Trenching to detached - lots of questions!

Hi Everyone,

So as my detached garage is slowly coming along, I need to think about all the lines - water, sewer, main electrical, coax, ethernet, 3-way 12 gauge for controlling eave and gable lights from the house, etc.

General trench questions - what are the rules around all these conduits, pipes, etc. being in the same trench?
I have a friend who has a mini-ex with a 12" bucket we will use for the trench - 140 feet from the house to the front of the garage for the main electrical.

Water line questions - I am planning on two hydrants on the back and side of the garage. (Half bath is in the back left corner of the garage) Since the block foundation is not backfilled yet, can I run my 3/4" water line next to it (by the footer) to the hydrants? It will be equal, if not deeper (after final grading), than the 18" frost line?
Since I am on a well, my contractor recommended 3/4" line from the house to maintain good pressure. Do I use black HDPE pipe? or Pex? I plan on just putting the line the ground and not conduit - or should I?
Since I will be branching off to my hydrants from the main pipe, what connections are recommended for underground? A manifold or just some "T"s?

Network question - From all the reading I have done, it looks like Cat6 would be fine to extend my network from the house router (Netgear AC1750 Smart Wifi Router model R6400v2). Run the cable to a switch in the garage to another router with DCHP turned off (think I have that right?) As for the cable itself, I plan on getting underground rated, even if it is in conduit - but should I get shielded? because it is in the same trench as my main electrical? Looking for advice here!

Attached is a pic of the proposed layout and the type of ground we have - clay!

Thanks!

I would ask your building inspector what they require. For your miscellaneous items, just run a few 1" conduits over with your other items when they are done.

They are not going to want sewer and water in the same trench. Usually these need to be 10' apart. If in the same trench you can "shelf" that water on higher undisturbed soil but I think the sewer has to be at least 3' below the water so depth is likely an issue. Dig a separate trench for water and throw the low voltage conduits in with it. That will give good separation. Check with your AHJ but I think everything else will be ok. I would use unshielded cable for ethernet.

If it were me I'd bring the water into the building and branch off to the hydrants inside above the floor,ability to valve things and no chance of a fitting leak below grade except at the connection to the hydrant.140' from the building to the garage and then the piping to the hydrants seems like a long way for 3/4",I don't know wells have only worked with city services so i could be wrong.

Look into using a smart device like Alexa with smart switches to turn light and such off and on from house. It will be on the same network so should work fine.
Don’t you have sewer layouts in your plans to the city? Thought you had to have site and elevation planned out by a pro before permit?


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OP is on private septic vs municipal sewer. I agree check with your AHJ first.

Short of the sewer (septic connection), I did similar to you recently.

In my 24" wide trench (that was the bucket size on the "free" mini-X) by 30" minimum deep trench (frost depth here in Northern VA), I have 1" communication on the bottom off to one side, 2" power on the bottom off to the other side, 1" conduit for outside lighting circuits adjacent the power, black poly water on the bottom middle, and RapidAir 1" direct burial air line. I then backfilled it about 16" and compacted with a plate tamper (netted about 12-14" after tamping), then ran a poly propane line with tracer (greater than 12" recommended separation to power), covered with about 6", placed caution tape, filled to finished grade and seed and straw.

I am also on a well. My County said they did not require permits for private water lines so I did not have to permit the yard hydrants. I ran 1" black poly for the hydrants.

There are several threads on this site regarding yard hydrants in how they can potentially contaminate the water due to groundwater inleakage via the drain port. I erred on the side of caution so I ran a 1" line for the hydrants, and a separate 1" line for potable water. The supply connection for the hydrants will utilize a Zurn dual check valve backflow preventer (1UFX1F-700XL).

I installed 2 different brand hydrants, a Woodford Y34 (New) and a Campbell (20-30 years old from parents estate). For shits and grins, I pressure checked them with water via backflowing thru the hose end connection (hydrants not installed yet). The Woodford would not allow simultaneous opening of the bleed port and the supply while the Campbell did. Not sure if I learned anything via this with regards to positive or negative proof regarding possible contamination but I liked how the Woodford was clearly one or the other not both.

My house has a basement, so I core drilled my foundation to bring in the water (cores slope down and out). Sleeved the drilled hole with PVC pipe (about 1/4" proud on interior and 1-2" proud exterior), parged PVC with hydraulic cement to wall, applied tar on exterior, used Fernco coupling from PVC to poly, dug down to draintile, filled with gravel, covered with geotech fabric (not shown), then backfilled.

