Who knew? Drainage Impact Studies just as “worthless” as Traffic counterparts

Slide used by HNTB’s Melissa Kennedy to depict changing Floodplain

Drainage Impact Studies (DIS) are required of every major subdivision preliminary plat submitted to Ascension’s Planning Commission for approval.  That is in addition to Traffic Impact Studies (TIS) long-recognized as “worthless” and not indicative of actual impact on parish roadways affected by every new subdivision.  This just in…DIS procedure is equally flawed.

Planning Commission Chairman Matt Pryor routinely blames the Parish Council for failure to enact meaningful legislation to regulate development, passing the buck with every rubber-stamped approval of every new subdivision preliminary plat.  Maybe, just maybe, Pryor’s straw man is in the process of being eliminated.

As with TIS improvement efforts, the attempt to update DIS originated in the Parish Council’s Strategic Planning committee.  On May 11, 2017 the committee’s agenda included:

Improvement of LDCs, Drainage Impact Studies (Chairman Daniel Satterlee, Jerome Fournier, Planning Director and Bill Roux, DPW Director)

And like TIS improvement efforts, consideration of DIS was removed from the Councilman Daniel “Doc” Satterlee-chaired committee.  TIS was removed to the Council’s Transportation Committee on April 13, 2017 where it seems close to resolution.  DIS was removed to East Ascension Drainage Board the following month.

Would either have been addressed without Doc Satterlee’s taking TIS and DIS on in the first place?  We believe not but what’s done is done.

Fast forward a year and the Council ordered Legal Counsel to draft an ordinance strengthening TIS policy…

Lawler criticizes Satterlee for delayed Traffic Impact (TIS) improvements; resigns from committee

and strides are, seemingly, being made to address ineffectual DIS.  It has been a long time coming.

On October 3, 2016 then Drainage Director Bill Roux, still reeling from disastrous flooding sIx weeks prior, promised a Floodplain Management Plan that would be “suggesting no fill in floodplains.”  Inexplicably, Roux did not attempt to engage the services of HNTB, Inc. until seven months later and that was delayed another three months when Council Chairman Bill Dawson insisted on the issuance of Requests for Qualifications to determine that HNTB was the right firm to undertake the task anyway (with CSRS, Inc. added in for good measure).

HNTB’s Melissa Kennedy delivered a preliminary report at the latest meeting of East Ascension Drainage Board which included Drainage Impact Study Policy study conclusions.

“For conveyance we added…an extension of the model upstream and downstream so that you’re covering beyond just your site to make sure you’re not having an impact upstream and downstream,” Kennedy summarized one of HNTB’s conclusions.

There were many more.

“Once you start adding a lot of fill, that floodplain goes, not only higher, but it extends out further,” she added.

Kennedy also addressed:

“…how to calculate the volume, basically, all fill below the Base Flood Elevation needs to be compensated for.  You can’t count dead storage (in detention ponds) which is, basically, any storage below normal pool.”

No more “counting of (storage) volume that (the developer is) already utilizing to attenuate runoff as part” of the site development.  Other problems with DIS procedures include:

  • Too many inconsistencies in Ascension’s Unified Land Development Code;
  • Outdated design criteria;
  • A disconnect between policy requirements and review procedure;
  • No ties to the parish’s Master Land Use Plan;
  • Significant gaps in policies and procedures.
  • Inconsistent application of design requirements.

HNTB concluded:

“More fill than what you’re wanting to be permitted.”

HNTB recommended

“No increase in upstream or downstream water surface elevation unless (the developer) can prove that there’s no adverse impact or adverse effect on any property…” and a requirement to “mitigate flow changes without increasing flooding upstream and downstream.”

HNTB did not deliver on Bill Roux’s “no fill in floodplains” promise, settling on “three-foot max fill” instead.  Melissa Kennedy did concede: “There are some locations that are just not going to be conducive (pause)…maybe you just shouldn’t build.”

Who knew?

District 4 Councilman Daniel “Doc” Satterlee

“The Drainage Impact Study, like our Traffic Impact Study, (land development) codes, ordinances, in-house policies; just what I and a lot of people thought and still believe…