A permitted install, start to finish
A conventional gravity system in Eastern Connecticut runs 30 to 40 years when the tank is set level, the distribution box sits within a quarter inch of dead true, the stone is double-washed, and the permit package actually matches what's in the ground. That's the whole job.
01 / What a permitted install actually includes
Built from a real three-bedroom conventional install we did in Canterbury last spring. Your site will drive the specifics — ledge, water table, slope, distance to a well — but the scope below is what walks out of our trucks on every job.
Most quotes you'll see hide the ledge line, the engineering line, and the permit fees in one blob labeled “allowances.” Ours doesn't. Our own excavators run the test pit before we quote, so we usually know whether ledge is in play before anyone signs. Call to get a real number for your lot.
02 / The system type follows the soil
System type isn't a preference. It's the answer to your lot's hydrogeology. Here's how the decision actually shakes out.
Default for about 70% of the lots we see. Requires: perc rate under 60 min/inch, seasonal high water table deeper than 4 feet, no ledge in the leach field footprint, and at least 100 feet from any drinking well. Effluent flows from tank to distribution box to leach field entirely by gravity — zero moving parts, nothing to break, lowest lifetime maintenance.
When the leach field has to sit uphill of the tank, or the grade of the lot won't support gravity fall, a pump chamber sits between the tank and the field. Typical on walkout-basement homes where the best soil is above the house, and on hillside lots in Pomfret, Woodstock, and parts of Killingly. Adds a pump (Zoeller M267 is our default), an alarm panel inside, and a second chamber — plus a 2–5 year pump warranty to track.
Required when the perc test fails (rate above 60 min/inch or below 1 min/inch), water table is within 4 feet of grade, or the property sits inside a reservoir watershed or inland wetlands buffer. An ATU (typically a Clearstream, Norweco, or Advantex) biologically treats effluent to near drinking-water quality before it reaches the reduced-size drainfield. A mound system builds a raised sand bed when native soil can't meet vertical separation to the water table.
You don't have to know which bucket your lot falls into before you call. The perc test answers it in about four hours, and we walk all three scenarios with you in the same site visit so you know what you're looking at before anything is signed.
03 / The permit pipeline, demystified
Covers nearly all of Windham County — Plainfield, Killingly, Putnam, Woodstock, Pomfret, Brooklyn, Canterbury, Sterling, Thompson, Hampton, Chaplin, Scotland, Eastford.
Covers Griswold, Lisbon, Norwich, Sprague, Voluntown and surrounding New London County towns. Slightly faster on review, slightly stricter on wetlands buffers.
Day 0–3
We visit the property, look at the existing system (if there is one), identify suitable leach field area, note well and wetlands distances, and mark test-pit locations.
Day 4–7
Two test pits dug to 54 inches, pre-soaked, percolation measured across 15-minute intervals. Soil scientist documents horizons and seasonal water table indicators (mottling, redox features).
Day 8–14
P.E. sizes the tank, calculates trench length from perc rate and daily design flow, draws the system layout at 1″ = 20′ scale, and signs the B-100A submittal.
Day 15–45
Package submitted. Sanitarian schedules a site visit within 10 business days. Plans are approved, revised once if needed, and the permit issues typically within 3–5 weeks of submittal.
Day 46–50
Tank set day one, trenches dug day two, components placed day three, sanitarian inspects open system, backfill on day four, final grade and seeding day five.
04 / The perc test, in detail
A percolation test is a rate measurement. We pre-soak a 6-inch-diameter test hole for four hours to saturate the surrounding soil, then pour in clean water and measure how fast the water level drops across three consecutive 15-minute intervals. The final stable rate — expressed in minutes per inch — is the number the engineer designs around.
A rate of 1–5 min/inch reads as coarse sandy soil: water passes fast but doesn't get treated, so the leach field has to be oversized to reduce concentration. A rate of 15–45 min/inch is the sweet spot — typical Eastern CT loam. A rate of 60+ min/inch is heavy clay or dense till, and conventional design is out; the system has to pressurize or upsize the field dramatically, and an advanced treatment unit usually makes more economic sense.
The soil scientist who walks the test pits with us is looking for something the perc test can't see directly: the seasonal high water table. Redoximorphic features (gray mottling, iron concretions, manganese staining) in the soil profile mark the depth water rose to during last spring, even if the pit is dry today. CT code requires at least four feet of vertical separation between the leach field bottom and that high water mark.
Between the perc rate and the water table depth, a sound engineer can lay out a system that works in almost any soil. There's no such thing as an un-septicable lot in Eastern CT — just lots that need a bigger design budget.
05 / The long view
Look at a tax map of Plainfield, Killingly, Brooklyn, or Woodstock and you'll notice the same building pattern: clusters of three-bedroom ranches and raised capes built between 1968 and 1988, most on lots between three-quarters of an acre and two acres, nearly all on private septic. That twenty-year window was when suburban Eastern CT built out fastest, and the systems those homes were installed with are now 36 to 56 years old. Concrete tanks from that era run 40 to 50 years before the riser grommets deteriorate and inflow starts overwhelming capacity. Leach fields biologically “age out” at 25 to 35 years — the biomat at the soil interface thickens until effluent can't infiltrate fast enough. The result is a predictable regional failure curve that's just starting to hit its knee.
