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Tech bulletin 19 09 presentation


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Technical Bulletin 19-09

Published in: Government & Nonprofit
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Tech bulletin 19 09 presentation

  1. 1. Technical Bulletin 19-09 Setting basement floor elevation above the groundwater table (SHWT) in residential construction
  2. 2. WHY? • Protect the homeowner • Protect adjacent properties
  3. 3. Which Plan Types? Single-family dwellings: • Infill Lot Grading Plans, • Conservation Plans (CON), • Bonded Lot Grading Plans (SDGP/SPGP) • Rough Grading Plans (RGP)
  4. 4. Which Plan Types? Townhouses: • Site Plans (SP), • Rough Grading Plans (RGP), and • Bonded Lot Grading Plans (SPGP).
  5. 5. WHEN does it apply? • When a Soils Report is already required (Class III and IV problem soils)
  6. 6. Determine Seasonal High Water Table (PFM) •Direct Observation November through May, should not use during June through October unless the value of the Palmer Drought Severity Index is > 2.0 (i.e., wet). •Soil morphology can be used throughout the year by a certified / licensed professional
  7. 7. FREEBOARD Case 1 Sump Crock 2.5 ft. • No groundwater mitigation req’d • Std. perimeter underdrains connected to a sump • Include foundation drain details on civil plans Freeboard > 2.5 feet SHWT
  8. 8. 2.5 ft. Case 2 Sump Crock FREEBOARD Freeboard 1 to 2.5 ft. • Raise basement to Case 1. If not feasible but topo allows for gravity outfall, install U/D system connected to a structure in gravity storm drain or gravity outfall. • If still not feasible install dual sump pump system with backup power SHWT
  9. 9. • Try to raise the basement or lowest FF to Freeboard > 2.5 ft. • If still not feasible, use crawl-space or no basement Case 3 Sump Crock 2.5 ft. Freeboard < 1 ft or SHWT above basement /lowest FF • If not feasible, raise basement or lowest FF to Case 2 (gravity outfall) NEGATIVE FREEBOARD SHWT
  10. 10. Technical Bulletin 19-09 QUESTIONS?