Overdig backfill compaction.

[PoolguyinCT]

There are definite code restrictions on the trench details of underground electric.

Not to spit hairs, lighting may be considered a branch run vs utility; particularly when a transformer is in service. ( the old adage; there is no trench, after backfill- comes to mind)

Big picture the contractor is cleaning it up; that’s what matters.

& yes to auto fill down stream of back-flow preventer.
-Ray

 

[MWengineer]

Instead of focusing on mechanical systems requirements for trenches, I looked for structural requirements of the deck/concrete and pool itself. I'm also thinking that the design professional would have something to say about the backfill compaction requirements, your contract does state that "Engineer Plans Included". Who is the Engineer and have you seen these plans?

Was there a permit pulled for this work? If so by who? Usually the party that pulled the permit is responsible for code compliance and in signing the permit makes that promise to the building official that the work performed will be fully compliant. To that end your building inspector would also be a good resource in this matter. Usually whatever they say, goes.

IRC 2018 (same quote through IRC 2006, as far back as I checked)
R506 Concrete Floors (On Grade)->R506.2.1 Site Preparation->Fill
"Fill material shall be free of vegetation and foreign material. The fill shall be compacted to ensure uniform support of the slab, and except where approved, the fill depths shall not exceed 24 inches for clean sand and gravel and 8 inches for earth."

Later Section R506.2.1 "Vapor Retarder" specifically makes an exception for "patios or other flatwork" which I interpret to mean that exterior flatwork is intended to be covered by the remaining requirements of R506 (otherwise it wouldn't need an exception) I think its obvious that compaction is expected by the IRC beneath the concrete flatwork, although the code is vague (as it often is) on specifying the degree or method of compaction.

Where some people are using #57, or another gradation with significant voids.....that material does require very little compaction effort. The issue I have (in addition to Rich's) is the high voids, somewhere on the order of 40% for #57. In the presence of ground water (or a leak in the pool) fines can migrate into the voids causing settlement. Encapsulating the stone in a suitable geotextile filter fabric would address that issue. but so would using a well graded aggregate.

I would also be careful with using flooding for compaction. Without adequate care, I would imagine that the pressure on the earth retaining side of the wall could easily rise above the design lateral earth pressure due to the hydrostatic pressure and lateral saturated earth pressure. Probably not a significant issue with only 4 ft depth to fill though. Still something I would think the design professional would be interested in.

 

[SPman]

Instead of focusing on mechanical systems requirements for trenches, I looked for structural requirements of the deck/concrete and pool itself. I'm also thinking that the design professional would have something to say about the backfill compaction requirements, your contract does state that "Engineer Plans Included". Who is the Engineer and have you seen these plans?

Was there a permit pulled for this work? If so by who? Usually the party that pulled the permit is responsible for code compliance and in signing the permit makes that promise to the building official that the work performed will be fully compliant. To that end your building inspector would also be a good resource in this matter. Usually whatever they say, goes.

IRC 2018 (same quote through IRC 2006, as far back as I checked)
R506 Concrete Floors (On Grade)->R506.2.1 Site Preparation->Fill
"Fill material shall be free of vegetation and foreign material. The fill shall be compacted to ensure uniform support of the slab, and except where approved, the fill depths shall not exceed 24 inches for clean sand and gravel and 8 inches for earth."

Later Section R506.2.1 "Vapor Retarder" specifically makes an exception for "patios or other flatwork" which I interpret to mean that exterior flatwork is intended to be covered by the remaining requirements of R506 (otherwise it wouldn't need an exception) I think its obvious that compaction is expected by the IRC beneath the concrete flatwork, although the code is vague (as it often is) on specifying the degree or method of compaction.

Where some people are using #57, or another gradation with significant voids.....that material does require very little compaction effort. The issue I have (in addition to Rich's) is the high voids, somewhere on the order of 40% for #57. In the presence of ground water (or a leak in the pool) fines can migrate into the voids causing settlement. Encapsulating the stone in a suitable geotextile filter fabric would address that issue. but so would using a well graded aggregate.

I would also be careful with using flooding for compaction. Without adequate care, I would imagine that the pressure on the earth retaining side of the wall could easily rise above the design lateral earth pressure due to the hydrostatic pressure and lateral saturated earth pressure. Probably not a significant issue with only 4 ft depth to fill though. Still something I would think the design professional would be interested in.

I'm going to inquire about the engineered drawings. The permit was pulled by the PB. I'll keep this updated. Thank you.

