Golden Gate was a Regional Command-Southwest,or RC-SW, combined-joint engineering mission toconstruct a bridge complex spanning the HelmandRiver in southwest Afghanistan. The operation designwas to improve mobility at the Sabit Qadam FloodPlain Crossing across the Helmand River. This strate-gic crossing links the Sangin, Musa Qa'lah and NowZad districts close to Forward Operating Base SabitQadam (Jackson).

The mission carried strong strategic importance forcoalition and Afghan National Security Forces, orANSF, as well as the local Afghan population. It alsocarried historical and inherent natural challenges. Thewaterways are highly unpredictable, as the shoals (in-termediate land masses) and surrounding areas typi-cally flood from January through May.

"The research, concept development and engineeringdesign surrounding the crossing of the Helmand Riverwas enormously difficult, especially conducting thisphase of the operation from a combat zone with min-imal resources," explained Maj. Michael J. Hults, P.E.,Regional Command-Southwest/West, or RC-SW/W,coordination cell officer in charge and OperationGolden Gate mission commander. "The Helmand is

considered a braided river due to the network of ad-jacent channels, shoals, sandbars and rapids. Braidedrivers are known for having erratic hydrologic activityand a dynamic topography which makes predicting ei-ther component extremely difficult. Further, any addedman-made feature will ultimately have effects that can-not be readily forecasted."

"Our specific scenario leads to a crossing point that isfurthermore a floodplain during the months of Marchthrough May when the Kajaki Reservoir swells from themelting of the surrounding mountain's snowpack,"Hults continued. "The river levels can fluctuate by asmuch as eight feet during these flood periods. How doyou construct a year-round expeditionary crossing pointfor both military and civilian traffic through, over or ontop of a floodplain that is highly unpredictable, all thewhile trying not to negatively impact the local popu-lace? Also, add to this scarce and subpar constructionmaterials, a small budget and the fact that it will be con-structed in a combat zone. Now, that's a challenge."

Hults said the solution began digitally by developinga virtual river model through software that uses empir-ical data and complex algorithms to predict the hy-draulic events and subsequent outcomes.

BAGRAM AIRFIELD, Afghanistan (Jan. 9, 2013) — As NATO forces work toward bridging thegap from military operations to a self-sufficient Afghanistan, Army, Navy and Marine engineersof Joint Task Force Empire took the mission literally as they conducted Operation Golden Gatenear Sangin, Helmand province, Afghanistan, through the months of November and December.

Local Afghans come ashore using a ferry as military engineers emplace one of two 17-bay Acrow bridges during Operation Golden Gate, a Regional Command-Southwest combined-joint engineering mission to construct a bridgecomplex spanning the Helmand River in southwest Afghanistan. The operation design was to improve mobility at theSabit Qadam Flood Plain Crossing across the Helmand River.

'Golden Gate' bridges strategic Afghan crossing

"The way it was actually solvedhere was to have theRC-SW/W coordination cell design around agreedupon assumptions, available materials, time con-straints and the various constructing unit's assets andabilities," said Hults. "Further, the cell identified andevaluated different risk factors and developed engi-neering solutions that could be implemented to miti-gate the potential negative outcomes to a point wherethe risk was acceptable."

"Another challenge to this mission was the highly ki-netic project site and the diminished battle spaceowner personnel. The [Marines] experienced a hugedrawdown of infantry personnel during the recentsurge recovery," Hults recalled as he described themany security aspects involved in a project of thisscale. "It took a combined joint effort to keep the con-structing units safe and secure. Even with the numer-ous entities coming together, the battle space ownerstill felt the pinch of thinning personnel resources dueto the requirements of this mission."

Coordinating with the local contractors for materialdelivery was another hurdle to overcome. The projectrequired crushed stone for soil stabilization and 60concrete box culverts for hydraulic pressure reliefalong the elevated causeway. The contractors werehired, but required security and, were susceptible todelays due to route clearance requirements along theroads to the site. Additionally, military dump trucks de-livered approximately 1,700 tons of riprap from CampLeatherneck to the project site.

"Riprap is large broken concrete or boulders used toshield shorelines, abutments and levees to preventscouring and erosion from flowing water," Hults elab-orated. "The riprap available at Leatherneck was plen-tiful and consisted of large chunks of concrete from anold air strip. Without the proper amount and type of

riprap emplaced on the bridge complex, the structurewould have surely failed during the first flood season."

The flood season caused major problems with pastprojects at the site. Two previous bridging operationswere beat back by the elevated water levels of theflood plain. Originally, a 12-bay medium girder bridgewas constructed in the area for seasonal crossing inAugust 2010. These bridges can cover a 31-metergap. A constructed earthen shoal ramp decreased theoriginal gap to 25 meters.

The high river level forced the removal of the MGB thefollowing January. A second attempt constructed an-other earthen shoal ramp, decreasing the gap to 28meters and emplaced an MGB in October 2011. Thehigh river level again forced an emergency bridge re-moval in March 2012. The repeated earthwork hadcaused the river to scour the shoal and increased thegap width to 50 meters.

"Each time this earthwork was introduced into theriver, it drastically changed the topography. During theflood season after the 2010 MGB emplacement, theriver cut through both earthen piers," Hults explained.

Riprap was added to the west side earthen pier inpreparation for the following crossing season.

"This caused the raging river to redirect the flow untilit not only erased the east side pier, it scoured approx-imately 20 meters of the hard pack shoal, therefore in-creasing the main river channel width," he said.

