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Chestnut Cove

Granite Falls, Washington


Green Valley Holdings


Cascade Surveying and Engineering 


E&D Excavating


October 2018

Chestnut Cove Apartments is a 54-unit, two story, 20,000 square foot apartment building with a 111 stall parking lot, on-site recreational facilities, and landscaping on a 1.92 acre site. The total detention footprint was 10,385 square feet.

A stormwater management system was needed to comply with detention and treatment regulations per the Snohomish County Stormwater Manual. The site had 12" min cover constraints, limited site slope, high ground water table, and a short construction window.

To address the treatment requirements Contech provided four catch basin StomFilters filled with ZPG media, a blend of zeolite, perlite, and GAC to improve the performance of perlite and target organics, soluble metals, and other pollutants.

To address the storage requirements Contech provided four underground detention systems made from a combination of pipe arch and round Aluminized Steel Type 2 providing The 27,000 cubic feet of storage.

  • System 1: 251 LF of 64’ span x 43’ rise pipe arch
  • System 2: 170 LF of 81”span x 59 rise pipe arch
  • System 3: 437 LF of 87”span x 53” rise pipe arch
  • System 4: 102 LF of 36” round pipe

E&D Excavating performed the installation, which went flawlessly. 

Technical Description:

  • 960 LF of Pipe Arch Aluminized Steel Type 2
  • (4) Catch Basin StormFilters 

800-338-1122 |

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