If you are writing or pricing an Ontario tender for manhole covers, catch basin frames or grates, OPSS 1850 is the specification the contract documents will name. It is a material specification, which in the Ontario Provincial Standards system means it says what the product has to be. It does not tell anyone how to install it and it carries no tender items.
This page covers where OPSS 1850 sits, which documents pull it into a contract, how it relates to the OPSD drawings and to the American AASHTO M306 standard, and where to get the current text for free. DomCast Metals supplies the frames, grates and covers Ontario buyers order under this heading. We are a Canadian-owned supplier serving the waterworks market for 80+ years.
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What OPSS 1850 is
OPSS 1850 is titled Frames, Grates, Covers, and Gratings, which is how it appears in the reference list of OPSS.PROV 407. Like every OPS specification it comes in two editions, a provincial one for MTO contracts (OPSS.PROV 1850) and a municipal one for municipal contracts (OPSS.MUNI 1850). Pick the edition that matches the contract you are on.
Its number tells you its job. The 2023 OPS User Guide sets the rule: construction specifications are numbered between 200 and 999 and specify the work required by tender items, while material specifications are numbered 1000 or higher, specify the requirements of material, contain no tender items, and are generally invoked when referenced by construction specifications. So OPSS 1850 almost never appears in a tender on its own. Something else calls it up.
What calls OPSS 1850 into a contract
Two construction specifications do the work, and they use the same sentence:
| Specification | Covers | Clause that invokes 1850 |
|---|---|---|
| OPSS.PROV 407 (Nov 2022) | Installation of new maintenance holes, catch basins, ditch inlets and valve chambers | 407.05.04 |
| OPSS.PROV 408 (Nov 2022) | Adjusting or rebuilding maintenance holes, catch basins, ditch inlets and valve chambers | 408.05.05 |
Both read: "Frames with covers or grates shall be according to OPSS 1850." The municipal edition of 407 adds "and as specified in the Contract Documents," which is the hook municipalities use to attach their own casting requirements on top.
One thing worth knowing before you plan submittals: in both OPSS.PROV 407 and OPSS.PROV 408, the Quality Assurance section reads "Not Used." The installation specifications add no QA step of their own. Whatever testing or documentation your job needs has to come from OPSS 1850 itself or from the contract documents you write. Confirm what the current edition of 1850 asks for before you assume a certificate arrives with the castings.
The drawing and the specification are two different documents
This trips people up constantly. An OPSD is a dimensioned standard drawing. OPSS 1850 is written text about material. They are published in different volumes and neither one cross-references the other in its mandatory text, so a complete tender item cites both.
You can watch Ontario municipalities split on this. The City of London's Design Specifications and Requirements Manual, Chapter 5 (Storm Sewers, 2024), says maintenance hole frames and covers "shall conform with OPSD 401.01" and never mentions OPSS 1850 at all. The City of Toronto goes the other way: its Chapter 6 Material Specification says maintenance hole and catch basin frames and covers "will be manufactured in accordance with material specification OPSS.MUNI 1850," with no OPSD number attached. Cite both and you avoid the argument.
- OPSD 400-series drawing gives the shape and dimensions. See our OPSD castings guide for the cross-reference table.
- OPSS 1850 gives the material requirements.
- OPSS 407 or 408 gives the installation and payment.
Marking requirements: check the edition, do not trust a summary
We are deliberately not telling you what OPSS 1850 requires cast into a frame or cover. The published versions we can see do not agree with each other, and the specification has been revised more than once over the years. Marking is precisely the clause that shifts between editions, and it is precisely the clause that gets a delivery rejected on site.
Do this instead: find the edition your contract documents name, pull that edition from MTO Technical Publications, and read the marking clause in it. If your contract documents just say "OPSS 1850" with no date, settle which edition governs before the castings are made, not after they arrive.
OPSS 1850 vs AASHTO M306
These are not interchangeable and they are not from the same system.
| OPSS 1850 | AASHTO M306 | |
|---|---|---|
| Published by | Ontario Provincial Standards (MTO and the Municipal Engineers Association) | AASHTO, in the United States |
| Type | Material specification | Standard specification built around a proof-load test |
| Invoked by | OPSS 407 and OPSS 408 | Nothing in OPSS 407 or OPSS 408 |
| Where you see it | Ontario tenders, provincial and municipal | US municipal specs, and some Ontario municipal material lists |
We read the full text of OPSS.PROV 407 and OPSS.PROV 408, both November 2022. Neither one mentions AASHTO or M306 anywhere, in the reference list or the clauses. That is the practical point: naming OPSS 1850 does not get you a proof-load test. If your road authority wants one, write AASHTO M306 and the H-20 or H-25 rating into the contract documents as a separate requirement. Our AASHTO M306 guide covers what that test involves.
Some Ontario municipalities do reference M306 in their own material lists, usually against specific product lines rather than as a blanket rule. Check the documents for the municipality you are bidding, not just the OPSS.
What OPSS 1850 does not cover
Adjustment units are the common mix-up. They are not in 1850. OPSS.PROV 408, clause 408.05.01, routes them to three separate material specifications:
| Adjustment unit material | Material specification |
|---|---|
| Precast concrete | OPSS 1351 |
| Rubber | OPSS 1853 |
| HDPE and expanded polystyrene (EPS) | OPSS 1854 |
OPSS.PROV 408 also caps how many you stack: there shall be a minimum of one adjustment unit on the top of the drainage structure, and no more than three are permitted without prior written approval from the Contract Administrator. DomCast supplies the HDPE units under OPSS 1854 terminology. See adjustment units for the sizes and slopes.
