Is it Safe and Permissible to Dig a Hole in your Backyard without Consulting Local Authorities?Rules and Regulations for Excavations on your Private Property | Depths of Underground Utility Services
So you have a little project that you want to do on your private property, and this project involves trench excavations, but before you proceed with your project, can you legally dig a hole in your backyard without permission from local authorities and utility operators?
You have been talking to a neighbour or friend who has an amazing garden, a beautiful landscaping feature like a water fountain, koi pond, stone/metal sculpture, pathway lamp posts, curb mailbox, tropical plant, palm trees or an outdoor structure like a pergola, gazebo, screen wall, boundary wall, a rustic outdoor shower cubicle, barbeque area or fireplace. Maybe it’s a septic tank, stormwater gulley, manhole or inspection chamber. All these outdoor home improvements, additions and works will require you to dig a hole, trench or excavation of some sort. The width and depth of the excavation will depend on what you are building or what you want to install. If you have building drawings of the structure, the draughtsman, engineer, architectural technician or landscape designer should show you the dimensions of the structure, i.e. the plan view, elevations and cross section details of the foundations that need to be dug. This information is required by local building authorities, so make sure you have the drawings and other information about your site at hand. Local building authorities need to know the depth and width of your excavations, as well as the site conditions before they give you a permit or permission to dig holes and pits on your property.
Regardless of where you live in the United States, digging a hole in your home yard comes with risks that may cost you legally or financially. You do not just stand a chance to violate local ordinances and get fined, but digging holes arbitrarily on your private property may pose a hazard to your health and physical well being. Your neighbours as well as the whole community may be affected by your actions. Hazards of digging holes in your backyard without consulting local authorities and utility operators include damaging underground water, sewer and gas pipes. Damaged water and sewer pipes can cause flooding in the surrounding environment. Hitting buried gas pipes can cause fire outbreaks and air poisoning. Broken electricity cables and wires left exposed pose a risk of electrocution and fire outbreaks.
According to CGA (Common Ground Alliance) and city council ordnances in various parts of the United States, you need to call 811 before you dig a hole on your property. There is no legal minimum depth that you can dig before calling 811. This is due to the fact that environmental conditions such as ground settlement, rainfall, floods, surface runoff, soil erosion and deposits can change the depth of topsoil, reducing or increasing the cover for underground services.
How to Contact 811 for Backyard Excavations
To call 811, simply visit the CGA site, choose your state and submit an online application for permission to dig holes on your property. Your state 811 call centre will create a ticket that allows you to follow up the progress on your application. Alternatively, you can pick up your phone and call 811 directly to speak with the call centre agents. The call centre agents will submit your request and notify you of utility operators who have responded to your application for excavating in your home yard. After submitting your request, you have to wait for responses from utility operators of underground services such as drainage pipes, gas pipelines, water supply lines, telecommunication and electricity cables. They provide feedback through your local 811 call centre, so you will only interface with the call centre.
It may take 2 to 3 days for utility operators to respond to your application, but the time varies with each state. Once your request is processed, the utility operators will send out their inspectors to come and mark the positions of underground services in your yard.
Remember, you cannot start digging until all utility operators have responded to your request and marked the positions of all underground services. Do not remove the paint markings or any flags that are used to locate underground services. If you lose the markings in the course of your construction activities, you will be required to submit another application for re-marking.
Rules and Regulations for Excavations on your Private Property
After you have obtained permission to dig holes inside your residential lot, there are a whole lot of rules and regulations that you have to abide with. Caution and care should be taken when digging near utility markings. OSHA and CGA provide health and safety guidelines for digging trenches, holes and excavations.
Distance from Utility Line or Service / Tolerance Zone
State building codes recommend digging 18 to 24 inches (457mm to 610mm) from the utility and its marking to avoid damage to the utility line. The homeowner and the contractor are prohibited from using mechanical equipment when digging within this perimeter, which is known as the tolerance zone.
You can only dig within the tolerance zone using hand tools and vacuum excavators which give you a high degree of control and precision. A vacuum excavator is the best option for “soft digging”. It breaks the earth and loosens soil particles by blowing air or water at high pressure. With this method, there is no risk of damage to underground pipes. On the other hand, hand tools can cause damage to buried lines if delicate and proper techniques are not used. While a hand tool will be useful for breaking hard surfaces such as concrete paving and slabs, you must verify that there are no service pipes or conduits embedded inside the concrete or too close to the slab.
Dig Alongside the Service Line, Not on Top
As a rule, you must not use a hand tool to dig on top of or over a buried service line. Dig alongside the utility line on both sides parallel to the line, and observe the tolerance zone stated above.
Scan for Underground Services Every 300mm of your Dig
Before digging alongside the buried utility line, you must use a CT Scanner to locate the depth of the service line as well as other possible uncharted services which might exist under the spot or working area. This device is also known as a Cable Locator or Cable Detector. However, you are not only going to use this device on your first dig, but you have to repeat the scanning procedure every 300mm (12 inches).
There are different types of scanners for detecting specific underground materials. Metal locators can only detect metal pipes and electric cables. They cannot detect non-metallic pipes such as plastic, PVC, clay, fibre cement (asbestos cement), HDPE and cement.
To ensure that non-metallic underground services are not missed in the cause of prospecting and scanning, you have to use a GPR device (Ground Penetrating Radar). A ground penetrating radar device can detect all types of buried lines, both metallic and non-metallic.
How Deep Can You Dig Without Calling 811?
