§ 914-14.012. Structures setback lines for unimproved earth channels.

(a)

"Structure setback line" means the line separating the structure setback area from the remainder of the lot. For unimproved earth channels within the subdivision, a structure setback line shall be shown on the final map or parcel map as follows: The thread of the channel shall be shown as accurately as possible, and a dashed line shall indicate the appropriate setback with a note describing the method used to determine the top of bank, selected from those set forth herein. The development rights for that portion of the lot on the creek side of the setback line, which is defined as the "structure setback area," shall be offered for dedication to Contra Costa County by separate instrument.

(b)

"Top of bank" means the point where the water surface plus sufficient freeboard for the design average recurrence interval runoff intersects the existing ground, or the point where a line with a slope of 2.5 horizontal to 1 vertical extending from the toe of the channel intersects the existing ground, whichever point is the greatest vertical distance above the channel invert. A separate top of bank shall be determined for each side of the channel.

(c)

The structure setback line for unimproved channels shall be determined by measuring the following horizontal distance away from the top of bank on each side of the watercourse:

Height of top of bank above channel invert	Horizontal distance between top of bank and setback line
less than 20'	30'
20' - 29.99'	35'
30' - 39.99'	40'
40' - 49.99'	45'
50' and greater	50'

 

(d)

Where significant riparian vegetation exists beyond the limits required above, the advisory agency may extend the setback line to include such areas.

(Ords. 89-28, 85-40 § 6, 78-5).