Storm Sewer; Idly Wondering

Makes them difficult to access.

Great question! I was thinking the same thing the last time I was swimming inside one and trying to get a measure up while treading water legs only. At least I had a heads up that was on the docket for the day and we brought a nice ladder to get in and out easily enough.

I've noticed a lot of the junction boxes in my area are tapped into and patched with newer or differing pipes. So based on that observation it seems that it could be anything from what the purchasing department bought(right or wrong) to perhaps modification or even mistakes that weren't caught. Although I like the making them more difficult to access theory...

I was always taught that junction boxes do not have outside access (no ring and cover), manholes have access.
There is a large sanitary sewer outfall near here where the line DOES NOT change direction at the manholes but downstream of the manholes, sometimes one joint of pipe and sometimes two joints. I have no idea why it was built this way and locating this line and the appurtenant easement can be a real pain.
Andy

In my career I've done street improvement plan review for several public agencies. All had a policy of requiring new manholes to be placed in the center of travel lanes for the reasons you state. Problem is, that over years more traffic capacity is needed so medians get shrunk and roads restriped to add additional lanes. So manholes that were initially nicely centered end up between two travel lanes. Also, sometimes existing utilities conflict with the ideal placement of new lines. Oh, and on the west coast, "storm sewers" are generally called storm drains. We usually don't have the combined abominations that carry both sewage and storm runoff. But the idea of putting either's access points in the middle of a travel lane still applies.

Imagine the manhole centered over the vault. The steps which are going to be along one wall, maybe a couple feet from the hole, you are hanging there trying to swing over to the ladder steps so you can climb down, it's no more complicated than that. Open the manhole and you should be able to have it next a wall with steps inbedded in the wall to climb straight down, the hole has to be offset. Either that or the vault is not much wider than the manhole.

Only on rare occasions have I come across a manhole with the lid centered on the structure. The only cases I can recall are for very shallow holes and a couple of old/deep brick holes. As Moe states, it would be hell to get down. Depending on the project requirements, I have a code for center of structure and center of lid for manholes.

Thanks. These structures are usually 4'-5' deep and I can't recall seeing any ladder rungs, but Most precast manholes I've seen don't have them anyway.
The older brick and mortar manholes did have rungs, at least from what I've seen.

OtherHand, post: 456733, member: 12932 wrote: Oh, and on the west coast, "storm sewers" are generally called storm drains. We usually don't have the combined abominations that carry both sewage and storm runoff. But the idea of putting either's access points in the middle of a travel lane still applies.

Storm and sanitary are two separate systems, here in Houston. I've only seen once, in a subdivision platted around 1900, where there was a connection between storm and sanitary, and that was an overflow pipe located a couple feet below the rim elevation. It was in a flood-prone area adjacent to a bayou, so I'm not sure which system the overflow facilitated.
There's an entire world of difference between your lane-centered storm structures and storm drainage here locally.

D Bendell, post: 456727, member: 12975 wrote: Great question! I was thinking the same thing the last time I was swimming inside one and trying to get a measure up while treading water legs only.

Good God! If they ever come up with an As-Built Of The Year Award, I will be voting for you. 😀

R.J. Schneider, post: 456766, member: 409 wrote: Thanks. These structures are usually 4'-5' deep and I can't recall seeing any ladder rungs, but Most precast manholes I've seen don't have them anyway.

Most, if not all, modern manholes in this part have rebar rungs pre-cast in the ring sections. The lids are aligned to be that side of the hole. Texas truly is a world of its own.

They switched from rebar rungs to plastic here a while ago sometimes you see some centered 4' dia manholes but after that they are all offset decks. There is usually a conscious effort to keep the casting out of the wheel paths one issue is typically the sewer locations are designed without the mfg. shop drawings and without those there isn't a clear picture where the steps are located.

R.J. Schneider, post: 456766, member: 409 wrote: Thanks. These structures are usually 4'-5' deep and I can't recall seeing any ladder rungs, but Most precast manholes I've seen don't have them anyway.
The older brick and mortar manholes did have rungs, at least from what I've seen.

