(A) Plan submittal procedure. For village approval of grading and rear yard drainage, the applicant shall furnish the Village Clerk with three sets of plans, along with any required fees and deposits. Detailed cost estimates shall be submitted concurrently. The Village Clerk will stamp two sets as authorized to be reviewed, and the applicant will submit these copies to the Village Engineer for review, comments and/or approval. The Village Engineer shall review the plans for conformity to the standards set forth herein and certify that they are consistent with the Village Master Drainage Plan, after which he or she will return one of the sets to the applicant with the appropriate comments. The applicant, after making changes requested on the set of plans returned to him or her, shall submit three sets of the revised plans to the Engineer for final approval. The Village Engineer shall review these revised plans for conformity to the comments mentioned heretofore and, if they have been properly made, will return one approved copy to the applicant.
(B) Design standards. A grading plan is required for all developments. Rear yard storm drainage systems are required for all residential projects.
(1) Grading plan. A residential development grading plan provides all necessary information for the building contractor to establish his or her house elevation and finish grade his or her lot so that good drainage is provided. Specific items to be included are:
(a) List bench mark descriptions and elevations to be used for the development. These must not be disturbed during construction. In nonresidential areas, each site must have storm drainage provided to it and will be required to have internal drainage. Provide two benchmarks within 1,000 feet of the property;
(b) The practical scale for residential subdivision grade plans is 1" = 100'. This scale requires repetitive labeling to be kept to a minimum and lettering to be small and neat.
(c) The grading plan shall be designed to ensure that if a failure occurs in the storm system, water will drain away in overland swales without flooding houses.
(d) Show the proposed earth elevation at the house, the first floor elevation of the house unit and top of curb elevation at the center of each lot to hundredths of a foot. Earth elevations at the house exterior are to be placed in rectangular boxes drawn to dimensions comparable to a typical house to be built in the development. These boxes are to be placed on each lot according to the front yard setback.
(e) The proposed earth elevation at the house shall meet the following condition: on lots with rear to front drainage, the earth elevation shall be no lower than one foot above the highest point at the road elevation.
(f) Rear yard drainage is required in all residential developments.
(g) Indicate rear yard catch basins. Show the proposed castings and invert of pipe elevation for all catch basins and manholes to the hundredths. Catch basins are required to be at a lot corner and the catch basin elevation shall be the only proposed elevation shown at that corner.
(h) Indicate perforated plastic rear yard underdrains and tees for sump pumps where they are called for in the storm sewer plans. Use different symbols for plastic underdrains and concrete storm sewer.
(i) All existing and proposed ground elevations are to be in tenths of a foot.
(j) Show proposed ground elevations at all corners and grade high points on the side property lines.
(k) Rear yard swales shall be no longer than 500 feet before being intercepted by a catch basin and shall have a minimum slope of 1%. Rear yard swales shorter than 300 feet may have a minimum slope of .6%.
(l) All positive low points shall have a catch basin. Storm sewer runs from positive low points must be 12 inches or more in diameter plain joint with pea gravel trench fill in a modified trench with fabric wrap.
(m) Show both the existing and proposed ground elevation at lot corners at the subdivision boundaries. Proposed elevations shall be equal to or lower than existing.
(n) Show the proposed side yard swale elevation between all houses. This elevation must be a minimum of .5 feet below the lower adjacent earth elevation at the house.
(o) Where topography prevents rear yard drainage from being practical, rear to front drainage may drain only the specific lot in question and the lot directly behind it. Other bordering lots shall not drain across this lot. Lots with rear to front drainage must have swales shown around the house with swale slopes of 1% minimum. The following swale elevations shall be shown:
1. The high point of the swale(s) located generally behind the house, a minimum of ten feet from the house and .5 feet below the earth elevation at the house;
2. The swale elevation located even with the back of the house;
3. The swale elevation located even with the front of the house.
(p) All drainage directions on the lot shall be indicated with arrows.
(q) Additional elevations and slopes shall be shown under special conditions and as required by the Village Engineer.
(2) Rear yard storm drainage systems and footing drain outlets. The following details and specifications will be required in all residential projects:
(a) A rear yard drain shall be located in a drainage easement provided along the rear or side lot lines as necessary. This easement shall give access to every lot adjacent and shall total not less than 12 feet wide. The storm sewer and under drain shall be located three feet from the property line in the easement. Where abutting unplatted property, it shall be located four feet from the property line.
(b) When under drain is used, it should be fabric wrapped and in a fabric lined trench.
(c) Catch basins shall be located:
1. At all bends of 30° or greater;
2. At positive low points;
3. So that rear yard swales shall be no longer than 500 feet before being intercepted by these catch basins. The minimum slope of these swales shall be 1%;
4. So that rear yard swales at a minimum slope of .6% shall be no longer than 300 feet before being intercepted by these catch basins.
(d) The rear yard drains must be placed with a minimum slope of .4%.
(e) The intermediate catch basin shall be four feet diameter and shall have a minimum 24-inch sump. A trap is not required for these basins. The catch basin cover shall be an E.J.I.W. No. 3000 with Type N Grate.
(f) No rear yard storm drainage shall be constructed until rear yard grading is completed and approved.
(g) Soil erosion controls must be in place prior to work start. If required, a soil erosion permit from Oakland County must be in hand before work is commenced.
(O.C. § 5.706) (Am. Ord. 268, passed 9-19-22)