| Reference Documents: | |
| 28-3CS01002 | Subsurface Investigation |
| 28-4CS06002A | Site Work and General Civil Drawings |
| 28 -4ACS640123 | Subsurface Investigation |
| 28-4ACS640120 | Property Survey |
| 28-4ECEM17 | Site Preparation and Reinstatement |
| 28-4ECEM18 | Earthworks |
| 28-GGE0050 | Topographical Surveys |
| 28-4ECSQ02 | Subsoil Investigation |
- Preparation
- If specified in contract documents as AP provided, obtain unit price rates from soil testing labs or engineering firms for soil inspections and reports. Check with the home office about writing a purchase order for their services.
- Some tests require an Air Products sourced testing company. The construction home office should write the purchase order with assistance from the field, to make sure that the company has met all insurance requirements.
- Make sure that all necessary permits are on hand and posted prior to start of construction. Project engineering is responsible to coordinate obtaining permits.
- Before any work begins in an operating facility the plant manager shall be contacted and a discussion had on access restrictions, site rules, safety work permits, local hazards, and muster points shall be held.
- It is recommended that fences or other rigid barriers be erected when working in existing plants, so that the work site and the operating plant can be considered two distinct areas, and contractors are restricted from entering the plant.
- If on a new site, access must be agreed to by the landowner and Air Products. Project Engineering and the Real Estate Group are responsible for negotiating the property owner access. A right-of-way and access summary table is to be included in the construction package.
- Make sure that proper precautions are taken against snakes, badgers, and other dangerous animals as well as ticks, fire ants, and other nuisance insects.
- Check all drawings for the items listed in specification 28-4CS06002A, to assure they are complete. Report any missing information to project engineering.
- Make sure a separate file of all stamped and dated building department drawings are kept in the trailer for review by local inspectors.
- After inspectors review the drawings, make sure the drawings are signed or initialed for the areas that the inspector has accepted.
- When issued a correction notice by the inspector, keep a separate file with the action taken, date completed, and other pertinent information for the next inspector to confirm.
- Make sure all soil technicians and surveyors produce daily time sheets. When Air Products procures these services they shall sign timesheets daily before the technician and surveyors leave the site. All costs should be in accordance with what was agreed to on the purchase order.
- Property Survey – General
- The survey shall be conducted by the office of a licensed surveyor or engineer, licensed to work in the state where the work is taking place.
- All surveys should relate all points on the survey to at least two permanent survey monuments, as shown on the drawings.
- Concrete monuments shall be set into the ground at each outside corner and intersecting corner and identified on the plats.
- If neighboring features such as buildings, driveways, or fences are encroaching on the property, measure the exact amount of encroachment and then contact the Project Engineer for resolution.
- Property boundary markers should be tied in to the site coordinate system.
- If an Air Products site coordinate system does not exist, the drawings need to give dimensions from the permanent survey station markers for all features.
- New survey stations should be erected as depicted on the drawings to an accuracy of 0.01’ (3.2 mm), and tied in to the site coordinate system. Normally, Air Products will put new stations near the corners of the property. These monuments need to be placed in direct line of sight. A minimum of three monuments shall be placed and located at 90 degrees to each other. Consideration must be given to future construction so that line of sight is not blocked as construction progresses.
- The surveyor should set several benchmarks around the site, listing their elevations and coordinates on a drawing.
- Make sure that the conversion from benchmark elevations to the Air Products elevation standard used for the mechanical work is clear and well documented.
- After the survey, the surveyor shall develop a legal description of the site, which corresponds with the survey plat. The legal description shall be forwarded to Project Engineering and the Real Estate Group.
- Property Survey – Drawing Requirements
- The surveyor needs to locate all right-of-ways and easements on or across the property. Cemeteries and burial grounds on the property must be shown by actual location.
- Surveys should identify the location and size of all site improvements, tied in to at least one monument. Location, width, access points, and names of adjacent roadways need to be identified as well.
- Locations of other surface items, such as fences, wooded areas, utilty poles, manholes, and fire hydrants on the property, adjoining or paralleling the property should also be identified and placed on the drawing.
- All railway lines adjacent to the property should be shown. When there will be a spur line into the site, the surveyor also needs to record information related to the track, elevation of the existing track, and all structures or utilities that interfere with the rail spur.
- Location and depth of all ditches, drains, or culverts on the property, adjoining or paralleling the property need to be identified. Confirm that all crossings are sufficient for construction traffic, or place necessary warning signs.
- If the property is on the water, the high and low tides need to be indicated on the drawings, along with channel width / depth, and harbor, pier head, bulkhead, or channel lines shown.
- All known underground utilities, such as, sewers, pipelines, and cables, etc.. need to be located and identified on the drawings with their service and elevation. Contact the utility companies (811 or local one call system) and other authorities for assistance with this.
