Did you know that HDD can reduce the environmental impact of your utility projects by 70% or more, at the same or less cost than open trench methods?
With HDD, the impact zone is reduced to an area 1.5 times the diameter of the pipe, as compared to open-cut methods.The vast majority of sewer and water projects are designed to be installed by traditional open trench methods.
Many owners are not aware that HDD (Horizontal Directional Drilling) offers a solution which drastically reduces environmental and public impact, and can reduce project costs as well.
Environmental Benefits
Using HDD greatly reduces carbon emissions because less diesel fuel is used to install the pipe.
Take a look at the fuel required for a typical day installing 300’ of 8” water main, in asphalt.
OPEN TRENCH METHOD HDD METHOD
40 ton excavator (digging): 10 GPH 27,000lb directional drill 5 GPH
20 ton excavator (compaction) 7 GPH 1000 gallon vacuum trailer 1 GPH
4 yard wheel loader 9 GPH Rubber tired backhoe 3 GPH
(5) end dump trucks 28 GPH Dump truck 7 GPH
rubber tired backhoe 2 GPH (partial use) Mixer truck 2 GPH (partial use)
water truck 2 GPH (partial use) (2) 1 ton gang trucks 2 GPH (partial use)
(2) 1 ton gang trucks 2 GPH (partial use)
Total: 62 gallons per hour Total: 20 gallons per hour
or 496 gallons per day or 160 gallons per day
The above example shows that just 32% of the diesel fuel required for open trench was used for HDD.
Now consider the impacts of the import of aggregate base and asphalt, trench bedding and backfill.
When using HDD the consumption of these items is reduced by 80 – 90%.
Less Public Impact
Less equipment on the road means smaller lane closures. Because HDD is linear and does not need access to the side of a trench (i.e. 2 lane widths); many times the installation can be made without disrupting two-way traffic. In tighter areas, flaggers can be used to maintain one-way traffic, whereas full road closure would have been required with open trench. Also, surrounding area traffic and roads are subjected to fewer semi trucks for
the duration of the project.
The installed pipe is enveloped in hydraulically-placed slurry which dries to leave no voids and 360° pipe support.Standard Pipe Products
HDD can now be used to install most of the standard pipe products you’ve specified in the past. Restrained joint C900 pvc, dr 21 and 26 sewer pipe, ips and dips hdpe, restrained joint ductile iron, and fusible pvc are all readily available and warranted by the manufacturers for installation by HDD.
HDD requires less space; makes less impact. In street installations the equipment can be staged in a linear fashion to reduce width. Workers are only exposed to trench depths at tie-in locations.Reduced Costs
Since fewer resources are needed to install pipe via HDD, in many cases a cost savings will be realized.
Cost savings are subject to several factors:
• Less Material: Asphalt paving, aggregate base, trench backfill, and pipe bedding are all reduced by 80%-90%.
• Utility Conflicts: Much of the damage to unmarked utilities which occurs during open trench construction is eliminated, as the drill passes harmlessly under many lines that would have been ripped out while excavating to grade.
• Design Changes: When a known utility is found to be in conflict with the design, elevation changes can be less expensive with HDD, particularly when the change calls
for increased depth.
• Traffic Control: Due to the narrower work footprint, flagging labor can be eliminated in many cases.
Traditional open cut methods by necessity impact a large area. Workers are exposed to deep excavations for the entire trench length.Quality Assurance
As with any utility construction, HDD must be performed correctly to ensure
a quality installation. MGE Underground can assist you during the design
phase with technical specification language, inspection requirements, and
can review your 50% drawings for constructability.
Please call or email us with any questions you may have. We are eager to help you make HDD a valuable part of your construction program.