We have received the first PRELIMINARY results from several tests (science) conducted on the dam area. Per the engineers they are still refining the depths of the void areas (holes under the concrete areas). The void survey was exclusive to the top of the dam (overflow spillway) and the downstream side. Primary focus was the concrete portions of the dam. Attached is a preliminary executive summary of the engineer s interpretations of Radar-view s findings. It should be noted that we still need to brush through the report with a fine toothed comb, but there are indications that there currently exists approximately 229 cubic yards of voids. Nearly 100 yards, of which, are located beneath the impact slab. It is too premature to say of this loss of material was caused exclusively from the low flow valve(s)/conduits, water from the upstream side of the dam, or a combination of both. We would air on the conservative side and say a combination of both. INTRODUCTION This memorandum constitutes approximated calculations to the voids beneath the concrete service spillway associated with the Wildwood Property Owners Association s (WPOA) Lake Kimble Dam. The data was obtained from Radar-view s subsurface void survey performed on February 26 and April 12, 2016 as part of the Dam Safety Engineering Services Associated with Lake Kimble Dam - Phase II of the Master Agreement for Professional Services task authorized by WPOA on January 13, 2016. SUMMARY Figures 1, 3, 5, and 7 on subsequent pages depicts the photographs of the surveyed areas. Figures 2, 4, 6, and 8 on subsequent pages represent the surveyed area s results using ground penetrating radar (GPR). Per Radar-view s report, the areas outlined in yellow represents shallow void-like features while the areas outlined in black represents voids deeper than a foot. Using this information, the shallow (yellow outline) areas were assumed to be voids with a 1-foot depth and deeper (black outline) areas were assumed to be voids with a 3-foot depth. Tables 1, 2, 3, and 4 on subsequent pages depict the approximate void areas using the dimensions of the slabs (feet) as a scaling reference. The voids were calculated from left to right and progressed downward (similar to reading a book) and converted to cubic yards (CY) of volume. The total void volume beneath the concrete service spillway at Lake Kimble Dam is estimated to be 229 CY. For reference, 2.5 CY equates to approximately one loaded and leveled bed of a standard full size pickup truck.
Page 2 of 5 SPILLWAY SLOPE Figure 1 - Photo of Surveyed Figure 2 - Void Survey Results The spillway slope measures 36-feet in width and 200-feet in length. The void volume equates to approximately 103 cubic yards as shown in Table 1. Table 1 - Calculated (approximate) voids 80 1 80 155 1 155 99 1 99 24 1 24 56 1 56 98 1 98 105 1 105 156 3 468 224 1 224 93 1 93 91 1 91 850 1 850 142 3 426 TOTAL 2769 TOTAL (CY) 103
Page 3 of 5 SPILLWAY CREST Figure 3 - Photo of Surveyed Figure 4 - Void Survey Results The spillway crest measures 12-feet in width and 200-feet in length. The void volume equates to approximately 18 cubic yards as shown in Table 2. Table 2 - Calculated (approximate) voids 131 1 131 312 1 312 23 1 23 TOTAL 466 TOTAL (CY) 18
Page 4 of 5 SPILLWAY LEFT SLAB Figure 5 - Photo of Surveyed Figure 6 - Void Survey Results The spillway crest measures 16-feet in width and 102-feet in length. The void volume equates to approximately 14 cubic yards as shown in Table 3. Table 3 - Calculated (approximate) voids 19 1 19 93 1 93 181 1 181 69 1 69 TOTAL 362 TOTAL (CY) 14
Page 5 of 5 SPILLWAY DOWNSTREAM CONCRETE APRON Figure 7 - Photo of Surveyed Figure 8 - Void Survey Results The spillway downstream concrete slab measures 21-feet in width and 200-feet in length. The void volume equates to approximately 94 cubic yards as shown in Table 4. Table 4 - Calculated (approximate) voids 2517 1 2517 TOTAL 2517 TOTAL (CY) 94