(a) Licensed engineer. A surface skimming system or perimeter overflow (gutter) system constructed on or after the effective date of this subchapter shall be planned and designed by a licensed engineer.(b) Surface skimming design. A surface skimming system or perimeter overflow system shall be planned and designed as required in §265.159 of this subchapter (relating to Suction Outlets, Gravity Flow Systems, and Return Inlets) and shall be capable of providing 100% of the design system flow, unless the department has approved an alternate method of disinfectant.(c) Safe design of surface skimming and perimeter overflow systems. A surface skimmer or perimeter overflow system shall be designed and installed to prevent body and limb entrapment.(d) Effective skimming action maintained. Surface skimmers shall be located to maintain effective skimming action throughout the lagoon.(e) Hydraulic capacity of perimeter overflow system. The hydraulic capacity of a perimeter overflow (gutter) surface skimming system shall be capable of handling 100% of the circulation flow, unless the department has approved an alternate method of disinfectant.