Chapter 18.21 CRITICAL AREAS AND RESOURCE LANDS

English ivy (Hedera helix);

Himalayan blackberry (Rubus discolor, R. procerus);

Evergreen blackberry (Rubus laciniatus); and

Scotch broom (Cytisus scoparius);

The removal of trees from critical areas and buffers that are hazardous, posing a threat to public safety or posing an imminent risk of damage to private property; provided, that:

The applicant submits a report from a certified arborist, registered landscape architect, or professional forester that documents the hazard and provides a replanting schedule for the replacement trees;

Tree cutting shall be limited to pruning and crown thinning, unless otherwise justified by a qualified professional. Where pruning or crown thinning is not sufficient to address the hazard, trees should be removed or converted to wildlife snags;

All vegetation cut (tree stems, branches, etc.) shall be left within the critical area or buffer unless removal is warranted due to the potential for disease or pest transmittal to other healthy vegetation;

The landowner shall replace any trees that are removed with new trees at a ratio of two replacement trees for each tree removed (2:1) within one year in accordance with an approved restoration plan. Replacement trees may be planted at a different nearby location if it can be determined that planting in the same location would create a new hazard or potentially damage the critical area. Replacement trees shall be species that are native and indigenous to the site and a minimum of one inch in diameter-at-breast-height (dbh) for deciduous trees and a minimum of six feet in height for evergreen trees as measured from the top of the root ball;

If a tree to be removed provides critical habitat, such as an eagle perch, a qualified wildlife biologist shall be consulted to determine timing and methods or removal that will minimize impacts; and

§ 18.21.050 General critical area protective measures.

Hazard trees determined to pose an imminent threat or danger to public health or safety, to public or private property, or of serious environmental degradation may be removed or pruned by the landowner prior to receiving written approval from the city; provided, that within 14 days following such action, the landowner shall submit a restoration plan that demonstrates compliance with the provisions of this chapter;

Measures to control a fire or halt the spread of disease or damaging insects consistent with the State Forest Practices Act; Chapter 76.09 RCW; provided, that the removed vegetation shall be replaced in-kind or with similar native species within one year in accordance with an approved restoration plan; and

Unless otherwise provided, or as a necessary part of an approved alteration, removal of any vegetation or woody debris from a habitat conservation area or wetland shall be prohibited;

Chemical Applications. The application of herbicides, pesticides, organic or mineral-derived fertilizers, or other hazardous substances, if necessary, as approved by the city; provided, that their use shall be restricted in accordance with State Department of Fish and Wildlife Management recommendations and the regulations of the State Department of Agriculture and the U.S. Environmental Protection Agency;

Minor Site Investigative Work. Work necessary for land use submittals, such as surveys, soil logs, percolation tests, and other related activities, where such activities do not require construction of new roads or significant amounts of excavation. In every case, impacts to the critical area shall be minimized and disturbed areas shall be immediately restored; and

Navigational Aids and Boundary Markers. Construction or modification of navigational aids and boundary markers. (Correspondence from 2/1/24; Ord. 1107 § 2, 2023; Ord. 995 § 12 (Exh. A), 2015).

Critical Area Markers and Signs.

The boundary at the outer edge of critical area tracts and easements shall be delineated with permanent survey stakes as established by local survey standards.

The boundary at the outer edge of the critical area or buffer shall be identified with temporary signs prior to any site alteration. Such temporary signs shall be replaced with permanent signs prior to occupancy or use of the site.

These provisions may be modified by the administrator as necessary to ensure protection of sensitive features or wildlife needs.

Financial Guarantee to Ensure Mitigation, Maintenance, and Monitoring.

When mitigation required pursuant to a development proposal is not completed prior to the city final permit approval, such as final plat approval or final building inspection, the city shall require the applicant to post a financial guarantee in a form and amount deemed acceptable by the city. If the development proposal is subject to mitigation, the applicant shall post a financial guarantee security in a form and amount deemed acceptable by the city to ensure mitigation is fully functional.

The bond shall be in the amount of 150 percent of the estimated cost of the uncompleted actions or the estimated cost of restoring the functions and values of the critical area that are at risk, whichever is greater.

The bond shall be in the form of an assignment of savings account in the city trust fund.

Financial guarantees shall remain in effect until the city determines in writing that the standards bonded for have been met. Bonds or other security shall be held by the city for a minimum of five years to ensure that the required mitigation has been fully implemented and demonstrated to function, and may be held for longer periods when necessary.

Depletion, failure, or collection of bond funds shall not discharge the obligation of an applicant or violator to complete required mitigation, maintenance, monitoring, or restoration.

Public development proposals shall be relieved from having to comply with the bonding requirements of this section if public funds have previously been committed for mitigation, maintenance, monitoring, or restoration.

Any failure to satisfy critical area requirements established by law or condition including, but not limited to, the failure to provide a monitoring report within 30 days after it is due or comply with other provisions of an approved mitigation plan shall constitute a default, and the city may demand payment of any financial guarantees or require other action authorized by the city code or any other law.

Any funds recovered pursuant to this section shall be used to complete the required mitigation.

Critical Area Inspections. Reasonable access to the site shall be provided to the city, state, and federal agency review staff for the purpose of inspections during any proposal review, restoration, emergency action, or monitoring period.

(Ord. 995 § 12 (Exh. A), 2015)

§ 18.21.060 Wetlands.

Designating Wetlands. Wetlands are those areas, designated in accordance with the Washington State Wetland Identification and Delineation Manual (1997), that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation adapted for life in saturated soil conditions. All areas within the city meeting the wetland designation criteria in the Identification and Delineation Manual, regardless of any formal identification, are hereby designated critical areas and are subject to the provisions of this chapter.

Wetland Ratings. Wetlands shall be rated according to the Washington State Department of Ecology (Ecology) wetland rating system found in the Washington State Wetland Rating System documents or as revised by Ecology.

Wetland Rating Categories.

Category I. Category I wetlands are those that:

Represent a unique or rare wetland type; or

Are more sensitive to disturbance than most wetlands; or

Are relatively undisturbed and contain ecological attributes that are impossible to replace within a human lifetime; or

Provide a high level of functions. These include estuarine wetlands, natural heritage wetlands, bogs, mature and old-growth forested wetlands, wetlands in coastal lagoons and wetlands that score more than 70 points in the 2004 rating system.

