant increase in flood waters because of this fact.
3. If Pine Brook drain is to be sealed up so that it will flow through the Pine Brook Drive area as a pressure conduit, it is logical that this portion of the work should be undertaken by the Pine Brook Drainage Commission. However, the supplementary drains and pumping station to remove rainfall that falls on this area within the Village would, of course, be a Village Expense.
4. This is to be construed as a preliminary report and the recommendation under Number 1 above could be directed by the office of the ViIlage Engineer, as now constituted, and be let out on contracts. However, it must be remembered that this recommendation will only prevent flooding of the area at times of extremely high tides and no rainfall. Any further solution to the problem as outlined in Numbers 2 and 3 would require a detailed engineering survey, requiring survey parties and additional personnel, and might be properly undertaken by the Pine Brook Drainage Commission and possibly the Engineering Department of the City of New Rochelle.

Respectfully Submitted,

Frank T. Griffin
Village Engineer
VILLAGE OF LARCHMONT