Dredge10-12" of dirt from boat slip - pump? Help!

So I just got a quote of $1500 to dredge out 18-20" of dirt out of my boat slip, where I'm starting to have an issue getting my boat off the lift.

I have a dock and a 9' by 25' covered slip, but because the slip area was never dredged prior to installation of the dock and lift, and because the level of my lake fluctuates (depending on rain, evaporation, etc), I have only a narrow margin of water level until I'm permanently stuck with my boat in the lift.

The front I-beam of the lift hits the ground at about 3.5 to 4 feet water depth, and I need to realistically get 12" of so of dirt out - specifically, the dirt that runs the length of the I-beam, which is about 12-13 feet across.

Obviously I can bite the bullet and pay the cash to have a barge come in and a huge piece of equipment with a bucket on it come in and scoop out 2 feet of dirt the entire width and length of my slip. BUT....

I was hoping someone here had some experience with using some sort of pump that could "re-locate" the dirt that is directly underneath the offending I-beam, and I could potentially save hundreds of dollars simply by renting something from NationsRent or someplace like that.

Anyone have some tips? I only have until tomorrow to make the decision because the barge won't be available in my area again for a couple of months...so post up!!!

Dave I hate to say it but I'd just bite the bullet. If it's $1500 to have a dredged and have the soil removed and hauled off I'd say it's worth it. What's your time worth, I'd say that would be a tedious job relocating that dirt yourself. It would probably end up back in the same place anyways in time. Did this quote include the removal of the dredged material?

(Message edited by 05mobiuslsv on January 14, 2008)

Yes, it's for removal and disposal of the soil. They said they'd do almost 2 feet of dirt removal for the entire length and width of the slip. I actually just got the guy to come down to $1300...

Hydrovac trucks can come in and suck it out from the land side. They use water jets to dig holes for pilings and posts. Can't see it being a lot less though.
Your could rent a pump with hose and nozzle. Then just erode the dirt yourself making the lake near you very muddy for a while. Good luck.

Art -
What kind of pump? Could I rent it?

I called NationRent and they didn't have a clue as to what I could use.

Just thinking out loud - could I possibly use a pressure washer and just put it under water and blow some of the dirt out that way? Would that be too tedious and time consuming?

Back your bu into your slip and tie off at a point were your prop clears the bottom then put your bu into forward with little or no throttle.
After 10- 15 min. move your bu a little forward and repeat. Now you have your very own dredged slip. Cost very little

Good thought, Mark, but it seems like I'd have to get the prop down to almost dirt level in order to use that propulsion to move the dirt. The lift and I-beams are in the slip permanently, so I'd have to take everything apart in order to get the boat in backwards and down to dirt level. Also, this could potentially dredge out the center of the slip, but it wouldn't help the sides where the I-beams actually run beneath the dock under the decking. I don't think the power of the prop would reach that width...

Interesting idea though for sure.

David, you rent a gas powered Honda pump, or some other brand. They're 5 hp or more and need hose like a firehose. You put a suction hose in the lake, the pump on the shore, and walk out with the pressure hose and nozzle. It's not so much the pressure as the gallons per hour that you need
They look like a small generator, and they all rented out whenever there is a flood.

Will that type of setup transport the mud/sand mixture on the bottom of the lake? Or will it clog up with the sediment once it's running for a while?

David, we had the exact same issue in summer of '06. All the north Texas lakes were low. There were guys paying a fortune to have dredging work done.

The cheap answer - a PWC. Actually, it is the only good use for a PWC. It is much faster than the pump method. Any inboard will shoot a water stream at too much of a downward angle and you end up with a deep hole.

Tie the PWC / Jetski at the end of the slip facing out to the lake then start directing the jet stream where you need to carve out the bottom. Have some guys in the water with shovels to break stuff up as it is getting hit with the stream. You can move literally tons of material in a short amount of time. Make the "dished out" area a little bigger than you need because it will gradually fill in. Obviously, you can do this whenever necessary without renting equip, assuming you can work out a trade with a PWC-owning neighbor.

BTW, a small boat with an outboard motor will work too.

You can rent a Vac trailer from Nations Rent. It will cost you probably around 350$ a day rent. Ya might get it done in one day. The problem with vac trailers is it can only hold so much material so you would be stopping to dump quite few times. Also would need somewhere to dump material. If youre slip is 12x28 (just guessing) and you removed 2' of material it would be approx. 25 cubic yards.Which would be like 2 ten wheeler truck loads.