Category II. Category II wetlands are difficult, though not impossible, to replace, and provide high levels of some functions. Category II wetlands in western Washington include wetlands scoring between 51 and 69 points in the 2004 rating system.

Category III. Category III wetlands are those with a moderate level of functions (scores between 30 and 50 points). Wetlands scoring between 30 and 50 points generally have been disturbed in some ways and are often less diverse or more isolated from other natural resources in the landscape than Category II wetlands.

Category IV. Category IV wetlands have the lowest levels of functions (scores less than 30 points) and are often heavily disturbed.

Date of Wetland Rating. Wetland rating categories shall be applied as the wetland exists on the date of adoption of the rating system by the local government, as the wetland naturally changes thereafter, or as the wetland changes in accordance with permitted activities. Wetland rating categories shall not change due to illegal modifications.

Mapping. The approximate location and extent of wetlands are shown on the critical area maps prepared by the community development department. These maps are to be used as a guide for the city, project applicants, and/or property owners, and may be continuously updated as new critical areas are identified. They are a reference and do not provide a final critical area designation.

The exact location of a wetland's boundary shall be determined through the performance of a field investigation by a qualified professional wetland scientist applying the Washington State Wetlands Identification and Delineation Manual as required by RCW 36.70A.175.

Activities Allowed in Wetlands. The activities listed below are allowed in wetlands in addition to those activities listed in, and consistent with, the provisions established in allowed activities, and do not require submission of a critical area report, except where such activities result in a loss to the functions and values of a wetland or wetland buffer. These activities include:

Conservation or preservation of soil, water, vegetation, fish, shellfish, and other wildlife that does not entail changing the structure or functions of the existing wetland.

The harvesting of wild crops in a manner that is not injurious to natural reproduction of such crops and provided the harvesting does not require tilling of soil, planting of crops, chemical applications, or alteration of the wetland by changing existing topography, water conditions, or water sources.

Drilling for utilities under a wetland; provided, that the drilling does not interrupt the ground water connection to the wetland or percolation of surface water down through the soil column. Specific studies by a hydrologist are necessary to determine whether the ground water connection to the wetland or percolation of surface water down through the soil column is disturbed.

Enhancement of a Wetland through the Removal of Nonnative Invasive Species. Weeding shall be restricted to hand removal and weed material shall be removed from the site. Bare areas that remain after weed removal shall be revegetated with native shrubs and trees at natural densities. Some hand seeding may also be done over the bare areas with native herbs.

Wetland Analysis.

A written assessment and accompanying maps of the wetlands and buffers within 300 feet of the project area, including the following information at a minimum:

Wetland delineation and required buffers;

Existing wetland acreage;

Wetland category;

Vegetative, faunal, and hydrologic characteristics;

Soil and substrate conditions;

Topographic elevations, at two-foot contours; and

A discussion of the water sources supplying the wetland and documentation of hydrologic regime (locations of inlet and outlet features, water depths throughout the wetland, evidence of recharge or discharge, evidence of water depths throughout the year: drift lines, algal layers, moss lines, and sediment deposits).

A discussion of measures, including avoidance, minimization, and mitigation, proposed to preserve existing wetlands and restore any wetlands that were degraded prior to the current proposed land use activity.

A habitat and native vegetation conservation strategy that addresses methods to protect and enhance on-site habitat and wetland functions.

Functional evaluation for the wetland and adjacent buffer using a local or state agency staff-recognized method and including the reference of the method and all data sheets.

Proposed mitigation, if needed, including a written assessment and accompanying maps of the mitigation area, including the following information at a minimum:

Existing and proposed wetland acreage;

Vegetative and faunal conditions;

Surface and subsurface hydrologic conditions including an analysis of existing and future hydrologic regime and proposed hydrologic regime for enhanced, created, or restored mitigation areas;

Relationships within watershed and to existing water bodies;

Soil and substrate conditions, topographic elevations;

Existing and proposed adjacent site conditions;

Required wetland buffers (including any buffer reduction and mitigation proposed to increase the plant densities, remove weedy vegetation, and replant the buffers);

Property ownership; and

Associated wetlands and related wetlands that may be greater than 300 feet from the subject project.

A scale map of the development proposal site and adjacent area. A discussion of ongoing management practices that will protect wetlands after the project site has been developed; including proposed monitoring and maintenance programs.

A bond estimate for the installation (including site preparation, plant materials and installation, fertilizers, mulch, stakes) and the proposed monitoring and maintenance work for the required number of years.

Title Notification. All activity in critical area protection areas shall be accompanied by a notice to title, recorded with the Thurston County auditor.

Wetland Performance Standards – General Requirements.

Activities may only be permitted in a wetland or wetland buffer if the applicant can show that the proposed activity will not degrade the functions and functional performance of the wetland and other critical areas.

Activities and uses shall be prohibited in wetlands and wetland buffers, except as provided for in this chapter.

Category I Wetlands. Activities and uses shall be prohibited from Category I wetlands, except as provided for in the public agency and utility exception, reasonable use exception, and variance sections of this chapter.

Category II and III Wetlands.

Water-dependent activities may be allowed where there are no practicable alternatives that would have a less adverse impact on the wetland, its buffers and other critical areas.

Where non-water-dependent activities are proposed, it shall be presumed that alternative locations are available, and activities and uses shall be prohibited, unless the applicant demonstrates that:

The basic project purpose cannot reasonably be accomplished and successfully avoid, or result in less adverse impact on, a wetland on another site or sites in the general region; and

All alternative designs of the project as proposed, that would avoid or result in less of an adverse impact on a wetland or its buffer, such as a reduction in the size, scope, configuration, or density of the project, are not feasible.

Category IV Wetlands. Activities and uses that result in unavoidable and necessary impacts may be permitted in Category IV wetlands and associated buffers in accordance with an approved critical area report and mitigation plan, and only if the proposed activity is the only reasonable alternative that will accomplish the applicant's objectives. Full compensation for the acreage and loss functions will be provided.

Wetland Buffers.