Most homeowners don't know this because nothing about their system's decline is visible until the day it isn't. A properly working septic is quiet, odorless, and invisible. The first sign of trouble is usually a toilet that's a little slow on a rainy weekend — the leach field is saturating because it's lost half its infiltration capacity, and the extra water table pressure from spring runoff is enough to back the system up. By the time the homeowner calls us, two-thirds of the time the leach field needs replacement. The tank is usually salvageable.
Replacement isn't the emergency people think it is. A failed leach field doesn't contaminate groundwater overnight (the biomat that's plugged is actually still doing most of the treatment work); it just means effluent is starting to surface. CT Public Health Code gives homeowners a reasonable window to replace a failed system once it's identified — typically 90 days during warm weather, longer if the ground is frozen. We've turned around emergency replacements in under two weeks when the district cooperates and the design is straightforward.
The real cost savings come from catching the decline early. A conventional replacement on a predictable schedule is $10,000 to $15,000. The same failure unaddressed for six months — while effluent starts percolating into a basement, saturating the finished space, or showing up in a well — can drive remediation and replacement into the $30,000 to $60,000 range. Pump your tank every three years (CT code minimum), have the system inspected with a dye test at seven or eight years, and you'll see the end coming with runway to plan a replacement on your timeline instead of the system's.
The other thing that kills an Eastern CT septic early is forgotten. Driving a dump trailer, a boat, or a well-drilling rig across the leach field collapses the distribution chambers. A water softener discharging 40 gallons of salty backwash into the tank every other night pickles the biological colony that's supposed to break down solids. Too much bleach, too many antibacterial wipes, and anything flushed that isn't toilet paper accelerates scum accumulation. Systems that fail at 15 years instead of 40 almost always fail for one of those three reasons.
06 / Warranty terms in plain English
| Component | Coverage | Term | Honored by |
|---|---|---|---|
| Tank placement + plumbing tie-in | Workmanship: leveling, grade, connections | 10 years | Roberts Excavation |
| Distribution box + effluent filter | Workmanship: elevation within 1/4 inch, sealed joints | 10 years | Roberts Excavation |
| Leach field grading + backfill | No settling over 2 inches in first 12 months | 1 year | Roberts Excavation |
| Concrete tank shell | Structural integrity against cracking | Lifetime | Tank manufacturer (Shea or equivalent) |
| Pump (if installed) | Motor and float switch | 2–5 years (model-dependent) | Zoeller / Liberty manufacturer |
| Engineering drawings | P.E. stamp, district compliance | Permanent record | Consulting engineer |
The workmanship warranty runs with the property, not the owner, so if you sell the house within ten years of install the next owner inherits the coverage. That's written into the contract, not a handshake.
07 / Questions we hear on site walks
In Windham and New London counties roughly 70–80% of lots perc under 60 minutes per inch, which supports a conventional gravity system. Glacial till areas with heavy clay, sloped lots over shallow ledge, and properties within 100 feet of wetlands or a drinking well are the common failures. A failed perc doesn't end the project — it moves the design to a pump system or advanced treatment unit with a higher install cost but the same long-term lifespan.
In Windham County (Plainfield, Killingly, Putnam, Woodstock, Pomfret, Brooklyn, Canterbury, Sterling, Thompson, and most surrounding towns) permits go through the Northeast District Department of Health out of Brooklyn, CT. In New London County (Griswold, Lisbon, Norwich, Sprague, Voluntown) permits are issued by Uncas Health District. Each district has its own submittal forms and review cadence — we submit multiple packages a month through both.
CT Public Health Code ties tank size to bedroom count, not occupancy. Three-bedroom homes require a 1,000-gallon tank. Four-bedroom is 1,250 gallons. Five-bedroom is 1,500 gallons. Planning a future addition? Upsize the tank now — adding the extra 250 gallons at install is $400–$800 versus replacing the entire system later when you add a bedroom.
Trench bottoms typically sit 24–36 inches below grade in Eastern CT, with 12 inches of 3/4-inch double-washed stone under the chambered distribution pipe and at least 12 inches of soil cover above. The exact depth depends on the perc rate, seasonal high water table, and whether the design is conventional or pressurized.
From the first phone call to a functioning system: typically 6–10 weeks. Site evaluation and perc test: 1 week. Engineering and permit submittal: 1 week. Health district review: 3–6 weeks. Actual excavation and install: 3–5 days once the permit is in hand. Emergency replacements move faster — we've turned around failed-tank jobs in under two weeks when the health district cooperates.
Ten years on our workmanship — tank placement, pipe alignment, distribution box leveling, backfill settling, final grade. The tank carries its own manufacturer warranty (lifetime on the concrete shell against structural defects, typical). The pump, if the system has one, is 2–5 years depending on the manufacturer — Zoeller and Liberty are our standard picks.
Three things, almost always: driving or parking over the leach field (compacts stone, crushes pipe), running water softener backwash or laundry bleach in heavy volumes into the tank (kills the biological colony), and skipping the 3-year pump schedule (solids migrate into the field). Avoid those three and a well-installed Eastern CT system runs 30–40 years with zero major repairs.
Yes. Most of our installs are replacements on lived-in properties. We stage equipment to leave one driveway lane open, coordinate with the household for the day water is offline (typically 4–6 hours during final connection), and sequence backfill so the yard is walkable by end of day two.
An on-site perc test takes one afternoon, tells you whether your lot is conventional or engineered, and gives you a hard number before you commit to anything. No deposit. No obligation.
typical response: same day · emergency replacements 24/7