18E.50.040 Aquifer Recharge and Wellhead Protection Area Standards.
A. General. All regulated activities that are not exempt, prohibited, or otherwise excluded in the following standards under the provisions of this Chapter shall ensure sufficient groundwater recharge. In order to achieve sufficient groundwater recharge the applicant shall either comply with the impervious surface limitations set forth in Table 18E.50.040-A or demonstrate that the volume of water infiltrated at the proposed project area will be the same or greater amount for post-development as the pre-development volume. Also see Title 18J PCC, Development Regulations – Design Standards and Guidelines, Chapter 18J.30 PCC, for additional impervious surface standards.
|
Comprehensive Plan Land Use Designation |
Maximum Impervious Surface Coverage (1) |
|---|---|
|
Urban Land Use Designations |
|
|
Employment Center |
60% |
|
Major Urban Center |
75% |
|
Activity Center |
50% |
|
Community Center |
50% |
|
Neighborhood Center |
50% |
|
Mixed Use District |
75% |
|
High Density Residential District |
50% |
|
High Density Single Family |
50% |
|
Moderate Density Single Family |
35% |
|
Public Institution |
60% |
|
Urban Military Land |
Not Applicable |
|
Master Planned Community |
20% |
|
Employment Based Planned Community |
20% |
|
Rural Land Use Designations |
|
|
Essential Public Facility Rural Airport North |
PUD |
|
Essential Public Facility Rural Airport South |
PUD |
|
Rural Activity Center |
60% |
|
Rural Neighborhood Center |
50% |
|
Gateway Community |
50% |
|
Rural Separator |
10% |
|
Rural Sensitive Resource |
10% |
|
Rural Farm |
10% |
|
Rural 10 |
10% |
|
Rural 20 |
10% |
|
Rural 40 |
10% |
|
Reserve 5 |
10% |
|
Master Planned Resort |
10% |
|
Rural Military Land |
Not Applicable |
|
Natural Resource Land Designations |
|
|
Designated Forest Land |
Not Applicable |
|
Agricultural Resource Land |
Not Applicable |
(1)The maximum impervious surface coverage is calculated for the total amount of impervious surface per each individual site. The percentage for maximum total impervious surface per lot or site may be exceeded if the applicant can demonstrate that the effective impervious surface on the site is less than or equal to what is allowed for the total impervious surface.
B. Prohibited Uses. Landfills (other than inert and demolition landfills), underground injection wells (Class I, III, and IV), metals mining, wood treatment facilities, pesticide manufacturing, petroleum refining facilities (including distilled petroleum facilities), and the storage of more than 70,000 gallons of liquid petroleum or other hazardous products are prohibited within aquifer recharge and wellhead protection areas.
C. Agricultural Activities. New agricultural activities that do not involve hazardous substance handling or application are allowed within an aquifer recharge or wellhead protection area subject to the following:
1. The applicant is required to submit a farm management plan prepared by the USDA, NRCS, Pierce County Conservation District, or Washington State University, Cooperative Extension Office that certifies that water quality and quantity within the aquifer recharge area is maintained. The farm management plan shall at a minimum address the following:
a. The limits of the proposed agricultural activities.
b. The proposed scope of agricultural activities, including the use of any pesticides, fertilizers, or other chemicals.
c. The existing nitrate levels on the site and any proposed increases in nitrate levels.
2. Integrated Pest Management (IPM) practices for pest control and Best Management Practices (BMPs) for the use of fertilizers, as described by the Washington State University, Pierce County Cooperative Extension Office shall be utilized.
3. Nitrate levels at down-gradient property line shall not exceed 2.5 mg/L or, if the background nitrate concentration exceeds 2.5 mg/L, that the concentration will not be increased more than 0.1 mg/L.
4. Additional protective measures may be required if deemed necessary by the Department or TPCHD to protect public health or safety.
D. Non-Hazardous Uses. Subdivision of land as defined in Title 18F PCC, residential structures housing three or more units and all commercial and industrial sites or activities that do not include or involve hazardous substance processing or handling in an aquifer recharge and/or wellhead protection area are allowed subject to the following standards:
1. Stormwater treatment and control shall be provided in conformance with the Pierce County Stormwater Management and Site Development Manual.
2. Floor drains shall not be allowed to drain to the stormwater system and must be designed and installed to meet the Uniform Plumbing Code (UPC) Section 303.
3. If any roof venting carries contaminants, then the portion of the roof draining this area must go through pretreatment pursuant to UPC Section 304(b).
4. All vehicle washing done somewhere other than at a residence must be self-contained or be discharged to a sanitary sewer system, if approved by the sewer utility, and is subject to UPC Sections 708 and 711.
5. Integrated Pest Management (IPM) practices for pest control and Best Management Practices (BMPs) for the use of fertilizers as described by the Washington State University. Pierce County Cooperative Extension Office shall be utilized.
6. For new or changes in regulated activities served by on-site sewage systems, the applicant must demonstrate to the TPCHD that nitrate levels at the down-gradient property line will not exceed 2.5 mg/L or that, if the background nitrate concentration exceeds 2.5 mg/L, the concentration will not be increased more than 0.1 mg/L.
7. Additional protective measures may be required if deemed necessary by the TPCHD to protect public health or safety.
E. Hazardous Uses – General. Hazardous substance processing or handling, hazardous waste treatment and storage facilities, animal containment areas, and solid waste facilities that require a Solid Waste Handling Permit from the TPCHD shall be allowed only in an aquifer recharge and/or wellhead protection area subject to review and approval of a hydrogeologic assessment by the TPCHD. For this Chapter, natural gas distribution systems are exempted. The TPCHD has the authority to apply whatever standards deemed necessary to mitigate any negative impacts that may be associated with the proposed development. At a minimum, the activity must employee AKART (all known, available, and reasonable treatment) to protect ground water quality.
F. Hazardous Uses – Storage Tanks. In addition to the requirement to submit a hydrogeologic assessment, the following standards apply to storage tanks in an aquifer recharge and/or wellhead protection area:
1. Underground Tanks. All new underground storage facilities used or to be used for the underground storage of hazardous substances or hazardous wastes shall be designed and constructed so as to:
a. Prevent releases due to corrosion or structural failure for the operational life of the tank;
b. Be protected against corrosion, constructed of non-corrosive material, steel clad with a noncorrosive material, or designed to include a secondary containment system to prevent the release or threatened release of any stored substance; and
c. Use material in the construction or lining of the tank which is compatible with the substance to be stored.
d. The installation of underground storage tanks shall also be subject to other state and local permit requirements.
2. Aboveground Tanks.
a. No new aboveground storage facility or part thereof shall be fabricated, constructed, installed, used, or maintained in any manner which may allow the release of a hazardous substance to the ground, groundwater, or surface waters of Pierce County within an aquifer recharge area.
b. A new above tank that will contain a hazardous substance will require both a double walled tank and a secondary containment system separate from the tank that will hold 110 percent of the tank's capacity. The secondary containment system or dike system must be designed and constructed to contain material stored in the tank(s).