Standard Buffer Widths. The standard buffer widths presume the existence of a relatively intact native vegetation community in the buffer zone adequate to protect the wetland functions and values at the time of the proposed activity. If the vegetation is inadequate, then the buffer width shall be increased or the buffer should be planted to maintain the standard width. Required standard wetland buffers, based on wetland category and land use intensity, are as follows:

Category I:

Natural Heritage Wetlands	250 feet
Bogs	250 feet
High level of function for habitat (score of 29 – 36 points)	300 feet
Moderate level of function for habitat (score of 20 – 28 points)	150 feet
High level of function for water quality improvement (24 – 32 points) and low for habitat (less than 20 points)	100 feet
Not meeting any other characteristics	100 feet

Category II:

High level of function for habitat (score of 29 – 36 points)	300 feet
Moderate level of function for habitat (score of 20 – 28 points)	150 feet
High level of function for water quality improvement and low for habitat (score for water quality 24 – 32 points and habitat less than 20 points)	100 feet
Not meeting any other characteristics	100 feet

Category III:

Moderate level of function for habitat (score of 20 – 28 points)	150 feet
Not meeting above characteristic	80 feet

Category IV:

Score for all three basic functions less than 30 points

50 feet

Measurement of Wetland Buffers. All buffers shall be measured from the wetland boundary as surveyed in the field. The width of the wetland buffer shall be determined according to the wetland category and the proposed land use. The buffer for a wetland created, restored, or enhanced as compensation for approved wetland alterations shall be the same as the buffer required for the category of the created, restored, or enhanced wetland. Only fully vegetated buffers will be considered. Lawns, walkways, driveways, and other mowed or paved areas will not be considered buffers.

Increased Wetland Buffer Widths. The administrator shall require increased buffer widths in accordance with the recommendations of an experienced, qualified professional wetland scientist, and the best available science on a case-by-case basis when a larger buffer is necessary to protect wetland functions and values based on site-specific characteristics. This determination shall be based on one or more of the following criteria:

A larger buffer is needed to protect other critical areas;

The buffer or adjacent uplands has a slope greater than 15 percent or is susceptible to erosion and standard erosion-control measures will not prevent adverse impacts to the wetland; or

The buffer area has minimal vegetative cover. In lieu of increasing the buffer width where existing buffer vegetation is inadequate to protect the wetland functions and values, implementation of a buffer planting plan may substitute. Where a buffer planting plan is proposed, it shall include densities that are not less than three feet on center for shrubs and eight feet on center for trees and require monitoring and maintenance to ensure success. Existing buffer vegetation is considered "inadequate" and will need to be enhanced through additional native plantings and (if appropriate) removal of nonnative plants when: (A) nonnative or invasive plant species provide the dominant cover, (B) vegetation is lacking due to disturbance and wetland resources could be adversely affected, or (C) enhancement plantings in the buffer could significantly improve buffer functions.

Wetland Buffer Width Averaging. The administrator may allow modification of the standard wetland buffer width in accordance with an approved critical area report and the best available science on a case-by-case basis by averaging buffer widths. Averaging of buffer widths may only be allowed where a qualified professional wetland scientist demonstrates that:

It will not reduce wetland functions or functional performance;

The wetland contains variations in sensitivity due to existing physical characteristics or the character of the buffer varies in slope, soils, or vegetation, and the wetland would benefit from a wider buffer in places and would not be adversely impacted by a narrower buffer in other places;

The total area contained in the buffer area after averaging is no less than that which would be contained within the standard buffer; and

The buffer width is not reduced to less than 75 percent of the standard width or 35 feet.

Buffer Consistency. All mitigation sites shall have buffers consistent with the buffer requirements of this chapter.

Buffer Maintenance. Except as otherwise specified or allowed in accordance with this chapter, wetland buffers shall be retained in an undisturbed or enhanced condition. Removal of invasive nonnative weeds is required for the duration of the mitigation bond.

Buffer Uses. The following uses may be permitted within a wetland buffer in accordance with the review procedures of this chapter; provided they are not prohibited by any other applicable law and they are conducted in a manner so as to minimize impacts to the buffer and adjacent wetland:

Conservation and Restoration Activities. Conservation or restoration activities aimed at protecting the soil, water, vegetation, or wildlife.

Passive Recreation. Passive recreation facilities designed and in accordance with an approved critical area report.

Performance Standards – Compensatory Mitigation Requirements. Compensatory mitigation for alterations to wetlands shall achieve equivalent or greater biologic functions. Compensatory mitigation plans shall be consistent with the state Department of Ecology Guidelines for Developing Freshwater Wetlands Mitigation Plans and Proposals, 1994, as revised.

Mitigation shall be required in the following order of preference:

Avoiding the impact altogether by not taking a certain action or parts of an action.

Minimizing impacts by limiting the degree or magnitude of the action and its implementation, by using appropriate technology, or by taking affirmative steps to avoid or reduce impacts.

Rectifying the impact by repairing, rehabilitating, or restoring the affected environment.

Reducing or eliminating the impact over time by preservation and maintenance operations.

Compensating for the impact by replacing, enhancing, or providing substitute resources or environments.

Mitigation for Lost or Affected Functions. Compensatory mitigation actions shall address functions affected by the alteration to achieve functional equivalency or improvement and shall provide similar wetland functions as those lost, except when:

The lost wetland provides minimal functions as determined by a site-specific function assessment, and the proposed compensatory mitigation action(s) will provide equal or greater functions or will provide functions shown to be limiting within a watershed through a formal Washington State watershed assessment plan or protocol; or

Out-of-kind replacement will best meet formally identified watershed goals, such as replacement of historically diminished wetland types.

Preference of Mitigation Actions. Mitigation actions that require compensation by replacing, enhancing, or substitution shall occur in the following order of preference:

Restoring wetlands on upland sites that were formerly wetlands.

Creating wetlands on disturbed upland sites such as those with vegetative cover consisting primarily of nonnative introduced species. This should only be attempted when there is a consistent source of hydrology and it can be shown that the surface and subsurface hydrologic regime is conducive for the wetland community that is being designed.

Enhancing significantly degraded wetlands in combination with restoration or creation. Such enhancement should be part of a mitigation package that includes replacing the impacted area meeting appropriate ratio requirements.

