By NPCA Manhole Product Committee and Eric Carleton, P.E.
While cutting back on project communication can add short-term advantages and save time, it will create long-term problems overall. Constant, effective communication among all project stakeholders ranks high among the factors leading to the success of a construction project. It is a key prerequisite for getting the correct things done before, during and after a project.
During Committee Week 2014, held in Indianapolis, the Manhole Products Committee discussed manhole project problems, and the relationship between precasters and installing contractors, their No. 1 customer. What follows is a list of 10 items that require solid communication and an overall solution that precasters can use to avoid these common situations.
10. Firm, stable, uniform bedding
Certain design assumptions are made based on normal construction practices to produce the most cost-effective manhole that meets design code. A primary design assumption is the soil foundation needs to be level and firm. If not, a crack can develop and lead to undesirable leakage.
9. Unauthorized repairs
Sometimes things do not go as planned and a field service repair may be needed. Set an expectation to be notified of the situation and to have an opportunity to evaluate the cause of the problem and determine the best remedy.
8. Improper placement of butyl sealant or not equalizing rubber gasket
Careful attention to details is imperative at all times, but it is particularly true in preparing and homing manhole rubber gasketed or butyl sealant joints. Successful joint installation requires training on the proper procedure to prepare and execute a properly homed joint, and communicating with crew supervision that it is critical the procedure is followed for every joint. With today’s low leakage requirements, one problem can ruin an entire project. Precasters should always offer the option for contractors to learn proper jointing techniques.
7. Incorrect stacking
No job is perfect, and products sometimes get misplaced by either the precaster or the contractor. Shop drawings show individual stack-out and pieces, but they do little good when they are reviewed five minutes before installation. With no lead time to correct the mistake, the result is often aggravation and hard feelings or worse, but if drawings are reviewed by both parties when the product is delivered, this situation can be avoided.
6. Not understanding manhole vacuum test standards
It is prudent for the contractor and the precaster to fully understand and agree on all testing requirements. This can reduce situations such as unattainable testing standards for the product specified or the price anticipated, or one party believing the manhole has failed, when in fact it has not.
5. Carelessly inserting pipe into resilient rubber pipe to manhole connector
Pipe crews must be properly trained on pipe insertion methods for the specific product, to avoid pushing the boot into the manhole.
4. Not using spreader bar or using improper rigging for lifting precast sections
Typically, the worst load a manhole base structure will see is not the installed condition, but the shipping and handling. The first manhole riser/base section can be fragile if it contains large pipe openings or deflection angles, since both can remove much of the riser wall. These wall sections cannot take a great amount of lateral loading while unsupported. A spreader bar is designed to reduce or eliminate bending while handling. Also, using a long set of handling cables or chains can increase the sling angle, and greatly reduce the lateral load placed on the structure. A good spreader bar will pay for itself by reducing damage to the manholes and increasing lifting safety on the job site.
3. Ordering and releasing product for fabrication prior to submittal approval
Releasing manhole sections for fabrication prior to receiving approval from the reviewing agency is another concern. The result is often a manhole section that will no longer work for the designated structure due to a project change or a missed measurement found during the normal product submittal process. Typically, when analyzed, the root cause for releasing structures for fabrication prematurely is due to a communication breakdown between the contractor and precaster.
2. Shop drawings and products are not verified/reviewed upon delivery
Problems occur when shop drawings showing individual stack-out and pieces are not reviewed by the contractor to confirm time of delivery or that all sections are present from the precaster. The problem arises when drawings are consulted 5 minutes before the structure is installed in the excavated hole, only to realize a critical section is missing. Though the precaster acknowledges the missing section is their responsibility and can fix the problem with the next shipment to the job site, the situation has the potential to turn into an aggravating crisis with hard feelings and potential back charge threats. Both parties, prior to installation, can avoid all this with a simple review of the shop drawings of the delivered material.
1. Revisions not coordinated
The No. 1 concern discussed is when construction plan changes are made that affect structure fabrication, but are not sent to the precaster for review. This causes the precaster to unknowingly manufacture incorrect structures and wasted product, time and money. A rushed production schedule to manufacture the correct structures needed is often the result.
Honorable Mention: Lay schedules and site changes
The best practice is to establish early communication between the field contractor and the precaster to develop a lay schedule of the pipeline and the corresponding precast structures.
Communication is everything
As things happen in the field such as unmarked utilities moved or right-of-way or permit issues, the schedule and products can be adapted.
The common remedy for all these potential issues is active communication. The famous line in the movie Cool Hand Luke, “What we have here, is a failure to communicate,” definitely applies to the construction industry.
Within the life of a precast order there are many opportunities for the lines of communication to be broken or confused. Part of the problem lies with the fact there are many different players involved in the process on both sides of the order.
The precaster may have a salesman, take-off person, production foreman, dispatcher or field representative. The contractor may have an estimator, purchasing agent/department, area project supervisor or project foreman. All of these people involved and interacting on a single precast can be difficult.
It is imperative from the beginning to clarify the lines of communication of who is specifically responsible for what. Often the original concept and expected delivery dates of the estimator are revised by the time the job gets to the field crews.
Similarly, many precasters typically have a specific person designated to receive order shipment releases or notices of project revisions.
For your next precast concrete manhole project be sure to be proactive with lines of communication to keep your project running smoothly.
Eric Carleton, P.E. is NPCA’s vice president of Technical Services.