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<br />. sufficient anchorage and embedment to prevent collapse from seaward rotation of the cap <br />or toe <br /> <br />. return walls extending landward of the seaward face of the building or structure being <br />protected and landward of the effects of erosion and scour <br /> <br />2.3.12 DRAINAGE AND DRAINAGE STRUCTURES <br /> <br />The BPAT observed the remains of several new stormwater discharge structures adjacent to <br />or between multifamily buildings. These structures consisted oflarge--diameter corrugated plastic <br />pipes, probably intended to carry stormwater runoff from parking areas and other impervious <br />areas to the beach. Unfortunately, the seaward portions of these pipes were destroyed during the <br />storm and their pre-storm configurations are not known with certainty. <br /> <br />It did appear, however, that erosion beneath habitable structures near these damaged discharge <br />pipes was more severe than at areas away from the pipes, possibly a result of direct discharge of upland <br />stormwater runoff adjacent to or beneath the habitable structures. It is likely that the pipes failed <br />because of erosion and scour caused by the storm or because of the loss of protective seawalls and <br />bulkheads. It is possible, but not known for certain, that the pipe failures and discharge adjacent <br />to the multifamily buildings contributed to foundation damage at those buildings. <br /> <br />2.4 INCORPORATION OF PRE-FIRM CONSTRUCTION INTO NEW CONSTRUCTION <br /> <br />Many single-family structures appeared to have been constructed above or adjacent to portions <br />of older pre-FIRM structures and probably resulted from efforts to expand and/or reconstruct <br />older, smaller structures. This type of construction is vulnerable to storm damage because the <br />foundations of the pre-FIRM and post-FIRM sections can respond differently to storm forces and <br />erosion. For example, the BPAT found a damaged house in Mexico Beach that was supported by <br />two types of foundations. One part of the house was supported on concrete block piers placed on <br />the old pre-FIRM slab-on-grade. The remainder of the house, which extended beyond the original <br />pre-FIRM footprint, was supported on timber piles set in concrete encasements. Although the piles <br />and slab survived the storm, the concrete block piers did not. 'With the loss of the piers, the house <br />listed to the unsupported side and the floor beams separated from the newer, pile foundation. Had <br />the entire house been supported on timber piles, it may have survived with little or no damage. <br /> <br />2.5 DESIGN, CONSTRUCTION, AND WORKMANSHIP <br /> <br />Mter observing hundreds of damaged or destroyed structures, the BPAT has concluded that <br />many structures seem either to have been built without the aid of detailed design plans (prepared <br />by a design professional) or not to have been built in accordance with plans that were available. <br />Failure of non-engineered or poorly designed foundations, structural systems, and critical <br />connections often led to major damage or complete loss of structures. Such losses are preventable. <br /> <br />Numerous instances of poor workmanship were also noted by the BPAT during its <br />inspections. In particular, the BPAT found several examples of misalignment of timber <br />foundation piles and poor framing practices in platform-type construction. The BPAT also noted <br />recurring problems with concrete construction. For example, reinforcing steel was missing from <br />or misplaced in slabs, footers, and wall grade beams, and welded wire fabric reinforcement was <br />frequently at the bottom of, not centered in, the slabs. Although no damage was observed that <br />could be definitively linked to these examples of poor workmanship, such practices should be <br />avoided in any construction, especially in areas subject to coastal storm forces. <br /> <br />HURRICANE OPAL IN FLORIDA <br /> <br />2-13 <br />