specs

Section 02200
Page 3
B. In areas where buildings are proposed the existing fill soils to be over-excavated to undisturbed native ground
as observed and approved by the construction Soil Engineer. It is expected that excavations to elevations
ranging from +1 to +5 feet should be expected resulting in over-excavation depths of 5 to 11 feet (not
including existing stockpiles).
C. Excavations to extend a minimum of 5 feet laterally beyond the building footprint and the area replaced with
engineered fill as noted below.
D. In other areas (non-building or parking lots), the upper 3 feet (minimum) of the subgrade to consist of
engineered fill. Where over-excavation is required (north half of the site), the area should be excavated to a
depth of 2 feet, the bottom 12 inches scarified and compacted in-place, and replaced with engineered fill. The
south half of the site will require more than 3 feet of fill to achieve the design grades and over-excavation is
not expected to be needed.
E. The existing stockpiles which cover a portion of the site must be removed. After removal of existing
stockpiles, the surface of the areas to be graded will require stripping to remove vegetation and/or other
deleterious materials. It is estimated that stripping depths of about 1 to 2 inches may be necessary; however,
the actual depth of stripping to be determined in the field by the construction Soil Engineer. Stripped material
from the site may not be used as engineered fill, but may be stockpiled and used later for landscaping purposes.
F. As part of this project, the roadway Hartle Court (old) is to be demolished. Road improvements (including
curb/gutter/sidewalk) and any utilities which will not remain in service must be demolished and removed from
the site. The exception is that the aggregate base, asphalt concrete and Portland cement concrete may be
crushed and used on the site as general fill.
G. Any conflicting utilities which run through the site must be abandoned and/or relocated.
H. Satisfactory materials acceptable for filling and backfilling work may be temporarily stockpiled on site.
I. Make excavations large enough to permit placing and removal of shoring, forms, and for inspection of the
work.
J. Excavation for Structures:
1. Level bottoms of trenches reasonably level. Change elevation at right-angled steps with forms or
bulkheads. Step trenches in 8-inch maximum depth and 24-inch minimum length increments.
2. Fill excess depth in trench excavations with concrete. Form excess width in size, or fill with concrete.
3. Surfaces of excavations shall be within one inch per foot and any excessive depth in excavations shall be
filled with lean concrete.
K. Remove all excess excavated material from the job site.
3.03 BACKFILLING
A. Backfilling includes filling and compaction beneath slabs and structural concrete; against and around concrete
foundation walls after forms have been removed and foundation inspection completed.
B. Native clay soil subgrade may be soft, wet and unstable making placement of fill with conventional
earthmoving equipment difficult. A stabilization layer of fill maybe required at the bottom of the excavations.
Stabilization layer to consist of Tensar BX1200 (or approved equivalent) geogrid overlain by an 18 inch thick
layer of 6 inch minus crushed rock overlain by Mirafi 600x (or approved equivalent) geotextile followed by
engineering fill placement. The requirement for stabilization and the method may be modified in the field by
the construction Soil Engineer.
C. Do not start backfilling operations until foundation drainage system and waterproofing have been reviewed and
tested.
D. After stripping and over-excavation of existing firm and loose fills, and prior to any additional fill placement,
the upper 12 inches should be scarified, moisture conditioned as necessary and compacted to a minimum
degree of relative compaction of 90% at 2 or more percent above optimum moisture content as determined by
ASTM D1557 Laboratory Test Procedure. Mitigation of wet/unstable soils is discussed above.
E. Just prior to placement of select fill, all traces of organic, loose or obviously compressible material must be
removed.
F. Ensure areas are free from debris, snow, ice and water, and that ground surfaces are not in frozen condition.
G. Backfill areas to grades, contours, levels, and elevations indicated.
H. Backfill systematically and as early as possible to allow maximum time for natural settlement and compaction.
NAPA CENTURY CENTER XD 12
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