How deep can you legally dig in your backyard? As has been said previously, there is no minimum or maximum legal depth of which you can dig holes in your backyard residential lot without calling 811 or consulting the local building authorities, meaning that you have to call 811 before digging any kind of hole. However, for practical purposes (leaving the legal requirements aside), it is generally safe to dig holes no more than 300mm deep (12 inches) on your property, and it’s much safer and non-risky to dig holes no more than 100mm deep (4 inches). It will be quite safe as long as you are digging within your residential lot, and not outside the lot, for example on street paving etc. Digging holes on your street curb and paving will require a permit in most cases, depending on your state laws.
Earthwork Support for Deep Trenches
Earthwork support to prevent the risk of collapse must be installed inside a trench with a minimum depth of 1.5m (5 feet). Timber shoring is a common method of preventing the walls of a trench from collapsing onto the worker. Trench boxes and sloping are other protective measures that can be used. You cannot work inside in a trench that is 1.5m or deeper if there is no earthwork support.
Permit for Deeper Trenches
A permit will be required for trenches that are 5 feet (1,520mm) or deeper. Workers may not enter or start working in such trenches unless they have obtained a permit from DOSH which satisfies the requirements for earthwork support and safe access in and out the trench.
Safe Access and Exit from Excavation
The contractor or anybody responsible for digging pits and trenches on your residential lot must provide a safe means of access and exit for workers. This is required for trenches which are 4 feet (1,220mm) or deeper. Safe means of access and exit can be provided by making use of steps, ladders and ramps.
Safe Load / Traffic Distance from Excavation
As a rule, all mobile and static loads should not encroach within 1000mm (3.3 feet) from the excavation or trench. No machinery, vehicles, equipment, materials or people should stand within 1000mm from the excavation. Material excavated from the trench should be stored outside the 1000mm perimeter on both sides of the excavation.
Protection of Exposed Utility Services
Once underground services have been safely exposed, they should be protected from damage by people, machines, tools, vehicles and weather elements. Make sure that the services are supported as required, but you cannot remove them without a permit.
Protection of People from Exposed and Hazardous Utility Services
Exposed services can be hazardous especially if they are not protected or if they are damaged by workers. In order to prevent hazards and provide a safe environment for both workers and the community, you may be required to disconnect the services temporarily. If your neighbours and the community are going to be affected by this, they should be notified in advance.
Damaging a gas pipeline with your tools will cause hazardous fumes to escape and ignite fires. Damaged electrical cables pose a risk of electrocution and fire outbreaks. Hitting a water supply pipe or drainage pipe can cause flooding in the yard. State and city authorities impose fines for damage to utility services.
Safe Backfilling of Trenches and Excavations
When you are done with your work or outdoor project, you have to place and align the services back in their original position. Make sure that the backfill bed on which the pipe is lying is compacted to a suitable AASHTO density to avoid earth settlement. The trench backfilling must be free from organic material, rocks, concrete, bricks, stones, frozen material and other hardcore material. Do not encase, cover up, bury or embed the service pipes in wet concrete because it will be difficult and hazardous to break up the hardened concrete during a utility dig-up.
Backfill the exposed utility trenches with squeegee or well-graded sand, loam soil, silt sand or any Class D bedding from excavated material.
Depths of Underground Utility Service Pipes and Cables
It’s important to know the depth at which various underground utility services are buried.
Electricity Conduits / Cables:
The minimum depth of underground electricity cables is 450mm (18 inches), and they can be as deep as 1000mm (40 inches) or more depending on the voltage they are carrying. The higher the voltage, the deeper the cables should be, but the depth may vary depending on the method of wiring, type of wire sheathing (conduit) and zoning/land use requirements in a state.
Underground gas pipelines are buried at various depths, depending on their location, land use, zoning, as well as the type of pressure they are carrying. Gas pipes on private residential lots are buried at a much lower (shallow) depth than those laid under or near roads, highways and pedestrian walks. On private residential lots and building entrances, gas pipes are laid 375mm (15 inches) under the ground. On pedestrian sidewalks, they are found 600mm (24 inches) under the ground, and on roads and highways, they will be buried much deeper at 750mm (30 inches).
High-pressure gas pipelines are buried much deeper than low-pressure pipes due to the significant damage that they can cause in enclosed and confined spaces in the event of a rupture. The minimum depth of underground high-pressure gas pipes is 900mm (35 inches).
Water Supply and Drainage Pipes:
Site water reticulation pipes and waste/rainwater drainage pipes must be laid deep enough to withstand freezing caused by temperature drops at night, in the morning and winter season. As a result, main water pipes, drains and sewerage pipes should be buried 4 to 5 feet under the ground, but a minimum depth of 900mm (3 feet) is the standard. On a private residential lot, the minimum depth can be reduced to 750mm (2.5 feet).
Water and drainage pipes can be installed at a much shallower depth in regions with warm, sunny and hot climates where the depth of soil freezing is low (closer to the surface). In cold climates, the depth of soil freezing is very high, which means that frost will penetrate deeper into the ground.
Major Hazard Pipelines:
Natural gas pipelines and other pipelines which carry oil, highly explosive gas and liquids are known as major hazard pipelines due to their extremely high risk of causing explosions and fires when the escaping gas is ignited. As a result, they are buried deeper than 900mm (3 feet). Under trafficked areas such as highways and railway lines, the pipes are laid even deeper. The minimum cover for pipes under railway crossings is 5.5 feet (168 metres) for cased pipes, and 10 feet (305 metres) for uncased pipes.
Telecom cables running under the road and highway are installed 600mm (2 feet) deep under the surface of the ground.
Internet Optic Fibre Cables:
Underground internet cables are buried in a trench with a minimum cover of 450mm (1.5 feet). A much lower minimum cover of 300mm (1 foot) is required when the cables are running under a concrete path or driveway.
In cold and freezing climates, the cables are laid deeper, at a minimum depth of 762mm (30 inches) and up to 1067mm (42 inches). The depth is also much higher in conditions where the fibre optic cables are running under roads, highways and railway tracks.