Storm and sanitary are two separate systems, here in Houston. I've only seen once, in a subdivision platted around 1900, where there was a connection between storm and sanitary, and that was an overflow pipe located a couple feet below the rim elevation. It was in a flood-prone area adjacent to a bayou, so I'm not sure which system the overflow facilitated.
There's an entire world of difference between your lane-centered storm structures and storm drainage here locally.

There are all kinds of depths here, topography and of course you want water to be at least 6'deep to the top of pipe (frost lines), mileage can vary for that with sewers. One of the crews was trying to get an invert on one crossing a road in a hilly subdivision, dang thing was 34' deep, goofy if you ask me.

MightyMoe, post: 456782, member: 700 wrote: There are all kinds of depths here, topography and of course you want water to be at least 6'deep to the top of pipe (frost lines), mileage can vary for that with sewers. One of the crews was trying to get an invert on one crossing a road in a hilly subdivision, dang thing was 34' deep, goofy if you ask me.

My mistake here. The junction boxes that I'd seen off-center were around 4'-5' deep, there are quite a few storm and sanitary lines considerably deeper than that. I've actually measured around 30' +/- to a flowline on storm and sanitary. There are some deeper than that here in Houston.

John Putnam, post: 456769, member: 1188 wrote: Most, if not all, modern manholes in this part have rebar rungs pre-cast in the ring sections. The lids are aligned to be that side of the hole. Texas truly is a world of its own.

Possibly. I couldn't speak for all of Texas, or all of the Houston area for that matter, but the thought occurs to me having a series of rungs directly below an access point could foul a winch process deploying or extracting equipment or personnel. I really don't know.

Drainage structures are not the same everywhere. Different locales use different arrangements. The systems here in the PNW are more geared towards long term moderate rainfall. Those in Oklahoma are made to handle their gully washer T-storms. Structures even differ between the various local municipalities

John Putnam, post: 456769, member: 1188 wrote: Most, if not all, modern manholes in this part have rebar rungs pre-cast in the ring sections. The lids are aligned to be that side of the hole. Texas truly is a world of its own.

Yup. Like that, mostly. They design the barrel to fit the pipes, then the manhole location can be field adjusted - by rotating the cap donut - to keep the manhole lid out of the likely wheel rut. In the old days before pre-cast the manholes were built up of red brick, which was coned up to a manhole sized opening at the top. But that made climbing down side rungs difficult.

.

R.J. Schneider, post: 456766, member: 409 wrote:
Storm and sanitary are two separate systems, here in Houston. I've only seen once, in a subdivision platted around 1900, where there was a connection between storm and sanitary, and that was an overflow pipe located a couple feet below the rim elevation. It was in a flood-prone area adjacent to a bayou, so I'm not sure which system the overflow facilitated.
There's an entire world of difference between your lane-centered storm structures and storm drainage here locally.

I'm interested to know which subdivision that is R.J. I sometimes felt that I popped open put near every manhole in Houston and I never saw a combination sewer.

I spent a few years in Los Angeles, but I was an office guy and only did two lot surveys out there, so didn't pop any manholes. I never saw much in the way of storm sewers. The gutters were sufficient to drain the 0.2" of rain that one could expect in a month.

Now, when I first got to Fort Wayne, doing my first job and opening up a manhole, I was amazed. I didn't know what the heck I was looking at. I got back to the office and was explaining it to the engineer, and he calmly told me it was a combination sewer. I honestly did not know such a thing existed. He told me that they must have them in Houston and I assured him there was no such thing there.

BlitzkriegBob, post: 456981, member: 9554 wrote: I'm interested to know which subdivision that is R.J. I sometimes felt that I popped open put near every manhole in Houston and I never saw a combination sewer.

Garden Villas. It's been 23-24 years though, the memory is sketchy on the location, not the cross-over pipe though.