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 So, I made a phone call to the Dept. of Engineering and was given a few measurements over the phone. Please refer to the illustration. The measurements I was given were as follows:
UPPER manhole, East 2+50 The entire conversation lasted about three minutes. Let's define some terms. Sewage flows from the UPPER manhole to the LOWER manhole. The elevation of the bottom of the upper manhole is higher than the elevation of the bottom of the lower manhole. You can verify the direction of flow by lifting a manhole cover. The flow is always from upper to lower. The STATION is where your lateral line (usually 6" clay or PVC) connects to the street main in the street. The station is always between your upper and lower manholes. Don't let the plus (+) signs confuse you, ignore them. Municipalities use the plus sign instead of saying the word— hundred. It is engineering short-hand. 2+50 means 250 ft. The rest is a cinch. I walked to the center of the street in front of the house. I looked to the east and saw the upper manhole. I looked to the west and saw the lower manhole. I visually drew a string between them, that's where the street main is. The station was 100ft from the upper manhole (350ft - 250ft) and 200ft from the lower manhole (550ft - 350ft). I walked to the closer of the two manholes, in this case it was the upper, east of the property. With a 100 ft measuring tape, I measured from the center of that manhole along my visual string line for a distance of 100 ft. I was now standing directly above the house's street connection (8" x 6" wye) in the middle of the street. From that point I measured straight back towards the property for a distance of 25 ft, my lateral length. I was now on the edge of the sidewalk, closest to the house— the property line. Directly below me, 5 ft deep was the connection I was looking for. It takes just a couple of minutes. This method will be enough to tell you where the connection is, if the line runs under a driveway, retaining wall or goes to an easement—and that's what we needed to know. The contractor now knew where his excavation would start, where it would conclude and how deep his final connection would be. If he were to expose the old pipe and lay the new one in exactly the same trench, any other tie-ins would be exposed automatically and tied-in to the new sewer. Just re-connect them to the new pipe. Usually you can see any additional connections with your camera but in this case we were blind. There were many mature trees above the old sewer with large surface roots that needed to be chopped or cut to get to the old line. It was obvious that a re-route of the sewer was in order. It would save time, work and money. Cutting all those roots may kill the trees as well and it just wasn't necessary. Once again the contractor became a little nervous of extra connections that needed to be re-routed and was ready to spike his bid higher (just in case) in the event of extra work.
I assured him that we could find out with a very simple test, at least in this case, if there were any connections that we would miss on a re-route. We cut the original line 2 ft from the house (see drawing), where the building drain becomes the sewer, where our excavation would begin and the required building cleanout would be installed. Now, one-at-a-time, we ran water in each fixture to see if it flowed to where we had just cut the line. They all did—great. We checked around for other fixtures that may have been added during a remodel. Laundry drains in a garage is always a suspect. If all drains flow to where you've cut the sewer, there will be no other tie-ins along the sewer path. You may re-route with confidence, trenching a path of least resistance. If any fixture drained outside of our test area it would have to located separately and routed to our new line. This may all sound overwhelming, but I assure you it is not difficult. This may be an ideal time to sell a new water service too! Usually you can utilize a portion of the same trench for both sewer and water. This combination saves your customer money and gives you a bigger sale—it is a win-win deal.
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