If you are a GC estimator, civil engineer, or developer civil lead bidding a commercial project anywhere between Summerville and Mount Pleasant, storm drainage is almost never the glamour trade. It is, however, the trade that stops a project cold when the stormwater conveyance does not tie in cleanly, when compaction testing fails at a catch basin boot, or when Berkeley County kicks back a SWPPP deficiency at the pre-final walk. JSW Construction is a Charleston storm drain contractor handling CSI 33 40 00 scope across the Lowcountry, and this post breaks down exactly what that scope covers, how we equip for it, and how we price it so your bid package lines up clean.
What Is CSI 33 40 00?
CSI 33 40 00 is the MasterFormat division covering Storm Drainage Utilities. It is the umbrella spec section a design team uses to organize every component that moves stormwater from inlet to outfall on a commercial site. On a bid package, you will typically see it broken into these sub-sections:
- 33 41 00 Storm Drainage Piping covers the mainline and lateral conveyance itself, whether HDPE pipe, RCP (reinforced concrete pipe), or dual-wall corrugated.
- 33 42 00 Culverts covers cross-drainage structures, including headwall and endwall assemblies and the flared end section on open-channel outfalls.
- 33 44 00 Storm Utility Water Drains covers the collection structures, meaning the catch basin, inlet grates, yard drains, and area drains you see on the plan sheet.
- 33 46 00 Subdrainage covers the perforated collection systems behind retaining walls, under athletic fields, and under pavement sections where groundwater has to be intercepted.
A complete 33 40 00 bid from a commercial storm drainage subcontractor in SC should price every one of those sub-sections plus the earthwork, flowfill backfill where specified, proof-roll of trench subgrade, and the compaction testing coordination with the owner's third party geotech. If a sub is only pricing pipe and structures, you are about to field a change order.
Scope of Work on a Typical Commercial Storm System
Our crews handle the full 33 40 00 scope on commercial, industrial, and large subdivision projects. On any given week you will find us running mainline at Camp Hall Commerce Park, setting structures on a Nexton commercial pad, tying in laterals at Cainhoy, and building subdivision storm systems in Carnes Crossroads and Cane Bay. Scope on those jobs consistently includes:
- Mainline storm trenching and pipe installation in HDPE and RCP, with diameters from 12 inch laterals up to 60 inch trunk line.
- Catch basin, curb inlet, drop inlet, and manhole structure setting, including boot installation, grouting, and grade-ring adjustment to finished pavement.
- Headwall and endwall pours, flared end section placement, and rip-rap apron at every outfall.
- Storm drain tie-in to existing county or municipal systems, including pothole of crossing utilities and coordination with Berkeley County, Dorchester County, or Charleston Water System as required.
- Flowfill backfill under pavement and structural zones, with trench-zone compaction testing documented for the geotech.
- Proof-roll of trench subgrade prior to bedding placement, documented for the civil engineer of record.
- SWPPP compliance support, including inlet protection, coordination with the E and S control sub, and maintenance of BMPs through substantial completion.
County Requirements Across the Lowcountry
One of the reasons a local CSI 33 40 00 subcontractor in the Lowcountry matters is that Berkeley, Dorchester, and Charleston counties each have their own stormwater requirements, and the design engineer's spec does not always call out the county's preferred detail. Berkeley County leans heavily on pre-cast structures with specific boot gasket requirements on HDPE tie-ins. Dorchester County stormwater review will often require revised E and S control sequencing before an inlet is cut into an active conveyance. Charleston County stormwater ordinance enforcement has tightened on SWPPP inspection documentation, and inlet protection has to be maintained and logged through final stabilization. A sub that has worked all three jurisdictions will catch these before they become a punchlist item.
Equipment Capability and Depth Chart
Storm drainage gets expensive fast when a sub shows up undergunned for the mainline depths. We run an owned fleet sized specifically for Lowcountry commercial storm scope, from 18 foot trunk line down to lateral tie-in and final restoration.
| Equipment | Typical Use | Practical Trench Depth |
|---|---|---|
| 80,000 lb excavator | Deep mainline, large diameter RCP, structure excavation | Up to 18 ft |
| 60,000 lb excavator | Mainline HDPE and RCP, manhole and junction structure sets | Up to 15 ft |
| 8,000 lb mini excavator | Lateral work, inlet tie-ins, tight-access trenching | Up to 8 ft |
| Skid steer with attachments | Backfill, grading, topsoil, restoration | Surface work |
That mix is what lets us self-perform the full vertical of a storm system without subbing out deep work to a second excavation crew, which is usually where schedule slips on a commercial job.
Typical Project Sizes and Budget Ranges
GC estimators asking for a ballpark before the plan drop usually want order-of-magnitude numbers. These are representative of completed and active 33 40 00 scopes we have priced in the Charleston market. Final pricing moves with depth, dewatering, structure count, and pipe material.
| Project Type | Typical LF of Mainline | Structure Count | Budget Range |
|---|---|---|---|
| Small commercial pad (retail, QSR, medical) | 400 to 900 LF | 6 to 12 | $120K to $320K |
| Mid-size commercial (office, flex, light industrial) | 1,200 to 2,500 LF | 15 to 30 | $400K to $900K |
| Large industrial or distribution | 3,000 to 6,000 LF | 30 to 60 | $1.0M to $2.4M |
| Subdivision storm system | 4,000 to 12,000 LF | 40 to 120 | $900K to $3.5M |
Expert Insight from Nikki Walker
"The biggest bid-package risk I see on commercial storm scope is a sub who has priced the pipe and structures but left out proof-roll, compaction testing coordination, flowfill under pavement, and SWPPP inlet protection maintenance. Those four items alone can add six figures on a mid-size job. When we quote CSI 33 40 00 for a GC, we price the whole section the way the civil engineer specified it, and we call out our exclusions in writing so the estimator is not guessing at scope gap on bid day. That is the difference between a storm drain contractor and a storm drain subcontractor you can actually build a schedule around."
Nikki Walker, JSW Construction
How to Bid Us on Your Next Commercial Project
We prefer to see the civil set (C-series), the geotech report, the project specs for Division 33, and any county stormwater review comments if they have come back. From there we will turn a line-item 33 40 00 bid, a written exclusions list, and a realistic duration so your schedule is not built on a fantasy. If you are working a project in Berkeley, Dorchester, or Charleston County and need a commercial storm drainage subcontractor who can self-perform the full vertical, visit our commercial division page or request a bid directly.