Quote :

"At the January 19 Raleigh City Council meeting, the Council approved a contract with Faulconer Construction Company, Inc. for nearly $2.3 million for the Lake Johnson Dam Rehabilitation project. In June of 2006, Tropical Storm Alberto dropped 7.2 inches of rain on the Lake Johnson watershed. The water level at Lake Johnson rose to within approximately one foot of the crest of the dam and caused extensive damage to the spillway. The City completed emergency repairs within six weeks and completed a comprehensive engineering evaluation study of the dam and the spillway. The study indicated that the existing spillway had less than 20 percent of the capacity necessary to pass the Spillway Design Flood as required by North Carolina regulations. It recommended a system of articulated concrete blocks (ACBs) to provide overtopping protection as the most cost-effective approach to bring the dam into compliance with State regulations. In addition to the ACB protection on the dam, which was originally built in 1923, existing manually operated sluice gates at the intake tower will be replaced with motorized gates. Also, the greenway at the dam will be rerouted around the construction site. Minority- and Women-Owned Business Participation is 13.4 percent."

http://tinyurl.com/y9gv6qo

teh ghey...

2/1/2010 5:33:28 PM

Wait, so instead of fixing the spillway so it works properly and can handle what had happened, they are going to just make the wall higher so it will take longer to flood over???

2/1/2010 5:37:06 PM

we need a CE here but my impression is that ACBs allow some water to flow through the top part of the dam rather than washing away the top of the dam

i am curious how they plan to reroute the greenway around the construction site . . . probably just going to tell people to go down to lake dam, cross the bridge, and back up

2/1/2010 5:51:54 PM

is the greenway going to be rerouted permanently or just during construction?

I did a project on raising the lake johnson water level a year ago, and looking at the DEM's and topos, there is not much more the dam could be raised to significantly improve capacity. The entire area to the north of the dam (where the greenway path is) would be in danger of spilling over if the water level were to rise by any significant amount. I wonder if they plan to extend this wall through that area as well?

2/1/2010 5:58:25 PM

Im no CE but from what Im reading the spillway got damaged due to it not opening/opening too much. I dont think it splashed over, but am reading that if it did, more damage could have occured.

2/1/2010 5:59:22 PM

http://www.shoretec.com/

(articulated concrete block system)

2/1/2010 6:00:37 PM

this thread should probably be moved to the lounge.

2/1/2010 6:02:52 PM

i lost my pocket knife out there while looking at the meteor shower

2/1/2010 8:14:18 PM

i was wondering how long they were gonna leave that shit all fucked up and half ass looking

2/1/2010 10:07:30 PM

Quote :

"Tropical Storm Alberto dropped 7.2 inches of rain on the Lake Johnson watershed"

Obligatory: I'll drop 7.2 inches into your watershed.

2/1/2010 10:26:10 PM

you'd bitch if they didn't fix it

2/1/2010 10:42:17 PM

Quote :

"we need a CE here but my impression is that ACBs allow some water to flow through the top part of the dam rather than washing away the top of the dam"

Most earth dams have a clay core that starts below grade and extends to almost near the top of the dam. Water already flows through the same albeit very slowly. I think this will just let water flow through/over the dam without washing out the soil.

2/1/2010 10:50:42 PM

Quote :

"Minority- and Women-Owned Business Participation is 13.4 percent.""

you got to love how $250,000 worth of tax money will be used to pay for what should have cost $100,000.

2/1/2010 11:03:30 PM

Nah, don't sweat it man. Most contractors just register the business in their wife's name so they can bid on these government contracts.

2/1/2010 11:07:32 PM

I'm very familiar with that practice. Usually the guy in charge gives 51% controlling interest to his wife, get caught cheating, loses half of their 49% during the divorce settlement, ends up losing the other half to legal fees, and I get stuck dealing with a bitch who has absolutely no clue what's going on yet insists that I should do business through her and not her construction foreman with 25 years experience.

at least this is what tends to happen with hauling companies.

2/1/2010 11:15:18 PM

2/2/2010 9:05:53 AM

"usually" is a strange word to use when talking about something that happened once

2/2/2010 9:11:19 AM

Ok, Alberto ended up damaging the spillway (not the dam) because the spillway was too small to handle the amount of water coming through it. Water ended up topping the spillway's walls and eroding around the spillway. the emergency maintenance was to fix the erosion and raise the walls, as well as install a couple of emergency overflow pumps.

The dam is probably supposed to be (and may have been) designed for the 1/2PMP to full PMP (possible maximum precipitation) storm-event. I say may have been because in 1923 the PMP rainfall depth may be much less than what it is now. Anyways, dams like this are typically designed to this PMP rainfall depth so that they are basically never overtopped.

I believe the future plans now are to use the ACB system along the backside of the dam so that the backside of the dam is protected in the case of overtopping where as right now, if the dam were overtopped, the backside would just erode out. In the end, this won't affect much at all for park users, except for seeing blocks on the backside of the dam instead of grass. There is virtually no other feasible way to get the dam/spillway into compliance without using the existing dam as a secondary emergency spillway. From what I know, there are no plans to raise the dam's elevation.














[Edited on February 2, 2010 at 10:12 AM. Reason : can you see this pictures?]

2/2/2010 10:10:02 AM

Nice shots dude!

2/2/2010 10:30:51 AM