 

[Rich D]

Instead of focusing on mechanical systems requirements for trenches, I looked for structural requirements of the deck/concrete and pool itself. I'm also thinking that the design professional would have something to say about the backfill compaction requirements, your contract does state that "Engineer Plans Included". Who is the Engineer and have you seen these plans?

Great point. Every engineered plan I receive has these designs specs specifically listed and I am required tho follow these specs Unless I receive authorization from the design engineer to vary from them. I did receive a copy of my "engineered plan" and there were no notes or references to these specifications. There must be some specification on the backfill material to be allowed against the pool walls, I mean I am sure the design engineer does not want 3'+ boulders to be rolled against it. So if there is a spec on it I would assume it would also include a spec on the compaction required while placing it.

 

[Rich D]

I'm going to inquire about the engineered drawings. The permit was pulled by the PB. I'll keep this updated. Thank you.

I assume you never received a copy of the engineered drawings?

I would definitely take MWengineer's advice and contact the building inspector to inquire if compaction is a requirement against the pool walls and beneath your patio just to get his input on the matter.

 

[SPman]

Instead of focusing on mechanical systems requirements for trenches, I looked for structural requirements of the deck/concrete and pool itself. I'm also thinking that the design professional would have something to say about the backfill compaction requirements, your contract does state that "Engineer Plans Included". Who is the Engineer and have you seen these plans?

Was there a permit pulled for this work? If so by who? Usually the party that pulled the permit is responsible for code compliance and in signing the permit makes that promise to the building official that the work performed will be fully compliant. To that end your building inspector would also be a good resource in this matter. Usually whatever they say, goes.

IRC 2018 (same quote through IRC 2006, as far back as I checked)
R506 Concrete Floors (On Grade)->R506.2.1 Site Preparation->Fill
"Fill material shall be free of vegetation and foreign material. The fill shall be compacted to ensure uniform support of the slab, and except where approved, the fill depths shall not exceed 24 inches for clean sand and gravel and 8 inches for earth."

Later Section R506.2.1 "Vapor Retarder" specifically makes an exception for "patios or other flatwork" which I interpret to mean that exterior flatwork is intended to be covered by the remaining requirements of R506 (otherwise it wouldn't need an exception) I think its obvious that compaction is expected by the IRC beneath the concrete flatwork, although the code is vague (as it often is) on specifying the degree or method of compaction.

Where some people are using #57, or another gradation with significant voids.....that material does require very little compaction effort. The issue I have (in addition to Rich's) is the high voids, somewhere on the order of 40% for #57. In the presence of ground water (or a leak in the pool) fines can migrate into the voids causing settlement. Encapsulating the stone in a suitable geotextile filter fabric would address that issue. but so would using a well graded aggregate.

I would also be careful with using flooding for compaction. Without adequate care, I would imagine that the pressure on the earth retaining side of the wall could easily rise above the design lateral earth pressure due to the hydrostatic pressure and lateral saturated earth pressure. Probably not a significant issue with only 4 ft depth to fill though. Still something I would think the design professional would be interested in.

I'm going to inquire about the engineered drawings. The permit was pulled by the PB. I'll keep this updated. Thank you.

I assume you never received a copy of the engineered drawings?

I would definitely take MWengineer's advice and contact the building inspector to inquire if compaction is a requirement against the pool walls and beneath your patio just to get his input on the matter.

I'm going to request a copy of these drawings and reach out the the building inspector.

 

[MWengineer]

From a contractual perspective....
Notes on drawings provided by the PB should be something you can use to get the work redone, seek a credit, or additional warranty.
Requirements of the building official above and beyond what is explicitly stated in your contract docs could be up for negotiation and result in added costs.

 

[SPman]

The entire trench will be redug and all foreign matter removed. The plan is to fill and compact in 6" lifts after the initial 18“ of cover on top of the plumbing. I'm OK with this solution. Thank you to all who contributed to this thread.

 

[Rich D]

Great news.
I have been in the excavation business for over 30yrs and have found there will always be a few contractors that will deliberately ignore the standard practice of compacting any structural area to try to increase there profits or they are just plane lazy. In general construction and home building these are more the exception then the rule. It would seem to be just the opposite in the pool building industry. As noted before almost every pool will most certainly have a deck placed on top of the pool backfill. To knowingly leave a customer with soil that will settle under there ??? Thousand dollar deck is nothing short of deceitful.