Similar threads to yours I created to guide me thru the electrical aspects are linked below. At this time, I have only pulled power to the barn and pressure checked the water lines (not yet tied into the house - progress photo)
https://www.garagejournal.com/forum/showthread.php?t=426420
https://www.garagejournal.com/forum/showthread.php?t=426614

Thanks everyone for the feedback. Looks like a visit out to the building inspector is order.

While the Alexa controlled lights is a great idea, and we have the Sonos speakers with Alexa built in, I think I want to go old school with a simple switch out to the garage.

Regarding the hydrants vs. spigots on the side of the garage:
I would rather do the spigots, but since i am not sure when I will insulate, drywall and heat (mini split) the garage I worry about freezing in the block up the wall. Unless someone can propose a solution...
I also think that if I run the water lines to the hydrants for now, I can always remove the hydrant, dig down next to the foundation and then go up the block wall and add the spigot later - correct? When I am ready to heat, insulate, etc.

I ran 1” poly to my pole barn along with “Ts” to feed two hydrants. No pro/lens...been 25 years.

Two words.

Spare conduits.

Network wise, Run 2 or 3 (OR 4!) cables! As to what you have on the end of it, so long as your under 100m you can just plug a PC into the end it. If you want more than 1 device just put a switch in there and away you go.

Black poly is cheap and made for direct burial. You can use pex to however. If you do use black poly make sure you get full stainless hose clamps. 3/4in would be the smallest i would use for this. As for making the connection to the hydrants in the building you can...but why? Your only putting this water pipe 18in in the ground. Thats like 15min work to dig up if you ever have issues.

As far as i know cat6 is basicly shielded cat5 with minor other difference.

X2 Two words.

Spare conduits. and make them 3 or 4"

Bretny said:

Black poly is cheap and made for direct burial. You can use pex to however. If you do use black poly make sure you get full stainless hose clamps. 3/4in would be the smallest i would use for this. As for making the connection to the hydrants in the building you can...but why? Your only putting this water pipe 18in in the ground. Thats like 15min work to dig up if you ever have issues.

As far as i know cat6 is basicly shielded cat5 with minor other difference.

Click to expand...

Hydrants only 18" deep? OP is in Richmond VA. I am in northern VA (Warrenton - 90 miles north) and the frost line is 30" here which is the min burial for water lines.

He said his frost is 18in. So i guess he will be having more issues than what pipe to use.

Sorry i cant do the hoework for your project too.

Yes, get shielded... here’s a decent price on shielded cat 6a direct burial cable.. you’ll need the proper shielded RJ connectors to terminate it with.

https://www.showmecables.com/85-665...MIpp6ewtLB5QIViZWzCh3ZDgddEAQYASABEgKXqvD_BwE




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Here is the info from my county website regarding frost line:

Goochland County maintains the following design criteria:

• Ground Snow Load: View the Snow Load Map.
• Wind Speed: 90 to 105 miles per hour - 3 second gusts
• Rainfall: 3.3 inches per hour
• Seismic Category: B
• Weathering: Severe
• Frost depth: 18 inches
• Termite: Moderate to heavy
• Winter design temperature: 17 Degree Fahrenheit
• Mean annual temperature: 56.1 Degree Fahrenheit
• Ice barrier underlayment: Yes
• Flood hazards: Contact Environmental Engineer 804-556-5849
• Air freezing index: 1500 or less
• Shrink Swell Soil: View the Shrink - Swell Map.

So I was going to go with this:
https://www.lowes.com/pd/Woodford-Y34-IOWA-Yard-Hydrant-2-ft-Bury-Depth-3-4-in-Female-Orange-Brass-Hydrant/3572496

Does Black Poly split if it freezes?
I don't think PEX does?

jfish said:

Two words.

Spare conduits.

Click to expand...

You cannot anticipate what the future may hold and a couple spare conduits make good sense. If you do not put them in and later want to add you are kinda pooched. I'm going through this right now. With our power outages I have purchased a generator and while I had kinda/sorta planned on a location, that spot 6 yrs later is not correct...so I have been informed. I have two spare 1" conduits from the main pole to the house panel to handle the underground pull for the wires. Short money for the spares, comparatively.

