The depth of subsurface facilities can never be guaranteed. Prior to any new development, utility lines are normally constructed. The depth of any subterranean utility lines will alter if the terrain is graded, leveled, or reshaped in any way. The depth will also alter due to natural earth settling. If you need to dig near the locate marks, hand-dig (with a shovel) or soft-dig (with air or water pressure) within 24 inches of either side to prevent damaging the markings.
How close can you dig to a utility line?
- Maintain a distance of at least 18 inches between your trenches or holes and the 811 markers. Because the equipment used to find subterranean wires aren’t always perfect, 811 standards recommend keeping holes or trenches at least 18 inches away from marked lines on both sides.
- If you built subterranean wiring or pipelines yourself, look up their location in your notes. Because most irrigation pipes and low-voltage wires are shallow, you can locate them by drilling a series of test holes by hand.
- Private location services can evaluate your property and locate any subsurface pipes, conduits, or wires for a fee. This is especially useful for private utility lines that were not installed by the government.
- Slowly dig. Irrigation lines and landscape lighting conduits and cables are not detected by 811 locating services, so dig slowly and deliberately, inspecting the excavation for unexpected pipes and wires on a regular basis.
How deep should a water line be to avoid freezing?
“Bury it deep,” as the old adage goes, is the best way to protect water pipes from cold weather damage. Water lines should be protected from freezing if they are positioned below the lowest level of frost penetration (five to six feet or more in many cold climate settings).
This may be simple enough with contemporary building equipment. However, it isn’t always the best option. The biggest issue arises when bedrock is near the surface, or when the water pipe must cross another utility line, and the underlying rock makes digging further problematic or demands blasting.
Water lines that must pass through environmentally sensitive places, such as wetlands, are another issue. It’s possible that deep digging won’t be allowed.
Utility pipe burying practices in Norway and other cold European countries are significantly less conservative than in the United States. Even here in the United States, many cold-climate water departments have come to their own judgments on the practicalities of shallow burial with protected pipe and are now using it.
Engineers, on the other hand, are still wary of the idea of shielded shallow burial. They’re looking for hard evidence, not empirical “real-life” stories. The Cold Regions Research & Engineering Laboratory (CRREL) of the US Army Corps of Engineers is supplying the information.
The subsurface burial approach, according to CRREL researchers, has merit for the US construction industry and the city governments it serves. Utility installations can be sped up with significant time and labor savings if a sound process for insulating water pipes to keep them from freezing can be created. Shallower ditches also save time and money by avoiding the need for shoring, which is required by OSHA after excavation reaches a specific depth.
The Hanover, New Hampshire-based Research & Engineering Laboratory proposed a multi-part effort to illustrate the idea of insulating water lines to prevent them from freezing.
First, CRREL and the University of New Hampshire would optimize and test an existing finite element computer program. A designer can use a finite element program to model various insulation configurations and do “what-if” calculations based on projected temperature and soil conditions. The designer’s capacity to change and adjust many conceivable settings and observe the consequences is the program’s beauty.
Second, an adequate insulation shield design and installation would be created. CRREL chose extruded polystyrene as the insulating material since it had already been used in a number of cold zone projects. Extruded polystyrene is robust (compressive strengths up to 100 psi are available), lightweight, moisture resistant, and easy to cut for installation. At 40 degrees Fahrenheit, it has an outstanding thermal resistance rating (“R” value) of 5.4 per inch of thickness.
The Corps of Engineers’ Civil Works Construction Productivity Advancement Research (CPAR) program was chosen by CRREL to create the project. CPAR requires an industry partner to share costs and oversee the plan’s technology transfer.
CRREL partnered with the Berlin Water Works in Berlin, New Hampshire, where the field study would be conducted. Owens Corning, a maker of Foamular extruded polystyrene insulation, was the third partner in the equation.
As part of the strategy, Owens Corning contributed the Foamular insulating materials and provided technical support in their installation. The Berlin Water Works provided the test sites, excavated the new pipe, and installed the insulation.
Berlin, NH, has a population of roughly 12,000 people and is located in the White Mountains, a cooler region than CRREL’s headquarters in Hanover, NH. It was also a good test location because the city is built on bedrock that is quite close to the surface, breaking the surface in several spots.
CRREL was first approached by Berlin’s waterworks firm for advise on freezing issues with an outdated water system made up of small 2″ to 6″ galvanized pipes. The testing could be completed with little additional construction expense because a number of EPA-mandated plumbing redesigns were due to be undertaken in various sections of the city.
The principal test site for CRREL was a dead-end hillside roadway. Because there was no direct flow of water and hence no heat transmission to the soil, the dead-end provided a very demanding test environment. A new protected water line with an 8″ diameter was numerically designed and then built. For three winters, it was monitored via a series of thermocouple placements.
For the first year, the shield was designed conservatively, with a 6″ thick covering of Owens Corning’s Foamular extruded polystyrene insulating inverted U around the 8″ ductile iron pipe. The sides of the U were 2′ tall, extending even with or slightly below the pipe’s bottom, which was 5 feet deep. The shield’s total width was 4 feet. Foamular was delivered as 2″ thick, 4 8 foot boards that could be snapped or cut to size on site.
During the second year, thermocouples were inserted to detect temperatures in an unshielded pipe, allowing the numerical model to be confirmed further.
