§ 21.85.180. Erosion and sedimentation control.

All grading, excavating and removal or destruction of natural topsoil, trees or other natural vegetation shall conform to an erosion and sedimentation control plan prepared by the subdivider and approved by the department of public works before the work may commence. The plan shall conform to the guidelines and policies in the report, Soil Erosion and Sediment Control (Municipality of Anchorage, 1978), or any other guidelines and policies on this subject approved by the department of public works, and to the following:

A.

The smallest practical area of land should be exposed at any one time during development.

B.

When land is exposed during development, the exposure should be kept to the shortest practical period of time.

C.

Sediment and other pollutants, including but not limited to oil, grease, nutrients, bacteria and heavy metals generated by development activity, should be removed from runoff waters from land undergoing development by means of appropriate water quality control measures before the runoff waters are permitted to be discharged into natural streams or lakes. Examples of water quality control measures which may be appropriate are debris basins, desilting basins or silt traps, oil/water separators, retention/detention basins and infiltration devices. This applies to groundwater where applicable.

D.

Provisions should be made to effectively accommodate the increased runoff and pollutant loads caused by changed soil and surface conditions during and after development. Such provisions should include both stormwater and water quality control measures.

E.

Ground cover should be replaced as soon as practical in the development.

F.

The development plan should be fitted to the topography and soil conditions so as to create the least erosion potential.

G.

Wherever feasible, natural vegetation should be retained and protected.

H.

All slopes resulting from cut and fill operations shall not exceed a maximum slope of 50 percent. A lesser slope may be deemed necessary by the municipal engineer due to soil conditions. If slopes of greater than 50 percent are desired, such slopes will be supported by a retaining structure approved by the public works department.

I.

The proposed construction should not adversely affect spawning of anadromous fish, or significantly reduce upstream fish passage through the creation of excessive in-stream velocities.

(GAAB 21.10.050.C; AMC 21.85.085; AO No. 83-142)