Hillsborough is required to treat its wastewater at higher and more expensive standards than other sewer systems because it is in a watershed that drains into Falls Lake. The lake is a 12,000-acre reservoir in Durham, Granville and Wake counties. It is on the Environmental Protection Agency’s list of impaired waters and has been designated nutrient-sensitive by the North Carolina Division of Water Resources.

To protect and restore the lake’s water quality, the state created the Falls Lake Rules to reduce the amount of nitrogen and phosphorous that enter Falls Lake through rivers and streams. The first stage of the wastewater discharge rules went into effect in 2016, and the second stage is expected in 2036. 

In 2014, Hillsborough completed upgrades to its wastewater treatment plant in part to meet the Stage 1 wastewater rule. Additional upgrades to the Wastewater Treatment Plant likely will be required to meet the Stage 2 wastewater rules. 

Read more about the rules from the Upper Neuse River Basin Association.

Hillsborough's wastewater treatment work helps protect the Eno River, which is classified as nutrient sensitive. The town is dedicated to maintaining the high water quality of our river and has successfully reduced the total nitrogen discharged into the river by approximately 85% since 2004.

In 2022, the town discharged into the Eno River only 57.6% of the allowed total nitrogen and 56.7% of the allowed total phosphorus. The allowances are provided by the Falls Lake Rules.

The town's wastewater treatment must meet extremely high standards set by the town, state and federal governments. Hillsborough routinely tests for more than 220 substances in the town's wastewater and solids and meets or exceeds the standards. See the annual Wastewater Quality Report.

Testing

Staff monitor and evaluate water 24 hours a day. The plant has a laboratory to perform frequent checks on the progress of wastewater treatment.

Staff also test various points in the Eno River. Tests occur:

• Upstream of the water intake
• Before and after wastewater discharge
• Downstream of wastewater discharge

The plant uses an enhanced biological nutrient removal process to treat wastewater. Naturally occurring nutrients can cause algae growth, depleted oxygen, and fish kills. The nutrients — like nitrogen and phosphorus — must be brought to safe levels before treated wastewater can be discharged into the Eno River.

Treatment Steps

1. Large item removal — Bar screens remove trash, wood and rocks, which then are compacted for disposal. 
2. Grit removal — Sand and dirt are removed for disposal. 
3. Secondary treatment — Organic materials and nutrients are removed through a series of aeration tanks and sent to large tanks called digesters (see 4). The remaining wastewater moves to the clarifiers (see 5).
4. Solids treatment — Organic materials and nutrients are treated in digesters and then thickened and trucked to a composting facility to be turned into a soil amendment.  
5. Clarification — Rakes slowly skim the wastewater surface for scum like grease, oils, plastics and soap. The scum is pumped to digesters (see 4). Solids settle and are removed for disposal.
6. Sand filtration — The remaining water moves through 6 feet of sand, which removes additional solids. 
7. Disinfection, final treatment — Chlorine is added to kill bacteria. Chemicals are added to neutralize the chlorine. 
8. Aeration — The water is re-aerated before discharge to remove dissolved gases and to oxidize dissolved metals. 
9. Discharge — The treated wastewater is returned to the Eno River at an outfall. 

Wastewater Treatment Plant employees are highly certified and operate and maintain the plant to ensure compliance with state and federal permits and regulations. 

The plant can treat up to 3 million gallons of wastewater per day. It was built in 1977, with upgrades in 2001 and 2007 to improve solids management, nutrient removal and treatment capabilities.

The most recent expansion and upgrade was completed in 2014, allowing the plant to meet state requirements to protect Falls Lake, where Hillsborough’s watershed drains. This upgrade Hillsborough’s discharged water quality among the best in the nation.

Awards

In previous years, the Wastewater Treatment Plant and its staff have won awards for:

• Professionalism in the Operation of a Wastewater Treatment Plant
• Solutions to Operational Problems
• Wastewater Treatment Plant Operations and Maintenance
• Wastewater Treatment Plant Operator

Tours

See what it takes to treat used water for return to the Eno River. 

• Public tours are offered at 1 p.m. on the second Friday of the month in March and September.
• Private tours can be scheduled separately for special groups.
• All tours are open to a maximum of 10 people with participants at least 10 years old.
• All tours require a completed request form.

