Tuesday, August 4, 2015

Flooding new cars - climate change, chromium and environmental responsibility

The Maryland Port Authority is troubled because a 250 year storm flooded and damaged 800 vehicles in August of last year. Then something similar happened this June. Now they are scrambling for bigger drains on this 200 acre car storage lot that once was a municipal airport.
Only aerial photography can capture the vast expanse of asphalt and cars at the port exceeding even the largest mall lots
in the suburbs

One would hope that not only brute force  engineering is the answer. But that is precisely what the engineering firm Whitney, Bailey, Cox and Magnani is proposing in form of underground vaults.

How about not sealing the full 200 acre area as one giant sea of asphalt? Pervious pavement, bio-swales, trees?

The usual green answers, though, may not work since the whole site has been the recipient of toxic soil deposits laden with the chromium from the Allied Signal plant that used to sit in the Inner Harbor and forced that site to be entirely sealed off from stormwater with a cap and containment wall. The contaminated soil may also be a big problem for the WCBM envisioned underground storage tanks and all the digging that comes with it.
 Dundalk Marine Terminal Tenants (2010)

A extensive study conducted by Honeywell  (the successor of the Allied Signal holdings) in collaboration with Maryland's Department of the Environment (MDE) under a 2006 consent decree and published in 2011 concluded this:
Investigations show that the only significant movement of hexavalent chromium is from
groundwater flow into storm drains, and from storm drains to the Patapsco River.
Hexavalent chromium has not been detected, however, at significant levels in the river
because it naturally changes to a nonhazardous form (trivalent chromium) in surface
 Hexavalent chromium in groundwater also rapidly reduces to the nontoxic trivalent
form before it reaches the river.
 Groundwater that enters the two largest storm drains during normal conditions of flow
is being captured and treated.
 Accessible portions of other storm drains have been inspected to assess their integrity.
To date, almost 2 miles of storm drains have been relined or replaced to prevent
hexavalent chromium from entering the drains. Tests have shown that relining can
significantly reduce groundwater infiltration into storm drains.
 The onsite water treatment plant has treated an average of 42 million gallons of
stormwater per year since 2006, and plant discharges meet MDE permit requirements.
The study than offered five remedial options and ultimately considered alternative three ("Enhanced Isolation and Containment") to be the preferred one:
Existing storm drain and treatment system (Remedial action report)
Alternative 3 enhancements include the following:
 Installation of tidal exclusion vaults at the remaining storm drains constructed in COPR
(the vaults will prevent flooding of the drains and allow them to be inspected, cleaned,
and sampled);
 Relining of the affected storm drains to mitigate groundwater intrusion;
 Rigorous pavement inspections and repairs using new and improved methods to verify
that COPR is being contained; and
 A Performance Management Program (PMP) to monitor the enhanced corrective
measures (the plan will include regular testing of air, groundwater, stormwater,
drinking water, river sediments and COPR movement).
Alternative 3 focuses on preventing contaminated groundwater from entering the storm
drains, in contrast to Alternatives 1 and 2, which focus on treating contaminated
groundwater that enters the storm drains. This focus on prevention is a more fundamental
and environmentally sound approach to limiting the movement of hexavalent chromium
into storm drains.
Alternative three did not include gigantic underground vaults. Stormwater management has taken on higher urgency since 2011 and new best practices and requirements have been released in Maryland. The "rain tax" is a well known part of that set of issues. It isn't clear why the Port Authority with its holdings directly adjacent to the Bay should do anything less, than what are the best practices of stormwater management; even if it employs 13,500 people and is an economic power house. Or maybe just because of it.  A non bid single-source procurement of the engineering services as it is proposed in this case is not promising for a transparent bets practice approach in which a public agency is held accountable for doing the right thing.  The matter is especially interesting since a similar set of issues occurs a bit downstream on the larger (much larger) former Bethlehem Steel site, Americas largest industrial waterfront redevelopment site.

Klaus Philipsen, FAIA

Sun article about flooding 8/4/15
Remedial report

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