WQ0035809_Memo_20120326

Memorandum
D March 26, 2012 RECEIVI�D
Subject: Stateside WWTF, WQ0035809, Weyerhauser Real Estate APR 0 4 2012
To: Chonticha McDaniel
CENTRAL FILES
From: Linda Willis, Environmental Engineer, DWQ, SWPS � ®WQi80G
Through: Jim Gregson, Wilmington Regional Supervisor, DWQ SWPS
7) ��
The application for the Stateside High Rate Infiltration WWTF was received by the Division of Water Quality Surface
Water Protection Section (SWPS). A total of 1.4 MGD is proposed for discharge from the groundwater lowering
system. As stated in The Clark Group's Hydrogeologic Characterization and Evaluation Report Addendum, the
proposed discharge flows are as follows: 400,000 GPD for each infiltration basin 3, 4, and 5, and 100,000 GPD for
infiltration basins 1 and 2. Groundwater will enter an 8" screen pipe that conveys groundwater to an under drain
clean out that discharges to wetlands adjacent to Margaret Branch via level spreaders. There is one discharge
location proposed for the groundwater lowering system around infiltration basins 1 and 2 and two discharge locations
proposed for the groundwater lowering system around infiltration basins 3, 4 and 5. Please include the following
requests and comments on behalf of the SWPS:
1. Somewhere in the narrative, it was stated that the groundwater would be pumped, please explain what size
and number of pumps are proposed.
2. Provide the calculations that demonstrate the level spreaders are adequately sized to prevent discharge
velocities that will result in scouring. Provide plans that show how the level spreaders will be constructed.
Provide a means to increase the dissolved oxygen in the discharges from the level spreaders to ensure any
channelizing of groundwater to Margaret Branch will not be void of oxygen.
3. Explain how turbidity, total suspended solids and settleable solids concentrations will be controlled to avoid
discharges that would result in fill of sediment in the wetlands or turbidity violations in stream should the
discharge from the groundwater lowering system reach Margaret's Branch.
4. Monitoring is requested for the groundwater lowering system at the point of discharge from. each of the level
spreaders and in accordance with the attached tables 3 and 6.
5. Margaret Branch is classified C — NSW (nutrient sensitive water). Upstream/downstream surface water
monitoring in Margaret Branch will be required for pH, total nitrogen, ammonia nitrogen, total phosphorus,
and dissolved oxygen. Samples will be collected 2 times per month and on the same day as samples are being
collected for the groundwater lowering discharge.
6. Field parameter certification is required for the in -field analyses of DO and pH. Proper sample collection and
preservation applies for all samples collected for analyses. All non field parameters must be analyzed by a
State Certified laboratory. All samples collected must meet the appropriate hold times. Please contact Linda
Willis in the Wilmington Regional Office for instructions concerning the submittal of all analytical data. Data
will be due in this office within 30 days of receiving analyses from the laboratory.
CC: DWQ WiRO WQ Files w/att
DWQ CO Files w/att
DWQ APS WiRO attn: Morelia King