§ I. Unmapped Streams where Regulatory Flood Elevations or Floodways have not been provided.

The following governs setbacks for planned construction activities adjacent to small, unmapped streams. Provisions of the stormwater and floodplain ordinances overlap, and both ordinances may apply to development and/or construction along small unmapped streams.

The stormwater ordinance, adopted on May 31, 2007, requires compliance with the federal Phase II Stormwater regulations promulgated pursuant to the Federal Water Pollution Control Act of 1972.

Said stormwater ordinance provides for special setbacks from small unmapped streams if new development and/or construction activities will result in a disturbed area of one acre or more. Under the provisions of the stormwater ordinance, a thirty feet wide undisturbed buffer area shall be maintained along each side of small unmapped streams, and structures and/or impervious surfaces cannot be constructed for a perpendicular distance of twenty feet from the said buffer line.

For new development where the total area of disturbance is less than one acre and the drainage area for the creek or stream adjacent to the planned construction is greater than 25 acres, the following requirements shall apply:

(1)

No building or fill material shall be located closer to the centerline of the adjacent streambed than the distance determined by adding the distance "x" from Table A below to the average width of the streambed adjacent to the site.

TABLE A

Area of Drainage Basin (Acres)	Distance "X" (Feet)
25 to 100	15
101 to 200	20
201 to 400	25
400 to 640*	30

 

*Or limits of detailed flood study by FEMA

(2)

The lowest floor, including basement, of residential structures shall be elevated not less than two (2) feet above a reference elevation that is to be determined as follows:

a.

The elevation of the lowest point where stormwater would overtop the curb, pavement, fill material, etc. above the nearest downstream culvert pipe, bridge, dam, etc. that crosses the adjacent stream shall be determined.

b.

The reference elevation shall be the sum of the elevation determined in (a) above plus the amount of the change in elevation of the streambed between a point adjacent and perpendicular to the most downstream point of the proposed structure and the streambed at the downstream location used in (a) above.

(3)

The lowest floor, including basement, of nonresidential structures shall be elevated not less than two (2) feet above a reference elevation that is determined as follows, or together with attendant utility and sanitary facilities be flood proofed to this required elevation.

a.

The elevation of the lowest point where stormwater would overtop the curb, pavement, fill material, etc. above the nearest downstream culvert pipe, bridge, dam, etc. that crosses the adjacent stream shall be determined.

b.

The reference elevation shall be the sum of the elevation determined in (a) above plus the amount of the change in elevation of the streambed between a point adjacent and perpendicular to the most downstream point of the proposed structure and the streambed at the downstream location used in (a) above.

(4)

This section shall not apply to streams, channels or drainage ways that serve as an outlet for drainage basins that have a drainage area upstream from the proposed site of less than twenty-five (25) acres.

(Ord. No. 2017-23, 9-19-17)