Except as otherwise provided herein, impervious surfaces on a lot shall not exceed 15% of the total area of the lot; provided, however, if LID Regulations are employed in the development of the lot, then the lot may, by special exception issued by the Zoning Board of Appeals, receive a 5% impervious surface bonus to allow for a maximum of 20% impervious surfaces on a lot. The LID practice(s) must provide a "Primary Stormwater Treatment Practice" as described in Section 6.2 of the 2004 CT Stormwater Quality Manual, as amended, that will accept, at the least, the water quality volume (first inch of rainfall) of stormwater generated by the activities on the property that are in excess of the 15% limit.