Type and Location of Mitigation. Unless it is demonstrated that a higher level of ecological functioning would result from an alternate approach, compensatory mitigation for ecological functions shall be either in kind and on site, or in-kind and within the same stream reach, subbasin, or drift cell. Mitigation actions shall be conducted within the same subdrainage basin and on the site as the alteration except when all of the following apply:

There are no reasonable on-site or in-subdrainage basin opportunities or on-site and in-subdrainage basin opportunities do not have a high likelihood of success, after a determination of the natural capacity of the site to mitigate for the impacts. Consideration should include: anticipated wetland mitigation replacement ratios, buffer conditions and proposed widths, hydrogeomorphic classes of on-site wetlands when restored, proposed flood storage capacity, potential to mitigate riparian fish and wildlife impacts (such as connectivity);

Off-site mitigation has a greater likelihood of providing equal or improved wetland functions than the impacted wetland; and

Off-site locations shall be in the same subdrainage basin unless:

Established watershed goals for water quality, flood or conveyance, habitat, or other wetland functions have been established and strongly justify location of mitigation at another site; or

Credits from a state certified wetland mitigation bank are used as mitigation and the use of credits is consistent with the terms of the bank's certification.

Mitigation Timing. Mitigation projects shall be completed with an approved monitoring plan prior to activities that will disturb wetlands. In all other cases, mitigation shall be completed immediately following disturbance and prior to use or occupancy of the activity or development. Construction of mitigation projects shall be timed to reduce impacts to existing fisheries, wildlife, and flora.

The administrator may authorize a one-time temporary delay, up to 120 days, in completing minor construction and landscaping when environmental conditions could produce a high probability of failure or significant construction difficulties. The delay shall not create or perpetuate hazardous conditions or environmental damage or degradation, and the delay shall not be injurious to the health, safety, and general welfare of the public. The request for the temporary delay must include a written justification that documents the environmental constraints that preclude implementation of the mitigation plan. The justification must be verified and approved by the city and include a financial guarantee.

Mitigation Ratios.

Acreage Replacement Ratios. The following ratios shall apply to creation or restoration that is in kind, is on site, is the same category, is timed prior to or concurrent with alteration, and has a high probability of success. These ratios do not apply to remedial actions resulting from unauthorized alterations; greater ratios shall apply in those cases. These ratios do not apply to the use of credits from a state certified wetland mitigation bank. When credits from a certified bank are used, replacement ratios should be consistent with the requirements of the bank's certification. The first number specifies the acreage of replacement wetlands and the second specifies the acreage of wetlands altered.

Category I	6 to 1
Category II	3 to 1
Category III	2 to 1
Category IV	1.5 to 1

Increased Replacement Ratio. The administrator may increase the ratios under the following circumstances:

Uncertainty exists as to the probable success of the proposed restoration or creation;

§ 18.21.070 Critical aquifer recharge areas.

A significant period of time will elapse between impact and replication of wetland functions;

Proposed mitigation will result in a lower category wetland or reduced functions relative to the wetland being impacted; or

The impact was an unauthorized impact.

Wetlands Enhancement as Mitigation.

Impacts to wetland functions may be mitigated by enhancement of existing significantly degraded wetlands, but must be used in conjunction with restoration and/or creation. Applicants proposing to enhance wetlands must produce a critical area report that identifies how enhancement will increase the functions of the degraded wetland and how this increase will adequately mitigate for the loss of wetland area and function at the impact site. An enhancement proposal must also show whether existing wetland functions will be reduced by the enhancement actions.

At a minimum, enhancement acreage shall be double the acreage required for creation or restoration. The ratios shall be greater than double the required acreage where the enhancement proposal would result in minimal gain in the performance of wetland functions and/or result in the reduction of other wetland functions currently being provided in the wetland.

Mitigation ratios for enhancement in combination with other forms of mitigation shall range from 6:1 to 3:1 and be limited to Class III and Class IV wetlands.

Performance Standards – Land Divisions. The division, redivision, or adjusting of boundary lines of land in wetlands and associated buffers is subject to the following:

Land that is located wholly within a wetland or its buffer may not be subdivided.

Land that is located partially within a wetland or its buffer may be subdivided; provided, that an accessible and contiguous portion of each new lot is:

Located outside of the wetland and its buffer; and

Meets the minimum lot size requirements of [locally adopted zoning dimensions].

Access roads and utilities serving the proposed subdivision may be permitted within the wetland and associated buffers only if the city determines that no other feasible alternative exists and when consistent with this chapter.

(Ord. 995 § 12 (Exh. A), 2015)

Critical Aquifer Recharge Areas Designation. Critical aquifer recharge areas are those areas with a critical recharging effect on aquifers used for potable water as defined by WAC 365-190-030(2). A critical aquifer recharge area has prevailing geologic conditions associated with infiltration rates that create a high potential for contamination of ground water resources or contribute significantly to the replenishment of ground water.

Designation of Critical Aquifer Recharge Areas. The entire city of Yelm and its urban growth area is identified as a highly susceptible critical aquifer recharge area.

Performance Standards – General Requirements.

Activities may only be permitted in a critical aquifer recharge area if the applicant can show that the proposed activity will not cause contaminants to enter the aquifer and that the proposed activity will not adversely affect the recharging of the aquifer.

The proposed activity must comply with the water source protection requirements and recommendations of the U.S. Environmental Protection Agency, Washington State Department of Health, and the Thurston County environmental health division.

All new development, redevelopment, and small parcel development shall meet the water quality requirements of the stormwater manual as adopted by the city of Yelm.

Performance Standards – Specific Uses.

Storage Tanks. All storage tanks proposed to be located in a critical aquifer recharge area must comply with local building code requirements and must conform to the following requirements:

Underground Tanks. All new underground storage facilities proposed for use in the storage of hazardous substances or hazardous wastes shall be designed and constructed so as to:

Prevent releases due to corrosion or structural failure for the operational life of the tank;

Be protected against corrosion, constructed of noncorrosive 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 substances; and

Use material in the construction or lining of the tank that is compatible with the substance to be stored.

Aboveground Tanks. All new aboveground storage facilities proposed for use in the storage of hazardous substances or hazardous wastes shall be designed and constructed so as to:

Not allow the release of a hazardous substance to the ground, ground waters, or surface waters;

Have a primary containment area enclosing or underlying the tank or part thereof; and

§ 18.21.100 Geologically hazardous areas.

A secondary containment system either built into the tank structure or a dike system built outside the tank for all tanks.

Vehicle Repair and Servicing.

Vehicle repair and servicing must be conducted over impermeable pads and within a covered structure capable of withstanding normally expected weather conditions. Chemicals used in the process of vehicle repair and servicing must be stored in a manner that protects them from weather and provides containment should leaks occur.