- Make sure that the surveyor or project engineering knows about all property line building restrictions. All such restrictions should be shown on the civil drawings with a building “set-off” line and a written list of the restrictions and penalties.
- Unless the project requirements are otherwise, all topographical line drawings should be on 2’ intervals with spot grade elevations every 50’.
- Geotechnical Studies – General
- Proctor and soil tests that are to be done on all sub-grades and borrow areas need to be completed at least three days prior to fill or backfill operations.
- If the land is not purchased yet, coordinate with landowners prior to core boring.
- All active utilities need to be located prior to any digging or core boring. Most states have a “one call” system where all utilities will be marked out on a given property. Even if the utilities are marked on a drawing, make sure their location is identified in the field.
- Documents concerning past usage of the site must be made available to the geotechnical engineer, and referenced in their final report.
- If at any time there is any indication of contamination in the soil or groundwater, all work should stop immediately and project engineering needs to be contacted.
- Make sure the technician identifies the level of organic materials found in the soil. Air Products design needs to review this information and give their approval.
- The geotechnical engineer’s field logs should have soil descriptions, consistency evaluations, boring depths, penetration blow counts, location of samples taken and groundwater conditions.
- The geotechnical report should include information on soil bearing strength for crane and equipment outriggers, as well as the soil class, which is needed for excavation safety.
- The bearing strength, optimum moisture content, dry density and density-to-percent moisture relation information are needed for all backfill soil types, to determine proper compaction and necessary outrigger size for cranes set on backfilled areas.
- Geotechnical Studies – Core Borings
- The drawing for core borings should also include a list of plant equipment sizes and locations so the geotechnical engineer can provide foundation recommendations.
- Contact project engineering to get tolerances on core bore locations, in case existing features prevent using the location depicted on the drawing.
- The depth of all soil borings should be decided by the geotechnical engineer, if not specified on the drawings. Normally, soil borings depths should be equal to twice the foundation width at a minimum.
- Basic field tests that should be done with core borings include soil sampling, standard penetration resistance, and cone penetration resistance.
- Make sure the bedrock thickness and composition is determined if required by the contract. This is usually done with a diamond core drill during the soil core borings.
- Boreholes need to be filled after all samples are taken. Unless specified in the contract, the filling material should be a mixture of Portland cement and bentonite.
- Geotechnical Studies – Other tests
- Trial pits need to have a record that details the sub-strata found, depth of strata changes, details on groundwater, site test results of cohesive soils, and details of the pit bottom.
- Trial pits need to be covered, so that the weather does not affect results or observations. Covers should be well marked and not be a hazard.
- California Bearing Ratio tests need to be conducted in accordance with applicable ASTM methods and procedures.
- Soil resistivity needs to be taken at the depths and locations as specified on the drawings, using a four-electrode method. Single probes are not allowed. If not specified, resistivity needs to be checked in four locations, and at all depths that piping will be installed.
- Soil resistivity also needs to be checked in the soils laboratory with a soils sample.
- Disturbed and undisturbed soil samples should also be taken around site, and sent back to the soils lab for analysis.
- Groundwater and soil samples must be taken and analyzed for contaminant levels.
- Soil proctors need to be taken from the borrow pit soil supply, if applicable, to confirm that the soil is acceptable for backfill. Inform project engineering immediately if the borrow soil does not meet the specifications.
- Cut and Fill – Preparation
- The contractor must check the site topography against the drawings and any discrepancies need to be identified prior to construction. All structure, monument, and benchmark locations and elevations also need to be confirmed by the contractor.
- The contractor shall issue a letter, confirming that all drawings of the site surface features are accurate. Save this in the QC documents file.
- When existing utilities will conflict with construction, the contractor needs to contact the proper authorities to disconnect and blank off and bypass as necessary. The contractor needs to supply written confirmation that all services have been properly blanked.
- Local restrictions concerning noise, dust, and other nuisance laws need to be noted and passed on to all contractors.
- When work will occur near or alongside existing roads, the contractor needs to provide barriers and lights to keep traffic a safe distance away, or provide alternative access ways. All precautions need to meet the requirements set by Air Products and local officials.
- A fence around the site may be required if hazards to bystanders wandering in or adjacent to the site is apparent. Discuss with project engineering if not in the plans.
- Layout and design of temporary roads needs to have Air Products approval.
- Check with the geotechnical engineer or the soils report to see if there are any sub-grade preparation recommendations.
- All trees, hedges, and shrubs should be cut down and their roots removed. Organic material cannot remain in the backfill. Many areas will not allow burning, and have specialized landfills for organic materials. Check with project engineering.
- Stake out locations of underground utilities such as electrical lines, telephone lines, and hazardous pipelines. Pothole and locate these installations by hand digging prior to excavation work in the area of each underground obstruction.
