Attch_5_208.06_Modified_Supplmental_Spec.pdf

208 - Structure Excavation and Backfill for Selected Major Structures

Modified by HEB Engineers, Inc. 08/27/14

208.04_nat_us_08_05_2009

Construction Requirements

208.04 General.

Add the following to the end of the second sentence of the third paragraph:

"... to the CO a minimum of 5 days prior to beginning excavation work."

Add the following to the end of the third sentence of the third paragraph:

"...to the CO a minimum of 15 days prior to installation."

208.06 Cofferdams

Add the following to the second paragraph:

(h) Furnish drawings in accordance with Section 104.03 that bear the seal and signature of a professional engineer in the pertinent design field if the cofferdam is being utilized for stream runoff bypass that include the following:

(1) Accomodation of the 25-year flood event without compromising the ability to perform work.

(2) Specify opening size of bypass.

208.09 Foundation Preparation.

Add the following after the first paragraph:

The foundation elevation is defined as the bottom of footings, for spread footing placement; the bottom of the pile cap, for construction of pile foundations; and the toe of the wall, for construction of retaining walls, except wingwalls at bridges.

Replace all material from any over-excavation below the designated footing elevation with concrete, compacted gravel, or foundation fill at the direction of the CO.

When boulders or irregular, fractured, or seamed bedrock precludes excavation to the designated footing elevation without further loosening of previously solid material, the CO may order removal of such loose material and allow payment for concrete, gravel, or structural backfill that is required to restore foundation material to the designated elevation

208.13 Measurement.

Add the following to the second paragraph:

(f) Material excavated to construct end walls or wing walls which lie outside the excavation limits specified above.

Add the following paragraph:

Foundation over-excavation and the resulting replacement material will not be measured for payment unless the CO determines the over-excavation was unavoidable because of the nature of the material.