Connect Private Storm Drains to City Sewers

The importance of seamless stormwater tie-ins

Ontario’s growing urban footprint demands reliable Connections from Private Storm Drains to Municipal Storm Sewer Systems to safeguard property, infrastructure, and waterways. When a commercial parking lot in Milton, a condo tower in Toronto, or a logistics hub in Brantford conveys runoff, that flow must integrate flawlessly with the public network—not overwhelm it.

Delta Group specialises in designing, permitting, and constructing Connections from Private Storm Drains to Municipal Storm Sewer Systems across Bolton, Brampton, Brantford, Burlington, Caledonia, Cambridge, Dundas, Etobicoke, Flamborough, Georgetown, Grimsby, Guelph, Halton Hills, Hamilton, King City, Kitchener, Milton, Mississauga, Niagara Falls, North York, Oakville, Orangeville, Paris, St. Catharines, Toronto, Vaughan, Waterloo, and Waterdown.

This guide equips civil engineers, municipal planners, project managers, municipal officials, developers, and commercial property owners or managers with the knowledge to execute compliant, future-ready Connections from Private Storm Drains to Municipal Storm Sewer Systems—from concept to commissioning.

1 | Stormwater fundamentals for private-to-municipal tie-ins

Hydraulic compatibility – The private system’s peak outflow must not exceed the municipal allowable release rate.
Water-quality objectives – Municipalities require that Connections from Private Storm Drains to Municipal Storm Sewer Systems remove target percentages of total suspended solids (TSS), hydrocarbons, and nutrients.
Elevation & grade – Outlet elevation must match municipal sewer obvert, considering future resurfacing.
Capacity assurance – Upstream private pipes and control structures must be sized for the 100-year event plus climate change uplift.

Short-sighted tie-ins risk surcharge flooding, environmental fines, and demolition orders.

2 | Regulatory landscape in Ontario

Authority / Guideline	Relevance to Connections from Private Storm Drains to Municipal Storm Sewer Systems	Delta Group advantage
Municipal design manuals (e.g., City of Toronto Wet Weather Flow)	Set release rates, Low Impact Development (LID) minimums	Library of 30+ municipal specs
Conservation Authorities	Floodplain, erosion, and phosphorus-loading controls	In-house watershed modellers
MECP Stormwater Management Manual	Quality & quantity targets, Enhanced protection	Early adoption of 2021 draft
Environmental Activity & Sector Registry (EASR)	Registration for on-site works < 5 ha	Streamlined filings
Ontario Building Code / Plumbing Code	Roof drain flow timing	BCIN design sign-off

Delta Group’s permitting team accelerates approvals for Connections from Private Storm Drains to Municipal Storm Sewer Systems, preventing costly delays.

3 | Step-by-step tie-in workflow

Site hydrology & hydraulic modelling
- SWMM or PCSWMM to simulate pre- vs. post-development flows.
Conceptual design
- Select LID features, OGS units, detention sizing, and outlet control devices.
Municipal & conservation approvals
- Submit engineering drawings, modelling files, maintenance plans.
Utility locates & CCTV of municipal sewer
- Verify capacity and structural condition at proposed tie-in point.
Construction & QA/QC
- Precisely grade pipes, install OGS, pour headwalls, grout manhole cores.
Testing & inspection
- Mandrel tests, CCTV, oil-grit separator vacuum certificates.
As-built documentation
- GIS-ready CAD, survey files, maintenance manuals.

Each phase ensures durable, compliant Connections from Private Storm Drains to Municipal Storm Sewer Systems.

4 | Key engineering considerations

4.1 Release-rate control
Most Ontario municipalities cap post-development discharge to 2–20 L/s/ha. Delta Group uses orifice plates, vortex valves, or smart actuated gates to achieve precise rates.

4.2 Water-quality treatment
Oil-grit separators, enhanced swales, or bioretention cells must capture 80–85 % TSS before flow enters the city pipe.

4.3 Pipe material selection

PVC SDR-35 – common for ≤900 mm diameter.
HDPE dual-wall – flexible, watertight, ideal for trenchless pulls.
Concrete – high load capacity for road crossings.