Finally, a second shield design was created and erected on another street during the third year. The design was purposefully more aggressive this time, with the pipe elevated at 3.5′ and surrounded by a 4″ shield. Over the course of a winter, thermocouples were used to monitor this test installation, and once again, a good connection was found between theoretical and real temperature data.
From start to finish, the project took around 3 1/2 years. Its achievements included proving CRREL’s finite element technology’s capacity to accurately calculate underground heat flow. Before committing to a specific course of action, designers can apply any settings they are comfortable with and watch and analyze the results on the screen.
The merit of building a water pipe system for cost savings and ease of construction, rather than merely digging deep, is a second conclusion to be derived from the test. Overall, studies have demonstrated that frost shields are a realistic and effective alternative when cost is a factor.
A shield can be created to satisfy specific site criteria using finite analysis and extruded polystyrene insulation technologies. Bottom-line cost savings are a benefit for the construction industry, municipal governments, and the communities they serve. Taxpayers pay less, and the government saves money.
Is there a need for an air gap in Idaho?
When potable water is discharged into the drainage system, an acceptable air gap of two pipe diameters from the supply inlet must be used, but the distance must never be less than one inch (25.4 mm).
Is it possible to have a gas outlet for an appliance in another room?
The gas supply outlet must be located in the same room as the appliance, and the connector cannot be hidden within or routed through any wall, floor, or barrier.
Can I go as far as I can before dialing 811?
This figure comes from the Common Ground Alliance (CGA), and if it sounds disturbingly high to you, it’s because many people are unaware that they must call 811 before digging.
While the ground may not have thawed where you are, April is National Safe Digging Month, and it’s a good reminder to know what you need to do before breaking ground on this year’s projects.
According to data collated by CGA from various industry associations, there are more than 100 billion feet of subsurface utilities in the United States, so you can’t assume your customer’s property is free of them.
There is no limit to how deep a person can go before calling 811. CGA advises that any time you put a shovel in the ground, whether it’s to plant little shrubs or build a fence, you should contact because many utilities are buried just a few inches below the surface.
Even if an area has been designated previously, erosion and root system growth might change the depth or location of buried wires, so call each time you start a job.
Calling 811 is also not an optional chore, as every state has a different statute that requires people to contact before digging. While the amount of time you have to call 811 before digging differs by state, you can find your state’s standards here.
It is a frequent misperception that dialing 811 costs money; nevertheless, dialing 811 is completely free. Utility companies cover the cost to protect you, your staff, and your customers. When you don’t call, hit a utility line, and are held liable for the damage, the true expenses effect your business.
Some utility companies charge not just for the expense of dispatching a staff to repair or replace the damaged property, but also for the loss of service caused by the outage.
In recent years, some states have enacted penalties and fines to aid in the enforcement of the law. Mississippi passed a law in 2016 requiring first-time offenders to complete a compliance training course.
Second-time offenders within a five-year period must complete a training course or face a fine of up to $500 per offense. Malicious activities with the aim to destroy subsurface lines result in a training course and fines of up to $5,000 per event for third-time crimes in a five-year period.
Here’s how the 811 system works and what to expect:
- Two to three days before digging, call 811 or submit an online request to your local one-call center.
- The affected utility companies will be notified by the one-call center. Wait two to three days for the utility operators to react to your request (this varies by state). For each request, an average of seven to eight operators are notified.
- Verify that all of the operators who are affected have responded to your request. The process for confirmation varies by state.
- Dig around the designated locations with care. The majority of state rules prevent machines from being used within 18 to 24 inches of a utility that has been marked. Hand dig or use vacuum excavation if you need to dig closer.
Keep in mind that depending on the state, the locate ticket is only good for a set amount of time, and if you want to continue, you’ll need to call 811 for a re-mark.
Stop working immediately if one of your employees accidentally hits a pipeline. The processes that follow differ depending on the type of utility line hit.
When dealing with natural gas, propane, or petroleum lines, leave the area and contact 911 as well as the facility operator. Don’t do anything that could start a blaze, and make sure everyone is aware of the situation. Keep the public out by cordoning off the area. Stay away from the gas and do not attempt to repair the pipe on your own.
Warning everyone in the area, including emergency responders, that the ground and objects near the point of contact may be energized in the case of electrical wires.
If you have a radio or phone, call the electricity utility operator or the fire department. Otherwise, stay on the excavator and ask someone to call for utility and emergency help.
Those near the excavator or point of contact should keep both feet together and remain still. They must not come into contact with the excavator or the material. Only leave the excavator and the surrounding area after an official from the electric utility has declared it safe. If a fire, explosion, or other hazard requires quick evacuation, jump (not step) from the apparatus and land with both feet. Make sure you’re at least 25 to 30 feet away. Take no ordinary walking steps.
Notify the facility owner of any damaged communications cables, and do not study or stare at broken, severed, or disconnected fibers. Keep a safe distance away and block the area to keep others out.
Contact the pipeline operator after examining the situation and ensuring that nothing appears to be harmed. Minor nicks or dents can lead to major issues in the future.
If a homeowner has consulted you but intends to do it themselves, remind them that calling 811 isn’t just for professionals; anyone planning to dig must dial this number.
What is the minimum depth at which an electrical line must be buried?
Metal conduits should be buried at least 6 inches below the soil surface. You can also run them under a 4-inch concrete slab at a depth of 4 inches. The conduits must be buried beneath your driveway at a depth of 18 inches, and they must be buried beneath a public road or alleyway at a depth of 24 inches.