How Ontario municipalities layer on top of it
OPSS 1850 is a floor, not a ceiling. Local documents add to it, and they are not always recent.
- Toronto. Chapter 6 Material Specification puts frames and covers under OPSS.MUNI 1850, and opens with a blanket rule: alternate materials are not permitted without written consent of the General Manager, Toronto Water. Substitutions are a formal approval, not a conversation on site.
- Windsor. Standard Specification S-1 requires OPSS 1850 plus the City's own drawings AS-301 to AS-304. Watch the dates on both ends. S-1 is the Standard Specifications for Sewers dated January 1999, while the City's drawing index (April 2025) shows AS-301 and AS-304 revised March 2024, with AS-302 and AS-303 removed entirely. The spec and the drawings it names have moved apart.
- London. The Storm Sewers chapter of the Design Specifications and Requirements Manual sends maintenance hole frames and covers to OPSD 401.01 and does not cite OPSS 1850. If you need the material spec on a London job, put it in yourself.
Always confirm against the contract documents governing your project. They win over the provincial specification.
Where to get the current text
Free, from the MTO Technical Publications website. The 2023 OPS User Guide states that standards are no longer published in hard copy and are available exclusively online at no cost in PDF. Material specifications live in Volume 6 for the provincial edition and Volume 8 for the municipal edition. The 400-series drainage drawings are in Volume 3. Archived versions of superseded standards are posted alongside the current ones, which is what you want when your contract documents name an older edition.
Two timing details worth putting in your calendar. The OPS User Guide states that OPS standards are updated twice yearly, on the last business day of April and November. And MTO's own portal notes that use of OPS standards is not mandatory: each infrastructure Owner decides which standards it will use, if any, and when to adopt or cancel them. A municipality can be several editions behind the provincial release and be entirely within its rights.
Sample tender wording
"Frames with covers or grates shall be according to OPSS.MUNI 1850, current edition at time of tender. Castings shall match OPSD [number], revision date [date]. Install according to OPSS.MUNI 407. Submit shop drawings and material certification prior to delivery."
Add AASHTO M306 with the H-20 or H-25 rating as a separate line if the road authority requires a proof-load test, because OPSS 1850 will not get you there on its own. Naming the edition and the drawing revision date is the cheapest insurance on the page.
Common questions
What is OPSS 1850?
OPSS 1850, Frames, Grates, Covers, and Gratings, is the Ontario Provincial Standard Specification that Ontario tenders name for the castings on maintenance holes, catch basins, ditch inlets and valve chambers. It is a material specification, so it sets what the product has to be rather than how it gets installed or paid for. It is published in a provincial edition (OPSS.PROV 1850) and a municipal edition (OPSS.MUNI 1850).
Which specification invokes OPSS 1850?
The construction specifications do. OPSS.PROV 407 (November 2022), clause 407.05.04, reads "Frames with covers or grates shall be according to OPSS 1850." OPSS.PROV 408 (November 2022) repeats it word for word at clause 408.05.05. That is the normal OPS pattern: the 2023 OPS User Guide states that material specifications are numbered 1000 or higher, carry no tender items, and are generally invoked when referenced by construction specifications.
Is OPSS 1850 the same as AASHTO M306?
No. AASHTO M306 is an American standard built around a proof-load test, and OPSS 1850 is the Ontario material specification. We checked the full text of OPSS.PROV 407 and OPSS.PROV 408 (both November 2022): neither document mentions AASHTO or M306 anywhere. Some Ontario municipalities do name M306 in their own material lists, so if you want a proof-load test on an Ontario job, write it into the contract documents yourself rather than assuming OPSS 1850 carries it.
Does OPSS 1850 cover adjustment rings?
No. OPSS.PROV 408, clause 408.05.01, sends adjustment units to three other material specifications: precast concrete to OPSS 1351, rubber to OPSS 1853, and HDPE and EPS to OPSS 1854. The same specification also requires a minimum of one adjustment unit on the top of the drainage structure, and no more than three without prior written approval from the Contract Administrator.
What does OPSS 1850 require for markings on a casting?
Published sources disagree, so we will not state it. Different published versions describe different marking requirements, and OPSS 1850 has been revised more than once. Marking is exactly the kind of clause that changes between editions, and it is the kind that gets a delivery rejected. Pull the current edition from MTO Technical Publications, check the edition your contract documents actually name, and read the marking clause there.
Where do I download OPSS 1850?
From the MTO Technical Publications website. The 2023 OPS User Guide states that standards are no longer published in hard copy and are available exclusively online at no cost in PDF, and that OPS standards are updated twice yearly on the last business day of April and November. Material specifications sit in Volume 6 for the provincial edition and Volume 8 for the municipal edition. Archived versions are posted too, which matters when your contract documents name an older edition.
Are DomCast castings certified to OPSS 1850?
Compliance is confirmed per SKU at quote. Send us the specification edition, the OPSD number and the revision date you are citing, and we will tell you what documentation exists for that part. We do not publish blanket conformance claims.
Sources: OPSS.PROV 407 (Nov 2022) · OPSS.PROV 408 (Nov 2022) · MTO Technical Publications, Ontario Provincial Standards · OPS User Guide (Jan 2023) · City of Toronto Chapter 6 Material Specification · City of Windsor Standard Specifications · City of London DSRM Ch. 5, Storm Sewers. We have not reproduced clause text from OPSS 1850 here. Compliance is confirmed per SKU at quote time.