Be careful - we've ran into issues even with using hot pressure washers on boat docks and slips, because the hot water or pressure can/will dislodge oils from the concrete and the pressure treating on the wood (if any).

I called anonymously into our local DEQ about this, and they actually said that they would shut down the job if we used a pressure washer on the docks (ridiculous to me).

Kind of left me saying - "Uhhhh, how can we clean this then??". They did however approve the MSDS on the green wash though. Just said to employ best practices to limit overspray directly into the water.

We ended up spraying green wash and letting them know that it would take a couple weeks for them to see the results. We sprayed, agitated and left it. Rains came through within a day or two and they were happy with the results.

Yeah it did - not as dramatic as with bleach added, but customers were very happy with it. They did not want to pressure wash because they were concerned about degradation of surfaces (mostly wood & some concrete that was starting to crumble).

Brandon,

Do you happen to have any before and after pictures of this job?  Were you treating just the concrete, or the wood decks/planks as well?  I know I can't use bleach on docks unless I somehow rig a 100% collection which could difficult and costly.  If the Green Wash would be some what effective and the DEQ didn't shoot it down, that may give Mark Fermoyle and myself (and others on the SWS forums) a way to handle the docks and piers.  I'm currently living on the river and don't see anything being done to keep piers and boat houses maintained.