aquifer (confined)--soil or rock below the land surface that is saturated with water. There are layers of impermeable material both above and below it and it is under pressure so that when the aquifer is penetrated by a well, the water will rise above the top of the aquifer.
All manufacturers wish that their product or products are used on construction projects; otherwise, they would not be in the business. But, on the design side, not every product is suitable for a given project, nor is there sufficient fee to research every product that could potentially be used on a project.Convenienceâ refers to conditions that benefit the contractor, the owner, or both. If permitted, the contractor may submit a substitution request if there is a significant advantage, such as lower cost in labor, material, or both; quicker delivery time; or other benefit to the owner.
Hazard substitution. Hazard substitution is a hazard control strategy in which a material or process is replaced with another that is less hazardous. Substitution is the second most effective of the five members of the hierarchy of hazard controls in protecting workers, after elimination. Substitution and elimination are most effective early in the design process, when they may be inexpensive and simple to implement, while for an existing process they may require major changes in equipment and procedures. The concep