Md. Code Regs. 26.04.02.04

Current through Register Vol. 51, No. 25, December 13, 2024

Section 26.04.02.04 - Site Evaluation

A. Site Evaluation Criteria.

(1) In determining whether to approve a lot or parcel for on-site sewage disposal the Approving Authority shall consider the following site evaluation criteria:

(a) The general topography, geology, soil classification, and hydrology;

(b) Surface and subsurface drainage conditions;

(c) Soil descriptions, test results, and boring logs;

(d) Requirements for seasonal testing; and

(e) Performance of on-site sewage disposal systems and wells in the area and the potential impact of new on-site sewage disposal systems on individual water well supplies in adjacent areas.

(2) The applicant shall submit, or make available, all soils information, design specifications and other data that the Approving Authority may require to complete its permit review responsibilities.

(3) The applicant shall make available to the Approving Authority all information on private soil testing and environmental factors on the property that may impact onsite sewage disposal or potable drinking water supplies.

(4) A site evaluation is conducted, and the results are evaluated, in accordance with the following requirements:

(a) An adequate number of site evaluations including percolation tests and other pertinent observations, as required by the Approving Authority, are conducted within the area designated for on-site sewage disposal as necessary to determine the suitability of the area for sewage disposal.

(b) The Approving Authority may require additional site evaluations and percolation testing where soil texture or structure varies or limiting geologic conditions are encountered, or when the Approving Authority deems it necessary to evaluate a larger disposal and recovery area for the estimated sewage flow.

(c) The minimum allowable percolation rate after prewetting is 1 inch per 30 minutes, except for a system approved under Regulation .05V of this chapter.

(d) A percolation rate faster than 2 minutes per inch, after prewetting, may not be approved west of the fall line and may also be disapproved east of the fall line if, in the opinion of the Approving Authority, adequate protection of the ground water may not be provided due to the rapid movement of water through the soil.

(e) A percolation rate of between 2 and 5 minutes per inch, after prewetting, may be grounds for disapproval if in the opinion of the Approving Authority adequate protection of the ground water may not be provided due to rapid movement of water through the soil.

(f) In carbonate rock areas a minimum of four treatment zone observation test pits, excavated perpendicular to the bed rock ridges, are required per sewage disposal area.

(g) Each limiting horizons that may restrict the vertical flow of effluent in the soil treatment zone within 2 feet of the infiltrative surface is described in the site evaluation report. If a limiting horizon is identified, the design of the on-site sewage disposal system is adequate to overcome this limitation.

B. Soils Testing Requirements. In an area where the soil survey maps, soil borings or historical data indicate moderate or severe limitations based on seasonally perched or seasonally high water tables; site evaluations, a soil percolation test and any other test that the Approving Authority requires is performed at the time of the year when the highest water table is present as indicated by observation wells, rainfall totals and site conditions at the on-site sewage disposal area. The applicant shall conduct all soil tests at the depth and in the soil intended to be used for the on-site sewage disposal system. The official source of soil information is the National Resource Conservation Service (NRCS) Soil Data Mart, a part of the National Soil Information System.

C. Soil Treatment Zones.

(1) Conventional on-site sewage disposal systems may not be approved where there is less than 4 feet of unsaturated, unconsolidated material sufficient to attenuate effluent below the bottom of the on-site sewage disposal system except as provided in §C(2) of this regulation and Regulation .05V of this chapter.

(2) In the coastal plain province where 4 feet of unsaturated, unconsolidated material sufficient to attenuate effluent below the bottom of the on-site sewage disposal system is not available, the Approving Authority may identify areas where on-site sewage disposal systems using less than 4 feet of unsaturated soil may be allowed, if:

(a) The aquifer is a Type III (other than Type I or Type II), pursuant to COMAR 26.08.02.09B; or

(b) The aquifer has limited potential to serve as a drinking water source. These aquifers shall meet one or more of the following conditions:

(i) Insufficient potable water to serve as a year-round supply due to seasonally fluctuating water tables;

(ii) Interconnection with tidewater such that if pumped for water supply, brackish water or saltwater intrusion into the aquifer has or would occur; or

(iii) Evidence the aquifer has already been polluted by, or is in imminent danger of being polluted, by activities in the area.

(3) All the following criteria are required for all areas in which aquifers have been designated, pursuant to §C(2) of this regulation, for installation of on-site sewage disposal systems using less than 4 feet of unsaturated soil below the bottom of the sewage disposal field or pit:

(a) The area is delineated in a ground water protection report prepared by the county government or its representative; and the groundwater protection report is approved by the county health department and included in the appropriate county water and sewer plan approved by the Department of the Environment.

(b) The groundwater protection report sets density, design, and construction requirements to minimize degradation of aquifers designated for discharge and justifies any variances to §C(3)(b)-(g) of this regulation.

(c) A quantitatively and qualitatively superior potable water supply is available from one or more deeper confined aquifers that are separated from the disposal aquifer by a confining aquiclude.

(d) Measures are taken by the county health department to ensure that the aquifer designated for waste disposal is not currently and will not be used for a potable water supply.