The Marine 8th Engineer Support Battalion conducteda recon of the site in June 2012 and determined anMGB could no longer span the gap. Additionally, theshoal was too severely scoured to emplace anotherearthen ramp. Combined recon teams revisited the site

in July, August and September. A final survey in De-cember was used to develop the "as-built" drawings.

The final solution consisted of two 17-bay Acrowbridges with a 300-meter interconnecting elevatedcauseway system. After providing a full design package,Joint Task Force Empire was tasked with the develop-ment and overseeing the construction of the project.

Regional Combat Team 7 secured the floodplain siteas the 12th Georgian Battalion and Afghan NationalSecurity Forces conducted security on the east sideof the river. Naval Mobile Construction Battalion 133,Task Force Anchor and the 12th Georgian Battalionsecured the immediate project site. The 507th Engi-neer Battalion, Task Force Warhammer, providedroute clearance patrols in the area as constant aerialover watch was maintained.

Through the efforts of the 2nd Battalion, 7th Marines,Afghan awareness of the project was increased withmeetings with district governors and various ANSF of-ficials as well as informative engagements with the localpopulace about project status and benefits. Afghan Na-tional Army escorts coordinated with the Marines to en-sure delivery of building supplies for the project.

Task Force Anchor took the onsite lead on the bridgecomplex construction. The Seabees modified the ex-isting pier by both increasing the elevation and width.They constructed levee systems and bridge abut-ments and formed the elevated causeway withcrushed stone and local fill. Finally, they compacted,shaped and graded the bridge complex. Box culvertswere installed within the elevated causeway. Ripraphauled by the ANA 2nd Battalion, 215th Brigade en-gineers was emplaced along the levees, bridge abut-ments, causeway and around the culverts.

Engineers worked 24 hours a day for 50 days straighton rotating 12-hour shifts under increasingly harsh win-ter conditions, with a steady diet of heater meals, longconvoys to and from the site, and a daunting task ahead.The engineers of Golden Gate faced the challenge.

"The morale was the lowest in the beginning of theproject when the extensiveness of the constructionseemed insurmountable," Hults recalled. "Once theSeabees started to extensively change the landscapeof the floodplain through their relentless efforts,morale continually improved until culminating with mis-sion completion."

"Morale was very high," agreed Sgt. 1st Class JasonArmano, 411th Engineer Brigade chief bridging non-commissioned officer. "They were eager to get thejob done. They worked 12-hour shifts. The night crewhad it the hardest. The temperature at night wasbelow freezing making it difficult to work in. Construc-tion went as smoothly as any construction projectgoes. It had its issues and hurdles that any construc-tion project needs to overcome, but the Army,Marines and Seabees worked through it to get themission accomplished."

Members of Joint Task Force Empire, Task ForceWarhammer and the 132nd Multirole Bridge Companyinstalled the first Acrow bridge Nov. 22-24, on theSangin side of the Helmand River. The bridge was 170feet long and 14 feet wide with the capability to spana 150 foot gap. It will support normal one-way traffic.

The river can rise 10 feet before causing the need toremove the bridge. A second, similar bridge was theninstalled Dec. 7-13, at the Musa Qa'lah side of theriver. The river level can rise nine feet before the bridgewould need to be removed.

"This was our first really big bridge build in country,"Sgt. Matthew Coleman, squad leader, 2nd Platoon,132nd MRBC. "What really made the difference werethe Soldiers out there doing the work. They were theones who made it happen. They worked hard. Theydidn't complain. They were out there ready to go. Wecame together as a team."

The ANA 215th Brigade soldiers provided projectsite security including vehicular checkpoints, ferrystation checkpoints, local contractor site securityand interpreter support. The ANA leadership pro-vided the local populace project-related informationkeeping a constant communication line open, furthergarnering strong support. Afghan Uniformed Policeassisted with ferry checkpoints, security support andtraffic control.

A contingency of Seabees will remain on SabitQadam to monitor the bridge complex and providemaintenance and emergency repair support, as theytransition the mission to the 215th ANA engineers.Members of JTF Empire will continue to regularly visitthe site to verify bridge integrity and provide mainte-nance support. During the flood season (January-April), data will be collected to provide RC-SWrecommendations for any site upgrades.

The mission's result is greatly improved freedom ofmovement for coalition members, ANSF and the sur-rounding Afghan population which had become de-pendent on lengthy alternate routes or a limited andcostly ferry system.

"The local population had to use a crude ferry systemto get their vehicles, livestock and themselves acrossthe area," explained Armano. "The ferries only operatedduring daylight hours. Now with the levee system andthe two bridges installed they can cross the area freely."

"A more accessible and quicker crossing point willsave logistic, engineer and security convoys valuabletime, especially when bases are few and far betweenand the distances required to travel grows. It will ben-efit the military base demilitarization process." addedHults. "The locals travel back and forth across the riverto bring their livestock and goods to the differentbazaars. Prior to the bridge, the locals relied on a ferrysystem as a paid service. The ferry process was alsoslow and unreliable. "

The meticulously planned and cooperatively executedmission has its biggest challenge waiting at the endof winter with the quickly approaching flood season.The engineers are steadfast in their confidence of thenew crossing, as well as its lasting effect.

"The mission was incredibly successful as witnessedby the construction of an impressive bridge complexwithin time and budget and, the extremely positive at-mospherics of the local population. From the stand-point of the local populace, ANSF, coalition forces andthe engineering community, this was a huge success,"stated Hults. "For the first time since we operated inthe Helmand province, It brings year-round freedomof movement while, providing a quality of life improve-ment for the locals. It strengthens security, commerceand prosperity for the local population."