Clusters of ConcernTo the Editor:I have been concerned for some time about very large and cluster systems that seem to be so popular today. Aside from some very real construction problems, of more concern is the dynamics of flow through the soil. I refer especially to the numbers for the large systems described in the article “Serving a Community” in the August Onsite Installer. The values commonly used for designing onsite soil treatment systems were developed for small systems. The values reflect the rate of liquid movement through a developed biomat. This would be through the trench or seepage bed