No dry wells shall be allowed in critical aquifer recharge areas on sites used for vehicle repair and servicing. Dry wells existing on the site prior to facility establishment must be abandoned using techniques approved by the state Department of Ecology prior to commencement of the proposed activity.

Use of Reclaimed Water for Surface Percolation or Direct Recharge. Water reuse projects for reclaimed water must be in accordance with the adopted water or sewer comprehensive plans that have been approved by the State Departments of Ecology and Health.

Use of reclaimed water for surface percolation must meet the ground water recharge criteria given in RCW 90.46.010(10) and 90.46.080(1). The State Department of Ecology may establish additional discharge limits in accordance with RCW 90.46.080(2).

Direct injection must be in accordance with the standards developed by authority of RCW 90.46.042.

(Ord. 995 § 12 (Exh. A), 2015)

§ 18.21.080 Frequently flooded areas.

Designation of Frequently Flooded Areas. Frequently flooded areas shall include special flood hazard areas identified by the Flood Insurance Rate Map(s) (YMC § 18.19.020) and areas mapped by Thurston County as high ground water flood hazard areas. The flood insurance maps and high ground water maps are hereby adopted by reference, declared part of this chapter, and are available for public review at the city.

Performance Standards – General Requirements. The following standards shall be adhered to in all frequently flooded areas, except as otherwise provided for in this chapter.

Approval of Work in a Frequently Flooded Area. Prior to any clearing, grading, dumping, drilling, dredging, filling, or the construction or reconstruction of any structure, the city shall have approved through the underlying permit or through approval of a critical areas report that the standards for development within a frequently flooded area have been met.

No activity within a high ground water flood hazard area shall increase the base flood elevation.

Performance standards within a special flood hazard area shall be as established in Chapter 18.19 YMC.

Performance Standards – General Requirements in High Ground Water Hazard Areas.

Flood Elevations. The base flood elevation for high ground water flood hazard areas corresponds to the elevation of the outer edge of the high ground water flood hazard area.

Delineation of the Base Flood Elevation. Applicants shall submit to the approval authority hydrologic and hydrogeologic studies as necessary to delineate the high ground water flood hazard area and the base flood elevation.

No development shall locate within 50 feet, measured on a horizontal plane, from the outer edge of the high ground water hazard area or extending to a ground elevation two feet above the base flood elevation, whichever is less.

The bottom of any infiltration facility for stormwater discharge shall be located at least six feet above the base flood elevation.

Uses and Activities Prohibited from Frequently Flooded Areas.

Critical Facilities. Critical facilities are prohibited from frequently flooded areas to prevent damage to such facilities, to avoid costs that will be incurred by the public, and to maintain functionality of such facilities during flood events. If such a prohibition is unreasonable, an allowance for critical facilities in frequently flooded areas with the following specific conditions:

Construction of new critical facilities shall be permissible within frequently flooded areas if no feasible alternative site is available.

Critical facilities constructed within frequently flooded areas shall have the lowest floor elevated three feet or more above the level of the base flood elevation (100-year flood).

Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into flood waters.

Access routes elevated to or above the level of the base flood elevation shall be provided to all critical facilities to the extent possible.

Wells Used for Potable Water. Water wells shall be located on high ground and are prohibited from being within the floodway.

On-Site Sewage Disposal Systems. On-site sewage disposal systems are prohibited from the floodway, the channel migration zone, and the 100-year floodplain elevation.

(Ord. 995 § 12 (Exh. A), 2015; Ord. 1107 § 2, 2023)

§ 18.21.090 Flood damage protection.

Subdivision Proposals.

All subdivision proposals shall be consistent with the need to minimize flood damage.

All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage.

All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage.

Where base flood elevation data has not been provided or is not available from another authoritative source, it shall be generated for subdivision proposals and other proposed developments which contain at least 50 lots or five acres, whichever is less.

Wetlands Management. To the maximum extent possible, in order to avoid the short- and long-term adverse impacts associated with the destruction or modification of wetlands, especially those activities which limit or disrupt the ability of the wetland to alleviate flooding impacts, the following process should be implemented:

Review proposals for development within areas of special flood hazard for their possible impacts on wetlands located within the floodplain;

Ensure that development activities in or around wetlands do not negatively affect public safety, health and welfare by disrupting the wetlands' ability to reduce flood and storm drainage;

Request technical assistance from the Department of Ecology in identifying wetland areas. Existing wetland map information from the National Wetlands Inventory (NWI) can be used in conjunction with the community's FIRM to prepare an overlay zone indicating critical wetland areas deserving special attention.

(Ord. 995 § 12 (Exh. A), 2015; Ord. 1107 § 2, 2023)

Designation of Geologically Hazardous Areas. Geologically hazardous areas include areas susceptible to erosion, sliding, earthquake, or other geological events. They pose a threat to the health and safety of citizens when incompatible development is sited in areas of significant hazard. Such incompatible development may not only place itself at risk, but also may increase the hazard to surrounding development and use.

Designation of Specific Hazard Areas.

Erosion Hazard Areas. Erosion hazard areas are at least those areas identified by the U.S. Department of Agriculture's Natural Resources Conservation Service as having a "moderate to severe," "severe," or "very severe" rill and inter-rill erosion hazard. Rill or inter-rill are areas subject to sheet wash, or steep-sided channels resulting from accelerated erosion. Erosion hazard areas are also those areas impacted by shoreland and/or streambank erosion and those areas within a river's channel migration zone.

Landslide Hazard Areas. Landslide hazard areas are areas potentially subject to landslides based on a combination of geologic, topographic, and hydrologic factors. They include areas susceptible because of any combination of bedrock, soil, slope (gradient), slope aspect, structure, hydrology, or other factors. Examples of these may include, but are not limited to, the following:

Areas of historic failures;

Areas with all three of the following characteristics:

Slopes steeper than 15 percent;

Hillsides intersecting geologic contacts with a relatively permeable sediment overlying a relatively impermeable sediment or bedrock; and

§ 18.21.110 Fish and wildlife habitat conservation areas.

