Griffin Farms is a mixed-use housing development featuring 100,000 sf of retail, 264 luxury apartments and 165 luxury single family homes. Land use efficiency and cost drove the use of underground infiltration. After evaluating all the options, engineers at Kimley-Horn selected a corrugated metal pipe (CMP) detention system from Contech Engineered Solutions.
CMP was selected as it provided the most cost efficient, compact solution. The ability of CMP to support traffic loading with minimum cover allowed for an increase in pipe diameter, maximizing storage efficiency. Incorporate risers and inlets directly into the system also resulted in saving on drainage structure cost.
This was the City's first underground storage project and they were focused on the long term maintenance and the longevity of the system. To approve the permit, the City required the use of CDS hydrodynamic separators to pretreat to the underground system. The CDS units will prolong the life of the system by removing debris and sediment that can collect on the invert and within the stone backfill voids. The CDS units are also easier to clean and maintain compared to the infiltration system itself. The average CDS unit can be cleaned via a vaccum truck in less than 30 mintues. The nine CDS units also acted as inlet structures, further reducing the cost of system.
Contech provided sizing calculations, drawings, and permitting assistance. Contech also provided installation and delivery support, coordinating the delivery of the CDS units and pipe to meet the contractor’s schedule, which called for the installation of 1,500 LF of pipe per day.