I did this with my MC 205 a number of years ago. With the boat tied off good, and sitting at the opening of the slip, I got back there with a shovel & just stirred up the mud. In about 15 minutes we moved like 3' of it in the middle, less around the sides.
The problem is where do you move the mud to? My slip was near a deeper section that only a few guys with jetskis & sailboats used so it wasn't a problem for it to be a bit more shallow there.
It lasted about 4 yrs till I moved away.

All of these are good suggestions! I have done the boat and it worked good but didn't get that close to the edges of dock. The best was using a pump as described and a power washer. One guy slowly walks the power washer along the bottom breaking it up and anther guy follows with the suction side of a gas pump. We left the waste side of the pump hose in the deep part of the canal and moved it after sucking up about 4 feet of dock space. Worked great we moved about 2' of dirt from the whole dock area in about 3hrs.

You may want to check your local laws. I have this sense (although I'm not 100% certain) if I were to hire a barge in Wisconsin to dredge my dock area, the DNR would come sniffing around pretty quickly.

The PWC sounds like a great, low-key way to do it.

Those are some awesome ideas everybody. Thanks for yours especially, Rich.

I'm going to go down there tomorrow AM and check out how I could get a PWC in there. My next door neighbor has 2 and I'm sure I could borrow one for a couple of hours and some beer...lol

A pressure washer will do a lot more than you think. I used to build boat houses and if we had a problem with depth in a certain area we used a washer. The only problem is you have to do it every couple of years because it will silt back in. Just buy you a gas powered washer from hardware store and get after it. Cheaper than paying someone and you will have the equipment to maintain it.

David. Go get That PWC Rich suggested.

Realistically, how far of a stream will a nice PWC fire below the water? Is it powerful enough that it would still be able to push material that is 10 feet away, as long as it's in the "line of fire?" I don't know if my slip is big enough to get a jetski in there sideways, so that may create some issues as well.

I know you can adjust the trim on some PWC's, so that would probably help along with the ability to "steer" the water jet using the handlebars.

I may try the pressure washer idea first, as I could probably tell within the first 15 minutes if what I'm doing is actually working or not...

I'll try to post up some pics of my dock structure too.

the Jetski will shoot a stream at least 15 or 20 feet. You can tie it off at different points in the slip to get it where you need. I'm not sure it will get down to the depth you are needing. When I did it we were carving out some shallow areas.

As far as tying it sideways, just tie the PWC at 4 points, facing out, and have someone move the steering side-to-side. Think of an oscillating fan. You can also get a big boy to sit on the back to tilt the jet stream down.

The other good thing is that the dirt and silt will be carried away pretty far. You just have to be careful you're not creating a problem somewhere else.

Does anyone have a jet boat with a Berkeley Marine 12J(C-G)pump on it? If you can find someone Berkeley has an nozzle that replaces the original with a firehose bib. They don't advertise it anymore but they will sell one to you. We used to dig some pretty huge holes and even made a passage way through an island on the Mississippi using this set up.

I have used a PWC (neighbors) all summer to dig out my lift. It works very well, just dont dig soo much your pilings get loose.

Use the jet ski suggestion. Any other method and you'll be breaking the laws in terms of disposal.

If you're in CA, you'll never be able to dredge unless you're a big agency with millions of dollars (just to go through the permitting process). You're talking about an environmental permit nightmare and at least a dozen of local, state, and federal agencies involved!!!

No matter what state you're in, you'd still need to get a disposal permit for dredged material from the Army Corps of Engineers.

But if the guy you contacted about dredging can get a permit to dispose of the spoiled, then do that. It'll be faster and you can enjoy your new ramp in a day!!!

BTW - if you're going this route, check to make sure he has the permit before he starts the work. As the owner, you're liable legally and financially.

(Message edited by kvoman on January 15, 2008)

(Message edited by kvoman on January 15, 2008)

Rich - what depth of soil do you think the PWC would be able to impact? I'm going to go out and measure it right now to see where the ground is in relation to the water level in the area I need to remove.

As far as where the displaced dirt/mud will go, I have quite a bit of room to the sides of my dock where the dirt can settle and not cause any issues for me or anyone else, so I'm in good shape there...

David, I have limited expertise but I think if you can manipulate the jetski angle by how you tie it off in the front, and with the weight on the back, you should be able to disturb the bottom enough. If someone is breaking chunks loose with a shovel, the moving water will carry the stuff away.

When we did it I was only trying to get the front of the slip from a depth of about 1' to over 2'. The stream of water flowing out from under the dock looked like a mudslide. Definitely take pictures (or video) of this project. It's good redneck fun, plus if something goes wrong, you could end up on TV or at least the internet.

hahahhaha... Good stuff Rich. I'm going out there to measure the depth of the area I'm trying to disrupt. I'll post back in a second.

Alright, now I'm having some second thoughts.

