A dam at the outflow of Lake Lulu in Winter Haven, FL is small in size but plays a large role for the Southern Chain of Lakes: flood control for surrounding communities, water level management for recreational use, and local water supply support.

The dam is classified as a Significant Hazard Potential structure, meaning failure would not be expected to cause loss of life but could cause serious property damage, environmental harm, and community disruption. During the latest inspection, engineers identified structural and geotechnical issues requiring immediate stabilization to avoid further deterioration.

Initial Assessment

Emergency spillway. Cracks in end walls, holes on the upstream side, and a major void under the downstream apron caused by soil erosion. Without repair, water could flow beneath rather than over the spillway, leading to structural failure.

Main spillway. Multiple long cracks extending from crest to waterline, prior failed patchwork, vegetation growth in cracks, exposed aggregate, and joint separation.

Constructed in the 1940s, the dam has undergone various repairs over the decades, but age-related deterioration and recurring seepage have reduced its structural integrity. While long-term replacement is inevitable, immediate action was needed to stabilize the structure through hurricane season and allow time for engineering and funding of a full replacement.

Proposed Solution

Helicon developed a dual-phase stabilization program addressing both short-term safety and long-term planning needs, using two polyurethane products.

Spillway grouting. Crews injected Spetec GT500, a one-part hydrophilic chemical grout, into cracks, holes, and voids within the spillways to seal leaks, restore concrete integrity, and prevent soil migration.

Soil stabilization and erosion protection. Crews injected AP Fill 720, a hydrophobic grout, beneath concrete structures where erosion had carved out hidden voids, filling subsurface cavities, restoring the foundation, and blocking future water intrusion pathways.

Procedures

1. Inspected both spillways to locate cracks, holes, voids, and joint separation
2. Injected Spetec GT500 into cracks and holes in the emergency spillway end walls and upstream face
3. Injected Spetec GT500 into the main spillway cracks running crest to waterline
4. Injected AP Fill 720 beneath the concrete structures to fill erosion voids, including the void under the downstream apron
5. Confirmed subsurface support and sealed water intrusion pathways

Results

• Immediately stabilized both the emergency and main spillways
• Filled voids and restored subsurface support, protecting against further erosion
• Extended service life of the dam until full replacement can be designed and funded
• Ensured the structure can safely function through upcoming storm events

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