Lot grading plans. Following final approval, but prior to the issuance of a building permit, the applicant shall, when required by the Planning Board as a condition of final approval, submit to the Borough Engineer for his approval a separate detailed grading plan of any lot, in duplicate, prepared by a licensed professional engineer, showing the existing contour lines of the plot upon which the dwelling structure is to be constructed; final elevations proposed for the corners of the plot; corners and floor level of the structure to be erected thereon. All swales, proposed terraces, sidewalks, steps and driveways, including the slopes thereof and provisions for the proper drainage thereof, shall be shown on said site plan. Upon receipt of said plan, the Borough Engineer shall review the plan and determine whether or not it meets the standards set forth in this chapter. Upon making such a determination, the Engineer shall retain one copy and forward one copy of the grading plan to the Building Inspector.