I just went out and measured the depth of the water at various points along my slip - at the front I-beam, between the 2 I-beams, at the rear I-beam, and at the end of the dock and here's what I got:

Front I-beam - 2'10"
between 2 beams - 3'2"
Rear I-beam - 4'0"
edge of dock - 4'3"

I honestly thought that the rear I-beam had 5+ feet of clearance underwater.

Now, my problem is that even if I am able to trench out the front I-beam (which is a 6" beam), I can realistically only remove about 6" of dirt/mud, because there are 2 connecting pieces that run the length of the dock and connect the front and rear I-beams - if I don't take out dirt the length of the connecting pieces in addition to the area under the front I-beam, I'll bottom out the connecting pieces even though there is room for the front I-beam to go down farther.

I might have to bite the bullet. I'm starting to feel like the PWC idea is a great one, but I might just have too much real estate to cover if I potentially have to remove 12" depth of a 10'x15' area.

(Message edited by tparider on January 15, 2008)

Okay, funny enough, now I'm back to the PWC idea...lol

I just spoke with the dredging company and they are leaving my canal tomorrow. In order to get them to do the work ($1300) I have to remove my boat lift first. Well, it's 57 degrees with mid-50's water temp, and I've never removed a lift before. I know how to do it, but execution is a different story. The dredging company wants another $350 to take the lift off and re-install it after the dredging.

Now I'm up to $1650, and the proposition of using the PWC on tbe new larger area between the front and rear I-beams is looking more appealing. From my calculations, it's about 16-17 yards of dirt/mud base that I'll be removing and relocating. Seems like a lot...??

.......I once removed a section 20 feet long by about 5 feet deep by 12-14 feet wide with my outboard while it was on the lift just enough out of the water so I could crank it.......all that dirt just dissappeared into the lake......mind you the cloud it made was huge but it dissappeared pretty quick. You could maybe do the same if you could locate the dirt a bit at a time behind your boat then lift the boat out somewhat so you can blow some of the dirt into the lake further out. I think your def. looking at a multi step process though.

Wow. That is a lot of dirt Michael. Thanks for the post. Looks like this will be a DIY project, especially now that I'm going to be paying extra for the lift removal and re-installation. If I could do this on a Saturday and save $1300-1400, it would be well worth it.

I don't know if this is a possibility but use a combination of a PWC and a water hose.

Use the water hose to stir up the sediments then let the jet ski shoot all that out the back as it's being stirred up by the water hose. Just another idea! At least this way, you can direct the dispersal of the water in the back.

How about a combination of both a water hose and a PWC? Use the water hose to stir up what you need to and the PWC to shoot it out the back, etc.

Possibly a combo of the pressure washer idea used in conjunction with the PWC idea....

hmmmm.

Well, I lost my opportunity to use the dredging company, so I guess I'm on my own. I'll post up when I get something done with this issue...

I'd like to see some pictures of this! Give someone a camera please and then post em!

No problem. We just had some rain yesterday so the lake is up a tad bit. Not in dire straits yet - so when the weather lets up a bit, I'm going to get in the water and give it a go.

Find a friend that has one of these. I have one but live in Louisiana. Cuts a trench like you would'nt believe and you can work it side to side.

http://www.godevil.com/GO-DEVIL_Engines.html

If you barrow a neighbors PWC be careful that you don't suck up any rocks. A jet can suck small rocks off the bottom at a depth of 3-4' into the impeller and ruin it. Impeller and wear ring will set you back $800-1000. Not to mention all the silt you will kick up into the water will harm the impeller and wear ring and get in to the engine. Trust me some of the sand and silt will get stuck in parts of the cooling jacket and exhaust manifold. Just thought I would let you know. I have seen many damaged impellers and wear rings from people getting to close to shore or starting a jet ski to close to shore. Just my 2 cents but I would say skip the Jet Ski method. Not worth ruining a neighbors PWC!

I'm thinking I'm going to have the PWC at the side of the dock perpendicular to the slip, and get in the water with a pressure washer to break up the mud/sand, then with the PWC running, it will blow away all the stuff I stir up with the pressure washer.

one more thing, you don't need as many RPM's as you might think. Start slow and just get a good current going. If you have some decent clearance under the PWC you can avoid pulling up sand into the impeller; just take it slow and watch out for that. The area with all the churned up debris will be well behind the PWC, not near the intake.

For sure Rich. I agree. If I have it set up the way I think I will, the back end of the PWC will be between 5-15 feet from the area that I'm stirring up with the pressure washer.

I'll be posting up some pics when I decide to take on this project. Hopefully it will get into the 60's in the next week or so and I'll get out there.