Chapter 4.10D
CRITICAL AREA REGULATIONS AQUIFER RECHARGE AREAS
Sections:
4.10D.010 Permitted uses and activities.
4.10D.040 Aquifer recharge areas minimum requirements.
4.10D.050 Determining vulnerability rating.
4.10D.010 Permitted uses and activities.
Uses and activities allowed within designated aquifer recharge areas are those areas permitted by the zoning district, subject to the provisions of this chapter. (Ord. 675 § 1 (Exh. A) (part), 2017: Ord. 562 § 1 (part), 2006)
4.10D.020 Classification.
A. Aquifer recharge areas are classified in accordance with the provisions of the comprehensive plan and are based on the potential for contaminants to enter the aquifer using data from the most current NRCS Soil Survey for Douglas County.
1. Hydrogeologic susceptibility will be characterized by looking at the following attributes:
a. Depth to groundwater;
b. Aquifer properties such as hydraulic conductivity and gradients;
c. Soil (texture, permeability, and contaminant attenuation properties);
d. Characteristics of the vadose zone including permeability and attenuation properties; and
e. Other relevant factors.
2. Contamination loading potential can be evaluated by considering the following:
a. General land use;
b. Waste disposal sites;
c. Agriculture activities;
d. Well logs and water quality test results;
e. Density of septic systems in use in the area; and
f. Other information about the potential for contamination. (Ord. 675 § 1 (Exh. A) (part), 2017: Ord. 562 § 1 (part), 2006)
4.10D.030 Designation.
No aquifer recharge areas are known to have been mapped within the city or surrounding planning area. Therefore, aquifer recharge areas in Bridgeport shall be designated based on recharge potential using the classification provisions in the comprehensive plan. Because the designation focuses on areas where recharge potential exists, protections shall be broad enough to preserve essential aquifer recharge functions and values. Maps EC1 and EC2 in the Map Appendix to the comprehensive plan designate potential aquifer recharge areas.
Additionally, if any of the following areas are established within the city’s urban growth area, they shall be included on these maps:
A. Sole source aquifer recharge areas designated pursuant to the Federal Safe Drinking Water Act;
B. Areas established for special protection pursuant to the Washington State groundwater management program;
C. Areas designated for wellhead protection pursuant to the Federal Safe Drinking Water Act; and
D. Aquifer recharge areas mapped and identified by a qualified groundwater scientist. (Ord. 675 § 1 (Exh. A) (part), 2017: Ord. 562 § 1 (part), 2006)
4.10D.040 Aquifer recharge areas minimum requirements.
A. Development permit applications shall provide appropriate information on forms provided by the city, including without limitation the information described below. Additional reports or information to identify potential impacts and mitigation measures to aquifer recharge areas may be required if deemed necessary.
B. The procedure for determining if a development proposal must complete a vulnerability rating shall be as follows:
1. The applicant shall submit a certified statement with the application materials indicating which of the criteria identified in subsection (C) of this section apply to the development proposal, if any. The application will not be considered complete until this certified statement is submitted.
2. If the applicant’s statement asserts that the criteria do not apply, as identified in subsection (B)(3) of this section, to the development proposal, the city will accept the statement and proceed with the development permit review. However, if the city has or obtains information prior to the permit or approval being finalized that clearly establishes the applicant’s statement is incorrect, the applicant will be advised in writing of the inconsistent information and must either: (a) provide an amended statement adding the evaluation criteria as being applicable and determine the vulnerability rating of the development pursuant to Section 4.10D.050; or (b) present sufficient countering information clearly establishing that the basis for the city’s concern is incorrect. If the applicant selects to proceed under subsection (B)(2)(b) of this section, after receiving the applicant’s information, the city shall review the information and obtain whatever additional assistance may be required to resolve the issue. The final determination as to whether a determination of vulnerability is required shall be made by the city.
3. If a development proposal meets criteria in subsection (C)(1), (2), (3) or (4) of this section, or if the site or development proposal meets any two of the remaining criteria, the application shall determine the vulnerability rating for the development proposal according to Section 4.10D.050.
4. If the development has a high or medium vulnerability rating, the development shall be subject to the general and specific standards contained within this chapter.
