Estimating civil costs 1

[WARose]

I'm a structural engineer and I've got a project where (as part of my estimate) I have been asked to take a stab at the civil engineer's costs. We don't have one on board yet. The good news is.....based on my reading of the local storm water regs (which may not be such a smart idea): we don't need a permit (as we are not disturbing enough ground nor are we increasing runoff); I don't think we need any kind of erosion & sediment control plan either. Basically the project is: we are adding a small building (50'x50' in plan view) to a site that is currently all pavement. (No we aren't in a flood plain.) I don't anticipate any new paving.

So what will civil likely issue? A link up with exiting utilities?

 

[dik]

I used to do a lot of stormwater management studies for small sites < maybe 5 acres. It's been two decades... I'll see if I can dig up the spreadsheet I wrote (I know I have it; it's among 20,000 files. It determines the runoff change between initial and final site based on 5 different surface types. Only problem is that it uses a rainfall formula that was developed for the Lindsay, Ontario region... and I don't know if you have a similar formula. I had to revise the formula for a park area north of Lindsay and had to calculate a new formula. A bit back, I uploaded a bunch of curve fitting formula... this was obtained at the time I fabricated the new program.

If I had the site data, there was about a days work in doing the calcs... slopes and the amount of the various surfaces.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[WARose]

At this point in the project, I can get by with the assumption (as stated in the scope) we aren't increasing runoff. But I am worried about the other stuff: what else might Civil issue given the criteria I mention? A link up with exiting utilities? Maybe a paving repair detail?

 

[dik]

If you're not changing the surface types, there should be no run-off issues... just a matter of making sure the water doesn't drain into the building and tidy up any swale issues if there are any.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[gbam]

Need to review your storm water regulations for updated water quality requirements. You may not be increasing the discharge but there may be requirements to clean the storm water before discharging because you are touching the site. Just a thought. This has bitten us in the back end before.

 

[WARose]

Thanks gbam. This is the kind of feedback I was looking for. The local county gives a flowchart to determine if any stormwater/sediment control permit is required.....and I came out with us needing nothing. (Famous last words.)

 

[SwinnyGG]

In any jurisdiction I've worked in, a project like this would require a stormwater management plan - because you're exposing subgrade, which is a sediment pollution source, for some period during construction; also the construction itself represents a potential source for contaminating surface runoff which then goes into the storm system.

So in theory you need a temporary stormwater management plan during construction, and here you would also need to file for a new stormwater permit for the site because although tributary area is not changing for the downstream storm system, you are changing surface treatments in the permitted area. In my jurisdiction this would be a relatively trivial review (for the modification to permanent stormwater tributary area) but the box must still be checked. Your jurisdiction may vary.

Typically around here you would need BMPs in place before you start sawcutting asphalt, and sediment control BMPs would need to remain in place until the exposed subgrade is permanently capped (IE your slab is poured). After that you would need temporary construction contamination BMPs in place until final completion (or TCO, depending on your JHA)

 

[dik]

Can you post a copy of the flowchart?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[WARose]

Can you post a copy of the flowchart?

https://www.greenvillesc.gov/DocumentCenter/View/1280/Stormwater-Permit-Flow-Chart-PDF?bidId=

 

[dik]

Thanks

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[WARose]

Can I get some more feedback from some (pure) Civil guys? What (if anything) are you use to issuing as far as (for example) connecting to utilities? Is it something fairly cookie cutter....or are we talking a lot of manhours here?

 

[SwinnyGG]

I'm not a civil guy, but I'm in construction management and I read drawings all day. For whatever that's worth.

If your building has utilities in it which do not currently pass under it, I would expect, at minimum:

-an electrical plan which details where any inground electrical needs to go, including the transformer to supply the feeder to the building. If that transformer already exists, connection to the transformer itself is typically via a standard detail which does not require a unique design, but the run itself needs to be sized and laid out

-For anything involving water, storm sewer, or sanitary sewer:

-1(total) overall utility plan which shows all utilities in the ground. If any of them require critical surveying information (example, a water line needs to tie to a specific in-ground valve which already exists) that information needs to be on this sheet

-1 (per utility type) plan & profile sheet which shows that particular utilities' run including any intermediate fittings (manholes, handholes, whatever). All elevations including fitting elevations and pipe inverts are required.

-1 (total) utilities detail sheet which contains Civil Firm X's standard details for utilities tie-ins. I.E. handhole details if they are needed, wet tap detail if there's water, pipe support or CIP thrust block details if necessary, etc etc​

So all of those sheets plus whatever submittal review/meeting/field inspection time the project specs require.

 

[cvg]

in general, buildings should be set above the surrounding ground level to limit flooding. often 2% slope away from the building to assist with drainage. setting the floor elevation and the minor grading is usually done by the civil engineer, not the structural or MEP. site plan showing the location is also usually done by the civil

 

[WARose]

Yeah, I know all that SwinnyGG.....it's the manhour(s) I'm looking for here (from a civil guy). I see drawings like that all the time too.....but I don't know what it takes for them to produce it.

In my case, the stormwater will likely just go out on the pavement (and go by the slope of the existing pavement to a existing detention pond).

The water & SS will need a hookup....but I am unsure as to what kind of effort we are talking here.

 

[WARose]

in general, buildings should be set above the surrounding ground level to limit flooding. often 2% slope away from the building to assist with drainage. setting the floor elevation and the minor grading is usually done by the civil engineer, not the structural or MEP. site plan showing the location is also usually done by the civil

All that WILL be done by the civil......we are in the estimating/MTO phase.

 

[SwinnyGG]

When we estimate for EPC projects, for civil, we typically carry 8 hours plus 4 additional hours per sheet. I suspect you want more specificity than that.

I know I'm not the experienced voice you want on this - hoping someone will chime in. Just trying to help out.