Springs or ground water seepage;

Areas that have shown movement during the Holocene epoch (from 10,000 years ago to the present) or that are underlain or covered by mass wastage debris of that epoch;

Slopes that are parallel or subparallel to planes of weakness (such as bedding planes, joint systems, and fault planes) in subsurface materials;

Slopes having gradients steeper than 80 percent, subject to rock fall during seismic shaking;

Areas potentially unstable because of rapid stream incision, streambank erosion, and undercutting by wave action;

Areas that show evidence of or are at risk from snow avalanches;

Areas located in a canyon or on an active alluvial fan, presently or potentially subject to inundation by debris flows or catastrophic flooding; and

Any area with a slope of 40 percent or steeper and with a vertical relief of 10 or more feet, except areas composed of consolidated rock. A slope is delineated by establishing its toe and top and is measured by averaging the inclination over at least 10 feet of vertical relief.

Seismic Hazard Areas. Seismic hazard areas are areas subject to severe risk of damage as a result of earthquake induced ground shaking, slope failure, settlement, soil liquefaction, lateral spreading, or surface faulting. One indicator of potential for future earthquake damage is a record of earthquake damage in the past. Ground shaking is the primary cause of earthquake damage in Washington. The strength of ground shaking is primarily affected by:

The magnitude of an earthquake;

The distance from the source of an earthquake;

The type of thickness of geologic materials at the surface; and

The type of subsurface geologic structure.

Mapping of Geologically Hazardous Areas.

The approximate location and extent of geologically hazardous areas are shown on the adopted critical area maps.

These maps are to be used as a guide for the city, project applicants and/or property owners and may be continuously updated as new critical areas are identified. They are a reference and do not provide a final critical area designation.

Performance Standards – General Requirements.

Alterations of geologically hazardous areas or associated buffers may only occur for activities that:

Will not increase the threat of the geological hazard to adjacent properties beyond pre-development conditions;

Will not adversely impact other critical areas;

Are designed so that the hazard to the project is eliminated or mitigated to a level equal to or less than pre-development conditions; and

Are certified as safe as designed and under anticipated conditions by a qualified engineer or geologist, licensed in the state of Washington.

Critical Facilities Prohibited. Critical facilities shall not be sited within geologically hazardous areas unless there is no other practical alternative.

Buffer Requirement. A buffer shall be established from all edges of landslide hazard areas. The size of the buffer shall be determined by the administrator to eliminate or minimize the risk of property damage, death, or injury resulting from landslides caused in whole or part by the development, based upon review of and concurrence with a critical area report prepared by a qualified professional.

Minimum Buffer. The minimum buffer shall be equal to the height of the slope.

Buffer Reduction. The buffer may be reduced to a minimum of 10 feet when a qualified professional demonstrates to the administrator's satisfaction that the reduction will adequately protect the proposed development, adjacent developments and uses, and the subject critical area.

Increased Buffer. The buffer may be increased where the administrator determines a larger buffer is necessary to prevent risk of damage to proposed and existing development.

Alterations. Alterations of an erosion or landslide hazard area and/or buffer may only occur for activities for which a hazards analysis is submitted and certifies that:

The development will not increase surface water discharge or sedimentation to adjacent properties beyond pre-development conditions;

The development will not decrease slope stability on adjacent properties; and

Such alterations will not adversely impact other critical areas.

Vegetation Retention. Unless otherwise provided or as part of an approved alteration, removal of vegetation from an erosion or landslide hazard area or related buffer shall be prohibited.

Seasonal Restriction. Clearing shall be allowed only from May 1st to October 1st of each year; provided, that the city may extend or shorten the dry season on a case-by-case basis depending on actual weather conditions, except that timber harvest, not including brush clearing or stump removal, may be allowed pursuant to an approved forest practice permit issued by the city or the Washington State Department of Natural Resources.

Utility Lines and Pipes. Utility lines and pipes shall be permitted in erosion and landslide hazard areas only when the applicant demonstrates that no other practical alternative is available. The line or pipe shall be located above ground and properly anchored and/or designed so that it will continue to function in the event of an underlying slide. Stormwater conveyance shall be allowed only through a high-density polyethylene pipe with fuse-welded joints, or similar product that is technically equal or superior.

Point Discharges. Point discharges from surface water facilities and roof drains onto or upstream from an erosion or landslide hazard area shall be prohibited.

Division of Land. The division of land in landslide hazard areas and associated buffers is subject to the following:

Land that is located wholly within a landslide hazard area or its buffer may not be subdivided. Land that is located partially within a landslide hazard area or its buffer may be divided; provided, that each resulting lot has sufficient buildable area outside of, and will not affect, the landslide hazard or its buffer.

Access roads and utilities may be permitted within the landslide hazard area and associated buffers if the city determines that no other feasible alternative exists; and

Prohibited Development. On-site sewage disposal systems, including drain fields, shall be prohibited within erosion and landslide hazard areas and related buffers.

(Ord. 995 § 12 (Exh. A), 2015)

Designation of Fish and Wildlife Habitat Conservation Areas.

Fish and wildlife habitat conservation areas are areas necessary for maintaining species in suitable habitats within their natural geographic distribution so that isolated subpopulations are not created as designated by WAC 365-190-080(5). These areas include:

Areas with which state or federally designated endangered, threatened, and sensitive species have a primary association;

Federally designated endangered and threatened species are those fish and wildlife species identified by the U.S. Fish and Wildlife Service and the National Marine Fisheries Service that are in danger of extinction or threatened to become endangered.

State designated endangered, threatened, and sensitive species are those fish and wildlife species native to the state of Washington identified by the Washington Department of Fish and Wildlife that are in danger of extinction, threatened to become endangered, vulnerable, or declining and are likely to become endangered or threatened in a significant portion of their range within the state without cooperative management or removal of threats.

State Priority Habitats and Areas Associated with State Priority Species. Priority habitats and species are considered to be priorities for conservation and management. Priority species require protective measures for their perpetuation due to their population status, sensitivity to habitat alteration, and/or recreational, commercial, or tribal importance. Priority habitats are those habitat types or elements with unique or significant value to a diverse assemblage of species. A priority habitat may consist of a unique vegetation type or dominant plant species, a described successional stage, or a specific structural element. Priority habitats and species are identified by the state Department of Fish and Wildlife.

Naturally Occurring Ponds under 20 Acres. Naturally occurring ponds are those ponds under 20 acres and their submerged aquatic beds that provide fish or wildlife habitat, including those artificial ponds intentionally created from dry areas in order to mitigate impacts to ponds. Naturally occurring ponds do not include ponds deliberately designed and created from dry sites, such as canals, detention facilities, wastewater treatment facilities, farm ponds, temporary construction ponds, and landscape amenities, unless such artificial ponds were intentionally created for mitigation.

