20120147 Ver 1_More Info Received_20120220

Strickland, Bev
From: Steenhuis, Joanne
Sent: Monday, February 20, 2012 2:26 PM
To: Strickland, Bev
Subject: FW: P1268B Camp Geiger Access Upgrades - PCN Package Additional Information DWQ #
120147
- - - -- Original Message---- -
From: Denise Freund [mailto:dfreund @wkdickson.com]
Sent: Tuesday, February 14, 2012 3:47 PM
To: Shaver, Brad E SAW; Steenhuis, Joanne
Cc: smtp - Becken, Jeff, Korenek CIV Martin G
Subject: RE: P1268B Camp Geiger Access Upgrades - PCN Package Additional Information
Brad - I'm glad to hear that most of the issues were clarified. Hopefully the following information will wrap it up
Temporary Impact - We did take another look at the width of the temporary impact and would be more comfortable leaving the
temporary impact as currently shown to ensure that the contractor will have sufficient working room for the construction of the
roadway fill slope and the trench box. We have provided a working area width of approximately 10 feet with an additional 5
feet in width to accommodate a double row of silt fence and a single row of orange safety fence at the perimeter of the work
along the edge of the wetland that will remain undisturbed.
Long Term Maintenance - The temporary impact is only for construction and the area will not be subject to long term
maintenance. Once the construction is finished, the cover type of the temporary impact area will revert to pre - construction
conditions.
Let me know if that clears up the issues or if you need some additional information
It was great to meet you yesterday. Hope we can have more site visits like that one
Thank you.
Denise Freund, PE
Project Manager
W.K. Dickson & Co., Inc.
909 Market Street
Wilmington, NC 28401
910 - 762 -4200 x232
Fax 910 - 762 -4201
www.wkdickson. com
- - - -- Original Message---- -
From: Shaver, Brad E SAW [ mailto : Brad. E.Shaver@usace. army. mill
Sent: Tuesday, February 14, 2012 3:32 PM
To: Denise Freund; Steenhuis, Joanne
Cc: smtp - Becken, Jeff, Korenek CIV Martin G
Subject: RE: P1268B Camp Geiger Access Upgrades - PCN Package Additional Information
Thanks Denise,

This additional avoidance and minimization information is exactly what I was looking for. The only thing we discussed that I
did not see was amount of temporary impact for the installation of the trench box. We discussed whether or not the 15 feet of
disturbance could be minimized further or not. You had mentioned that it may be reduced to 10 but you were going to check on
that restriction in construction.
Finally I want to make sure that there is no long term maintenance of the temporary impact area similar to what you may see
with a powerline corridor. If so, the Corps typically views that as a permanent impact when the cover type is permanently
changed, let's say from tree canopy to emergent vegetation.
I think these are pretty easy clarification points or at least hope so. Just let me know and should have this thing back to the Base
this week.
By the way, Happy Valentine's Day.
Brad
- - - -- Original Message---- -
From: Denise Freund [mailto:dfreund @wkdickson.com]
Sent: Tuesday, February 14, 2012 9:08 AM
To: Shaver, Brad E SAW; Steenhuis, Joanne
Cc: smtp- Becken, Jeff, Korenek CIV Martin G
Subject: P1268B Camp Geiger Access Upgrades - PCN Package Additional Information
Brad and Joanne - Per our telephone conversations last week, attached please find PDF's of the following plan sheets to more
fully describe the wetland impact adjacent to Campbell Street Extension.
Sheet CG -119 Campbell Street Extension Drainage and Erosion Control
* Sheet CG -501 Miscellaneous Details - Includes the detail for the concrete trench with perforated pipe demonstrating that
flow into the trench drain is only from surface water runoff.
Sheet CS -219 Campbell Street Extension Plan and Profile
Sheets CS -328 and CS -329 - Campbell Street Extension Roadway Cross Sections
With respect to your questions regarding avoidance and minimization of impacts to the wetlands, we offer the following
* The width of the roadway was limited to only the number of lanes required to safely convey vehicular traffic through the
intersection with Curtis Road and the connecting entrances to the commissary.
* The roadway could not be shifted closer to the commissary building given the building setbacks required by Anti -
Terrorism Force Protection (ATFP).
* Medians have not been provided in the center of the roadway in order to minimize the roadway footprint and impacts to
wetlands.
* The profile of the roadway was established to minimize impacts to the wetland and still provide connectivity to the
entrances to the commissary shopping center.
With respect to your questions regarding the concrete trench drain system, we offer the following:
* The wetland area currently drains by sheet flow into a roadside swale along the entrance road to the commissary parking
lot. After entering the roadside swale, it is conveyed to the existing wet detention pond behind the commissary parking lot. The

wet detention pond was not sized to accommodate the runoff from the wetland area and is inundated during rainfall events and
not functioning as designed.
* The design intent of the concrete trench drain system is to pick up runoff at the surface elevation of the wetlands and
convey it through a pipe system into an outfall ditch in order to bypass the existing stormwater pond. The concrete trench drain
system was designed in lieu of a graded swale along the toe of the fill slope from the Campbell Street Extension roadway as
there are multiple low points along the toe of the fill and the swale would have gotten fairly deep in some locations in order to
move the water along without the subgrade of the roadway being saturated with standing water. We were concerned that the
depth of the graded swale would draw water from the wetland area in addition to capturing the surface water runoff. As you can
see in the detail provided, there is no way for water to enter the concrete trench drain system other than at the surface elevation.
Please let me know if you have any questions or need additional information in order to complete your rei-iew of the PCN
package.
Thank you.
Denise Freund, PE
Project Manager
W.K. Dickson & Co., Inc.
909 Market Street
Wilmington, NC 28401
910 - 762 -4200 x232
Fax 910 - 762 -4201
www.wkdickson.com <http: / /www.wkdickson.com />