Storm drainage for my yard: channel drains, gullies, catch well

We own a plot of about 1,200 square metres on a gentle slope, roughly three per cent falling towards the street, with the house and a detached garage on the higher side. Every heavy rain leaves water standing in the same three places: a puddle about four by three metres in front of the driveway gates that takes two days to drain, a wash-out along the paved path from the porch to the bathhouse where water runs over the surface and carries the bedding sand away, and a soggy corner at the bottom of the lawn where the grass has already died back. I would like this solved properly once, instead of topping up sand every spring.

The scope I have in mind is a run of channel drains with gratings along the walkway and across the driveway entrance, roughly 34 metres in total: 22 metres beside the path and 12 metres across the gate line, rated for a car driving over them. Under four downpipes on the house and two on the garage I want gully pots with removable silt buckets, so leaves and grit can be lifted out by hand without opening anything up. All of it should be collected into a buried pipe and taken to a holding well in the lower corner of the plot. If the calculated volume of that well is not enough for a heavy storm, let us discuss the alternative of discharging beyond the boundary into the roadside ditch, but only where the local rules allow it. I do not want an unauthorised connection to anything.

On workmanship I expect trenches 60 to 90 centimetres deep allowing for frost, a steady fall of at least one centimetre per metre checked with a level rather than by eye, a crushed stone bed wrapped in geotextile, and backfill compacted in layers so that no trench line appears above the pipe a year from now. Inspection chambers at every bend and every 15 to 20 metres of straight run, with covers flush to the ground. After backfilling, the lawn has to be reinstated with topsoil and either seed or turf, and I would like both options priced separately.

Before any digging I would like a site visit, a levels survey, a layout drawing with invert levels and a materials list, plus a firm schedule. I am counting on a week and a half to two weeks of dry weather. Payment in stages: excavation, installation, then commissioning with a hose test while I watch.