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to accept a spline that ties each board to the adjoining boards above and below . The splines, constructed from % -in . aluminum, %z -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 I-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, sea( . 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 -