OAR 340-071-0315
Tile Dewatering System

(1) General conditions for approval. Construction permits may be issued for tile dewatering systems if the following requirements can be met:
(a) The site has a natural outlet that will allow a field tile installed on a proper grade around the proposed absorption facility to daylight above annual high water.
(b) Soils are silty clay loam or coarser textured and drainable.
(c) Soils must have a minimum effective soil depth of at least 30 inches in soils with temporary groundwater and at least 72 inches in soils with permanent groundwater unless otherwise authorized by the agent.
(d) Slope does not exceed 3 percent.
(e) All other requirements for the system, except depth to groundwater, can be met. After the field collection drainage tile is installed, the groundwater levels must conform to the requirements of OAR 340-071-0220 (Standard Subsurface Systems)(1), 340-071-0265 (Capping Fills)(1), 340-071-0290 (Conventional Sand Filter Systems)(2), 340-071-0302 (Recirculating Gravel Filter (RGF))(1), or 340-071-0345 (Alternative Treatment Technologies (ATTs))(8).
(2) Construction requirements.
(a) Field collection drainage tile must be installed on a uniform grade of 0.2 to 0.4 feet of fall per 100 feet. The tile drainage trench must be constructed to the minimum depth required in the approved site evaluation report.
(b) A field collection drainage tile trench must be constructed at least 12 inches wide.
(c) Maximum drainage tile spacing must be 70 feet center to center.
(d) The minimum horizontal separation distance between the drainage tile and absorption facility must be 20 feet.
(e) Field collection drainage tile must be rigid, smooth-wall, perforated pipe or other pipe material the agent approves with a minimum diameter of 4 inches.
(f) Field collection drainage tile must be enveloped in clean drain media or underdrain media to within 30 inches of the soil surface in soils with permanent groundwater or to within 12 inches of the soil surface in soils with temporary groundwater. Drain media must be covered with filter fabric, treated building paper, or other nondegradable material approved by the agent.
(g) Outlet tile must be rigid, smooth-wall, solid PVC pipe meeting or exceeding ASTM Standard D-3034 with a minimum diameter of 4 inches. The agent may require a flap gate or rodent guard.
(h) A silt trap with a 12-inch minimum diameter must be installed between the field collection drainage tile and the outlet pipe unless otherwise authorized by the agent. The bottom of the silt trap must be at least 12 inches below the invert of the drainage pipe outlet.
(i) The discharge pipe and tile drainage system are integral parts of the system but do not need to meet setback requirements to property lines, wells, streams, lakes, ponds, or other surface waterbodies.
(j) Before issuing a final site evaluation report approving the site, the agent may require demonstration that a proposed tile dewatering site can be effectively drained.
(k) The absorption facility must use equal or pressurized distribution.

Source: Rule 340-071-0315 — Tile Dewatering System, https://secure.­sos.­state.­or.­us/oard/view.­action?ruleNumber=340-071-0315.

340‑071‑0100
Definitions 340‑071‑0110
Purpose 340‑071‑0115
Technical Review Committee 340‑071‑0120
Jurisdiction and Policy 340‑071‑0130
General Standards, Prohibitions and Requirements 340‑071‑0135
Approval of New or Innovative Technologies, Materials, or Designs for Onsite Systems 340‑071‑0140
Onsite System Fees 340‑071‑0150
Site Evaluation Procedures 340‑071‑0155
Existing System Evaluation Report 340‑071‑0160
Permit Application Procedures — Construction, Installation, Alteration, and Repair Permits 340‑071‑0162
Permit Application Procedures — WPCF Permits 340‑071‑0165
Permit Denial Review — Construction-Installation, Repair, Alteration Permits 340‑071‑0170
Pre-Cover Inspections 340‑071‑0175
Certificate of Satisfactory Completion 340‑071‑0185
Decommissioning of Systems 340‑071‑0200
Prior Construction Permits or Approvals 340‑071‑0205
Authorization to Use Existing Systems 340‑071‑0210
Alteration of Existing Onsite Wastewater Treatment Systems 340‑071‑0215
Repair of Existing Systems 340‑071‑0220
Standard Subsurface Systems 340‑071‑0260
Alternative Systems, General 340‑071‑0265
Capping Fills 340‑071‑0275
Pressurized Distribution Systems 340‑071‑0280
Seepage Trench System 340‑071‑0285
Redundant Systems 340‑071‑0290
Conventional Sand Filter Systems 340‑071‑0295
Conventional Sand Filter Design and Construction 340‑071‑0302
Recirculating Gravel Filter (RGF) 340‑071‑0310
Steep Slope Systems 340‑071‑0315
Tile Dewatering System 340‑071‑0320
Split Waste Method 340‑071‑0325
Gray Water Waste Disposal Sumps 340‑071‑0330
Nonwater-Carried Systems 340‑071‑0335
Cesspools and Seepage Pits 340‑071‑0340
Holding Tanks 340‑071‑0345
Alternative Treatment Technologies (ATTs) 340‑071‑0360
Absorption Trenches in Saprolite 340‑071‑0400
Geographic Area Special Considerations. 340‑071‑0410
Rural Area Consideration 340‑071‑0415
For Cause Variances 340‑071‑0420
Hardship Variances 340‑071‑0425
Variance Officers 340‑071‑0430
Variance Hearings and Decisions 340‑071‑0435
Variance Permit Issuance, Inspections, Certificate of Satisfactory Completion 340‑071‑0440
Variance Appeals 340‑071‑0445
Variance Administrative Review 340‑071‑0460
Moratorium Areas 340‑071‑0500
Community Systems 340‑071‑0520
Large Systems 340‑071‑0600
Sewage Disposal Service Licenses 340‑071‑0650
Training and Certification Requirements for System Installers and Maintenance Providers 340‑071‑0800
Tables
Last Updated

Jun. 8, 2021

Rule 340-071-0315’s source at or​.us