.5% is what I designed it for. 18" dual wall HDPE.
Why is it time consuming? I presumed you could make an adapter to fit in the invert of the pipe, punch the slope into the laser and go from there?
If the slope is .5% I would just use a 4' level as that slope is basically level taking into the account the give and take of your bedding, etc. in that short of run. The job I am on now has a fair amount of 15" HDPE. Easy to work with compared to RCP and it's forgiving if you have to make adjustments. Just make sure you bed, haunch and backfill the pipe with proper material. Here we used #57 stone (1/4-1") clean washed stone. The backfill is an important structural part of HDPE pipe.
Let me clarify on the time consuming part, in my feeble mind I was thinking setting it with a regular laser and having to calculate each rise/fall in the joint and adjust the grade rod.
I have never used a tripod mount slope laser to lay pipe just standard pipe lasers.
It should be easy to set pipe with a tripod slope laser. Set the slope, account for your pipe thickness and set your bedding with the laser. I wouldn't want to do long or complicated runs as a pipe laser does two functions - slope and alignment but it would work on smaller runs that are easier to keep aligned.
Newb question, what are blue tops? Grade stakes with blue on the top that denote finished grade?
That's a good question, yes. Basically they are hardwood hubs, similar to what surveyors use for hub grades, that have blue plastic "whiskers" or "chasers" you tack on them once to grade. I use them for building pads and setting curb/gutter grades.
On a building pad, just set up your laser and reference the site benchmark to get your grade for the floor slab. When the pad is close, I have a grade checker (most times myself
) set hubs in a 30' pattern or so across the slab, keeping them somewhat in a grid pattern. Then take a dozer, skid or whatever you are using and grade to the hubs between the grid.
On curb and gutter, the surveyors will set offsets - here it's usually 3' or if you know the crew they'll set them at whatever you want. Get the curb line rough graded cut or fill. For cut, take a 4' level, place on the surveyors hub and level it. Use a folding rule or tape in tenths ( Home Depot has a 25' tape in tenths and inches and the wooden engineers rule) to measure the cut. Reverse the procedure for fill, placing the level on the fill and measure to the hub.
Keep in mind what grade the surveyors are giving you. Here it's standard to give top of curb, designated as "TC". You have to calculate your curb height and any paving section to achieve the subgrade elevation.
When you are within 2 tenths or so, set your hub using the method above and tack your whisker in. I like to leave the hub a little high before I tack the whisker in. That way it gives you a little room if your whisker takes a little more "persuasion" to tack on. It's aggravating and time consuming to reset the hub because when you tacked the whisker in you pounded it too deep.
