User Manual

6 Utility AirSpade Technical Applications Bulletin
DRY EXCAVATION – ADVANTAGES
Dry excavation tends to be the preferred methodology where soils
are not as compact, where water is not readily available, or where
immediate backfill of the hole is required. In smaller-scale excavation
projects, or when working around brittle underground utilities, this
method is often preferred due to lower operating pressures.
Dry excavation allows for back-
filling the hole with the same, dry
excavated spoils. This eliminates
the need to store and dispose
a wet/muddy slurry of material
generated by hydro excavation.
Dry spoils can also be off-loaded
on site as necessary. Backfilling
excavated spoils eliminates the
need to travel and pay for a
dump site.
Another advantage is that limit-
less quantities of compressed
air can be generated on demand.
Onboard compressors generate
compressed air as required vs.
the need to refill a water tank.
Finally, when working around
high voltage lines, dry excava-
tion is more often the preferred
choice since air is non-
conductive.
High-powered, mobile vacuum
units are essential pieces of
equipment for safely locating and
uncovering underground utilities.
Their effectiveness is greatly
enhanced when operating in
tandem with either compressed
air, or high-pressure water –
techniques known as
Dry Excavation and
Hydro Excavation.
In dry excavation, high-pressure
compressed air delivered by
a nearby air compressor, is
directed at the work surface
using a Utility AirSpade or
equivalent tool. The compressed
air agitates and loosens the soil,
partially propelling it airborne. A vacuum system then sucks up the
soil into a tank, where the soil is stored to be reused or transported
offsite.
Hydro excavation works in a similar manner. High-pressure water,
delivered by an onboard pump, is directed at the work surface where
it cuts through the soil, creating a slurry. The vacuum system then
sucks up the slurry into a tank where the soil is stored to be reused
or transported offsite.
DRY AND HYDRO EXCAVATION APPLICATIONS
Both dry and hydro excavation have become standard operating
practice for a wide array of applications including utility locating,
keyholing, potholing, installing light poles, valve box cleaning, repairing
water main breaks, cutting trenches for buried cable, fiber optic
repair, cathodic protection for gas and water lines, and even window
well installation.
Before deciding between these two techniques, understanding the
underlying soil conditions is essential for selecting the proper equipment.
Other factors include travel distance to the disposal site, State and
local weight restrictions, excavation distance from the unit, job site
requirements, and availability of water. Estimating the size of the job
(volume of spoils) is also critical so that the correct-sized debris body
(tank) can be employed to complete the work as efficiently as possible.
HIGHLIGHTING DIFFERENCES BETWEEN DRY AND HYDRO EXCAVATION