This CIR seeks clarification on whether a stabilized grass parking system can be counted in OPTION 1 calculations as open grid pavement. Our project is a cultural institution that receives a surge in visitors during the summer months. The stabilized grass system is proposed for the site\'s overflow parking areas that are required to meet the peak season parking demand. By using this system rather than other types of paving, these areas will be preserved as an open meadow during the remaining 9 months of the year. Town officials have approved the system; as a result we have been able to reduce the amount of paving required for parking by 44%. Designed to hold vehicular traffic while allowing for infiltration, this stabilized grass profile promotes healthy vegetation and prevents soil compaction. The structural base for this system is made up of a twenty inch profile consisting of twelve inches of crushed stone over eight inches of compacted sand and gravel. The strength of the profile arises from the stone on stone contact. The large pore spaces between the stones hold soil to support turf and meadow grasses. Over the crushed stone layer, a two inch veneer of planting soil provides the horticultural medium within which to grow grass. The planting soil is a sandy loam which water percolates through quickly. The water then moves through the crushed stone layer, through the sand and gravel layer, and finally to the subgrade. This system percolates more quickly than the native soils on the site. The stabilized grass parking system has a better hydraulic conductivity and therefore better infiltration rate than open grid paving. We have compared our system to Escofet Checkerblock, which is 77% open. The hydraulic conductivity of the stabilized grass system is 3"/hour. For the Checkerblock, the hydraulic conductivity of the turf soil is 1.5"/hour multiplied by the fraction of the checkerblock that is pervious (77%), the resultant rate for Escofet Checkerblock paving is 1.15"/hour. The hydraulic conductivity of the stabilized grass system will be guaranteed through conformance to the specification which reads, "The final mix shall have a hydraulic conductivity of not less that 3 inches per hour when compacted to a minimum of 94 percent Standard Proctor. Tests shall be by combined hydrometer and wet sieving in compliance with ASTM D422 after destruction of organic matter by ignition." The surface of the stabilized grass parking areas will be 100% vegetated rather than the 50% required for open grid pavement. This system was developed by the project\'s soil scientist and landscape architect. An installation using the same detail, soil profile, and soil blend was installed on an adjacent site and has been proven successful.