JOIN CITY PARK FRIENDS AND NEIGHBORS. BE AN ADVOCATE FOR CITY PARK: https://CPFAN.ORG . Membership is FREE. HIGHLY SKILLED & EXPERIENCED ENGINEER SAYS THE CHANCES FOR A DISASTER AT THE GLOBEVILLE OUTFALL ARE UNACCEPTABLE. IN I 70/VASQUEZ SUPERFUND SITE. He writes: "So I conclude that the Globeville Landing Outfall is an unacceptable location for the discharge of stormwater. Indeed, it is the worst possible place to locate it, because of a "perfect storm" of geotechnical, hydrological, environmental, and economic risks. Simply put, anywhere else along the river would avoid most or all of these problems, and the outfall should - must - be moved. " READ MORE "I visited the City's Globeville Landing Outfall presentation in Globeville last night, where there were displays of the City's Superfund "Response Action" and the Globeville Outfall side by side. Looking at them together for the first time I was horrified by what we are proposing - and are about to build - in terms of risk to the River, and financial risk to the City. The plan is to collect in excess of 5,000 cfs of water from a 100 year storm. to pipe it through the Superfund site landfill, and discharge it from the Globeville Landing Outfall, which will be built on the Superfund Hazardous Waste repository. Consider what happens if the outfall fails: 1. The stormwater flow will (easily) push the outfall structure into the river. 2. The flow will then back-erode the exposed piping through the repository. 3. The flow will then erode essentially all of hazardous waste repository contents (which are loose) into the river. 4. The river (which will be in flood) will distribute the hazardous materials for many miles downstream. 5. The hazardous materials will settle as sediment on the river channel and overbank areas, contaminating the river channel. 6. The City will then be required to conduct a cleanup action, which based on similar Superfund responses will cost in the order of billions of dollars. 7. There will be permanent residual damage to the river and its ecosystem. And is failure likely? I judge that it is, for the following reasons: 1. The outfall is to be constructed on very poor foundation material (the hazardous waste landfill), which will require massive amendment (I read gravel injection, rather than concrete piling, on cost grounds). Settlement is guaranteed, and this approach to support will be highly vulnerable to erosion from any large flood in the river. 2. The outfall is located on a bend in the river, with a levee on the western side, constricting flood flow in the river, and directing it towards the vulnerable outfall structure and the uncemented gravel piers supporting it. 3. The outfall will receive a high-energy stream of water at flow rates at least 20 times the normal flow in the South Platte (for visualization), and is designed to dissipate that energy before discharge into the river. That translates into a lot of lateral force being applied to a very weakly founded resisting structure, which depends for its stability on basal friction - in lay terms, it isn't nailed down. Worse, the driving force increases as the square of the flow rate, so this problem gets much worse if we have greater than a 100 year storm. 4. The outfall is located immediately south of the soon-to-be-constructed I-70 trench, which will have a protective wall which will direct to the west any surface stormwater flow from the south and east that does not get collected in the pipe, focusing erosive surface flow on the landfill and on the outfall structure resting on it. This will likely exceed the ability of the current temporary remedial cover to resist erosion, and will likely undermine the outfall structure. The outfall is designed to accommodate the flow collected upstream in a 1:100 year storm. So, conservatively, the probability that the flow will exceed the design flow during any year is 1%, putting the probability of failure in the design life of (I assume) 30 years at 30%. This is unacceptable for a civil engineering structure, and for the reasons stated above, the probability of failure is likely higher. So I conclude that the Globeville Landing Outfall is an unacceptable location for the discharge of stormwater. Indeed, it is the worst possible place to locate it, because of a "perfect storm" of geotechnical, hydrological, environmental, and economic risks. Simply put, anywhere else along the river would avoid most or all of these problems, and the outfall should - must - be moved. At the presentation I asked the City's Project Engineer (Bret Banwart, P.E.) whether a risk analysis and a mitigation analysis had been performed for the GLO, and he said that it has not been addressed to his knowledge. And I asked the EPA person who was there (whose name I do not remember) if EPA had required a risk analysis and mitigation analysis for the response action (as they always do), and she said that they would not, because "EPA does not get involved in land use issues". I bring up this issue because I am very possibly the only person in the city with the combination of foundation, hydrological, environmental, Superfund, contamination and remedial cost expertise, so I guess it falls to me to identify this threat. ___________________________ SIERRA CLUB , Rocky MT. Chapter, (http://www.sierraclub.org/rocky-mountain-chapter) asks the EPA to halt the digging in Globeville until there has been credible Community Involvement Plan that reaches out to all sectors of neighborhoods affected by contamination in I 70/Vasquez Superfund Site. Denver, it seems , tried to keep the health risks a "deep dark secret." Ms. Dania Zinner Remedial Project Manager (RPM) U.S. EPA Region 8 1595 Wynkoop Street Denver, Co 80202 zinner.dania@epa.gov Dear Ms. Zinner, On behalf of the Sierra Club, area residents, fish & wildlife, the area's ecosystem, and project workers, please immediately impose a delay for the beginning of the City of Denver’s work on the Platte to Park Hill Drainage project located in the I-70 / Vasquez Superfund Site until EPA has had an opportunity to develop and execute a robust Community Involvement Plan as Congress described when it passed the CERCLA laws. READ MORE: http://files.constantcontact.com/90ff2371301/7823d55b-3310-49a9-bac1-2b7a5641265a.pdf?ver=1478289854000 EMAIL MS. ZINNER AND TELL HER TO STOP THE DIGGING IN GLOBEVILLE UNTIL THEY DO A COMMUNITY INVOLVEMENT PLAN. Please pass this update along on Facebook and to your email lists.