Lake Lawne Stormwater Facility, Orlando, Fl
CPWG has been tasked by Orange County to investigate the water quality improvement alternatives and prepare construction plans for the Lake Lawne Stormwater Irrigation Facility at Barnett Park. Given the historic low water quality of Lake Lawne, the Total Maximum Daily Load (TMDL) limits and the Basin Management Action Plan, Orange County is investigating alternatives to improve the water quality in Lake Lawne and by association the entire Little Wekiva River Watershed, as Lake Lawne is in the headwaters of the Wekiva River Watershed. CPWG Stormwater experts will evaluate water quality data and recommend potential improvement alternatives for the western tributary of Lake Lawne at Barnett Park. Another beneficial by‐product of this project that will be explored is the conservation of freshwater supply by using stormwater for irrigation purposes.
The primary objective of the CPWG Stormwater Management team is to design and permit a regional stormwater facility (RSF) on the County parcel that captures nutrient‐rich stormwater prior to its discharge to Lake Lawne. The captured stormwater can then be used to irrigate greenspace within Barnett Park. The design will include modification of the C‐6 canal to create a new water feature and associated amenities. The proposed RSF will address flooding issues, water quality treatment, erosion and sedimentation control.
The purposes of this project are to:
- Update the plans to mitigate the impacts from the Pine Hills Trail Project;
- Investigate value engineering options to reduce the construction cost of the project;
- Obtain additional geotechnical information or better quantify the volume of muck that will need to be removed; and
- Obtain an updated construction cost estimate for the project.
Construction plans for the project were completed a year ago by CPWG Engineers. The project was placed on hold due to grant funding issues and higher than expected construction bids. During this past year the design for the Pine Hills Trail has been completed, which impacts portions of the Lake Lawne RSF Project. A conceptual plan will be developed that allows the Lake Lawne Regional Pond to be constructed with minimal impacts the Pine Hills Trail Pond and amenities. The only part of the Lake Lawne Regional Pond footprint that will be updated is in the area of the Pine Hills Trail Pond.
CPWG Stormwater experts have already developed an existing condition and proposed condition ICPR model. Based on the engineering changes made above, our team will update the proposed condition ICPR model for Peak stages within the basin and the peak flow rates to Lake Lawne will be evaluated. The Pine Hills Trail stormwater inputs will be add to the model. A watershed review, to verify any changes to the basin since the last modeling event will also be performed. The modeled storm events are the Mean Annual, 10‐Year, 25‐Year, 50‐Year and 100‐Year, 24‐Hour storms. The CPWG team and the County will review the revised model prior to application to the St. Johns River Water Management District (SJRWMD).
CPWG Engineers will update construction plans for the Lake Lawne Stormwater Irrigation Facility as necessary for construction. Submittals will be made at the 60%, 100% and final levels of completion. For each submittal, a preliminary draft submittal will first be made for review. Upon receiving review comments, the formal submittal will be prepared for the County. The CPWG construction plans will also include three add alternates.
- Trash Trap Cage (Band‐a‐Long) at the south end of the project
- Northern most bridge with fishing pier
- Gazebo at the east end of the north bridge
CPWG Engineers will use their knowledge of previous projects to prepare probable construction costs for the project at 60%, and 100% (final) levels of complete. The cost estimate will include the additional alternates. The cost estimate previously developed will be reviewed and newer FDOT unit costs will be used. Other bids recently submitted will also be used to better quantify the cost estimate.