Friday morning 1###-####

Follow up inspection and turbidity testing

Minimal overnight rain, Pond water was murky and did not appear to have settled much. Runoff no longer flowing. Pump was not running. RP Steve on duty.

Turbidity testing:
- bypass pipe dicharge to drainage 149 NTU (not in compliance, down from 260 NTU sampled Thursday)
- storm drain outlet pipe from existing subdivsion from Ridgepoint 70 NTU
- Approximately 75 yards down stream in drainage: 134 NTU
- Ridge Point pond water 156 NTU
- pond inlet water 50 NTU
- curb water draining into pond 54 NTU
- BH # 6 stormwater pond outflow 49 NTU


Correction requests:

- continue to pump down turbid water out of stormwater pond down to reservoir to reduce amount of water able to flow offsite through bypass pipe
- clean gutter along Ridge Point and the storm drain on Stone Ridge that drops into pond
- install sediment controls at construction entrance on Trent Point
- fix silt fence sections that have come untrenched above the BH # 6 stormwater pond
- rebuild berms or install silt fence perimeters around the 2 lowest lots at top Vortex intersection
- repair Vortex check dams and/or provide road mix base

Did not observe any significant slope erosion or issue within the subdivision. Silt fence permeter and vegetative buffer are effective. Possible that the slow settling turbidity in the pond could be from the crushed rocks used to line the pond or mix of deicing agent placed on roadways.

Follow up scheduled for Monday 2/10

Note: incident reported 1/28 was caused by setting a dewatering hose out without energy dissipation. Disturbed bank has been covered and will be repaired later. Dewatering hose attached to a sediment bag and placed uphill on the grass.

Follow up inpsection from 4-5 PM to conduct turbidity testing.

The flow of muddy water into pond had been stopped by earthwork and redirected to flow downhill to the no-outlet reservoir for settling - less than 1/4 full. Pump was running to suck water out of Ridge Point Pond down into the reservoir.

Turbidity testing results:

Ridge Point pond inlet (culvert outlet at uphill end of pond) is street runoff and from BH#6 stormwater pond : 52 NTU

Stormwater bypass outlet pipe of Ridge Point pond water: 260 NTU (not in compliance)

Bottom of drainage @ Warm Springs before entering stormwater channel/pond : 208 NTU

No plume observed at outlet @ Walling Creek