C. The applicant shall be required to determine the vulnerability rating for any development permit, not otherwise exempted from this chapter, if the site or development meets criteria in subsection (C)(1), (2), (3), or (4) of this section or if it meets two or more of the remaining criteria below:
1. The development proposal is within a wellhead protection area designated under Chapter 246-290 WAC, Public Water Supplies;
2. The development proposal is within an aquifer recharge area mapped and identified by a qualified groundwater scientist;
3. The site will be utilized for processing, storing, or handling a hazardous substance (as now or hereafter defined in Chapter 70.105D RCW, Hazardous Waste Cleanup—Model Toxics Control Act), in applications or quantities larger than is typical of household use;
4. The site will be utilized for hazardous waste treatment and storage as set forth in Chapter 70.105 RCW, Hazardous Waste Management, as now or hereafter amended;
5. The site contains highly permeable soils as designated in the NRCS Soil Survey for the Bridgeport Area;
6. The development proposal is within a sole source aquifer recharge area designated pursuant to the Federal Safe Drinking Water Act;
7. The development proposal is within an area established for special protection pursuant to a groundwater management program, Chapters 90.44, Regulations of Public Ground Waters, 90.48, Water Pollution Control, and 90.54 RCW, Water Resources Act of 1971, and Chapters 173-100, Ground Water Management Areas, and 173-200 WAC, Water Quality Standards for Ground Waters of the State of Washington;
8. The development proposal involves a major or short subdivision and includes present or future plans to construct three or more dwelling units where the dwelling units will not be connected to a public sewer system and any of the lots are less than one net acre in size;
9. The development proposal involves a commercial and/or industrial site that is not on a public sewer system and the main structure exceeds four thousand square feet;
10. The development is within two hundred feet of the ordinary high water mark of a perennial river, stream, lake or pond. (Ord. 675 § 1 (Exh. A) (part), 2017: Ord. 562 § 1 (part), 2006)
4.10D.050 Determining vulnerability rating.
A. General. The vulnerability matrix is used to determine the vulnerability of the development and to rate it as high, medium or low. This can be done by determining the “contaminant loading potential” of a proposed land use and the natural “susceptibility” of the site as outlined in this chapter and creating a numerical vulnerability value for a proposed land use. When a proposed use is determined to have a medium or high vulnerability rating, the protection measures described in this chapter shall be implemented that protect the potable water supply.
B. Determining Susceptibility. There are three basic components to determine a site’s susceptibility, as follows:
1. Permeability of the Vadose Zone. The vadose zone is composed of both the soil and the geologic materials underlying the soil. To adequately determine the overall ease with which water will travel from land surface to the aquifer, it is necessary to determine the overall permeability of both soil and geologic media. Soil permeability can be determined through use of the NRCS Soil Survey for Douglas County. The values shown on these pages are given in the inches per hour that water moves downward through a saturated soil. A determination of the permeability of the geologic material underlying the soil is more problematic.
a. Incrementally, the permeability of local soils (upper vadose zone) is grouped into four ranges that are assigned a relative value to be used for determining susceptibility on the matrix. Where conclusive information does not exist for permeability of the soil, a relative rating value of 3 will be assigned.
|
Condensed Description |
Soil Survey Description |
Permeability (in/hr) |
Permeability (cm/sec) |
Rating |
|---|---|---|---|---|
|
Very slow |
Very slow |
< 0.06 |
< .00453 |
0 |
|
Slow |
Slow |
0.06 — 0.20 |
.00453 — .0141 |
1 |
|
Moderately slow |
0.20 — 0.60 |
.0141 — .0423 |
||
|
Moderate |
Moderate |
0.60 — 2.0 |
.0423 — .1411 |
2 |
|
Moderately rapid |
2.0 — 6.0 |
.1411 — .4233 |
||
|
Rapid |
Rapid |
6.0 — 20 |
.4233 — 1.411 |
3 |
|
Very rapid |
> 20 |
> 1.411 |
b. Permeability of the lower vadose zone can be estimated using the Geologic Matrix Table below by determining the material type and assigning the appropriate permeability range for the material(s) overlying the uppermost aquifer. In cases where heterogeneous material is encountered, the least permeable layer with a thickness of not less than five feet shall determine the overall permeability to be applied to the entire vadose zone, excluding the soil layer. Where conclusive information does not exist for permeability of the geologic matrix, a relative rating value of 3 will be assigned.
|
Condensed Description |
Geologic Matrix |
Permeability (cm/sec) |
Rating |
|---|---|---|---|
|
Very slow |
Unfractured igneous or metamorphic bedrock, shale |
10-13 — 10-9 |
0 |
|
Marine clay, clay, dense sandstone, hardpan |
10-9 — 10-7 |
||
|
Slow |
Loess, glacial till, fractured igneous or metamorphic bedrock |
10-8 — 10-5 |
1 |
|
Silt, clayey sands, weathered basalt |
10-7 — 10-3 |
||
|
Moderate |
Silty sands, fine sands, permeable basalt |
10-4 — 10-1 |
2 |
|
Clean sands, karst limestone |
>.1 — 1.0 |
||
|
Rapid |
Sand and gravel |
>1.0 — 10 |
3 |
|
Gravel |
>10 — 100+ |
2. Depth to Groundwater. Depth to groundwater can be determined by utilizing local well log information or specific well information for the site. Depth to groundwater is also assigned a relative value used for determining susceptibility on the matrix. Where conclusive information does not exist for depth to groundwater, a relative rating value of 3 will be assigned.
