Well Drilling (C-57) · Lesson 2 of 6

Siting a Well: Separation Distances and the Encroachment Seal

"Siting a Well: Separation Distances and the Encroachment Seal" is lesson 2 of 6 in the Well Drilling (C-57) Learning Hub. It opens with "Why Location Is a Code Item" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. Why Location Is a Code Item
  2. The Four Printed Distances
  3. Greater or Lesser Distances
  4. Gradient, Flooding, Drainage, and Access
  5. Shallow Large-Diameter Community Wells

The worked example in the course applies this lesson to a realistic job in 5 steps.

What you'll be able to do

  • Explain the main idea of "Siting a Well: Separation Distances and the Encroachment Seal" in plain language you can use on the exam.
  • Apply this step with confidence: "Greater or Lesser Distances".
  • Apply this step with confidence: "Gradient, Flooding, Drainage, and Access".
  • Apply this step with confidence: "Shallow Large-Diameter Community Wells".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Well Site Check: Separation DistancesSewer lateral62 ftAnimal enclosure96 ftSeptic tank85 ftLeach field118 ft160 ftSeepage pitWELLRed dashed ring = 100 ftSourceActualMinResultSewer lateral62 ft50 ftOKSeptic tank85 ft100 ftSHORT 15Leaching field118 ft100 ftOKSeepage pit160 ft150 ftOKAnimal enclosure96 ft100 ftSHORT 4Septic tank short by 15 ft;animal enclosure short by 4 ft.Move the well, or get approval for alesser distance (Sec. 8.A, case by case).If approved closer, seal goes to 50 ft:domestic 20 ft to 50 ft = 30 ft more6.625-in casing in 10.625-in hole:30 x 0.3763 = 11.3 cu ft (about 84 gal)Proposed site fails 2 of 5 minimum separation distancesLesser distance only by agency approval, with a 50-ft annular sealSource: DWR Well Standards (Bulletin 74-90/74-81), Part II, Sec. 8.A distance table; Sec. 9.A, Item 2CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Why Location Is a Code Item

The DWR Well Standards (Bulletin 74-81 as supplemented by Bulletin 74-90, Part II, Section 8.A) require every water well to be located an adequate horizontal distance from known or potential sources of pollution and contamination. The list includes sanitary, industrial, and storm sewers, septic tanks and leachfields, sewage and waste ponds, barnyard and stable areas, feedlots, solid waste sites, petroleum and chemical tanks and pipelines, and pesticide and fertilizer storage and preparation areas.

Step 2: The Four Printed Distances

Section 8.A prints minimum horizontal separation distances between the well and the source: any sewer (sanitary, industrial, or storm; main or lateral) 50 ft; watertight septic tank or subsurface sewage leaching field 100 ft; cesspool or seepage pit 150 ft; animal or fowl enclosure 100 ft. For a radial collector well the distances apply to its furthest extended point. The distances assume a significant layer of unsaturated, unconsolidated sediment less permeable than sand between the surface and groundwater, and local conditions may demand more.

The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

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