You might think AE consultant scopes of work are automatically coordinated, but practice shows that proactive coordination led by the project architect is needed to assure completeness and consistency without duplication. Many change order claims that arise on building projects are related to construction document gaps inadvertently designed into a project by architects and consultants who were following their separate standard procedures.
Site and building engineering disciplines are typically separate design entities working on systems that must be coordinated in terms of characteristics and connections and delineation of contractor or subcontractor responsibilities. Plumbing sanitary waste lines leaving a building must meet site sanitary lines at a coordinated depth (invert elevation) and with sufficient capacity and slope. You might think that is obvious; if so, how is it possible for plumbing sanitary lines to leave a building too low to connect to the site sanitary lines? That happened on one project after the site engineer designed the site sanitary system to receive the building sanitary lines at an invert elevation one foot below the floor level based on preliminary information received before the interior plumbing layout was designed with a 250 ft. run at a slope of 1/4 inch per foot, requiring the building sanitary lines to leave the building approximately 5 feet below the floor level. Each consultant (plumbing and site) was following its own criteria, but the result was a mismatch that had to be corrected by the addition of an expensive sewage lift station (unexpected for a project located at the top of a hill). The preliminary information used by the site engineer did not consider the interior plumbing layout, length, and slopes of sanitary pipes that were being designed by the plumbing engineer. Coordination questions like this need to be asked and then revisited throughout the development of project design to make sure the construction documents issued for bidding and construction are complete and coordinated – as in this example, that site sanitary and plumbing sanitary systems are coordinated in size and depth (invert elevations).
Exterior grease traps and other waste tanks are similar items where site and building disciplines must be coordinated. Which discipline will specify the tank? What is the capacity? What are the sizes of entering and leaving pipes? Which contractor or subcontractor will furnish the tank, which will install the tank, and which will be responsible for connections to the tank? If the tank needs to be vented, who will install it and where will the venting go, back into the building and up through the roof? Will the tank require electric power, and, if so, what are the required power characteristics? Which contractor or subcontractor will be responsible for providing the electrical components, and which will be responsible for making the power connections? These are questions that may seem to have obvious answers until you have seen construction documents on numerous projects with inconsistent or incomplete information about tank requirements – where each engineering discipline points to another for requirements and responsibilities or where two different engineering disciplines on the same project both specify the same tank but with different characteristics, resulting in two tanks (and related costs) where only one tank is needed. Coordination of these questions should be proactive and thorough – deep in the weeds, as some would say, in order to achieve completeness and consistency.
Design changes, when they are necessary, should be fully coordinated into a project. Special attention to late changes is very important. For example, changes in a grading plan should consider the possible effects on underground utilities – will underground pipe inverts need to change to work with the revised grading? Late changes are sometimes made in a hurry without consideration of the related effects (the ripple effect). On one project, a late design change in site grading would have left some intended underground piping exposed above the ground. The questions that led to the grading change could have been asked earlier in the design process, when there was more time for follow-up coordination without having to use a construction change order to correct the discrepancy.
Bid Alternates can effect more than one discipline and need to be coordinated through the work of all affected disciplines. Bid Alternates that will affect several disciplines should be defined early in the project design process, because adequate time will be needed to coordinate the Bid Alternate through the design and construction documents that need to be developed by the affected disciplines. Last minute Bid Alternates should be avoided unless they can be limited to simple, single discipline items that do not affect other items or work.
These are but a few of the reasons design needs its own adequate time and coordination. On a large and complex project, consultant coordination, beginning with contract scoping, can be a job in itself.