|
Condensed Description |
Depth to Water (feet) |
Rating |
|---|---|---|
|
Very low |
Confined aquifer |
0 |
|
>50 |
||
|
Low |
25 — ≤50 |
1 |
|
Moderate |
10 — ≤25 |
2 |
|
High |
0 — ≤10 |
3 |
3. Slope. Slope, or gradient, is related to the infiltration characteristics of an area. The steeper the slope the less infiltration of surface waters occur. Slope is assigned a relative value used for determining susceptibility on the matrix. Where conclusive information does not exist for slope, a relative value of 3 will be assigned.
|
Slope—As a Percent |
Slope Relative Value |
|---|---|
|
>45% |
0 |
|
>30% — 45% |
1 |
|
15% — 30% |
2 |
|
<15% |
3 |
C. Determining the Susceptibility Rating. A susceptibility rating is determined by adding the relative values of permeability of the soils and geologic matrix of the vadose zone, depth to groundwater and slope. This is a baseline determination for susceptibility. The range of values are as follows:
1. High susceptibility rating equals total range eight to twelve.
2. Medium susceptibility rating equals total range four to seven.
3. Low susceptibility rating equals total range zero to three.
D. Determining the Contaminant Loading Rating. Contaminant loading potential is dependent on the presence of critical materials on the site. A critical material is a substance present in sufficient quantity that its accidental or intentional release would result in the impairment of the aquifer water to be used as potable drinking water.
1. For the purpose of administration of this section, the city will maintain a critical materials use activity list, which is a list of commercial and industrial activities known to use critical materials, coupled with the names of critical materials normally associated with the activity. The following situations will be considered as having a high contaminant loading rating, unless the project proponent provides assurances otherwise:
a. Proposed activities fitting one of the general business descriptions provided or having one of the specified standard industrial classification (SIC) codes identified on the city’s critical materials use activity list;
b. Sites or uses that the city believes would be utilized for processing, storing or handling hazardous substance(s) (as now or hereafter defined in Chapter 70.105D RCW, Hazardous Waste Cleanup-Model Toxics Control Act) in applications or quantities larger than is typical of household use;
c. Sites that the city believes will be utilized for hazardous waste treatment and storage as set forth in Chapter 70.105 RCW, Hazardous Waste Management, as now or hereafter amended, but may not be covered in the critical materials use activity list;
d. Other contaminants and/or SIC codes that are not currently found on the critical materials use activity list that are subsequently determined by the city to have a high contaminant loading rating.
Those uses or activities determined not to have a high contaminant loading rating are considered to have a low contaminant loading potential and rating.
2. The following process shall be used to determine whether or not critical materials are involved:
a. An initial screening will be performed by the city by comparing the proposed use and any other pertinent information provided by the proponent at his/her expense, with the critical materials use activity list. The city will exercise any discretion in judgment in the favor of aquifer protection.
b. If the proposed use is determined to meet one of the criteria under subsection (D)(1) of this section, the city shall require the applicant to provide a list of materials, including quantities to be used, stored or transported in conjunction with the proposed activity. Additional information may be required by the city to be provided by the proponent at his or her expense.
c. After the review of the information supplied by the applicant, the city will either confirm the designation as a critical materials use activity or nullify the tentative designation.
d. If the designation as a critical materials use activity is confirmed, the applicant may respond by accepting the designation as a critical materials use activity or he/she may appeal the designation through the procedures governing appeals of administrative decisions, according to Title 19 BMC. Where an appeal is filed, the Washington Department of Ecology, the Washington Department of Health and the Douglas-Douglas Health District shall be notified of all appeal proceedings.
E. Vulnerability Matrix. A determination of a high, medium, or low vulnerability rating is made by the city from the vulnerability matrix by identifying susceptibility and contaminant loading ratings, as identified above (susceptibility equals high [eight to twelve], medium [four to seven] or low [zero to three]; contaminant loading equals high or low). After determining the susceptibility and contaminant loading ratings for the proposed use and site, the appropriate box on each axis of the vulnerability matrix in this section will be checked to determine the vulnerability rating. The vulnerability of the site is then determined by the intersection of the susceptibility rating and the contaminant loading rating to be low, medium, or high.
