Before excavation, AQUALIS coordinated utility locating to confirm both the alignment and depth of underground infrastructure. Private and public utilities were identified and marked to reduce excavation risk and prevent service disruptions. A dig ticket was secured through Virginia 811 to verify existing records.
A certified surveyor performed pre-construction staking to establish limits of disturbance and mark critical structures requiring protection or temporary support. Traffic control plans outlining safe ingress and egress were finalized and submitted to local authorities as required. In addition to field verification, AQUALIS coordinated directly with municipal authorities regarding water main protection, electrical relocation and approved disposal procedures. Managing these conversations centrally reduced delays and ensured all work met local requirements. This early coordination created a clear framework for construction and minimized the potential for unexpected conflicts once work began.
Site Preparation and Environmental Controls for Stormwater Reconstruction
Mobilization included delivery of equipment and establishment of traffic control using signage, barricades and flaggers to maintain safe access through the active commercial property.
Environmental and site protection measures were implemented immediately. A stabilized construction entrance and concrete wash rack were installed in the designated staging area. Orange safety fencing and chain-link super silt fencing were placed around the work zone in accordance with approved plans. Additional silt fence, inlet protection and diversion controls were installed to manage sediment and stormwater during construction.
Diversion berms, perforated drain pipes and filtration logs redirected water away from the excavation area. Pipe plugs and dewatering pumps were deployed as needed to prevent inflow into the system while work was underway.
Because the excavation was located near an engineered retaining wall, ground protection mats and a gravel buffer were installed between the work area and the wall. The wall was inspected multiple times daily, with updates provided to the client and engineering team to ensure structural stability throughout construction.
Geotechnical Investigation Supporting Sinkhole Repair
Given the presence of a sinkhole and adjacent structural elements, geotechnical oversight played an important role in the project. Electrical resistivity testing was conducted in three areas across the parking lot to evaluate subsurface variability. Ground penetrating radar was used to further assess conditions near the sinkhole and partially along the retaining wall alignment. These tools provided a clearer picture of what was occurring below the surface before full excavation progressed.
The geotechnical engineer also evaluated the structural integrity of the retaining wall prior to and during construction. The data collected was compiled into a comprehensive report to guide decision-making as the project advanced. This level of oversight ensured that subsurface conditions were properly understood and that construction activities remained aligned with engineering requirements.
Demolition of Failing Underground Detention Infrastructure
Demolition began with saw cutting and hydraulic hammer removal of approximately 436 linear feet of curb and gutter. Roughly 12,000 square feet of asphalt was removed and transported offsite for disposal.
Site lighting was disconnected to allow for safe construction and later reinstalled following restoration. Electrical lines were relocated as necessary and the existing water main was temporarily supported to maintain service continuity.
Excavation proceeded to remove the existing 96-inch ridged metal pipe detention structure as well as an 8-foot CMP. Influent and outlet connections were disconnected in preparation for replacement. Debris was stockpiled and removed in accordance with environmental standards. Street sweeping was performed throughout the project to maintain a clean and safe site.
Installation of New 96-Inch Stormwater Detention System
After demolition, excavation and grading of the trench were completed in accordance with design plans. Approximately 720 linear feet of sheet piling was installed to support trench walls and maintain stability during deep excavation.
The trench bottom was over-excavated to achieve suitable subgrade conditions. Geotechnical engineered filter fabric was installed, followed by placement of one foot of 21-A aggregate to create a stable foundation layer.
Approximately 531 linear feet of new 96-inch corrugated metal pipe was installed and connected to existing inlet and outlet structures. Two Bilco access doors were integrated to provide safe entry points for future inspection and maintenance.
Backfill was placed in controlled 6-inch lifts with compaction performed at each stage. Structure fill testing and compaction testing verified that density requirements were met and that the system was properly supported. Once final elevations were achieved, subgrade preparation, base aggregate placement and asphalt repaving restored the parking surface.
Final Inspection, Testing and Site Restoration
Upon completion, a post-construction survey was conducted to produce accurate as-built plans documenting the final configuration of the detention system. These records provide clarity for future maintenance, inspections and regulatory reference.
Geotechnical oversight continued through final backfill and surface restoration to confirm that construction met performance standards. All debris and temporary materials were removed prior to demobilization.
Stabilized Parking Lot and Reconstructed Stormwater System
By managing utility coordination, environmental controls, geotechnical evaluation, phased demolition and full reconstruction under one scope, AQUALIS delivered more than a repair. The team served as the central point of coordination between the client, engineers, city officials and utility providers, ensuring every phase moved forward safely and efficiently.
The result is a stabilized site, a restored parking lot and a modern underground detention system built for long-term performance. Through careful phasing, technical oversight and hands-on construction management, AQUALIS provided a comprehensive solution that protected the client’s investment while minimizing disruption to ongoing operations.
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