On Sept. 29, the Chapel Hill Town Council received a petition to create a stormwater management manual.
And although their unanimous vote to adopt a Stormwater Management Master Plan is a fine approach to how we think about abstractions of storm runoff, it lacks specific clarity as to what re-developers of existing impervious locations like the rezoned Village Plaza property in the Ephesus-Fordham district are responsible for, unless, of course, their existing stormwater runoff conditions are considered acceptable.
Adoption of the petition by council will direct the town manager to create guidelines which will provide developers and citizens a predictable list of public expectations when land development/re-development occurs not only on raw pervious surfaces (although there is not much of that left in mixed-use/commercial zoning districts) but also on impervious, previously developed ones. Impervious has long been the “existing condition” in most of these Chapel Hill locations, and it is eroding our waterways.
The need to create the manual is based on a glaring inequity in Chapel Hill Land Use Management Ordinance (LUMO)-namely item 220.127.116.11.F.3 (allowed post-development stormwater runoff ) which was adopted last May and states:
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“The stormwater runoff rate leaving the site postdevelopment shall not exceed the stormwater runoff rate leaving the site pre-development (existing conditions) for the local 1-year, 2-year, and 25-year 24-hour storm events” (sic)
Runoff rate means volume of water which flows over time, and impervious surfaces (like pavements, roofs, etc…) have much higher runoff rates than do pervious surfaces (like grassed or wooded areas) in 1-yr, 2-yr and 25-yr storm events. In America, runoff rates are measured in cubic feet per second (cfs).
To illustrate the LUMO disparity, contrast the Village Plaza existing conditions (55 percent impervious) to the 35-Ac bucolic American Legion site (perhaps 10% impervious).
It will be much easier for the re-developer of Village Square Apartments (East West Partners) to ensure the post-development runoff rate not exceed the pre-development one because it is already highly impervious. The existing Legion site (assuming it will one day be re-developed under the new higher density zoning), being much more pervious, will be much more challenging to re-develop under LUMO’s post/pre-development parity requirement. In other words, the potential re-developer of the Legion property will face a much steeper challenge and significantly greater expense to sustain its low-impact runoff while LUMO states the acceptability that Village Plaza be allowed to continue making its high impervious impact on Booker Creek.
Is this LUMO approach a reasonable one for the major re-developments slated throughout Chapel Hill municipal limits like the Ephesus-Fordham district?
In mid-July this year, Booker Creek was flooded at an erosive, polluted and turbid rate just below a proposed Village Square Apt’s access road, conceived for connection with Elliott Road across from Burger King.
While the town has proposed funding $1.2 million for stormwater management in the Ephesus-Fordham district, no Ephesus-Fordham re-developer will be held responsible for the already erosive flows their existing properties dump into Booker Creek. While stormwater management is an acknowledged top priority in our town, it is conspicuously absent in LUMO requirements.
And why should taxpayers be compelled to pay for appropriate stormwater management when the Ephesus-Fordham re-developers will reap the benefit not only from increased densities, but from the fact that they will avoid the cost of remediating continued negative impact on our watersheds thanks to LUMO’s acceptance of these unstable, unacceptable pre-existing conditions?
Dale Coker is a former two-term member Community Design Commission.