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Preparing for Tomorrow's Flood

posted Sep 3, 2018, 10:38 AM by Lori Lilly   [ updated Sep 3, 2018, 11:12 AM ]

Based on the reports referenced below, being a member of the Flood Workgroup since 2014 and my own experiences trying to find solutions to flooding in Ellicott City for the past 7 years - and which I am still actively doing through my NGO efforts that include the Ellicott City Soak It Up campaign, researching biochar for runoff remediation, designing a stream restoration project on the Hudson Branch and exploring projects with BG&E - I am supporting the County's 5-year plan.  I do this with a heavy heart, and do not think the County's decision was made lightly nor in the interests of developers or anyone's pocketbooks.

 

It is not just a "demo plan" as many have started and it does not disregard the 2016 McCormick Taylor (McT) H&H plan. It is a mixture of upstream mitigation, conveyance improvements, floodplain expansion and planned overflows and does not mention an extensive monitoring system being put in place by the Dept. of Homeland Security, a new floodproofing grant program being launched this fall, additional culverts proposed for removal/enlargement and comprehensive storm drain improvements along Church St.  

 

I do not believe that a 5-year plan exists that will solve this problem. People including Preservation MD are saying, "just implement the McT plan." All of those retention projects, conveyance improvements and borings will get most of the water off the street on Lower Main - but that is not a 5 year plan, that is decades and decades, and it is not a 50MYN dollar plan, it easily hundreds and hundreds of millions for projects whose actual feasibility is unknown (just because it is a concept in the plan does not necessarily mean that it can be implemented), and then the Patapsco back-watering will still be a concern for Lower Main rending upstream mitigation ineffective. You can look at Preservation MD's options B-D each of which are many tens to 67MYN but those options are only addressing the 10 structures and are still not doing anything for flood mitigation.

 

I've walked the stream channels several times per year for years with crews pulling debris out and doing our part to prevent blockages which were definitely a contributing factor to 2016. The channel walls are failing with successive storms. The May 2016 retaining wall inspection report by KCI was alarming - and that was two floods ago. There are walls with questionable structural integrity supporting buildings in Lower Main – see the picture below – on the left is photos from KCI’s report indicating a wall that is compromised in May, 2016 and on the right, of course this wall blew out from the 2016 flood.  This is under Old Columbia Pike.  What if one of the Lower Main walls supporting a structure were to fail when we get the next flood? Because it's not “if,” it's “when” we get the next flood. It could come tomorrow. We need to be planning for tomorrow's flood, not the flood 5 years from now. We simply do not have the time. 


 McT's study tells us that the water cannot be contained. This watershed would flood even if it were entirely wooded.  If all of the upstream mitigation projects were to be implemented (less the borings whose feasibility is unknown), there would still be water on the street on Lower Main.  We can look at some other retention options, but we're not going to find the storage. It's been looked at comprehensively. The retention that is effective and takes care of some of the problem are very large in-line retention ponds with high hazard dams. Emergency action plans will need to be created to prepare for the situation if the dams should fail. That is the extent of the measures that will only partially address this problem, if they are even feasible. Do you expect that those living below the high hazard dams will be very happy about a potential failure because it helps Ellicott City? I don't know that I would be.

 

The structures that are proposed for removal under this 5-year plan were selected to allow the water to move the way it needs to, today, with our new high intensity storms that are becoming the norm. The floodplain expansion at the bottom of the watershed is necessary to accommodate the extremely heavy flows. The New Cut Branch is the biggest contributor of flows, and it comes in very low in the watershed behind the Caplans building. With all upstream mitigation proposed by McT put in the ground, there are still huge flows – more than 2500 cfs - coming from the New Cut. The 10' openings do not accommodate the 18' flows that were trying to get through there in 2018.  You don’t need to be an engineer to see that problem and if you need evidence, check out Ron Peter’s video footage.

 

The 5-year plan needs to be put within the context of a 20-30 year plan. Because that is what it is going to take. This is going to be ongoing through multiple administrations and continued changing climate. Instead of figuring out how to get rid of all the water, we need to talk about how much water we can risk and are willing to live with on the streets – and on which streets.  I'm not defending the County's process for how they unrolled the 5-year plan.  I want to see as much of the structures preserved as possible - in a different location. If calling this an emergency is what it will take to make the hard decisions, then I think we should do that. We've been waiting and advocating and fighting for projects for a long time, it's time to move forward.  

 

       2006 Lower Patapsco Watershed Restoration Action Strategy  (Center for Watershed Protection)

       2003 and 2008 Lower Patapsco Biological Assessments (Tetra Tech and KCI)

       2012 Tiber Hudson Subwatershed Restoration Action Plan (Center for Watershed Protection)

       2012 Tiber Hudson Stream Corridor Assessment (S & S Planning and Design, LLC)

       2014 Ellicott City Flood Study and Concept Mitigation Report (McCormick Taylor)

       2015 EC Flood Workgroup Final Report

       2016 Ellicott City Retaining Walls Inspection Report (KCI)

       2017 Tiber Hudson Stream Corridor Assessment (S & S Planning and Design, LLC)

       2016 Ellicott City Hydrology / Hydraulic Study (McCormick Taylor)

       2018 Army Corps of Engineers Nonstructural Floodproofing Study

       2018 Howard County 5-year plan

 

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