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v r to accept a spline that ties each board to the adjoining boards above and below. The splines, constructed from % -in . aluminum, 'h -in. marine plywood, or other appropriate material and supplemented by appropriate sealants or lubricants (e.g. , beeswax or non-toxic grease) , will largely eliminate between- board leakage while they also significantly strengthen each individual board by transferring to the adjacent boards a portion of the bending moment produced by hydrostatic pressure. Third, to address the issues of adjustability, the modifications include installing steel or wooden cantilevered-beam hangers above each weir from which the contractor will hang commercially-available, adjustable scaffolding similar to that used in commercial painting or window washing . The scaffolding will provide the contractor 's designated weir operators a safe means to lower the weir boards from the weir walkway to the correct level for installation . The scaffolding will also provide an adjustable work platform, safely suspended above the discharge flow, from which the weir operators can efficiently place and fasten the weir boards to the flange extensions. The remainder of this section discusses the concept of the required modifications in more detail. 2. 3. 1. 1-Beam Channel Flange Extensions As stated above, the I-beam channel flange extensions will serve two functions. First, they will provide a wide and smooth surface against which the back (downstream) face of the weir boards will seat to form an effective, although imperfect, seat . Although not completely water-tight, this seal will greatly reduce the likelihood of significant leakage around the ends of the boards . Second, they will also provide a means to connect and secure each weir board in position without resorting to wedges that may be dislodged by changes in water level or pressure. The contractor will fabricate the flange extensions from nominal 2x8 PT lumber (finished dimensions — 1 %Z in. x 7 '/. in . ) and install the wooden extensions vertically against the inside face of the downstream flange of each W8xl8 I-beam channel that holds the ends of the weir boards. Adjacent vertical members restrict access and prevent bolting the flange extensions through the I-beam flange itself. As a result, the flange extensions must be bolted through the flange of the adjacent C1503 . 9 channel , with a metal spacer or rubber bushing inserted between the outside face of the C-channel flange and the wooden flange extension (Figure 2 . 1a). This length of the spacer or the compression applied to the bushing must be adjusted to insure that the flange extension remains parallel to the I-beam flange against which the flange extension must seat. - 6 -