I am looking at bidding a nice sized crushed stone rip rapping project. It is pretty straight forward detail for the most part. 2' thickness of rip rap on a 1:3 slope with a 15' bank height with a non-woven geofabric underneath the rip rap. The detail that has me a little concern is the toe of the embankment. The engineer's detail shows the rip rap at the toe to be dug 3' beneath the existing stream bed and out 6' into the stream. The geofabric has to be installed under the rip rap that goes out into the stream. The stream has about 3' of water running in it right now. My question is how to dig out this 6' wide and 3' deep toe trench into the stream bed. As soon as I dig down 3' into the stream bed, the sandy bottom will undoubtedly flow right back in. Then I have to try to bed the fabric and place the rip rap. Seems like a very difficult detail to build. Any help would be appreciated.
I would see if you have the OK to damm the stream up and pump the water down stream. A bunch of sand bags and a 3" pump with 150' or so of discharge hose would do you, depending on how big the stream is. Or you could divert the channel and do it a half at a time if the stream is good sized.
1 way or another,the water simply can not be there.I don't know what Iowa has for laws on siltation and disturbance of waterways,but before you do anything, I would check that.In NY,to get approval for those specs would require an act of Congress,actually, it would never happen.Anyway,if it is allowed,either pumping or a diversion is in order.
Emergency Watershed Program? Sounds like an NRCS job. I just finished one on the river here and it had about 5 feet of water flowing in it. The bank was being washed away and flooding the waste water treatment plant. We had to drive sheet piling and put down 3500 tons of 24" rip rap on the redesigned bank with filter fabric under it. We couldn't figure out why they didn't use a poured concrete toe for the rip rap. Fortunately, we were in a drought when this being done and the river was lower than when the plans were drawn so we got lucky. I'd go along with what the other guys said about damming it and pumping it down. I'd also figure in using some portland cement to stabilize the mud you're going to be left with since it's sandy. I had to use lime to stabilize the bank cause it had lots of clay in it. Don't underbid it, you need extra money in there for surprises. Thank goodness we made $60,000 on a sheet piling material substitute cause it started raining before we got through and continued for 3 solid months.
we use sheet piling... to riprap into creeks... I'm sure it can be rented or loaned if you are on good terms with a contractor that has it. The last one I did we had to keep the pumps running full time to keep the water level down... then when we finisihed we had to call the inspector to view the work...several times... before rock and after rock... before we turned the pumps off... It was about 20'x20' in the river bottom and maybe 20' up the bank.... with about 5' of water... It had 6' of toe trench on 3 sides and 2' of fill rip rap in the center... I took about two weeks start to finish
Rip Rapping We decided to pass on the project. We were coming to the same conclusion with sheet piling and pumping. I hate to guess what this is going to cost. The project has to be completed by June 10th and is bid today. I am assuming about a 2 week turn around on contracts. Then 1,800 tons of rip rap will need to be made at the quarry. Plus the rip rap spec is a little on the crazy side. -0% fines less than 6" -a representative sample of rip rap must be made at the quarry and kept there until the end of the project -all loads to be inspected prior to placement and if a load does not pass you go directly to jail and do not collect $200 -the gradation does not meet a IDOT standard -the out of state Engineering firm seems to have the "I am going to show u guys how rip rapping in done The cost of the rip rap is $4.50 higher than what it would be for a standard state gradation and the other b.s involved in the spec. Currently there is no rip rap on this bank. This problem could be fixed easily imho if the bank could be reslope and large rip rap placed to hold the toe and protect the bank during normal flow. This is not a NRCS project. Those guys are somewhat reasonable. Just my 2 cents.
Arra I talked to the NRCS guy the other day and he said that a bunch of their jobs are going to have to be cancelled because they only have enough money to fund projects that are bid and completed by Sept 30th. Seems our POTUS has let his bark overload his *** on the Recovery Funds. Watch out for these crazy completion times, we had one bid the other day on April 5th, they wanted you to start on April 6th and be done on April 16th. Had to have your submittals all ready to go. I think it was 550 tons of 24" rip rap on a creek bank. Federal money on a state highway bridge, I don't think it was administered through NRCS either. I couldn't get to it or I'd have given them an equally ridiculous bid and would have been glad to get it or glad I didn't. Betcha you wouldn't have gotten paid that quick either.
Is a divert possible?, over here if you pump an attenuation pond/filter bed has to be used,also the cost of running a pump 24/7 can be expensive between hire,diesel and the fact it has to be monitored,nothing worse than returning to a flooded site.Caution needs to be used if binder material is placed in the bed of the watercourse especially if you are pumping as the cementious or lime material will seriously pollute the water way and kill the fish.then the proverbial hit the fan......