4.4 Frost & depth
The invert of Connections from Private Storm Drains to Municipal Storm Sewer Systems must be below 1.5 m (Southern Ontario frost depth) or insulated.

4.5 Backflow prevention
Check valves prevent municipal surcharge during extreme events.

5 | Trenchless innovations

Horizontal Directional Drilling (HDD)

Ideal under arterial roads in Mississauga or rail lines in Hamilton.
Up to 1,200 mm pipe with minimal disruption.

Pipe-jacking & micro-tunnelling

Laser-guided for deep Connections from Private Storm Drains to Municipal Storm Sewer Systems in rock strata (e.g., Niagara Escarpment).

Cured-in-Place Pipe (CIPP) laterals

For upgrading ageing laterals without open-cut—popular in North York infill.

6 | Quality assurance & commissioning checklist

QA step	Standard	Acceptance criteria
Deflection test	CSA B182	≤5 % post-installation
Low-pressure air test	OPSS 410	No pressure loss in 5 min
OGS inspection	MTO Guidelines	0 mm residual oil on outlet
CCTV	NASSCO PACP	Grade 0–1 defects only
Hydraulic draw-down test	Municipal spec	Pond drains within 48 h

Delta Group’s digital QA platform timestamps every activity, ensuring transparent delivery of Connections from Private Storm Drains to Municipal Storm Sewer Systems.

7 | Sustainability & LID integration

Permeable asphalt lots in Georgetown reduce runoff by 60 %.
Green roofs on Toronto offices delay roof flows, lowering tie-in size.
Rainwater harvesting in Oakville for irrigation offsets municipal demand.

These features shrink required pipe diameters, cutting costs and environmental impact.

8 | Case study: downtown Burlington mixed-use

Challenge: Constrained streetscape with historic storefronts required three Connections from Private Storm Drains to Municipal Storm Sewer Systems without lane closures.

Solution: Delta Group performed night-time hydro-excavation, installed 450 mm HDPE laterals via HDD, and tied into a 1,050 mm city trunk using a stainless-steel saddle tee and internal drop. Smart sensors relay flow data to Burlington’s SCADA.

Outcome: Zero daytime disruption; project delivered two weeks early; 85 % TSS removal verified.

9 | Maintenance & lifecycle management

Semi-annual basin clean-out around catch-basins to prevent sediment transport.
OGS vacuuming at 50 % capacity.
Hydro-jetting laterals every five years.
Inlet grate inspections after major storms.

Delta Group offers multi-year service contracts, preserving performance of Connections from Private Storm Drains to Municipal Storm Sewer Systems.

10 | Frequently asked questions

Q1: How long does municipal approval take?
Typically 4–8 weeks, depending on complexity and Conservation Authority review.

Q2: Can existing private outlets be upsized?
Yes—through pipe-bursting or slip-lining, avoiding full open-cut excavation.

Q3: What if the municipal sewer lacks capacity?
Delta Group conducts downstream capacity modelling and can design on-site detention to offset.

11 | Why Delta Group leads Ontario in storm-drain tie-ins

Turnkey delivery – From hydrologic modelling to final CCTV.
Safety excellence – COR™ certified; zero lost-time injuries in five years.
Municipal rapport – Trusted by inspectors in 30+ cities.
Innovation-driven – Utilising IoT water-level sensors and trenchless tech.
24/7 response – Crews on standby for emergency tie-ins or repairs.

Connect with confidence

Reliable Connections from Private Storm Drains to Municipal Storm Sewer Systems preserve public safety, support sustainable growth, and meet stringent environmental targets. Delta Group’s integrated approach—combining engineering prowess, regulatory expertise, and field precision—delivers future-ready solutions across Ontario’s diverse municipalities.

From Bolton to Toronto, Hamilton to Niagara Falls, partner with Delta Group to ensure your storm-drain connection is compliant, resilient, and cost-effective.

Let’s build better water infrastructure together—contact Delta Group today.