Waters of the State. Waters of the state include lakes, rivers, ponds, streams, inland waters, underground waters, salt waters, and all other surface waters and watercourses within the jurisdiction of the state of Washington.

Areas of Rare Plant Species and High Quality Ecosystems. Areas of rare plant species and high quality ecosystems are identified by the Washington State Department of Natural Resources through the Natural Heritage Program.

Land useful or essential for preserving connections between habitat blocks and open spaces.

All areas within the city meeting one or more of these criteria, regardless of any formal identification, are hereby designated critical areas and are subject to the provisions of this chapter and shall be managed consistent with the best available science.

Mapping. The approximate location and extent of habitat conservation areas are shown on the critical area maps adopted by the city.

Performance Standards – General Requirements.

Nonindigenous Species. No plant, wildlife, or fish species not indigenous to the region shall be introduced into a habitat conservation area unless authorized by a state or federal permit or approval.

Mitigation and Contiguous Corridors. Mitigation sites shall be located to preserve or achieve contiguous wildlife habitat corridors in accordance with a mitigation plan that is part of an approved critical area report to minimize the isolating effects of development on habitat areas, so long as mitigation of aquatic habitat is located within the same aquatic ecosystem as the area disturbed.

Approvals of Activities. The administrator shall condition approvals of activities allowed within or adjacent to a habitat conservation area or its buffers, as necessary to minimize or mitigate any potential adverse impacts. Conditions shall be based on the best available science and may include, but are not limited to, the following:

Establishment of buffer zones;

Preservation of critically important vegetation and/or habitat features such as snags and downed wood;

Limitation of access to the habitat area, including fencing to deter unauthorized access;

Seasonal restriction of construction activities;

Establishment of a duration and timetable for periodic review of mitigation activities; and

Requirement of a performance bond, when necessary, to ensure completion and success of proposed mitigation.

Mitigation and Equivalent or Greater Biological Functions. Mitigation of alterations to habitat conservation areas shall achieve equivalent or greater biologic and hydrologic functions and shall include mitigation for adverse impacts upstream or downstream of the development proposal site. Mitigation shall address each function affected by the alteration to achieve functional equivalency or improvement on a per function basis.

Approvals and the Best Available Science. Any approval of alterations or impacts to a habitat conservation area shall be supported by the best available science.

Buffers.

Establishment of Buffers. The administrator shall require the establishment of buffer areas for activities adjacent to habitat conservation areas when needed to protect habitat conservation areas. Buffers shall consist of an undisturbed area of native vegetation or areas identified for restoration established to protect the integrity, functions, and values of the affected habitat. Required buffer widths shall reflect the sensitivity of the habitat and the type and intensity of human activity proposed to be conducted nearby and shall be consistent with the management recommendations issued by the Washington Department of Fish and Wildlife. Habitat conservation areas and their buffers shall be preserved in perpetuity through the use of native growth protection areas and critical area tracts. Native growth protection areas includes area where native vegetation is preserved for the purpose of preventing harm to property and the environment including, but not limited to, controlling surface water runoff and erosion, maintaining slope stability, buffering, and protecting plants and animal habitat.

Seasonal Restrictions. When a species is more susceptible to adverse impacts during specific periods of the year, seasonal restrictions may apply. Larger buffers may be required and activities may be further restricted during the specified season.

Habitat Buffer Averaging. The administrator may allow the recommended habitat area buffer width to be reduced in accordance with a critical area report, the best available science, and the management recommendations issued by the Washington Department of Fish and Wildlife, only if:

It will not reduce stream or habitat functions;

It will not adversely affect salmonid habitat;

It will provide additional natural resource protection, such as buffer enhancement;

The total area contained in the buffer area after averaging is no less than that which would be contained within the standard buffer; and

The buffer area width is not reduced by more than 25 percent in any location.

Divisions of Land. The subdivision and short subdivision of land in fish and wildlife habitat conservation areas and associated buffers is subject to the following:

Land that is located wholly within a habitat conservation area or its buffer may not be subdivided.

Land that is located partially within a habitat conservation area or its buffer may be divided; provided, that the developable portion of each new lot and its access is located outside of the habitat conservation area or its buffer and meets the minimum lot size requirements.

Access roads and utilities serving the proposed may be permitted within the habitat conservation area and associated buffers only if the city determines that no other feasible alternative exists and when consistent with this chapter.

Performance Standards – Specific Habitats.

Endangered, Threatened, and Sensitive Species.

No development shall be allowed within a habitat conservation area or buffer with which state or federally endangered, threatened, or sensitive species have a primary association, except that which is provided for by a management plan established by the Washington Department of Fish and Wildlife or applicable state or federal agency.

Whenever activities are proposed adjacent to a habitat conservation area with which state or federally endangered, threatened, or sensitive species have a primary association, such area shall be protected through the application of protection measures in accordance with a critical area report prepared by a qualified professional and approved by the city. Approval for alteration of land adjacent to the habitat conservation area or its buffer shall not occur prior to consultation with the Washington Department of Fish and Wildlife for animal species, the Washington State Department of Natural Resources for plant species, and other appropriate federal or state agencies.

Bald eagle habitat shall be protected pursuant to the Washington State Bald Eagle Protection Rules WAC 232-12-292. Whenever activities are proposed adjacent to a verified nest territory or communal roost, a habitat management plan shall be developed by a qualified professional. Activities are adjacent to bald eagle sites when they are within 800 feet or within one-half mile (2,640 feet) and in a shoreline foraging area. The city shall verify the location of eagle management areas for each proposed activity. Approval of the activity shall not occur prior to approval of the habitat management plan by the Washington Department of Fish and Wildlife.

Riparian Habitat Areas. Unless otherwise allowed in this chapter, all structures and activities shall be located outside of the riparian habitat area.

Establishment of Riparian Habitat Areas. Riparian habitat areas shall be established for habitats that include aquatic and terrestrial ecosystems that mutually benefit each other and that are located adjacent to rivers, perennial or intermittent streams, seeps, and springs.

A riparian habitat area width of 150 feet is established along Yelm Creek and Thompson Creek, both Type 5, intermittent streams with low mass wasting potential as defined in WAC 222-16-031.