Vulnerability Matrix
(Ord. 675 § 1 (Exh. A) (part), 2017: Ord. 562 § 1 (part), 2006)
4.10D.060 General standards.
The following minimum standards shall apply to all development activities determined to have a high or medium vulnerability rating, as determined by this chapter:
A. Development activities within an aquifer recharge area shall be designed, developed and operated in a manner that will not potentially degrade groundwater resources.
B. Alternative site designs, phased development and/or groundwater quality monitoring shall be required where necessary to reduce contaminant loading where site conditions indicate that the proposed action will potentially degrade groundwater quality.
C. Open space may be required on development proposals overlying areas that are highly susceptible to contamination of groundwater resources.
D. When wells are required to be abandoned, the applicant shall ensure that they are abandoned according to the State Department of Ecology requirements.
E. Known contaminants shall be removed from stormwater runoff prior to their point of entry into surface or groundwater resources using available and reasonable best management practices.
F. Changes in occupancy and/or use of an existing site, and/or expansions of existing activities are subject to complete evaluation by the city under the provisions of this chapter. (Ord. 675 § 1 (Exh. A) (part), 2017: Ord. 562 § 1 (part), 2006)
4.10D.070 Specific standards.
The following standards shall apply to the activity identified in this section, in addition to the general standards outlined in Section 4.10D.060.
A. Any agricultural activities shall implement best management practices concerning waste disposal, fertilizer use, pesticide use, and stream corridor management. If necessary, farmers shall seek technical assistance from the Foster Creek conservation district, WSU cooperative extension agent and local field agents.
B. Landfills, junkyards, salvage yards and auto wrecking yards are prohibited within designated critical aquifer recharge areas. Landfills, junkyards, salvage yards and auto wrecking yards proposed to be located outside of designated critical aquifer recharge areas and that have a high or medium vulnerability rating must satisfactorily demonstrate that potential negative impacts to the groundwater would be overcome in such a manner as to prevent adverse impacts to groundwater.
C. Fertilizer, herbicide and pesticide management practices of schools, parks, golf courses and other nonresidential facilities that maintain large landscaped areas shall utilize best management practices as recommended by the cooperative extension service.
D. Commercial and industrial shall comply with the following minimum provisions:
1. All commercial and industrial uses that are rated as having a medium or high vulnerability, shall submit a contingency plan that identifies the following:
a. Types of hazardous wastes that would be used for the proposed land use.
b. On-site containment facilities designed to handle accidental releases of critical materials.
c. Spill response and notification procedures.
2. All activities designated as critical materials use activities shall only be approved so that:
a. Facilities will be designed and built so that any spilled or leaked materials are contained on site; and
b. Facilities will be designed and built so that any spilled or leaked materials cannot infiltrate into the ground; and
c. No permanent disposal of any waste containing critical materials shall be allowed on site.
3. Commercial or industrial activities designated as critical materials use activities shall have specially designed and installed storm runoff drainage facilities in areas where spills might occur. Such facilities shall be designed and installed to:
a. Prevent the commingling of storm runoff and critical materials spills; and
b. Enhance spill cleanup procedures.
E. Utility facilities shall be reviewed and approved consistent with the requirements of subsection (D) of this section.
F. Underground storage tanks and on-site sewage disposal systems are prohibited within designated critical aquifer recharge areas. Underground storage tanks and on-site sewage disposal systems that are proposed to be located outside of designated critical aquifer recharge areas and that have a high or medium vulnerability rating must satisfactorily demonstrate that potential negative impacts to the groundwater would be overcome in such a manner as to prevent adverse impacts to groundwater.
G. All residential land divisions within the city of Bridgeport urban growth area shall be connected to the city’s sanitary sewage collection and treatment facilities. Where an area subject to a land division process occurs within a designated aquifer recharge area, as described by this chapter, a notation shall appear on the face of the final plat indicating the aquifer recharge area designation, and referencing the requirements of this chapter.
H. As defined and regulated in Chapter 173-24 WAC, Underground Injection Control Program, Class I, II and IV underground injection wells are prohibited. Class II injection wells are permitted under Chapter 173-24 WAC by the Washington State Department of Ecology in conjunction with the Washington State Department of Natural Resources. Class V injection wells, involving the injection of critical materials, may be prohibited by the Washington State Department of Ecology or a permit may be required by said agency. In addition, commercial or industrial uses proposing the injection of critical materials are subject to the provisions of this chapter. (Ord. 675 § 1 (Exh. A) (part), 2017: Ord. 562 § 1 (part), 2006)