(e) Discharge to a surficial aquifer does not contaminate a deeper aquifer of Type I or II, pursuant to COMAR 26.08.01-.04, or any aquifer used for water supply.

(f) If a water supply well taps a confined aquifer beneath the disposal aquifer the permitee shall grout through the disposal aquifer.

(g) The on-site sewage disposal system and recovery area is located 100 feet from any well in a confined aquifer.

(h) Unimproved lots served by these on-site sewage disposal systems may not be less than 2 acres in size.

D. Approvals for lots in the Appalachian physiographic province of the State (see the map of Maryland Physiographic Provinces and Their Divisions in this chapter), where 4 feet of unsaturated, unconsolidated soil sufficient to attenuate effluent below the subsurface disposal system is not available, may require concurrent approval of the Department of the Environment at the discretion of the Water Management Administration. Training and assistance by the Water Management Administration personnel will be provided at the request of the Approving Authority. In limestone or dolomite areas of the Appalachian physiographic province, deviation from the 4-foot requirement may not be given for new development.

E. Sewage disposal areas shall meet all physical and distance requirements outlined in regulations .03 and 04 of this chapter, exclusive of easements, rights-of-way, buildings, and any other permanent or physical objects, and may not be disturbed by earth moving, compaction, tree removal or grading after approval by the Approving Authority without prior authorization of the Approving Authority.

F. The sewage disposal area for a dwelling unit or other building for human occupation on an individual lot recorded and approved by the Department on or after November 18, 1985, shall meet the following criteria:

(1) The area is adequate for the installation of an initial and two replacement on-site sewage disposal systems; and

(2) For each dwelling unit, or other buildings for human occupation, the area shall not be less than 10,000 square feet.

G. The sewage disposal area for a dwelling unit or other building for human occupation on an individual lot recorded and approved by the Department on or after November 18, 1985, shall meet the following criteria:

(1) The area is adequate for the installation of an initial and two replacement on-site sewage disposal systems; and

(2) For each dwelling unit, or other buildings for human occupation, the area shall not be less than 10,000 square feet.

H. The sewage disposal area for a dwelling unit or other building for human occupation on an individual lot, recorded and approved by the Department before November 18, 1985, shall meet the following criteria:

(1) The area is adequate for the installation of an initial and one replacement on-site sewage disposal system; and

(2) For lots created subject to a minimum 10,000 square foot sewage disposal area, a minimum 10,000 square foot area is maintained.

I. The Approving Authority shall use the best available water usage information in determining estimated daily flows for institutional and commercial establishments for determining required sewage disposal area including area for initial and required replacement systems..

J. An on-site disposal system and replacement area may not be located in flood plain soils or on slopes in excess of 25 percent.

K. The following horizontal separation distances are required to be maintained between the on-site disposal system including its recovery area and the features listed although greater distances may be required at the discretion of the Approving Authority:

Feature	Separation Distance
(1) All steep slopes (>25 percent)	25 feet
(2) Springs	100 feet
(3) Drainage ways and gullies	25 feet
(4) Flood plain soils	25 feet
(5) Rock outcrops	25 feet
(6) Elevation of spillway crest water level in a water supply reservoir	300 feet
(7) Stream bank 3,000 feet or less upstream from a water intake on a water supply reservoir or intake on a stream used as a potable water supply	200 feet
(8) Stream bank greater than 3,000 feet upstream from a water intake on a water supply reservoir or intake on a stream used as a potable water supply	100 feet
(9) Water bodies not serving as potable water supplies including intermittent and perennial streams	100 feet
(10) Water well system in unconfined aquifers	100 feet
(11) Water well system in confined aquifers	50 feet
(12) Sink holes underlain by karst topography	100 feet
(13) Building foundations	10 feet

L. A lot located within 2,500 feet of the normal water level of an existing or proposed water supply reservoirs, measured horizontally, within a 5,000-foot radius upstream from a water intake on a stream used as potable water supply source, or within a 5,000-foot radius of a water intake located within a reservoir shall have an area of not less than 2 acres and a minimum width of 175 feet. An on-site sewage disposal system may not be located within 300 feet, measured horizontally, of the normal high water level of a water supply reservoir. Normal water means the elevation of the spillway crest. These limitations do not apply to areas below the dam forming the reservoir.

M. The Approving Authority may consider an application for a variance from the requirements listed in §K of this regulation in order to cluster lots as provided under local law. However, the number of clustered lots under two acres may not exceed the number of lots that would have been approvable under §K of this regulation. A variance may not be granted that allows the transfer of density units or development rights to a subdivision located within 2,500 feet of a water supply reservoir.

Md. Code Regs. 26.04.02.04

Regulations .04 effective November 16, 1953; amended effective July 1, 1957, November 15, 1957, June 8, 1965, October 15, 1966, April 1, 1967, December 1, 1970
Regulations .04 adopted effective November 18, 1985 (12:23 Md. R. 2218)
Regulation .04 amended effective November 3, 1986 (13:22 Md. R. 2398)
Regulation .04J amended effective July 4, 1994 (21:13 Md. R. 1160)
Regulations .04 adopted effective 41:9 Md. R. 522, eff.5/12/2014