Increased Riparian Habitat Area Widths. The recommended riparian habitat area widths shall be increased, as follows:

When the administrator determines that the recommended width is insufficient to prevent habitat degradation and to protect the structure and functions of the habitat area;

When the frequently flooded area exceeds the recommended riparian habitat area width, the riparian habitat area shall extend to the outer edge of the frequently flooded area;

When the habitat area is within an erosion or landslide hazard area or buffer, the riparian habitat area width shall be the recommended distance, or the erosion or landslide hazard area or buffer, whichever is greater.

Riparian Habitat Area Width Averaging. The administrator may allow the recommended riparian habitat area width to be reduced in accordance with a critical area report only if:

The width reduction will not reduce stream or habitat functions, including those of nonfish habitat;

The width reduction will not degrade the habitat, including habitat for anadromous fish;

The proposal will provide additional habitat protection;

The total area contained in the riparian habitat area of each stream on the development proposal site is not decreased;

The recommended riparian habitat area width is not reduced by more than 25 percent in any one location;

The width reduction will not be located within another critical area or associated buffer; and

vii.

The reduced riparian habitat area width is supported by the best available science.

Riparian Habitat Mitigation. Mitigation of adverse impacts to riparian habitat areas shall result in equivalent functions and values on a per function basis, be located as near the alteration as feasible, and be located in the same subdrainage basin as the habitat impacted.

Alternative Mitigation for Riparian Habitat Areas. The performance standards set forth in this subsection may be modified at the city's discretion if the applicant demonstrates that greater habitat functions, on a per function basis, can be obtained in the affected subdrainage basin as a result of alternative mitigation measures.

Aquatic Habitat. The following specific activities may be permitted within a riparian habitat area, pond, lake, water of the state, and marine habitat or associated buffer.

Clearing and Grading. When clearing and grading is permitted as part of an authorized activity or as otherwise allowed in these standards, the following shall apply:

Grading is allowed only during the dry season, which is typically regarded as beginning on May 1st and ending on October 1st of each year; provided, that the city may extend or shorten the dry season on a case-by-case basis, determined on actual weather conditions.

Filling or modification of a wetland or wetland buffer is permitted only if it is conducted as part of an approved wetland alteration.

The soil duff layer shall remain undisturbed to the maximum extent possible. Where feasible, any soil disturbed shall be redistributed to other areas of the project area.

The moisture-holding capacity of the topsoil layer shall be maintained by minimizing soil compaction or reestablishing natural soil structure and infiltrative capacity on all areas of the project area not covered by impervious surfaces.

Erosion and sediment control that meets or exceeds the standards set forth in the [locally adopted stormwater management regulations] shall be provided.

Shoreline Erosion Control Measures. New, replacement, or substantially improved shoreline erosion control measures may be permitted in accordance with an approved critical area report that demonstrates the following:

Natural shoreline processes will be maintained. The project will not result in increased beach erosion or alterations to, or loss of, shoreline substrate within one-quarter mile of the project area.

The shoreline erosion control measures will not degrade fish or wildlife habitat conservation areas or associated wetlands.

Adequate mitigation measures ensure that there is no net loss of the functions or values of intertidal habitat or riparian habitat as a result of the proposed shoreline erosion control measures.

The proposed shoreline erosion control measures do not result in alteration of intertidal migration corridors.

Streambank Stabilization. Streambank stabilization to protect new structures from future channel migration is not permitted except when such stabilization is achieved through bioengineering or soft armoring techniques in accordance with an approved critical area report.

Roads, Trails, Bridges, and Rights-of-Way. Construction of trails, roadways, and minor road bridging, less than or equal to 30 feet wide, may be permitted in accordance with an approved critical area report subject to the following standards:

There is no other feasible alternative route with less impact on the environment;

The crossing minimizes interruption of downstream movement of wood and gravel;

Roads in riparian habitat areas or their buffers shall not run parallel to the water body;

Trails shall be located on the outer edge of the riparian area or buffer, except for limited viewing platforms and crossings;

Crossings, where necessary, shall only occur as near to perpendicular with the water body as possible;

Mitigation for impacts is provided pursuant to a mitigation plan of an approved critical area report;

vii.

Road bridges are designed according to the Washington Department of Fish and Wildlife Fish Passage Design at Road Culverts, 1999, and the National Marine Fisheries Service Guidelines for Salmonid Passage at Stream Crossings, 2000; and

viii.

Trails and associated viewing platforms shall not be made of continuous impervious materials.

Utility Facilities. New utility lines and facilities may be permitted to cross watercourses in accordance with an approved critical area report if they comply with the following standards:

Fish and wildlife habitat areas shall be avoided to the maximum extent possible;

Installation shall be accomplished by boring beneath the scour depth and hyporheic zone of the water body and channel migration zone, where feasible;

The utilities shall cross at an angle greater than 60 degrees to the centerline of the channel in streams or perpendicular to the channel centerline whenever boring under the channel is not feasible;

Crossings shall be contained within the footprint of an existing road or utility crossing where possible;

The utility route shall avoid paralleling the stream or following a down-valley course near the channel; and

The utility installation shall not increase or decrease the natural rate of shore migration or channel migration.

Public Flood Protection Measures. New public flood protection measures and expansion of existing ones may be permitted, subject to the city's review and approval of a critical area report and the approval of a federal biological assessment by the federal agency responsible for reviewing actions related to a federally listed species.

Instream Structures. Instream structures, such as, but not limited to, high-flow bypasses, sediment ponds, instream ponds, retention and detention facilities, tide gates, dams, and weirs, shall be allowed only as part of an approved watershed basin restoration project approved by the city and upon acquisition of any required state or federal permits. The structure shall be designed to avoid modifying flows and water quality in ways that may adversely affect habitat conservation areas.

Stormwater Conveyance Facilities. Conveyance structures may be permitted in accordance with an approved critical area report subject to the following standards:

No other feasible alternatives with less impact exist;

Mitigation for impacts is provided;

Stormwater conveyance facilities shall incorporate fish habitat features; and

Vegetation shall be maintained and, if necessary, added adjacent to all open channels and ponds in order to retard erosion, filter out sediments, and shade the water.

On-Site Sewage Systems and Wells.

New on-site sewage systems and individual wells may be permitted in accordance with an approved critical area report only if accessory to an approved residential structure, for which it is not feasible to connect to a public sanitary sewer system.