- Before beginning demolition of objects on site, confirm if project engineering wants to save any of the structures or materials. Demolition should proceed in a safe manner.
- While doing site demolition or excavation, the contractor is responsible for all adjacent buildings and foundations. Proper supports or sheet piling need to be used.
- Regardless of the experience of the contractor, no blasting is allowed without involvement of project engineering and local officials.
- Soil Cuts and Excavations
- All contaminated soil must be disposed of in a legal manner. Obtain the addresses and names of certified dumpsites from the contractor. Confirm with the Air Products environmental group and the property owner if they are acceptable.
- All topsoil needs to be stripped off, and stored in an appropriate location and protected, if there are landscaping and top soil requirements at the end of the job. Excess topsoil needs to be disposed in an appropriate manner.
- Any artificial underground features that are discovered, such as old foundations, vaults, or utility services, and are not identified on the drawings, should be reported to project engineering. Work should stop in this area until project engineering has made a decision.
- All pipes, ducts, cables, mains, and other services exposed by excavations should be properly temporarily supported. Their as-built locations and depths should be noted, and any damage found evaluated, repaired, and reported to the owner or responsible party.
- Excavations should be barricaded, and benched or sloped according to safety regulations if people are going to be near the face of the excavation.
- Excavated material should not be placed near the sides of unstable slopes.
- It is recommended that about 6” of soil be allowed to remain above the finish elevation of paved surfaces, or the bottom of concrete foundations until just before work on those areas is about to start. This layer will help protect the soils underneath from the weather.
- Placing Fill
- Depending on project requirements, underground structures may be filled in place, or removed and the space backfilled with appropriate material. All underground structures that remain in place should have holes drilled in the bottom, so that water can drain out.
- When naturally occurring soft spots or natural underground obstructions are encountered at the final subgrade level, they need to be removed.
- Areas where the contractor over excavated, or did not take proper precautions against the weather and the soil has become unsuitable, must be excavated and backfilled with the proper material, at the contractor’s cost.
- All rocks or plain concrete pieces larger than 6”, concrete with rebar, and asphalt cannot be buried. Make sure these materials are stored separately and disposed of properly.
- Make sure that all excavated surfaces are tamped well before starting backfilling.
- Backfilling should only be done with the approved material. Sometimes the excavated material can be used as backfill, but check the geotechnical report or specifications.
- Make sure all imported backfill material has been tested and a soil proctor developed for checking the compaction of the soil later.
- The following materials are not suitable for any backfill operation:
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- Topsoil
- Material from swamps, marshes, or bogs
- Peat, logs, stumps, wood chips, and other organic material
- Material susceptible to spontaneous combustion
- Frozen material
- Clays which exceed a liquid limit of 80 or plasticity index of 55
- Overly wet materials
- Cut and Fill – Useful Materials and Techniques
- If the wood and brush on site is being chipped, contact local parks and municipalities if they would like the chips. Usually they will remove the chips at no cost. Excess soils should never be given away though, due to environmental liability concerns.
- Consider having all temporary roads, parking areas, trailer areas, and contractor assembly areas lime injected or otherwise surface stabilized, especially when working in wet areas. Talk with the project engineer about this if it is not being done.
- Crushed concrete is a good surface material for temporary construction roads and as a base for permanent roadways.
- Large size aggregate, such as #3 sized stone, can help stabilize muddy areas. However, #3 sized stone can get caught between paired truck tires and then get flung out at high speeds. Make sure #3 stone is embedded in mud or has a cover layer of smaller stone.
- Powdered lime scattered onto muddy surfaces and then “raked” with a backhoe or trackhoe bucket can help fix soft areas. Limestone aggregate can also help.
- For footpaths, use less than 1-1/2” stone aggregates, such as pea gravel or #57 sized stone. Larger stones can cause awkward shifts and lead to knee sprains or tears.
- Cement stabilized sand can be useful for providing protection to buried temporary electrical feeds, or for other protection or stabilization concerns. Maintain as build drawing of all underground temporary construction utilities.
- Consider having “underdrains” located in places where water tends to gather and sit, especially near roads. Install all underdrains before soil stabilization.
- Consider placing caissons under construction permanent roads in various locations before surface stabilization occurs. If caissons are called for, consider doubling the amount.
- QC Documentation
- Certifications for survey equipment when required.
- Certified stamped drawings of survey including all monuments, benchmarks, and elevations.
- Copy of building permit.
- Certifications for the soils lab and their technicians.
- Calibrations for soil testing equipment when required.
- Copy of the soil report.
- As-built locations of all underground obstructions.
- Letter from contractor documenting accuracy of the drawings.
- Letter from contractor documenting the blanking / rerouting of existing utilities.
- Copies of all compaction tests with locations clearly marked.