Page 228 - Villas at Savona Close-out Manual

Geotechnical Investigation Report
Villas at Savona
Resources (ADWR) Well Registry indicated the regional depth to groundwater is greater than 130
feet (ADWR, 2015). Groundwater is not anticipated to impact this project.

6.0 DISCUSSION AND RECOMMENDATIONS

The SPT N value of less than 10 was used as the approximate gauge of soft soil that may be
indicative of collapsing soils, or other moisture-sensitive materials that may be present beneath
the buildings. The TerraPacific investigation generally encountered soft soils within the man-made
fill within the upper 4 feet, but the native soils were generally hard. A summary of the Amec Foster
Wheeler field investigation is summarized in Table 6.1.

Table 6.1- Summary of Field Investigation
1
Depth of soft soils encountered
Building Boring ID
(feet)
3 B-2 2
6 B-3 and B-5 6
13 B-6 1
1 Soft soils defined as possessing a SPT blow count of 10 or less.

The offset distance (10 to 15 feet) may be a factor in the depth of soft soils encountered within
the borings. It is recommended for estimating purposes that the depth of treatment is 10 feet
beneath the building foundation. The actual depths of soft soils will likely vary across the project
site.

Given the site conditions and the settlement issues, the on-site soils would appear susceptible to
settlement upon moisture increases. Thus, it is recommended the mitigation should address site
drainage in addition to settlement.

6.1 Site Drainage

During the field investigation, which occurred after a recent rain event, the on-site drainage was
noted to pond near certain buildings.

Positive site drainage should be provided and maintained thereafter for long-term performance of
foundations. Where possible, asphaltic pavement or concrete slabs should immediately adjoin
structures. Otherwise, the ground surface should be sloped away from the perimeter of the
structure at a minimum grade of 2 percent for a distance of 15 feet. Additionally, below grade
plumbing should be evaluated for leakage.

Planting within 15 feet of the structure should be restricted to short-rooted vegetation requiring
only light watering. Otherwise, planting within 15 feet of the structure should be contained in
moisture-proof planter boxes with provisions for positive drainage of excess irrigation waters.

Roof runoff should be carried away from the structure by non-erosive devices at the ground
surface, and in no case should long-term ponding of water be allowed near the building during or
after construction.

Heerup Engineering, PC
Chandler, Arizona December 30, 2015 Page 3