Section 840.126  Final Cover System

The owner or operator of Ash Pond D must design and install a final cover system for Ash Pond D.  The final cover system must consist of a low permeability layer and a final protective layer. 

a)         Standards for the low permeability layer.  The low permeability layer must be designed to minimize surface infiltration and must consist of a geosynthetic membrane cover and be constructed in accordance with the following standards: 

1)         The geosynthetic membrane must have a minimum thickness of 40 mil (0.04 inches) and, in terms of hydraulic flux, be equivalent or superior to a 3 foot layer of soil with a hydraulic conductivity of I x 10^-7 centimeters per second.

2)         The geosynthetic membrane must be placed over a prepared base free from sharp objects and other materials that may cause damage. 

b)         Standards for the final protective layer.  The final protective layer must:

1)       Cover the entire geosynthetic membrane.

2)       Be at least 3 feet thick and must be sufficient to protect the geosynthetic membrane from freezing and minimize root penetration of the geosynthetic membrane.

3)       Consist of soil material capable of supporting vegetation.

4)       Be placed as soon as possible after placement of the geosynthetic membrane.

5)       Be covered with vegetation to minimize wind and water erosion.

c)         Construction Quality Assurance Program. The final cover system must be constructed according to a construction quality assurance program that meets the requirements of Section 840.146 of this Subpart.