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.
A substitution is a mutation that exchanges one base for another (i.e., a change in a single chemical letter such as switching an A to a G). Such a substitution could: 1  change a codon to one that encodes a different amino acid and cause a small change in the protein produced.2  For example, sickle cell anemia is caused by a substitution in the beta-hemoglobin gene, which alters a single amino acid in the protein produced. For example, sickle cell anemia is caused by a substitution in the beta-hemoglobin gene, which alters a single amino acid in the protein produced. 2  change a codon to one that encodes the same amino acid and causes no change in the protein produced. 3  These are called silent mutations.