A pump station is a collection chamber that uses pumps to lift wastewater from a lower elevation to a higher elevation, where the wastewater can flow by gravity. It pumps into a pressurized main called a force main, which ends in a sewer manhole. There, wastewater can flow by gravity to the Wastewater Treatment Plant.

The pump stations require frequent maintenance and weekly inspections. Improperly disposed rags, wipes or other trash can cause expensive repairs. Failures can result in larger sanitary sewer overflows than from a gravity sewer, with subsequent fines from the state.  

Why Pump Stations?

Hillsborough has more pump stations per customer than surrounding water and sewer systems because of the town's terrain. Also, the systems were likely preferred decades ago due to the low upfront costs. Some of the pump stations were built by developers and turned over to the town to own and operate. 

The town assesses sewer blockages to determine the cause and location — whether they are on the utility or property owner's side of a sewer line. Customers may be responsible for the cost of investigation and repairs if their  actions cause a blockage in the town’s sewer main.

Responsibilities

• The town owns and maintains the sewer main or sewer service line in public rights of ways or easements. It will clear blockages of lines in public rights of ways or easements. The town may require property owners to install or relocate cleanouts to the town's specifications. The town may agree to perform the work but may require reimbursement and the granting of property access from the customer.

• Property owners are responsible for blockages in the sewer service line between the house or structure on their property and the public right of way or easement. The town can require installation or relocation of a cleanout at the right of way or easement if one is not present.

Sewer Cleanout

A sewer cleanout is a capped pipe that allows access to the sewer line for maintenance and inspections. Cleanouts typically indicate the ownership line when located at the edge of the public right of way or easement.

The town’s primary responsibility for the sewer system is to protect the environment by maintaining unobstructed wastewater flow in the collection system’s main lines. Crews routinely do preventative maintenance and repairs, remove roots and clean sewer lines with pressure washers. 

Every year, staff is required by state mandate to hydraulically clean a minimum of 10% of the gravity sewer lines in the system. 

Smoke Testing

Crews use non-toxic, non-staining vapor resembling smoke to identify leaks in the sewer system. During testing, it is normal to see smoke escaping from roof vents and from sinks or bathtubs that are not used frequently. If smoke appears from the sink or bathtub, try running water down the drain to fill the dry trap. 

If you see smoke indoors that is not due to a dry trap or that appears to be arising from the ground in your yard, call the Hillsborough Water Distribution and Collection Division at 919-296-9650 to have the problem investigated. 

The town will notify customers of private connection issues that require repair. The town will address issues with public sewer lines. For town and customers responsibilities, see the town Code of Ordinances, sections 14-21 and 14-22. For more information, contact the utility maintenance supervisor at 919-296-9652. 

The Wastewater Collection Division cleans and repairs sewer lines and maintains sewage lift or pump stations. The town has:

• 100.82 miles of sewer lines, which includes:
  • 84.06 miles of gravity sewer lines
  • 16.76 miles of force main sewer lines
• 27 public pump stations
• 2,163 sewer manholes

Awards

In previous years, the Wastewater Collections Division and its staff have won awards from the N.C. American Water Works Association-Water Environment Association for:

• Outstanding Wastewater Collection Operator of the Year
• Small Wastewater Collection System of the Year

Fats, oil and grease poured down the drain will collect and stick to plumbing and sewer lines. Over time, lines can become blocked, causing sewer backups or overflows.

Properties that discharge greasy wastewater are required to have interceptors for fats, oil and grease. Residential customers can obtain a free fat trapper from the town. They also should:

• Discard used fats, oil and grease with other garbage or recycle at an Orange County solid waste convenience center.
• Avoid or limit use of garbage disposals.
• Scrape plates into trash cans.
• Use paper towels to wipe leftover oils and fats from pots and pans.

Fat Trappers

The town provides fat trappers to water and sewer customers to help keep grease and oils out of the sewer system. To receive a fat trapper or additional bags, contact the utilities infrastructure protection supervisor or visit the Town Hall Annex, 105 E. Corbin St., where water bills are paid.

Video

• Fats, Oils and Grease Program

Only waste and toilet paper should be flushed.

Household cleaning and personal hygiene products labeled as flushable or safe for sewer or septic systems do not dissolve. Additionally, do not dispose of trash, medicine or other items in the sewer system. These items clog sewer lines and can damage sewer pumps and other equipment. 

For more information, contact the utilities infrastructure protection supervisor.

Video

• No Wipes in the Pipes