Sorry for the delay. I lost this thread. Good info here, thanks.
You'll want a sloping laser if doing it the way you described in the OP.. or like cutting edge says you can get away with a regular(non-self leveling) laser to set slope.
A couple questions... are you digging the whole 300 feet before placing pipe? using shoring? any helper or is this a one man show?
Idk. I'm open to suggestion. It'll be closely checked by the inspector, but then an open 7' ditch for any length of time is a hazard. One man show.
I was talking to our engineer last night, an he said, if you do a lot of pipe work, a pipe laser is the way to go. You can set it up at your start point. On top of a man hole, on top of your first concrete pipe, or even on an over turned milk crate. You can mark your grades on a piece of strapping and away you go. If you are only doing tie ins and residential stuff, he said a spin laser is more versatile and less expensive. He said to be aware that some beacon lights will interact with the receiver, and another spin laser on sight can throw it off as well
I don't understand "mark your grades on a piece of strapping". You mean tape on the excavator stick? I'm only doing this and one other job, but will look into a pipe/grade laser. Green lasers seem to be easier to see, but may not be compatible with stick receivers.
I wouldn't attempt this without a slope laser unless you are familiar with pipe laying. We put in sewer line for close to 20 years before our first laser in the late 90's. After using a 4' level, a laser was definitely an upgrade. I'm going to guess, based on your vague description of the job, that you are doing a hookup from the main to a structure? Is the grade going to be established, or will you have to set it up? Three hundred feet is quite a distance for a sewer drop, the slope will probably be between 1 and 2% (more than 1/8" per foot, but less than 1/4"). These kind of jobs need a pretty high level of precision, slight variations can affect the flow and allow for blockage, which is why they are requiring it to be inspected.
Back to your original question, you would be able to dig this with a straight grade laser, but it will require a little work. You would need to set yourself benchmarks, and be checking against those every 10-20' to do this right. I have quite a few more ideas and suggestions, but I'll let you respond to this before going further.
Putting in an 8" lateral from the main, to hook up 5 houses. I first need to have a surveyor set a marker for a height reference, then grade the land to the drawings. Have the street work done by somebody for water, sewer, and storm, then dig for the lateral, water, and storm onto the property. Checking the drawings, the lateral is actually about 200'.
What I've had in mind is a laser receiver on a magnetic stick with lights all along its length. This way I can gauge as I go, trying to allow for movement of the stick. Although, if I can find a grade laser for anything like a reasonable price I could do with a single-point receiver, although those seem to alert within a frickin' millimeter or two.
I don't really trust Topcon from things I've read. Bosch and Spectra seem alright.
and it doesn't move from the time you start digging til' you're done.