Section 8-703 Minimum Construction Standards and Groundwater Investigation Determinations
8-703.A. Water Proof Foundations Required and Permanent Dewatering Prohibited. Foundations designed and constructed below the water table shall not incorporate permanent dewatering capabilities, and shall be waterproofed. Dewatering is permitted during the construction phase only. Dewatering activities shall be undertaken pursuant to direction found within the applicable groundwater investigation and the standards described within Section 8-705, unless otherwise directed by the Town. Dewatering activities shall occur during periods of low water in the Town and when the water table is most likely to be negatively impacted; generally, this period occurs between August 15 of one year and March 31 of the following year. Suggested waterproofing techniques include, but shall not be limited to, double-walled foundations, specialized concrete coatings, or other foundation layering methods.
A waterproof structure may include permanent, emergency dewatering capabilities. Emergency dewatering systems must not be designed to drawdown the water table beneath and surrounding a structure. These systems shall only be allowed to remove water seeping into a structure through an unanticipated leak or leaks in the water proofing system.
8-703.B. Maximum Water Table Intrusion. Unless authorized by P&Z, the depth of permanent subsurface construction other than spread footer foundation support shall be limited to one level below pre-construction grade of the site, unless groundwater is not encountered. Authority to exceed this limit may be authorized by P&Z at a public hearing noticed pursuant to Section 5-204. P&Z may approve exceeding this limit only if: 1) P&Z finds that adequate evidence exists to ensure that the proposed construction will not cause negative impacts on groundwater flows in the Town; 2) the land owner fully accepts responsibility to correct any potential negative impacts on groundwater flows; and, 3) assessments of all potential alternatives to the proposed subsurface construction are completed by the applicant.
8-703.C. Preliminary Groundwater Investigations Required. Preliminary investigations, and if necessary, detailed groundwater investigations, shall be required of all development applicants proposing projects in Zone 1, pursuant to Section 8-704.
8-703.D. Groundwater Investigations Outside Zone 1.
8-703.D.1. If, in the opinion of the Town there is a reasonable probability that a project will encounter groundwater, a preliminary investigation is required, pursuant to Section 8-704. (By way of example, if an applicant is proposing a structure which will use a shallow spread footer foundation it is highly improbable that groundwater will be encountered and no investigation should be required. However, if the applicant is proposing a deep basement, a preliminary investigation would be appropriate.)
8-703.D.2. Excepting single family and duplex home development in Zone 3, a detailed groundwater investigation is required outside of Zone 1 anytime it is determined that construction dewatering is required. This investigation requirement may be triggered by the results of a preliminary investigation, or when construction activity encounters groundwater. If groundwater is encountered during construction, a detailed investigation of dewatering impacts must be conducted immediately. The investigation and recommended construction standards shall be completed pursuant to Section 8-704.B.