A new concept proposed for 21st Street
Creative ways to slow down storm water proposed
Last updated 3/20/2017 at 5:12pm
South 21st Street between Josephine and East Carson Street may be the most unique street in South Side. Sections of 21st Street currently accommodate two travel lanes and up to four lanes of parking in spots while serving as an entrance to South Side Park.
Currently, a design process is underway to make the street more attractive and environmentally friendly by capturing storm water.
Recently, representatives from Environmental Planning & Design (EPD), Groundwork|Civil (GC), Western Pennsylvania Conservancy (WPC), Pittsburgh City Planning and Pittsburgh Water and Sewer Authority (PWSA) presented concepts for the 21st Street Complete Green Street Project.
Building on a 2014 visioning process with a 21st Street design charrette, the streetscape project will have a heavy focus on green infrastructure with both underground and above ground components.
Faced with a solution to Pittsburgh's combined sewer overflow problem that will cost in the billions of dollars, planners are looking at different areas of the city and the 21st Street corridor is a top priority.
Katherine Camp, Green Infrastructure Program Manager for PWSA, addressed the audience about the city's sewer system saying the old way of doing things was to move the water away very quickly by combining the storm water and sewage. When there was a lot of rain, it would result in overflow.
With more development in the city, there has been more storm water run-off and more impervious surfaces resulting in more spikes of overflow. Other problems, such as poor water quality and flooding also result from storm water not being managed the way it should be.
One solution to better manage storm water is to keep it on the surface and out of the sewer system.
The focus on storm water management needs to get up to regulatory requirements, affordable to the city, it's got to work, and it has to have benefits, she said. Over the last two years, PWSA has been working on a solution that can be applied on a city-wide level.
PSWA identified the top 30 sewer sheds in the city and narrowed it down with the 21st Street area, designated M-16, one of the six priority areas. In a typical year, M-16 has 61 occurrences, or 434 hours, of storm water overflow totaling 10.2 million gallons of combined sewage and storm water.
The goal is to keep 85 percent of the storm water out of the sewers using a variety of landscaping elements including trees, bioswales and storage tanks.
Although the 21st Street area is only two acres, they are looking at accommodating a larger amount of run-off from South Side Park and the surrounding area in the plan.
In addition to the green infrastructure (bioswales, storage tanks, planting, water polishing, etc.), existing fixed surface elements such as curb cuts, fire hydrants, utility poles, and underground vaults and utility lines have to be taken into account in the design.
As part of the project, Pittsburgh City Planning undertook a parking analysis of 21st Street. Currently, there is a mix of metered, permit and unregulated (illegal) parking in the corridor.
Of the 103 parking spaces in the program area, 64 spaces are down the middle of the street and are unregulated or illegal. Other spaces are metered parking and still others are in a Residential Permit Parking Program area. The parking spaces are technically illegal because the sight lines don't provide a 10' buffer area for those parking to pull out.
The 21st Street corridor from Josephine to East Carson provides unique opportunities in South Side because of the width of the street. Design elements that wouldn't work on a narrower street can be explored because of the street is so wide.
Using overlay maps of all the surface and sub-surface elements, designers were able to start piecing together plans on where water could be stored and absorbed slowly.
A.J. Schwartz from EPD, explained that all of the green infrastructure elements could be described as different kinds of sponges with some holding more water than others. Each block in the four-block area has an opportunity to have a different type of "sponge" due to underground utility lines and vaults.
There is enough capacity on 21st Street to take care of the water coming in the street and adjoining buildings in addition to some of the water coming from South Side Park. The real question, Mr. Schwartz said, "how do you want to see it?"
He presented four "concepts" to the audience to learn which they were interested in seeing happen and which they "just don't want to see happen."
Much of the discussion surrounded parking, in each of the concepts the total number of spaces is reduced, but the number of "legal" spaces increases. Some of the designs kept parking along the curb but eliminated it in the middle of the street in favor of green infrastructure.
One design provided for reversed angle parking down the center of 21st Street requiring drivers to back into the space, improving sight lines when exiting.
Another design called for the street to "meander," or slightly move from side to side. Suggestions also included adding an up-only bike lane connecting eventually to South Side Park.
Each of the designs provides a variety of green infrastructure elements.
Once a design is agreed upon, they will be able to develop a cost estimate and begin pursuing funding for the project.
A copy of the presentation slides is available at: http://bit.ly/2mhJkYI.