Every grading permit issued hereunder shall expire at the end of six months from the date of issuance. The permittee shall fully perform and complete all of the work required to be done within the time limit specified in the permit. If the permittee shall be unable to complete the work within the specified time, he/she shall, within 30 days prior to expiration of the permit, present in writing to the Township, a request for an extension of time, setting forth therein the reasons for the requested extension. If, in the discretion of the Township Engineer, such an extension is warranted, the Township Engineer may grant additional time for the completion of the work. Where the Township Engineer determines that the extension of time will require a substantial modification of the erosion and sedimentation control plan and/or grading plan, any extension of a permit shall be subject to approval of such revised plans in accordance with the applicable procedure of this chapter.