Some parcels remain open for new construction. RP for Tahoe Homes maintained DI on alley for phase 11. This permit is for the actual subdivision development/grading/paving by Knife River, but is open to keep an eye on this area of heavy construction and potential for ESC issues.

phase 11 construction yet to begin

activities on phase 11 have not begun

Reviewed new submittals and issued the following comments via email to Knife River and Syman:
1. The most pressing concern that comes up is that grading has already begun in Phases 10 and 11. What permit is currently covering this disturbance?
2. Section 2.2 indicates the project will discharge to the MS4 however the NOI filed with the EPA states that there will be no discharge to the MS4. Conversations with both of you confirmed that there will be no discharge to the MS4 system. Please correct this in the SWPPP.
3. Table 1 lists Warm Springs Creek as a direct receiving water however, neither the dewatering plan or the map makes any reference to this discharge point. Conversation with Kim at Syman indicated that all water from dewatering will be allowed to infiltrate onsite and there will be no offsite discharge.
4. Section 2.5 discusses Phase II stabilization of the common areas to be completed by August 2013. Please show on the map where these common areas are located. This will give me an idea of how much land will be exposed during the wet weather.
5. Table 2.5 does not list the excavation/trench dewatering as an anticipated allowable non-stormwater discharge.
6. Please insert the new page with the corrected disturbance limits as listed into section 2.3 into the resubmittal.
7. Section 4.10 and 4.11 lists a conveyance channel and sediment basin. Are these for the purposes of construction dewatering? Or are they for the permanent stormwater treatment system? Please clarify and show on the map as applicable.
8. The dewatering practices listed in section 4.13 do not coincide with the dewatering plan.
9. The Dewatering Plan states that all water pumped from the excavations will be pumped to a settling pond. The settling pond size, calculations, location and figures were not included in the submittal. Note this settling pond must be shown on the plan map.
10. The Dewatering Plan indicates that after passing thru the settling basin, the water will be discharged to the subsurface groundwater drainage system that has already been installed on site. Please forgive me for not being familiar with this system as I was not involved in the previous permitting. Can you please elaborate? I was under the impression from one of our telephone calls that all water would be allowed to infiltrate on the adjacent property. Is this no longer the case?
11. Page 2 of the Dewatering Plan lists several backup options if the water is still turbid after treatment. Where will the check dams be installed? Please provide installation details and spacing parameters for the check dams.
12. Since these corrections are significant enough that the plans must be resubmitted, please also correct the disturbance areas for each of the phases in section 2.3 in the resubmittal
13. Please submit a new map that is at least 18”x24” that shows all of the BMPs with installation details that will be used during construction. This includes the BMPs for dewatering.

Dewatering plan and revised section 2.3 submitted to show actual disturbance amounts

Called Nichole at Knife River to notify grading and drainage must be submitted. Cannot issue ESC permit without.