Buy 300 of black poly and run one water and one for ********. If I wanted to dump a little water, fill a tank or run any sprinklers would be tempted to use inch especially if on a well where pressure varies and can go as low as 30#. 3/4 is ok, inch and you never know you are on an extension. But,,, I am used to a few circuits a bit longer than that and bit higher volumes, unless there is a special demand and the capacity behind it 3/4 is a bit easier.

Hi Everyone,

Ok - so time to do some ordering and I want to ensure I have everything.
I bought a roll of 1" black poly 160psi from Lowes (https://www.lowes.com/pd/ADS-1-in-x-300-ft-160-PSI-Plastic-Coil-Pipe/3514730)

Based on what larry4406 did, I would add a backflow preventer (https://www.supplyhouse.com/Zurn-1UFX1F-700XL-1-x-1-Wilkins-700XL-Dual-Check-Valve-Union-FNPT-x-FNPT-Lead-Free) in the line to the yard hydrants - which will be Woodford Y-34-3.

For the connections between the poly and the pex - I was thinking the combo in the pic below with the gray combination tee and the male sharbite adapter.

Then between the black poly and the backflow preventer, just using a gray poly adapter (pic attached). All the barb fittings will use two stainless hose clamps per side.

For the first yard hydrant I would use the same combination tee but then use a 6"ish (black or brass?) pipe to connect to the hydrant. The last hydrant on the run would just have a 90 degree combination elbow (pic below)

Thoughts? Am I missing something? Thanks!

jfish said:

Two words.

Spare conduits.

Click to expand...

This guy is right. Have a backup plan.


I can't tell how your soil is, but where I am, I actually have used gray PVC as a protective shell over what I'm trying to put through the yard. Not sure how the local inspectors will take this, but I am sure that I can run over a PVC 2" water line that's also encased in 3" PVC all day long...

I like "unbroken" lines like single piece PEX for water. Leak test before covering. Note there are a bunch of different attachment means for PEX these days, some better than others and some better ID than others.

I trench to 24", but we really don't have freeze issues.

jpcjguy said:

Hi Everyone,

Ok - so time to do some ordering and I want to ensure I have everything.
I bought a roll of 1" black poly 160psi from Lowes (https://www.lowes.com/pd/ADS-1-in-x-300-ft-160-PSI-Plastic-Coil-Pipe/3514730)

Based on what larry4406 did, I would add a backflow preventer (https://www.supplyhouse.com/Zurn-1UFX1F-700XL-1-x-1-Wilkins-700XL-Dual-Check-Valve-Union-FNPT-x-FNPT-Lead-Free) in the line to the yard hydrants - which will be Woodford Y-34-3.

For the connections between the poly and the pex - I was thinking the combo in the pic below with the gray combination tee and the male sharbite adapter.

Then between the black poly and the backflow preventer, just using a gray poly adapter (pic attached). All the barb fittings will use two stainless hose clamps per side.

For the first yard hydrant I would use the same combination tee but then use a 6"ish (black or brass?) pipe to connect to the hydrant. The last hydrant on the run would just have a 90 degree combination elbow (pic below)

Thoughts? Am I missing something? Thanks!

Click to expand...

Don't use those plastic fittings. Get brass ones

Every trench I did I put two extra 1” grey (power), at least a 2” power, dropped a water line in in case I needed it later or to place existing if there was an issue, a conduit for hardlined security cameras, a 3/4” for cable TV or similar.

The extras lines have come on very handy over the years. I added a remote gate, trees decorative lighting, a wood shed that needed lites...etc.

I have a vague, fuzzy, memory from somewhere (NEC?, an electrical construction spec at work?) that the cross-sectional area of insulated electrical cables in a conduit should not exceed 40% of the cross-section of the conduit. I won't swear that is accurate so don't bet the farm on it, but you may want to investigate a little.

As already suggested, definitely run a spare 2" conduit.

Bert_ said:

Don't use those plastic fittings. Get brass ones

Click to expand...

I guess this would work:
https://www.homedepot.com/p/Water-Source-1-in-x-1-in-x-1-in-Brass-Yard-Hydrant-Tee-HT111NL/203990064

Then I just need a fitting from the 1" MNPT to 3/4" pex barb
edit: like this: https://www.lowes.com/pd/SharkBite-3-4-in-x-1-in-dia-Brass-PEX-Female-Adapter-Crimp-Fitting/1000181461

Ended up ordering some brass fittings from supplyhouse.com