If any existing land drainage structures, such as french drains, are encountered during the course of construction of any development, no septic system or any part thereof shall be installed on any lot within 400 feet thereof without the prior approval of the Toms River Township Board of Health. Such approval shall only be granted if new percolation tests, taken at least two months after such drainage structures are removed, show that satisfactory soil conditions exist and that installation of such septic system in the area affected by the removal of the drainage structures will not be detrimental to the health of the Township residents or cause pollution of any of its waters.