At a recent 2030 District Partner meeting, Pittsburgh Water and Sewer Authority’s James Stitt shared updates about how PWSA is using its stormwater fee system to encourage and implement solutions to our region’s challenges. Here is a summary of what we learned.
Several major factors come together to make stormwater a major issue for the Pittsburgh region. Firstly, most of the sewer system in Pittsburgh is a combined sewer system, meaning wastewater and stormwater travel through the same set of underground pipes.1 The sewer pipe system leads to ALCOSAN’s wastewater treatment plants, but when the system becomes overloaded with water during storm events, sewer outfalls discharge the excess water and sewage into the rivers.1 According to ALCOSAN, approximately 9 billion gallons of wastewater overflow into the region’s rivers each year.2 Remember the warnings to not swim in the river after large storms? This is why.
Secondly, the frequency and intensity of storms has been increasing over the past few decades and is projected to continue to increase due to climate change. Both factors contribute to the increasing amount of precipitation the region receives.
Thirdly, Pittsburgh’s expansion and development over the past 100 years has resulted in a drastic increase in the number of impervious surfaces across the region – areas like concrete and pavement where water can’t seep into the ground and creates runoff.4 The decline of green space and the buildup of impervious surface increases the amount of stormwater which enters the sewer system.3 Pittsburgh’s already stressed sewer system cannot handle the increasing amounts of rainfall that are expected over the coming decades.
Both PWSA and ALCOSAN are working on strategic plans to help minimize the amount of wastewater reaching our rivers. A major portion of the solution to this problem is increasing the amount of green infrastructure within the region. Green infrastructure utilizes vegetated areas or permeable surfaces to capture stormwater and allow it to infiltrate into the ground, reducing the amount of stormwater flowing in the sewer system. To help fund the implementation and maintenance of green infrastructure and stormwater management projects across the region, PWSA has created a stormwater fee.
PWSA’s stormwater fee is not tied to water use but is based on the amount of impervious surface a property has. Every parcel of land in Pittsburgh has been mapped for impervious surfaces, and the amount of impervious land on each parcel determines the amount of the fee. PWSA defines impervious surfaces as all manmade surfaces that prevent or limit water infiltrating into the ground.4 Most commonly, this refers to buildings and concrete and asphalt surfaces, but for a full list of impervious surfaces, see PWSA’s stormwater FAQ.
PWSA’s stormwater rates are based off the number of equivalent residential units (ERUs) of impervious surface that each land parcel has. ERUs are the industry standard, and in Pittsburgh, one ERU is defined as 1,650 square feet of impervious surface. The fee is applied differently for residential and non-residential properties: residential properties are grouped into one of three tiers approximating 0.5, 1, and 2 ERUs, whereas non-residential properties are charged for each exact ERU of impervious surface on their land parcel. For example, if a non-residential property had 16,500 square feet of impervious surface, that would equal approximately 10 ERUs (any partial calculations are rounded up). In 2022, the stormwater fee for each ERU was $5.96, and this will increase to $7.95 for 2023.
All land parcels in Pittsburgh can be found on PWSA’s Stormwater Fee Finder website. The image below shows an example. Selecting a parcel reveals the calculated square footage of impervious surfaces and the corresponding number of ERUs. Multiplying the number of ERUs for a parcel by the stormwater rate will result in the stormwater fee for the parcel.
Note: Customers who believe that their impervious surface area was calculated incorrectly can dispute the calculation with PWSA using their website (www.pgh2o.com/report-an-issue), or by calling their customer service line (412-255-2423 #5). Disputes will be reviewed by PWSA’s engineering department, and if approved, will be credited to the account for all prior bills.
PWSA has a credit program to reduce the stormwater fee on parcels that have installed stormwater management systems. The credit applied depends on how much stormwater runoff is captured. It is important to note that the credit only applies to the amount of impervious area that is affected by the installed stormwater management systems. A property does not have to capture runoff from all of the property’s impervious surfaces but can receive credit for capturing any portion of runoff from the property. The credit varies depending on the property type and amount of runoff captured; the different options are listed in the table below.
| Credit | Requirement | |
| Residential | Lower fee tier, or 50% reduction for Tier 1 properties | Capture ¾" of water from impervious surfaces on property |
| 2016 Standard (non-residential only) | 45% reduction on affected ERUs | Capture ¾” of water from impervious surfaces on property |
| 2019 Standard (non-residential only) | 60% reduction on affected ERUs | Capture 1” of water from impervious surfaces on property |
| Enhanced Volume Control (non-residential only) | 75-100% reduction on affected ERUs | Capture at least 1¼” of water from impervious surfaces on property |
The credit process begins with an application, which requires details of the stormwater management system capacity and its associated documentation. This form can be submitted online or mailed to PWSA. The application will be reviewed within 3-30 days, and if approved, will last 3 years before it needs to be renewed.
A list of accepted stormwater management systems, also known as best management practices (BMPs), is listed below. Details on these can be found in Chapter 6 of the Pennsylvania Stormwater BMP Manual.
This project was completed in September of 2022 and installed permeable pavers, storm inlets, and underground stone storage in the parking lanes on portions of Kentucky Avenue and Howe Street.6 Also incorporated were sidewalk and tree replacements.6 This project will reduce the street and basement flooding that was common in this area and reduce the occurrences of combined sewer overflows.6
This project has two phases. The first phase redeveloped the existing park, installing new equipment, amenities, and a large rain garden, complete with additional underground stormwater storage.7 The second phase will direct rainwater from surrounding streets into the park’s green infrastructure and underground storage.7 In total, the project can hold over 350,000 gallons of water and are expected to be able to help manage two million gallons of stormwater each year.8 The Wightman Park project demonstrates that green infrastructure can be incorporated into city redevelopment to provide multiple benefits to the community.
One of the first green infrastructure projects that PWSA developed, this man-made, vegetated trench known as a bioswale runs alongside a 585-foot-long section of Centre Avenue.9 The length of this bioswale prevents around one million gallons of stormwater from entering the sewer system each year.9 Water that enters the trench infiltrates into the ground or is absorbed by the plants. This project includes underground storage tanks to capture additional stormwater and slowly release it into the sewer system.9
These projects are just several examples of initiatives that PWSA is implementing to help Pittsburgh’s stormwater problem. The stormwater fee helps fund the projects above and is ultimately just one tool in our toolbox for cleaning our rivers and improving the region!
https://www.pgh2o.com/your-water/sewer/our-combined-sewer-system
