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| Company | Location | County | Certifications | License # |
|---|---|---|---|---|
| H.i. Stone & Son Inc | Southbury, CT | — | Septage Hauler | 887 |
| Hallman Septic Serv Llc | Portsmouth, RI | — | Septage Hauler | 704 |
| Harry A Miller | East Greenwich, RI | — | Designer (Class II) | D2101 |
| Harry Cole | North Kingstown, RI | — | Installer | L0259 |
| Harry Hawker | Exeter, RI | — | Installer | L1658 |
| Harry J Woloohojian | Cranston, RI | — | Installer | L1239 |
| Haulin Oats | West Greenwich, RI | — | Septage Hauler | 942 |
| Henry DiLibero | West Warwick, RI | — | Installer | L0269 |
| Henry J Kulpa | Tiverton, RI | — | Installer | L1569 |
| Herbert G Dyer | West Kingston, RI | — | Installer | L0812 |
| Horace Lindo | Oakdale, CT | — | Installer | L1302 |
| Howard I Frederickson, | North Scituate, RI | — | Installer | L1091 |
| Howard I Frederickson, III | North Scituate, RI | — | Designer (Class I) | D1134 |
| Hugh B Webb | Warwick, RI | — | Designer (Class IV Soil Evaluator) | D4104 |
| Hugo Key | Wakefield, RI | — | Installer | L1884 |
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