OR Well Driller cheat sheet

Oregon requires a minimum annular seal of 6 inches of neat cement or bentonite from the top of the screen or perforated interval to land surface, or to a depth of at least 18 inches below land surface where a pitless adapter is used.

Casing must extend at least 12 inches above finished grade and be firmly anchored; in areas subject to flooding, the top must be at least 24 inches above the 100-year flood level.

The annular space must be sealed with a low-permeability grout (neat cement or bentonite) placed by tremie or positive displacement method; free-falling grout is prohibited.

Well development must continue until the water is clear and sand-free; minimum development time is typically until turbidity is below 10 NTU or stabilizes.

A well must be disinfected with a chlorine solution of at least 50 mg/L for 24 hours, or 100 mg/L for 12 hours, before being placed into service.

The wellhead must be capped with a sanitary seal that is watertight and vermin-proof; a vent pipe with a screen is required if the casing is sealed.

Abandoned wells must be filled with grout from bottom to top using a tremie pipe; the top 5 feet may be filled with compacted bentonite or concrete.

Oregon requires a minimum horizontal distance of 50 feet between a well and a septic tank or sewer line, and 100 feet from a drainfield or livestock enclosure.

Oregon water rights are administered by the Oregon Water Resources Department (OWRD) under the prior appropriation doctrine: first in time, first in right.

A water right permit authorizes construction and use but does not confer a vested right until a certificate of water right is issued after proof of beneficial use.

Beneficial use must be completed within the time specified in the permit (typically 5 years for domestic, 10 years for irrigation) unless an extension is granted.

The rate and duty of water are specified in the permit; for irrigation, typical duty is 1/80 cubic foot per second per acre (cfs/acre) in eastern Oregon.

Groundwater rights are subject to the same priority system; a junior right may be regulated (shut off) in favor of a senior right during shortages.

Exempt uses (e.g., domestic use up to 15,000 gallons per day) do not require a permit but must still be registered and are subject to regulation.

A water right certificate confirms the priority date, amount, point of diversion, and place of use; any change requires a transfer application.

The public interest review and the “no injury to other water rights” standard apply to all new permits and transfers.

Darcy's law: Q = K × i × A, where Q is discharge, K is hydraulic conductivity, i is hydraulic gradient, and A is cross-sectional area.

Transmissivity (T) = K × b, where b is saturated thickness; storativity (S) = specific yield + specific retention for unconfined aquifers.

The Theis equation: s = (Q / (4πT)) × W(u), where u = (r²S) / (4Tt); used for transient drawdown in confined aquifers.

Cooper-Jacob approximation: s = (2.303Q / (4πT)) × log10(2.25Tt / (r²S)), valid for u < 0.01.

Specific capacity = pumping rate / drawdown; it decreases with pumping time and indicates well efficiency when compared to theoretical drawdown.

Well efficiency = (theoretical drawdown / actual drawdown) × 100%; typical values range from 60% to 80% for properly developed wells.

Radius of influence for a confined aquifer can be estimated as R = 3000 × s × √K (empirical), where s is drawdown in feet and K in ft/day.

Pumping water level must be measured at least 24 hours after pumping begins and before pumping stops to establish static and dynamic levels.

Oregon requires a Water Well Report (OWRD Form WW-1) to be submitted within 30 days of well completion, modification, or abandonment.

The report must include: location, depth, diameter, casing material, screen settings, grout type and quantity, static water level, yield test data, and driller's signature.

A copy of the well report must be provided to the well owner within 30 days of completion.

Well contractors must be licensed by the Oregon Construction Contractors Board (CCB) and hold a Water Well Contractor license from OWRD.

All water wells must be constructed by a licensed water well driller or under direct supervision of one; the driller is responsible for compliance.

Land use compatibility and well siting setbacks (e.g., 50 feet from septic tanks, 100 feet from drainfields) are enforced by OWRD and local health departments.

Records of well construction, alteration, and abandonment must be kept for at least 5 years by the contractor and made available for inspection.

Failure to submit a well report or comply with construction standards may result in civil penalties up to $5,000 per violation per day.